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  • History of fires and vegetation since the Neolithic in the Cantabrian Mountains
    Land Degrad. Dev. (IF 9.787) Pub Date : 2018-01-19
    Virginia Carracedo, Raquel Cunill, Juan Carlos García-Codron, Albert Pèlachs, Ramon Pérez-Obiol, Joan Manuel Soriano

    Abstract Fire has been one of the main causes of disturbance of vegetation over time, and since the Neolithic has become an irreplaceable tool for the opening of forest spaces and maintenance of pastures. Previous studies showed that the intensity and effects of wildfires are related to the biomass and controlled by climate factors. However, in regions such as Cantabria, where agriculture and livestock have spread throughout the territory since prehistory, fires should also be closely related to human land uses. The aim of this paper was to investigate the history of fires and vegetation since the Neolithic in the Cantabrian Mountains, using sedimentary charcoals and pollen data to study the role of human activities in the processes that have shaped ecosystems throughout the Holocene. The asynchrony and quantitative differences in the results obtained at different sites indicate significant variations in fire patterns at regional scale since the Neolithic, although the type and size of each basin also had a strong influence on charcoal accumulation. Maximum values for charcoal accumulation rate (CHAR) at La Molina were observed between the Neolithic and the Bronze Age, but occurred after about 3500 cal years BP at El Cueto de la Avellanosa. At El Sertal, low CHAR values were observed, probably because the sequence begins in a space that already had been cleared; the maximum values occurred during the most recent millennium. These data provide evidence that fire has been a key factor in forest retreat and in maintaining open landscapes since the Neolithic.

    更新日期:2018-01-21
  • MODELING VARIATIONS IN SOIL SALINITY IN THE OASIS OF JUNGGAR BASIN, CHINA
    Land Degrad. Dev. (IF 9.787) Pub Date : 2018-01-19
    Ligang Ma, Shengtian Yang, Zibibula Simayi, Qing Gu, Jiadan Li, Xiaodong Yang, Jianli Ding

    Abstract Soil salinization leads to a significant degradation for oasis land. Variations in soil salinity are controlled by geologic, geomorphic, climatic and hydrologic factors that are scale dependent. Many factors characterize soil salinity and its variations. Empirical mode decomposition (EMD) and correlation analysis are usually applied to examine the variations of soil salinity at different scales. However, fewer researches have been conducted on the modeling of these variations among different scales which requires further development and refinement. This paper investigates the potential of assessing scale-specific variations in soil salinity via EMD using two modeling approaches (random forest and linear models). The remotely sensed environmental factors including land surface temperature, evapotranspiration, TRMM precipitation and DEM products were used as inputs for the models. The Junggar Basin in Xinjiang Province of China was selected as study area because the oasis was quite typical in the whole country and even in mid-Asia. Soil salinity data and environmental factors were first decomposed using the EMD algorithm. Then, the decomposed components of the remotely sensed environmental factors were evaluated, and the most important components of each factor were selected to model the salinity variations which were represented by the decomposed components of soil salinity. The salinity variations estimated from the environmental factors were favorably consistent with the decomposed components of the soil salinity data, with coefficients of determination (R2) ranging from 0.24~0.52 and 0.73~0.98 for the linear and Random Forest models, respectively. In addition, land surface temperature and salinity were coupled well at the 326 and 334-km scale. Our results showed that reasonably accurate results can be obtained using the proposed approach.

    更新日期:2018-01-19
  • IDENTIFYING SEDIMENT SOURCE AREAS IN A MEDITERRANEAN WATERSHED USING THE SWAT MODEL
    Land Degrad. Dev. (IF 9.787) Pub Date : 2018-01-19
    Giovanni Francesco Ricci, Anna Maria De Girolamo, Ossama.M.M Abdelwahab, Francesco Gentile

    Abstract This study aims to evaluate the suitability of the Soil and Water Assessment Tool (SWAT) model in simulating runoff and sediment loss in the Carapelle (SE Italy), a typical Mediterranean watershed, where continuous measurements of streamflow and sediment concentration were collected over a five-year period, on a half-hour timescale, processed on a daily timescale. After sensitivity analysis, the model was calibrated, and validated for runoff and sediment. Statistics show generally satisfactory efficiency. To further improve sediment simulation performance, we used a seasonal calibration scheme, in which data recorded in the dry and wet seasons were used to calibrate sediments separately, on a seasonal basis. We also tested the model's capability in identifying the major sediment source zones, and river segments where there is sediment deposition. On the basin scale, the average water yield (186mm) corresponds to 27% of the total rainfall (686mm) and average annual sediment load was estimated to be 6.8 t ha-1 yr-1. On the sub-basin scale, a gradient of sediment yield was found that is characterised by a large difference among the upper (7 to 13 t ha-1 yr-1), central, and lower parts (<1 t ha-1 yr-1) of the study area. Conversely, deposition in channel flow has its highest values in the central part of the watershed, where there is an alluvial plain. Winter wheat and olive landuse are the major source areas, in terms of sediment. This study confirms that the Mediterranean watershed is a fragile ecosystem, and measures are needed to mitigate soil depletion.

    更新日期:2018-01-19
  • Drift Sand Fields as a Result of Past and Curent Deforestation in the Silesian-Cracow Upland, Poland
    Land Degrad. Dev. (IF 9.787) Pub Date : 2018-01-16
    Renata Dulias

    Abstract The Silesian-Cracow Upland, due to the exceptionally large reserves of various natural resources, was under the influence of intense human activity throughout the last millennium. Economic development of the Upland began in the Middle Ages by mining and smelting of iron ore, silver, and lead; from the 18th to the 20th century, the area experienced intense exploitation of coal, zinc and lead ores, stowing sands, as well as dolomites and limestone. Mining and metallurgy have almost always been associated with deforestation. The sandy substrate devoid of vegetation was subjected to aeolian processes, resulting in numerous fields of drift sands. In this paper, based on the analysis of archival and contemporary cartographic materials, as well as historical and archaeological studies and field research, spatial distribution of drift sands was determined, its origin, the time of creation and durability in the landscape. Research showed that drift sands appeared in the Middle Ages and its “desert” character persisted for 200-300 years, often even for 400-500 years. In the second half of the 20th century, most of the former areas with drift sands were afforested. Currently bare sands are found only on two areas in the Silesian-Cracow Upland. As unique landscapes, they require special protection because of the bio- and geodiversity. Research confirmed that historical interpretations are a valuable source of information about the old landscapes. This knowledge can and should be used by local authorities, institutions, and societies to manage the space, respecting the traces of the settlement and the economic past.

    更新日期:2018-01-17
  • INCREASED SOIL METHANE EMISSIONS AND METHANOGENESIS IN OIL CONTAMINATED AREAS
    Land Degrad. Dev. (IF 9.787) Pub Date : 2018-01-15
    Juejie Yang, Guanghe Li, Yi Qian, Fang Zhang

    Abstract Crude oil exploration and related activities cause severe soil contamination and land degradation. However, how soil CH4 and CO2 fluxes respond to oil contamination is poorly understood. To address this question, we conducted in situ investigation of CH4 and CO2 emissions in the Shengli Oilfield, China. CH4 emissions from contaminated soils were 60 – 1800 μg m–2 h–1, much higher than those from uncontaminated soils (29 – 33 μg m–2 h–1). CO2 fluxes of 2 – 78 mg m–2 h–1 were lower from contaminated soils compared to uncontaminated controls (78 – 104 mg m–2 h–1). The variance of CH4 and CO2 fluxes could be explained to 78.0% by soil properties and oil well age (P < 0.001) as suggested by redundancy analysis and variance partitioning analysis. Based on the Illumina MiSeq sequencing of the archaeal 16S rRNA gene, the relative abundance of methanogens over archaea increased by 8 times in contaminated soils compared to that in the uncontaminated soils, suggesting enhanced methanogenesis processes. The proportion of hydrogenotrophic methanogens over the total methanogens increased from 35% in the uncontaminated soil to 43% in contaminated soils, consistent with the higher apparent fractionation factor (αC) in the stable isotope analysis. Both microbial and isotopic results suggested that the hydrogenotrophic methanogenesis relatively enhanced with the oil contamination, with less dominance of the acetoclastic methanogenesis. The dramatically increased CH4 emissions under oil contamination call for great attention as a potentially important anthropogenic source of CH4 in the atmosphere.

    更新日期:2018-01-15
  • Beta diversity diminishes in a chronosequence of desertification in a desert steppe
    Land Degrad. Dev. (IF 9.787) Pub Date : 2018-01-11
    Zhuangsheng Tang, Hui An, Guangyu Zhu, Zhouping Shangguan

    Abstract Biodiversity is a central and multifaceted concept of community ecology, but a major challenge remains in understanding the variation mechanisms of biodiversity. Two ecological phenomena are shown in Beta diversity: 1) spatial species turnover in space, and 2) nestedness-resultant of assemblages. Using a field experiment focusing on a desert steppe ecosystem, we show that desertification influences those two components in divergent ways depending on whether a deterministic or stochastic process is driving community composition. Desertification was a major driver of local environmental heterogeneity, which also resulted in decreased soil nutrients and led to increased turnover in a heterogeneous environment; however, spatial turnover of species decreased with desertification intensify. Desertification decreases resource availability, which causes species loss and reduced total beta diversity. Those desertification effects, therefore, had a homogenizing effect on the community. However, stochastic processes cannot be disregarded as a factor in community composition determination. Overall, these results indicated that the study of desertification effects on beta diversity would add our knowledge of the deterministic and stochastic processes that create and maintain biodiversity. This is crucial to assess the relative importance between stochastic processes and deterministic processes.

    更新日期:2018-01-12
  • COMPARING TOPSOIL CHARCOAL, ASH AND STONE COVER EFFECTS ON THE POST-FIRE HYDROLOGIC AND EROSIVE RESPONSE UNDER LABORATORY CONDITIONS.
    Land Degrad. Dev. (IF 9.787) Pub Date : 2018-01-11
    Sergio Alegre Prats, João Rafael Cardoso Brito Abrantes, Celeste Oliveira Alves Coelho, Jan Jacob Keizer, João Luis Mendes Pedroso Lima

    Abstract Wildfires typically transform vegetation and litter into a heterogeneous layer of ash and charred material covering the soil surface that can substantially modify the post-fire hydrological and erosive response. To further elucidate the influence of post-fire covering layers on sheet and concentrated flow erosion, we carried out laboratory rainfall and inflow simulations on five distinct soil surface conditions: bare soil, with a protective cover of char, ash, stones and a combination thereof simulating field conditions. Each of three replicate simulations per treatment involved four runs, the first two simulating just rain (at 56 mm h-1) under dry and wet soil conditions and the next two simulating rain together with inflow at high and extreme rates (0.76 and 1.4 l min-1). Overall runoff over the four runs together was lower for all four types of protective cover than for bare soil but ash and char were clearly less effective than stones and, in particular, field conditions with runoff reductions of 25, 23, 40 and 70%, respectively. Stones and field conditions were similarly effective in reducing overall erosion rates (with 47 and 77%, respectively), while ash and char even slightly increased overall erosion rates compared to bare soil. Ash and char were effective in reduction erosion but only during the first two runs under simulated rainfall. The greater effectiveness of the field conditions suggested synergistic effects between its three components, probably due to the stones enhancing infiltration and increasing flow resistance, thereby hampering detachment of ash and char and/or enhancing their deposition.

    更新日期:2018-01-12
  • DYNAMIC MONITORING OF SOIL EROSION IN THE UPPER MINJIANG CATCHMENT USING AN IMPROVED SOIL LOSS EQUATION BASED ON REMOTE SENSING AND GEOGRAPHIC INFORMATION SYSTEM
    Land Degrad. Dev. (IF 9.787) Pub Date : 2018-01-11
    Bing Guo, Guang Yang, Feifei Zhang, Fang Han, Chenggang Liu

    Abstract The upper Mianjiang catchment has suffered intensive soil erosion due to frequent geologic hazards and its fragile ecosystem zone with steep slopes. This study fully considers the topographic features and surface cover and introduces improved methods of K, LS, and C to establish a soil loss equation for the upper Mianjiang catchment based on remote sensing (RS) and geographic information system (GIS). Spatial-temporal change patterns of soil erosion intensity and its driving mechanisms are then analyzed and discussed. Results show that: (1) The soil erosion modulus of the upper Mianjiang catchment for 2005 and 2015 were 1,577.29 t km-2 a-1and 1,619.77 t km-2 a-1, both of which belong to a level of mild erosion. The slight and mild erosion zones covered the largest area and were widely distributed in the northern part of the study area, while zones of intensive and severe erosion were mostly concentrated in Wenchuan County, and the lower reaches of the Heishui and Zagunao Rivers. (2) During 2005–2015, changes in erosion intensity showed a trend of “overall stability, local deterioration.” Zones of mild, moderate, and intensive increase were mainly concentrated in the Longmen Mountain Fault Zone, such as southern Maoxian County and western Wenchuan County. (3) Returning cultivated land to forest and grasslands greatly reduced the erosion intensity and erosion amount, while geologic hazards aggravated the soil erosion condition. Zones with a slope of <35 degrees had a positive relationship with soil erosion intensity; these areas are crucial control areas for soil preservation and containing soil loss. In addition, grassland is more effective in conserving soil and water than forest land in the upper Mianjiang catchment in areas of steep terrain. These results provide an important reference for estimating soil loss intensity in southwest mountainous regions of China, particularly in the Hengduan Mountains, and greatly contribute to the planning of soil and water conservation.

    更新日期:2018-01-12
  • Treated Urban Wastewater Irrigation Effects on Bioenergy Sorghum Biomass, Quality and Soil Salinity in an Arid Environment
    Land Degrad. Dev. (IF 9.787) Pub Date : 2018-01-11
    Girisha Ganjegunte, April Ulery, Genhua Niu, Yanqi Wu

    AbstractLand degradation due to elevated salinity and sodicity is a serious problem affecting many irrigated regions of the world. Salinity coupled with freshwater scarcity has forced many farmers in arid regions to abandon agricultural lands. This study evaluated irrigation potential of marginal quality treated urban wastewater to produce bioenergy sorghum on saline soils collected from an abandoned degraded salt affected lands in Texas and New Mexico under greenhouse conditions. Study results indicated that the energy sorghum biomass production and quality under wastewater irrigation were comparable to that irrigated with freshwater on non-saline soils. Soil salinity especially in the subsurface increased over time under wastewater irrigation compared to that under freshwater irrigation. Soil sodicity (measured by sodium adsorption ratios) increased over time in all water-soil treatment combinations. Sodicity values were higher in treatments that received wastewater irrigation with no addition of calcium to counter sodium. Although sodicity exceeded the threshold value, no impairment in soil permeability was observed. Study results indicated a great potential for marginal quality water irrigation to improve degraded saline land productivity. Further field studies are required to confirm our greenhouse study results, potential of bioenergy crops especially on saline soils, and to highlight treated wastewater as a potential irrigation source.

    更新日期:2018-01-11
  • Postagrogenic Development of Retisols in the Middle Taiga (Russia, Komi Republic)
    Land Degrad. Dev. (IF 9.787) Pub Date : 2018-01-10
    A.A. Dymov, Y.A. Dubrovskiy, V.V. Startsev

    AbstractReforestation on abandoned agricultural lands is widespread in the belt of boreal forests. We analyzed the morphological and physicochemical properties of a Plaggic Glossic Retisol (Siltic, Cutanic) site that had been abandoned either 7-, 19- or 85-years-ago, as well as a Glossic Stagnic Retisol (Siltic, Cutanic) as a control. Involvement of forest soils in agricultural use results in the degradation of organic horizons, which are not restored until many decades after the termination of active agricultural use. Arable soil horizons were preserved and were clearly identified 85 years after the land had been abandoned. The morphological features of the eluvial and subeluvial horizons were determined at all sites. Soils at sites that had been abandoned for 7- and 19 years showed lower acidity and higher base saturation compared to the background soil. Total carbon stocks were lower at the abandoned sites. The slow increase of carbon stocks after the soil had been abandoned is caused by C increase as in the organic as in the top soil mineral horizons. Soils that had been abandoned for 7 and 19 years contained less water-extractable forms of C and N than the control and 85-year forest soils. Agricultural use leads to a reduction in C stocks of forest soils. The postagrogenic soil C sequestration rate was estimated to be 30–40 g m-2 y-1.

    更新日期:2018-01-11
  • COST OF AGRICULTURAL PRODUCTIVITY LOSS DUE TO SOIL EROSION IN THE EUROPEAN UNION: FROM DIRECT COST EVALUATION APPROACHES TO THE USE OF MACROECONOMIC MODELS
    Land Degrad. Dev. (IF 9.787) Pub Date : 2018-01-09
    Panos Panagos, Gabriele Standardi, Pasquale Borrelli, Emanuele Lugato, Luca Montanarella, Francesco Bosello

    Abstract Much research has been carried out on modelling soil erosion rates under different climatic and land use conditions. While some studies have addressed the issue of reduced crop productivity due to soil erosion, few have focused on the economic loss in terms of agricultural production and Gross Domestic Product(GDP). In this study, soil erosion modellers and economists come together to carry out an economic evaluation of soil erosion in the European Union(EU). The study combines bio-physical and macroeconomic models to estimate the cost of agricultural productivity loss due to soil erosion by water in the EU. The soil erosion rates, derived from the RUSLE2015 model, are used to estimate the loss in crop productivity (physical change in the production of plants) and to model their impact on the agricultural sector per country. A Computable General Equilibrium(CGE) model is then used to estimate the impact of crop productivity change on agricultural production and GDP. The 12 million hectares of agricultural areas in the EU that suffer from severe erosion are estimated to lose around 0.43% of their crop productivity annually. The annual cost of this loss in agricultural productivity is estimated at around €1.25 billion. The CGE model estimates the cost in the agricultural sector to be close to €300 million, and the loss in GDP to be about €155 million. Italy emerges as the country that suffers the highest economic impact, while the agricultural sector in most northern and central European countries is only marginally affected by soil erosion losses.

    更新日期:2018-01-09
  • Effective Carbon Sequestration In Italian Agricultural Soils By In Situ Polymerization Of Soil Organic Matter Under Biomimetic Photo-Catalysis
    Land Degrad. Dev. (IF 9.787) Pub Date : 2018-01-08
    Alessandro Piccolo, Riccardo Spaccini, Vincenza Cozzolino, Assunta Nuzzo, Marios Drosos, Laura Zavattaro, Carlo Grignani, Edoardo Puglisi, Marco Trevisan

    Abstract Facing an exploding population growth with consequent increase of agriculture intensification, new chemical technologies are being sought to limit organic matter losses and reduce land degradation. Here we report that an effective organic carbon sequestration in different cropped soils of Italy is obtained by an in situ photo-oxidative coupling among soil humic molecules, when catalysed under solar irradiation by a water-soluble biomimetic iron-porphyrin catalyst amended to field soils. A three-years long field study showed that the catalyst-assisted in situ photochemical polymerization of humic matter enabled a yearly sequestration of soil organic carbon that ranged from 2.2 to 3.9 t ha-1 y-1, despite the periodical soil disturbance due to a conventional tillage management. This significant stabilization of organic matter was observed not only in bulk soils but also in water-stable aggregates, whose loss of organic carbon during separation was limited in catalyst-treated soils. While crop yields were the same in treated and control soils, measurements of phospholipids fatty acids (PLFA) and soil enzyme activities indicated that the catalysed in situ photo-oxidative coupling of humic molecules did not alter the structure and activity of microbial communities and the biological functions of soils. This innovative and ecologically safe catalytic technology may be developed as an useful soil management practice to stabilize organic matter in situ in arable soils, while concomitantly ensuring soil functions and sustainability of crop production.

    更新日期:2018-01-09
  • Rapid increases in fine root biomass and production following cessation of anthropogenic disturbances in degraded forests
    Land Degrad. Dev. (IF 9.787) Pub Date : 2018-01-04
    Chun Feng, Zhe Wang, Qi Zhu, Songling Fu, Han Y.H. Chen

    AbstractDespite the critical importance of fine roots (FR, Ø ≤ 2 mm) in terrestrial carbon and nutrient cycling, we know little about FR dynamics following cessation of anthropogenic disturbances in degraded forests. We hypothesized that (i) FR biomass and production increase rapidly following cessation of anthropogenic disturbances and then decline with stands aging, and (ii) FR mortality and turnover are highest in degraded forests due to recurring disturbances. We used a replicated chronosequence to examine the effect of cessation of disturbances on FR dynamics by sampling stands with on-going anthropogenic disturbances such as fuelwood collection and domestic animal grazing and stands after six, 11, 21, and 31 years prohibited from anthropogenic disturbances using mountain closure in subtropical forests of eastern China. We found that FR biomass and production increased rapidly from stands without closure to those after six years of closure. As stands over-matured, biomass and production declined and stabilized thereafter. Both FR mortality and turnover decreased over time from stands without closure and after six years of closure to those closed for longer times. Biomass, production, and mortality correlated positively with the proportion of bamboo, overstorey species richness and herb layer cover, while turnover rate correlated negatively with stand density and basal area. Our results show evidence for rapid increases in FR biomass and production following cessation of anthropogenic disturbances. Our results suggest that stand-level FR dynamics following mountain closure are influenced by changes in overstorey species composition and richness and understorey vegetation cover.

    更新日期:2018-01-05
  • EFFECTS OF ENVIRONMENTAL FACTORS ON SOIL ORGANIC CARBON UNDER NATURAL OR MANAGED VEGETATION RESTORATION
    Land Degrad. Dev. (IF 9.787) Pub Date : 2018-01-02
    Pei-Lei Hu, Shu-Juan Liu, Ying-Ying Ye, Wei Zhang, Ke-Lin Wang, Yi-Rong Su

    AbstractTo expand the scientific understanding of soil organic carbon (SOC) accumulation in restored ecosystems, we used 246 soil samples from a rocky catchment (10.24 km2) in an ecologically fragile karst area of southwest China and measured the effects of environmental factors under different vegetation restoration types (managed, including forage grassland and plantation forest, or natural, including grassland, shrubland, and secondary forest) on soil organic carbon content (SOCC) and soil organic carbon density (SOCD). Significantly higher SOCC and SOCD were found in natural vegetation than in managed vegetation and tillage land, but no differences in SOCC or SOCD were detected between managed vegetation and tillage land. The environmental factors include rock outcrop ratio (ROR), bulk density (BD), altitude, soil depth, slope gradient, and pH, all showing significant effect on SOC. The proportion of variations in SOCC and SOCD explained by environmental factors was higher in natural vegetation restoration than in managed vegetation restoration, and this proportion increased along the successional gradient. However, the environmental factors driving variations in SOCC and SOCD differed according to vegetation type. Soil BD had the strongest effect on SOCC variation in all vegetation types, except for forage grassland, in which the variation was instead controlled by ROR. The variation of SOCD was mainly driven by ROR in most vegetation types, except for tillage land and forage grassland, in which the driving factor was altitude. This results indicated that natural vegetation restoration is more beneficial to SOC sequestration than managed vegetation restoration and thus for mitigating global climate change. Accordingly, future studies should take these different environmental drivers under different vegetation restoration types into consideration when modeling SOC and guiding restoration management.

    更新日期:2018-01-02
  • Gullies, A Critical Link in Landscape Soil Loss: A Case Study in the Sub-Humid Highlands of Ethiopia
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-12-26
    Assefa D. Zegeye, Eddy J. Langendoen, Christian D. Guzman, Dessalegn C. Dagnew, Seifu A. Tilahun, Tammo S. Steenhuis

    Abstract Land use changes in many landscapes result in gully formation, carving up agricultural land and playing a large role in filling up downstream reservoirs by connecting uplands with rivers. This includes the Ethiopian highlands. Our objective is to begin investigating the interaction of upland and gully erosion and to quantify the portion of eroded sediment originating from a gully to prioritize erosion control practices. For this purpose, a 5-m deep valley bottom gully of the 13-ha catchment in the Debre Mawi watershed in the sub-humid Ethiopian highland near Lake Tana was selected. The upstream and downstream gully discharge and sediment concentrations were measured over a 2-year period. The results show that the sediment concentration at the outlet was about 10 times greater than at the inlet. The sediment budget calculation showed that about over 90% of the sediment at the outlet originated from within the gully. Hysteresis analysis of the sediment concentration discharge relationship showed that sediment supply from the upland was limited, but sediment was always available to be eroded and transported in the gully because of bank failures and head cut retreat. Thus, to reduce sediment loads in rivers and consequent adverse downstream impacts, designing cost-effective measures to treat gullies should be a priority in the sub-humid Ethiopian highlands.

    更新日期:2017-12-27
  • Evaluation of Land-Use Change Effects on Runoff and Soil Erosion of a Hilly Basin of Yanhe River in the Chinese Loess Plateau
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-12-21
    Kaijie Yang, Changhe Lu

    Abstract Starting in 1999, the Grain-for-Green (GFG) programme has been implemented in the Loess Plateau to alleviate the severe soil erosion by converting steeply sloping croplands to forestlands or grasslands. To quantify the effects of these conservation efforts, this study identified the land-use changes between 2000 and 2015 and quantified their impacts on runoff and erosion using the Soil and Water Assessment Tools (SWAT) and a typical hilly watershed of the Yanhe River as a case study. To heighten the applicability of SWAT to the region, major model parameters were localized and calibrated for the period of 1975–1980 and were then validated for 1981–1987. The R2 and NS validation indices were 0.70 and 0.65 for the monthly runoff and 0.67 and 0.61 for the sediment load, indicating that the model performance was acceptable. Between 2000 and 2015, the slope croplands were reduced by 39.9%, the forestlands increased by 90.2% and the grasslands increased by 12.9%. These land-use changes were simulated using SWAT to reduce the watershed runoff by 13.8% and the sediment load by 50.7%. Spatial analyses using ArcGIS indicated that the simulated reduction in water yield due to cropland conversion to forestland was more obvious than that due to the conversion to grassland, but the reductions in the sediment yields were similar. The results suggest that the GFG practice during this period was effective for preventing soil and water losses.

    更新日期:2017-12-21
  • The Role of Human Activity in Decreasing Ecologically Sound Land use in China
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-12-21
    Jing Wang, Yifan Lin, Tianlin Zhai, Ting He, Yuan Qi, Zhifeng Jin, Yumei Cai

    Abstract Ecologically sound land (ESL) represents a meaningful geographical spatial unit that provides ecological goods and services at various scales. However, few studies focusing on national- or regional-scale changes in ESL use and the degradation of the land ecosystem in China have been based on reliable and up-to-date land survey data. The study was to analyze the relationship between the changes in ESL use and human activities and regional policies, as well as land ecosystem degradation. The results indicated that land capitalization, resulting from rapid industrialization, urbanization, and the effects of regional land policies and large land projects caused a clear decrease in grassland, and wetland ecosystems, and an increase in forest ecosystem, varying in extent during different periods. Land ecosystem degradation, according to the decreased Ecosystem Service Provision Index (CESPI), was concentrated in the Yangtze River Delta, the southwestern regions, and the Inner Mongolia Plateau, where human activity was concentrated. From 2009 to 2015, such degraded land amounted to 9.51% of the counties. The degradation in ESL use caused a decrease in the ecological goods and services provided by the ecosystems. Land ecosystem degradation resulting from the abandonment of natural grassland and farmland is a prominent and complex problem in China. Optimizing the regional spatial patterns of ESL use was critical for sustainable ecosystem management. Balancing compromises and synergies between providing ecological goods or socioeconomic benefits and ecological costs at a regional or national scale, were found crucial for land policy making.

    更新日期:2017-12-21
  • Assessment of Postfire Soils Degradation Dynamics: Stability and Molecular Composition of Humic Acids with use of Spectroscopy Methods
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-12-14
    Evgeny Abakumov, Ekaterina Maksimova, Anna Tsibart

    The effect of wildfires on the soils of the south taiga and forest-steppe environments of Central Russia (Histic Spodosols and Eutric Fluvic Arenosols) was investigated in terms of the content and quality of humic acids (HAs) using instrumental spectroscopic methods (solid state 13-C NMR and electron spin resonance). The bulk elemental composition of HAs was not essentially altered in post-fire soils; however, the organic matter of fire-affected superficial soil layers were characterized by changes in the structural composition and biochemical activity levels. Solid-state 13-C NMR spectroscopy showed that there is an intensive increase in aromatic compounds in HA molecules in soil from both the south taiga and forest-steppe environments. There is a pronounced and statistically significant decline of aliphatic chain content in response to exposure to fire. The free radicals content and the degree of molecular stabilization assessed with electron spin resonance showed an essential alteration of the HAs, expressed in the increase in the radicals portion, in post-fire soils compared with that found in soils not exposed to fire. It was also shown that the accumulation of aromatic compounds indicates only apparent stabilization of HAs due to the loss of periphery alkylic carbon species, which was confirmed by destabilization of the molecules as illustrated by the increase of free radicals.

    更新日期:2017-12-14
  • Phases or regimes? Revisiting NDVI trends as proxies for land degradation
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-12-14
    M.H. Easdale, O. Bruzzone, P. Mapfumo, P. Tittonell

    One of the main challenges in land degradation assessment is that a rigorous and systematic approach to addressing its complex dynamics is still missing. The development and application of operative tools at regional and global scales remain a challenge. Land degradation is usually defined as a long-term decline in ecosystem function and productivity. Due to its temporal and spatial resolution as well as data availability, the use of time series of spectral vegetation indexes obtained from satellite sensors has become frequent in recent studies in this field. Slope of linear trends of the Normalized Difference Vegetation Index (NDVI) is usually considered an accurate indicator and is widely used as a proxy for land degradation. Yet this method is built on a number of simplifying conceptual and methodological assumptions that prevent capturing more complex dynamics, such as cyclic or periodic behaviors. Our aim was to examine the limitations associated with using linear NDVI trends as proxies for land degradation by comparing outcomes with an alternative methodological procedure based on wavelet auto-regressive methods (WARM). We explored these issues in five case studies from Africa and South America. We observed that trend explained a marginal portion of total temporal variability and monotonic functions, such as linear trends, were unable to capture dynamics that were non-unidirectional, resulting in misinterpretation of actual trends. WARM results were encouraging as a step towards the application of more accurate methods to provide sound scientific information of land degradation and restoration.

    更新日期:2017-12-14
  • Multitemporal Assessment of Coarse Sediment Connectivity Along a Braided-Wandering River
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-12-14
    Milan Lehotský, Miloš Rusnák, Anna Kidová, Jozef Dudžák

    The article presents the post-flood period coarse sediment connectivity assessment (POPSECA) approach based on the holistic ideas of the interpretation of the long-term coarse sediment connectivity (CSC) in river channels. Seven sets of remote sensing data (1949-2009) were used as the basic information sources to study the CSC along the braided-wandering Belá River by using the patch-graph approach for assessment the structural connectivity. The bar areas (patches), with 200 m direct links between them, and the attribute of a deflection angle of a link to the flow direction were parameters used to estimate the integral index of connectivity (IIC), bar area (BAI) and bar link (BLI) importance indices. The higher values of the IIC fit with a well-developed bar system. Conversely, the values of the IIC decrease because of the progressive degradation of the braided pattern. The potential functional CSC was inferred from the variability of the values obtained by the balance indices represent the balance of the channel-floodplain connectivity (B1) and the bar-bar connectivity (B2). Eight types of the potential functional CSC based on the balance indices and the deduction of processes that conditioned the channel-floodplain and in-channel CSC linkages were identified. In order to assess the development of the braidplain pattern in terms of the structural connectivity during the study time span the linear trendline analysis of IIC associated with flood periods was applied. Based on the coefficient of determination, all reaches exhibit a decreasing trend in IIC values, but different response to flood periods.

    更新日期:2017-12-14
  • Amplified environmental change from land-use and climate change in medieval Minorca
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-12-14
    Andrea Luca Balbo, Arnald Puy, Jaime Frigola, Felix Retamero, Isabel Cacho, Helena Kirchner

    The debate on human environmental impact has often been locked into cause-effect reasoning, aiming at factoring human impact on top of climatic variability. Here we use evidence from Minorca and the Mediterranean region to show the potential for amplified environmental change emerging from complex feedbacks between climatic and historical events. Alluvial sediments collected in a gully reveal a 14 to 27-fold increase in sediment accumulation rates, leading to the rapid aggradation of the valley floor from c. AD 1300 onwards. These environmental changes coincided with the Feudal conquest of Minorca (AD 1287) and with the climatic shift from the Medieval Climate Anomaly (MCA, c. AD 900 - 1300) to the Little Ice Age (LIA, c. AD 1300 - 1850). This evidence of unprecedented sediment mobilisation, in context with climatic and historical events marking the Mediterranean region, highlights the implications for environmental vulnerability emerging from positive feedbacks between climate and land-use. Understanding such interactions in historical contexts is paramount to increase our capacity for anticipatory learning in the face of rapid climatic, economical and ecological transformations today.

    更新日期:2017-12-14
  • EFFECTS OF LAND PREPARATION AND ARTIFICIAL VEGETATION ON SOIL MOISTURE IN A HILLY LOESS CATCHMENT IN CHINA
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-12-12
    Feng Tianjiao, Wei Wei, Chen Liding, S.D. Keesstra, Yu Yang

    In the dryland and degraded regions, soil moisture is the primary factor determining ecological restoration. Proper land preparations and vegetation restoration can improve soil moisture and benefit land restoration. Identifying their effects on soil moisture is thus essential for developing suitable management strategies. In this study, four typical land preparation techniques (level ditches, fish-scale pits, zig terraces and level benches) and artificial vegetation types (Prunus armeniaca, Platycladus orientalis, Pinus tabulaeformis and Caragana microphylla) were designed at a semi-arid loess hilly catchment, China. Soil moisture was monitored by a time domain reflectometer (TDR), and its spatial-temporal variations were analyzed during the 2014-2015 growing seasons. The following results were captured. (1) Soil moisture was highest for the combination of Platycladus orientalis and fish-scale pits (Platycladus orientalis/fish-scale pits, 10.37%), followed by Prunus armeniaca/level ditches (10.23%), Platycladus orientalis/zig terraces (9.67%), Caragana microphylla/level benches (8.62%), Pinus tabulaeformis/fish-scale pits (8.05%), and Pinus tabulaeformis/ zig terraces (7.72%). (2) Fish-scale pits captured a better rainwater-harvesting capacity during the rainy months, while zig terraces had a higher water-retention capacity under extremely dry conditions (as indicated by the temporal soil moisture variation and soil water retention curves). (3) Pinus tabulaeformis consumed more water than other vegetation types (26.7% lower than that of Platycladus orientalis). (4) Soil moisture in shallower layers (0-80 cm) was more affected by land preparations while was more effected by vegetation types in deeper soil layers (80-180 cm). We thus suggest that fish-scale pits may be a better choice in wetter regions while zig terraces and Platycladus orientalis are more suitable in the driest parts of the Loess Plateau to restore the fragile ecosystems.

    更新日期:2017-12-12
  • CONTRASTING EFFECTS OF REINDEER GRAZING ON CO2, CH4 AND N2O FLUXES ORGINATING FROM THE NORTHERN BOREAL FOREST FLOOR.
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-12-12
    Kajar Köster, Egle Köster, Frank Berninger, Jussi Heinonsalo, Jukka Pumpanen

    Reindeer (Rangifer tarandus L.) are considered to be an important mammalian herbivore, strongly influencing Arctic lichen-dominated ecosystems. There is no wide knowledge about the effect of reindeer on greenhouse gas (GHG) fluxes in northern boreal forests. Ground vegetation plays an important role in absorbing nitrogen (N) and carbon dioxide (CO2) from the atmosphere. Lately, it has also been found to be a significant source of nitrous oxide (N2O) and a small source of methane (CH4). We investigated the influence of reindeer grazing on field layer GHG (CO2, CH4 and N2O) fluxes, ground vegetation coverage and biomass, soil physical properties (temperature and moisture) in a northern boreal forests. At our study site, the reindeer-induced replacement of lichen by mosses had contrasting effects on the GHG fluxes originating from the field layer. Field layer CO2 efflux was significantly higher in grazed areas. The field layer was a CH4 sink in all areas, but grazed areas absorbed more CH4 compared to non-grazed areas. While total N2O fluxes remained around zero in grazed areas, a small N2O sink occurred in non-grazed areas with lower moss biomass. Our results indicated that grazing by reindeer in northern boreal forests affects GHG fluxes from the forest field layer both positively and negatively, and these emissions largely depend on grazing-induced changes in vegetation composition.

    更新日期:2017-12-12
  • Land degradation effects initiated by trail running events in an urban protected area of Hong Kong
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-12-07
    Sai-Leung Ng, Yu-Fai Leung, Suet-Yi Cheung, Wei Fang

    Trail degradation is a common management problem in protected areas, especially those that accommodate high levels of trail users or organized sporting events. Trail running became popular in Hong Kong in the early 2000s, with a number of trail running events involving with a number of trail running events involving large numbers of runners organized in recent years. Although trail competitions are believed to produce very intense impacts on trails and their surrounding environments, limited research exists to quantify and characterize these impacts to inform policy and management responses. This study empirically examined and evaluated the impacts generated by a running competition on a remote trail in Hong Kong. Results indicated that a running competition can cause significant initial degradation on the trail. Although some degradation features (e.g., incision) can recover in six months, some negative effects (e.g., soil coarsening) can persist or worsen. It is recommended that trail running competitions should be regulated in protected areas both in terms of number of events and number of participants. Trail maintenance is crucially important for keeping the protected areas in good condition.

    更新日期:2017-12-11
  • Potassium Amendment Increases Biomass and Reduces Heavy Metal Concentrations in Lablab Purpureus After Phosphate Mining
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-12-07
    Katinka X. Ruthrof, Joseph B. Fontaine, Anna J.M. Hopkins, Mark P. McHenry, Graham O’Hara, Jen McComb, Giles E.St.J. Hardy, John Howieson

    Agricultural pursuits in post-mining environments are becoming increasingly important globally as many regions are challenged with food insecurity and post-mining land-use legacies. Although there are many advantages for agricultural production at post-mining sites, these substrates have abiotic and biotic challenges for plant growth, including poor fertility, heavy metals, and lack of beneficial soil microbes. We investigated whether increased potassium (K) levels in a post-phosphate mining substrate on Christmas Island, Australia, could improve plant productivity and reduce heavy metal concentrations. Addition of K (80 and 160 kg ha-1) significantly increased plant biomass, and enhanced root growth and mycorrhizal fungal colonisation rates. Potassium amendment was also strongly correlated with lower heavy metal concentrations in leaf material. Clearly, K is the critical limiting nutrient for legumes in post-phosphate mining sites on Christmas Island for enhancing biomass and health. We hypothesise that heavy metals were either being diluted in a larger biomass and/or healthy plants could also select against heavy metal uptake, however, this requires further investigation of the mechanisms involved. These results have significant global ramifications for sites transitioning from mining to agriculture.

    更新日期:2017-12-07
  • Urban Gully Erosion in Sub-Saharan Africa: A Case Study from Uganda
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-12-06
    Guido Zolezzi, Marco Bezzi, Daniele Spada, Elisabetta Bozzarelli

    The study examined gully erosion in Koboko, Northwestern Uganda, initially a war refugee camp, which progressively turned into a permanent rural town. A repeatable, low-cost methodology to quantify gully properties in data-scarce, resource-limited urban contexts is developed, which integrates collection of existing hydrological, land use data, topographic surveys, hydrological and hydraulic modeling, interviews to local inhabitants and stakeholders. Four main gullies have developed in the last 10-15 years along the eastern, hilly side of Koboko, with width to depth ratios not exceeding 3 and maximum scour depths of 9m. Their length ranges between 270 and 460m in the most densely populated area and is mostly unstable, especially for slopes exceeding 3%. Causes of the gullies include urban road development, changes in urban land cover to impervious surfaces, inadequate planning of the urban drainage system. The gullies hamper safety of people and buildings, and increase health risks in an already vulnerable community. Slope-area and slope-road length thresholds suggest Koboko to be less susceptible to gullies compared to other reported urban contexts, and support the anthropogenic origin of the observed gullies. The analysis allowed to design mitigation measures that still self-sustain after three years of implementation. Results upscaled at country level can be used to predict which other urban centers in Uganda may be susceptible to gullying. Gullying in rapidly developing urban areas in sub-Saharan Africa clearly show the co-evolution of a social and a geomorphic system, which should be accounted for in urban planning to avoid adverse societal effects.

    更新日期:2017-12-06
  • Pyrolysis temperature during biochar production alters its subsequent utilization by microorganisms in an acid arable soil
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-12-04
    Yu Luo, Jennifer A. J. Dungait, Xiaorong Zhao, Philip C. Brookes, Mark Durenkamp, Guitong Li, Qimei Lin

    Biochar amendment of agricultural soils can have a significant impact on microbial carbon (C) metabolism by providing C substrates and altering soil properties, including amelioration of soil acidity. It remains unclear whether available C of biochar or its pH effects determines the utilization of biochar by microorganisms. Compound-specific stable 13C isotope analysis of phospholipid fatty acids (13C-phospholipid fatty acid analysis) was used to explore which microbial group utilized biochar distinguished with pHs and C availability. C4 Miscanthus biochar (δ13C = −12.2‰) was prepared at 2 pyrolysis temperatures (350 °C and 700 °C) and applied (50 mg C g−1 soil) to a very acid soil (pH 3.7, δ13C = −27.7‰), which was sampled from the long term Hoosfield Acid Strip experiment at Rothamsted Research, and incubated for 14 months. Biochar700 increased soil pH to 5.1 and biochar350 increased soil pH to 4.3. All microbial groups (Gram-positive bacteria, Gram-negative bacteria, actinobacteria, and fungi) were more abundant in the biochar-treated soils. The 13C values of biomarker phospholipid fatty acid analysis suggested that all groups of microorganisms, and especially Gram-positive bacteria, were using the C from the biochar350, but not the biochar700, as a substrate. We conclude that its utilization of biochar by microorganisms after 14 months was largely determined by the pyrolysis temperature controlling the availability of biochar C, instead of the pH effects, in a very acidic soil.

    更新日期:2017-12-05
  • Impact of forest fires generated black carbon deposition fluxes in Great Hinggan Mountains (China)
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-29
    Chuanyu Gao, Jiabao He, Jinxin Cong, Shaoqing Zhang, Guoping Wang

    Black carbon is produced by incomplete combustion of fossil fuels and biomass. The production of black carbon over the last several centuries has been primarily influenced by human activities. Human exploitation of forest resources, together with increases in regional fire frequency and intensity, can increase regional black carbon emissions and can led more black carbon deposited into natural ecosystem. Here, based on 210Pb age-depth model, we investigated black carbon deposition over several key periods in the last 150 years in 5 peatlands of the Great Hinggan Mountains (Northeast China), an area that has been exploited by humans without forest protection policies. The results showed that average black carbon deposition fluxes from different peatlands in the Great Hinggan Mountains were 1.1 to 4.8 mg·year−1·cm−2, which were similar to other peatland distribution regions and higher than other ecosystems. Frequent and intense fire events during the exploitation period led to regional peak black carbon deposition before the 1980s. After the 1980s, fire events were controlled, and the government implemented forest protection policies that decreased the trend in regional fire frequency in the Great Hinggan Mountains and markedly decreased black carbon deposition. Fire events controlled by regional human activities are therefore the major factor that influence regional black carbon deposition fluxes, and frequent forest fires could increase black carbon deposition fluxes in surrounding ecosystem.

    更新日期:2017-11-30
  • Impact of biochar properties on soil conditions and agricultural sustainability: A review
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-29
    Mohammad I. Al-Wabel, Qaiser Hussain, Adel R.A. Usman, Mahtab Ahmad, Adel Abduljabbar, Abdulazeem S. Sallam, Yong Sik Ok

    This review summarizes the influences of pyrolysis conditions and feedstock types on biochar properties and how biochar properties in turn affect soil properties. Mechanistic evidence of biochar's potential for enhancing crop productivity, carbon sequestration, and nutrient use efficiency are also discussed. The review identifies the knowledge gaps, limitations, and future research directions for large-scale use of biochar. Both pyrolytic parameters and feedstock types are considered to be the main factors controlling biochar properties such as nutrient content, recalcitrance, and pH. Biochar produced at low temperatures may improve nutrient availability and crop yield in acidic and alkaline soils, whereas high-temperature biochar may enhance long-term soil carbon sequestration. Biochar can also improve the efficiency of inorganic and organic fertilizers by enhancing microbial functions and reducing nutrient loss, thereby making nutrients more available to plants. Integration of biochar and chemical or organic fertilizers generally provides for better nutrient management and crop yield in most types of soils. Although biochar can improve degraded soils, it is not a panacea; as such, soil- and crop-specific biochar are needed in order to ensure optimum crop yield and agricultural sustainability.

    更新日期:2017-11-30
  • Storage of C, N and P affected by afforestation with Salix cupularis in an alpine semi-arid desert ecosystem
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-28
    Yu-Fu Hu, Xiang-Yang Shu, Jia He, Yu-Lin Zhang, Hai-Hua Xiao, Xiao-Yan Tang, Yun-Fu Gu, Ting Lan, Jian-Guo Xia, Jing Ling, Guang-Deng Chen, Chang-Quan Wang, Liang-Ji Deng, Shu Yuan

    Few systemic assessments have evaluated the success of these afforestation programs in alpine semi-arid desert ecosystems in the Qinghai-Tibet Plateau. In this study, we investigated the influences of three Salix cupularis plantation age classes (6 yr, 18 yr and 34 yr) on the carbon (C), nitrogen (N), and phosphorus (P) storages and stoichiometry of the soil-plant ecosystem. The consequences of S. cupularis plantation induced soil spatial heterogeneity. The soil-plant ecosystem C storage increased after the plantation. The N storage showed an increasing trend from 6 yr to 18 yr and then slightly decreased. The P storage presented a continuously declining trend. The result indicated that the imbalance in soil N, P, C occurred with plantation age because of the imbalance of their inputs. The N and P uptakes from subsoil and redistribution to topsoil by S. cupularis may contribute to meet N and P demands for the understory plants. Leaf N:P ratios varied from 8.3 to 17.5. These results imply that N and P status are the main factors limiting plant growth in the alpine-cold desert ecosystem. Thus, we recommend adding N and P fertilizers during plant growth.

    更新日期:2017-11-29
  • RUSLE erodibility of heavy textured soils as affected by soil type, erosional degradation and rainfall intensity: a field simulation
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-28
    Xinliang Wu, Yujie Wei, Junguang Wang, Chongfa Cai, Yusong Deng, Jinwen Xia

    Soil erosion is a worldwide serious problem for the environment or humankind, exacerbating land degradation. However, little systematic knowledge is available about the erodibility of various types of soils at different erosional degradation levels, especially at the field scale. In this research, the spatiotemporal variations of the erodibility for five soil types (Calcic Luvisol, Ferric Luvisol, Plinthic Alisol, Plinthic Acrisol and Acric Ferralsol) from temperate to tropical climate were investigated with field rainfall simulation experiments on pre-wetted bare fallow heavy textured soils (silty clay loam, silty clay and clay) derived separately from Loess deposits, Quaternary red clays and Basalt. The experiments were performed under three erosion degrees (non, moderately and very-severely eroded) and two rainfall intensities (45 and 90 mm h-1). Soil erodibility was represented by the K factor of the Revised Universal Soil Loss Equation (RUSLE). Soil erodibility was the lowest for Ferralsol among all the soil types and was significantly lower in the very-severe than in the no or moderate erosion degrees. Soil erodibility tended to be larger at the high than at the low rainfall intensity (p<0.05) except for the very-severely eroded Luvisols and their difference between rainfall intensities in the erodibility varied with rainfall duration. Soil erodibility could be well predicted by the combination of illite, dry aggregate stability and amorphous aluminum oxides (Adj-R2=0.51, p<0.001), and its temporal variations were significantly related with particle density, 1.4 nm intergrade mineral and capillary porosity (p<0.05). Furthermore soil properties selected to account for soil erodibility varied with rainfall intensity. The integrated data indicated that soil erodibility was mainly influenced by clay minerals at the region scale and soil degradation degree at the pedon scale.

    更新日期:2017-11-28
  • Annual spreading of olive mill wastewater over consecutive years: Effects on cultivated soils physical properties
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-27
    Guy J. Levy, Arnon Dag, Michael Raviv, Isaac Zipori, Shlomit Medina, Ibrahim Saadi, Arkadi Krasnovski, Hanan Eizenberg, Yael Laor

    Several studies cautioned against potential negative effects of controlled olive mill wastewater (OMW) application on soil physical properties that could be associated with the possible adverse effects of K on soil structure stability. The objective of the study was to examine the effects of annual application of OMW over several years on selected physical properties of the upper soil layer (0-10 cm) and their link to exchangeable K levels. Two experimental field platforms were studied: field crops grown in a tilled clay soil (three years of OMW application), and olive orchard grown in a sandy loam soil (five years of OMW application). In the clay soil, OMW application did not affect organic carbon (OC) and only slightly increased exchangeable potassium percentage (EPP) from 3.3 in the control to ~4.5 in the OMW-treated plots. In the sandy loam soil, application of different rates of OMW resulted in an increase in both OC and EPP (>20) compared with the control (8). For both soils, addition of OMW improved aggregate stability; yet for the clay soil, the increase was not associated with changes in EPP or OC. In the sandy loam soil, aggregate stability was positively correlated with OC and EPP. Soil hydraulic conductivity (HC), tested for the sandy loam soil only, was not affected by OMW application. Overall, our study shows that consecutive 3 to 5 years of controlled OMW application in the range of 50-150 m3 OMW ha-1 y-1 does not result in the deterioration of soil physical and hydraulic properties.

    更新日期:2017-11-28
  • SPATIAL PATTERNS OF SEDIMENT CONNECTIVITY IN TERRACED LANDS: ANTHROPOGENIC CONTROLS OF CATCHMENT SENSITIVITY
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-16
    Aleix Calsamiglia, Josep Fortesa, Julián García-Comendador, Manuel E. Lucas-Borja, Adolfo Calvo-Cases, Joan Estrany

    In recent decades the dynamics of global change in developed countries has led to significant alterations in the hydrological and sediment dynamics of terraced land. Agricultural terraces were built to control overland flow and prevent erosion, acting as buffers and barriers throughout the sediment cascading system. Their abandonment and degradation increase the sensitivity of the catchment, promoting the collapse of dry-stone walls and the reworking of stored sediment. In this study, a geomorphometric Index of Connectivity (IC) –derived from high-resolution LiDAR data (0.9 pt m-2, RMSE < 0.2 m)– analysed the spatial patterns of structural connectivity in a small Mediterranean catchment (4.8 km2) characterized by a massive presence of terraces (37% of the surface area). The morphological characteristics of these anthropogenic features generated a dual effect: (1) general disconnectivity between different compartments of the catchment and (2) concentration of water and sediment flows along preferential pathways promoted by a cascade effect of collapse within the terraced areas. The fieldwork found that 73% of wall collapses were located on these pathways that showed high IC values (>Q8). This spatial matching was related to feedback dynamics between structural and functional connectivity, in which the failure of walls increases the concentration of runoff, which in turn accelerates the hydraulic processes causing their collapse. Identifying the most connected pathways within the most vulnerable structures in an integrated analysis could be a cost-effective strategy for establishing priority areas for the management of terraced lands.

    更新日期:2017-11-28
  • Crops and livestock under the sun: Obstacles to rural livelihood adaptations to hotter 21st century temperatures in eastern Senegal
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-26
    Leif Brottem, Bonnie Brooks

    This article evaluates the proposition that farmers in dryland West Africa will be compelled by midcentury to shift household resources from crop to livestock production due to changing climate conditions. The article investigates the prospects for such a livelihood transition in the semiarid part of eastern Senegal, where downscaled statistical models indicate temperature increases of at least 2°, that will have substantially negative impacts on crop yields. Based on survey of 448 households and focus groups conducted across an eco-climatological transect, the article presents evidence that this livelihood transition is already underway in many households but is increasingly out of reach for others. It uses statistical and qualitative analysis to argue that the most vulnerable households—crop-dependent smallholders in the geographic area where the livelihood shift is most needed—are the least prepared for it. The article shows that land degradation is both an additional cause of the transition and an obstacle to it. Soil exhaustion, made worse by the lack of opportunities to procure chemical fertilizer, is compelling many to seek to increase their livestock holdings. This strategy is constrained by rangeland degradation, which, made worse by expanding agriculture, reduces the viability of the transition for all but the wealthiest households. Households rely on migration to compensate for shortfalls in production, but this option is becoming closed off to those households who do not already have a member abroad. This is shown to raise the vulnerability of households who rely on a degraded resource base for their livelihoods.

    更新日期:2017-11-28
  • Simultaneous measurement of bacterial abundance and composition in response to biochar in soybean field soil using 16S rRNA gene sequencing
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-26
    Xiaorui Liu, Jia Li, Lu Yu, Hong Pan, Haiyang Liu, Yimeng Liu, Hongjie Di, Yong Li, Jianming Xu

    Biochar is an important soil conditioner. However, we have limited understanding of biochar effects on the microbial community traits of the rhizosphere and bulk soil in the field. The aim of this study was to examine the impacts of biochar amendment on microbial abundance and community in the rhizosphere and bulk soils in soybean-growing fields. We applied 16S ribosomal RNA (rRNA) gene sequencing with an internal standard gene to quantitatively investigate biochar-mediated changes in microbial composition and abundance in rhizosphere and bulk soils. The results indicated that the absolute abundance of bacterial taxa with internal standard can be more informative in describing soil microbial population distribution. A linear discriminant analysis effect size differential analysis showed that the biochar amendment significantly altered the soil microbial abundance and community composition. The bacteria in the rhizosphere soil showed more clear responses to biochar addition than the bacteria in the bulk soil. These results highlight the enhanced effect by biochar on bacterial population distribution in the rhizosphere. 16S rRNA gene sequencing with internal standard gene represents an effective method that can substantially improve 16S-seq based microbiome studies by determining the 16S rRNA gene abundance and bacterial community composition simultaneously.

    更新日期:2017-11-28
  • Development of alkaline electrochemical characteristics demonstrates soil formation in bauxite residue undergoing natural rehabilitation
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-26
    Xiangfeng Kong, Tao Tian, Shengguo Xue, William Hartley, Longbin Huang, Chuan Wu, Chuxuan Li

    Mining and mineral processing industries have generated a large amount of polymineral wastes, causing the destruction and degradation of huge areas of landscapes at extensive geographical locations. Rehabilitation of these mine waste landscapes is critical to social and economic sustainability of mining and metallurgy operations, such as alumina refineries. The Bayer process to refine alumina generates large amounts of highly alkaline bauxite residues that are hazardous to plant growth. Innovative methodologies are urgently needed to address this economic and environmental challenges, one of which is soil formation from bauxite residues. Mineral weathering appears the prerequisite to the initiation of soil formation and development of functional soil properties in bauxite residue disposal areas. The present study investigated natural changes of mineralogy, zeta potential, isoelectric point, surface protonation, active alkaline groups, and associated implications for rehabilitation of the bauxite residue disposal area. Alkaline calcite, hydrogarnet, and sodalite minerals were slowly transformed or dissolved with declining levels over weathering time. Amorphous and semiamorphous minerals also decreased with a corresponding decrease in specific surface area and sorption sites. Zeta potential curve of fresh residue had steeper slope than those of aged residues. The isoelectric point of fresh residue was significantly higher, but those of aged residues were significantly lower, with a significant decrease of isoelectric point with increasing time. These attributes in mineralogy and electrochemical characteristics such as transformation of alkaline minerals, and decreases of surface protonation and active alkaline groups, may be used to help the assessment of soil formation status in the bauxite residues of different age and associated rehabilitation requirements.

    更新日期:2017-11-28
  • Halophytes in biosaline agriculture: Mechanism, utilization, and value addition
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-26
    Ganesh C. Nikalje, Ashish K. Srivastava, Girdhar K. Pandey, Penna Suprasanna

    Land is considered as the life-sustaining platform for food and water. However, there are contaminants such as salt, heavy metal, and industrial waste that decrease land fertility, posing serious threat to sustainable agriculture. In recent years, novel crop varieties with improved tolerance against environmental contaminants have been developed, but most of them face severe yield penalty. Alternatively, naturally tolerant plants such as extremophiles can be screened for their potential as crops. These crops should be tolerant to various abiotic stresses, perform better under extreme conditions and produce higher biomass and yield. In view of this, the present review focuses on the effects of saline soil on plants and how a class of plants termed as “halophytes” can tolerate high levels of salt. The potential applications of halophytes in phytoremediation, desalination, secondary metabolite production, medicine, food, and saline agriculture have been discussed. A concept of saline agriculture has been proposed for rehabilitation of saline and degraded lands. In this context, a potential halophyte is cultivated in salt-contaminated soil for desalination. The harvested halophyte can have industrial value, and later on, rehabilitated soil can be utilized for agriculture purpose. Some success with halophyte cultivation has been demonstrated in environmentally degraded soils, and it is imperative that large-scale adoption of halophytes, as potential candidates, can be accorded top priority for rehabilitating contaminated soils, which can pave way for sustainable agriculture.

    更新日期:2017-11-28
  • Genetically engineering Crambe abyssinica - A potentially high-value oil crop for salt land improvement
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-24
    Weicong Qi, Iris E.M. Tinnenbroek-Capel, Elma M.J. Salentijn, Zhao Zhang, Bangquan Huang, Jihua Cheng, Hongbo Shao, Richard G.F. Visser, Frans A. Krens, Eibertus N. Van Loo

    Crambe abyssinica (crambe) is a new industry oil crop that can grow on saline soil and tolerant salty water irrigation. Genetically engineered crambe in which the seed-oil composition is manipulated for more erucic acid and less polyunsaturated fatty acid (PUFA) would be highly beneficial to industry. In this research, lysophosphatidic acyltransferase 2 RNA interference (CaLPAT2-RNAi) was introduced into crambe genome to manipulate its oil composition. The result showed in comparison with wild-type, LPAT2-RNAi could significantly reduce linoleic and linolenic acid content, simultaneously increasing erucic acid content. Systematic metabolism engineering was then carried out to further study CaLPAT2-RNAi, combined with the overexpression of Brassica napus fatty acid elongase (BnFAE), Limnanthes douglasii LPAT (LdLPAT), and RNAi of endogenous fatty acid desaturase 2 (CaFAD2-RNAi). Oil composition analysis on the tranformants’ seeds showed that 1) with CaFAD2-RNAi, polyunsaturated-fatty-acid (PUFA) content could be dramatically decreased, in comparison with BnFAE+LdLPAT+CaFAD2-RNAi, and BnFAE+LdLPAT+CaFAD2-RNAi+CaLPAT2-RNAi seeds showed lower linolenic acid content; 2) BnFAE+LdLPAT+CaFAD2-RNAi+CaLPAT2 could increase the erucic acid content in crambe seed oil from less than 66.6% to 71.6%, while the highest erucic acid content of BnFAE+LdLPAT+CaFAD2-RNAi was 79.2%; 3) although the four-gene combination could not increase the erucic acid content of seed oil to a higher level than the others, it led to increased carbon resource deposited into C22:1 and C18:1 moieties and lower PUFA. Summarily, the present research indicates that suppression of LPAT2 is a new, promising strategy for seed-oil biosynthesis pathway engineering, which would increase the value of crambe oil.

    更新日期:2017-11-24
  • Assessment of ecosystems: A system for rigorous and rapid mapping of floodplain forest condition for Australia's most important river
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-22
    Shaun C. Cunningham, Peter Griffioen, Matt D. White, Ralph Mac Nally

    Methods that provide rapid assessments of changing ecosystems at multiple scales are needed to inform management to address undesirable change. We developed a remote-sensing method in partnership with, and for use by, natural resource managers to predict annually stand condition of floodplain forests along Australia's longest river, the Murray River. A measure of stand condition, which was developed in collaboration with responsible natural resource managers, is a function of plant area index, crown extent, and the percentage live basal area. We surveyed a broad range of spatial and temporal variation in condition, built predictive stand-condition models using satellite-derived variables, and validated predictions with surveys of new sites. A multiyear model using data from 2 drought years and a year following extensive floods provided better predictions of stand condition than did models on the basis of the data for individual years. The model provided good predictions for data collected after the build for 50 sites and for resurveys of build sites in later years (R2 ≥ 0.86). There was limited, temporary improvement in stand condition after the extensive flooding (2010 to late 2010) that followed a 13-year (1997 to early 2010) drought. Forest condition can be mapped accurately and annually at medium resolution (25 × 25 m) for large areas (100,000s ha) if quantitative ground surveys, satellite imagery, machine learning, and future validation are combined. Regular assessments of forest condition can be related to likely causes of change by using regular, rapid assessments and hence can provide important management information.

    更新日期:2017-11-23
  • When and where did the loess plateau turn ‘green’? Analysis of the tendency and breakpoints of normalized difference vegetation index
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-21
    Zhi Cao, Yurui Li, Yansui Liu, Yufu Chen, Yongsheng Wang

    The Loess Plateau experiences the most serious soil erosion problems in China and possibly even globally. Many measures have been taken to increase the vegetation cover and to control soil erosion. Of these measures, the Grain for Green Project (GGP), launched in 1999, has been the most effective, changing the ecological and socioeconomic situation of the plateau significantly. Using time series Normalized Difference Vegetation Index (NDVI) data from 1981 to 2013, this study analyzed spatial patterns of changes in vegetation cover, detected spatial patterns of the abrupt-change time of NDVI trends and investigated factors that may contribute to these changes. The results showed that (1) vegetation restoration was obvious over the last decades, especially in the 2000s, and the increase in NDVI during 2000-2013 was more than 3 times that during 1990-2000. Approximately 54.99% of the plateau during 2000-2013 had a statistically significant increase, mainly distributing in loess hilly and gully region and loess gully region. (2) Vegetation restoration was comprehensively affected by climate change and human activities (e.g. the GGP, urbanization and policies), and the effects of each factor varied for different regions. (3) Vegetation in most of the plateau began to increase around 2007-2010, and four discrete areas with different timings of such breakpoints were detected. The difference in the timing of breakpoints in NDVI may be related with precipitation, reproducting tree species, management measures and survival rate. These results imply that integrating natural and human factors is important when making effective and suitable measures and policies.

    更新日期:2017-11-22
  • Composition of Microbial Community in Swine-Manure Biochar Amended Soils and Linkage to Heavy Metal Accumulation in Rice at Harvest
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-21
    Xinqiang Liang, Lingling Chen, Ziwen Liu, Yi Jin, Miaomiao He, Ziyi Zhao, Chunlong Liu, Christophe Niyungeko, Yuji Arai

    Manure biochar (MB) is recognized a beneficial material for absorbing heavy metals from soil and alleviating soil degradation. However, the addition effects of MB on the phospholipid fatty acid (PLFA) concentrations and their linkage to heavy metal accumulation in rice are poorly understood. A microcosm incubation experiment was conducted to study the effects of a swine manure biochar amendment on 1) the composition of soil microbial community in two soils (clay loam vs. silt loam); 2) heavy metal accumulation in rice grains and straws. MB amendment increased microbial diversity and bacterial had greater magnitude of increase than fungi in two soils after 98 days of incubation. The G– rather than G+ bacteria PLFA concentrations were significantly increased with MB amendment rates for both soils. The higher MB addition rate (1.5%) did not get more benefit for aerobic bacteria, but significantly led anaerobic bacteria proliferation as compared with the 0.5% MB treatment. 1.5% MB addition suppressed grain- and straw Pb, Cu, and As while increased grain- and straw Cd and Zn from two soils. Significant soil type × MB rate interactions were observed in most microbial indicators (except F/B and G+) and grain- Pb, As and straw Zn. Linkages of bacteria (mainly as G- and/or An), actinobacteria, fungi and protozoa (in silt loam soil) to the MB rate and heavy metal in rice were identified.

    更新日期:2017-11-22
  • Desertification Vulnerability Index - an effective approach to assess desertification processes: a case study in Anantapur District, Andhra Pradesh, India
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-21
    S. Dharumarajan, Thomas F.A. Bishop, Rajendra Hegde, S.K. Singh

    There is a need for the up-to-date assessment of desertification/land degradation maps which are dynamic in nature at different scales for comprehensive planning and preparation of action plan. The present paper aims to develop the desertification vulnerability index (DVI) and predict the different desertification processes operating in Anantapur District, India based on machine language techniques. Climate, land use, soil and socio-economic parameters were used to prepare DVI by a multivariate index model. The computed DVI along with climate, terrain and soil properties was used as explanatory variable to predict the desertification processes by using a Random Forest Model. About 14.2 % of area was created as a training dataset in 9 different places for modeling and remaining area was tested for prediction of desertification processes. We used desertification status map of Anantapur District prepared under Desertification status mapping of India – 2nd cycle (DSM -2nd cycle) as a reference dataset for calculation of accuracy indices. Kappa and classification accuracy index were calculated for training and validation data sets. We recorded overall accuracy rate and kappa index of 85.5 % and 75.8 % for training datasets and 71.0 % and 51.8% for testing datasets. The results of variable importance analysis of Random Forest model showed that DVI was the most important predictor followed by potential evapo-transpiration and NDVI for prediction of desertification processes. The results from the present work give new thought of using the existing knowledge on prediction of the desertification at unvisited areas and also quick update of DSM maps.

    更新日期:2017-11-22
  • Large-scale soil organic carbon mapping based on multivariate modelling: The case of grasslands on the Loess Plateau
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-21
    Yinyin Wang, Lei Deng, Gaolin Wu, Kaibo Wang, Zhouping Shangguan

    The Loess Plateau is considered one of the world's regions with severe soil erosion. Grasslands are widely distributed on the Loess Plateau, accounting for approximately 40% of the total area. Soil organic carbon (SOC) plays an important role in the terrestrial carbon cycle in this region. We compiled more than 1,000 measurements of plant biomass and SOC content derived from 223 field studies of grasslands on the Loess Plateau. Combined with meteorological factors (precipitation and air temperature) and the photosynthetically active radiation factor, the topsoil SOC contents of grasslands were predicted using the random forest (RF) regression algorithm. Predicted grassland SOC content (1.70–40.34 g kg−1) decreased from the southeast to the northwest of the Loess Plateau, with approximately 1/5 of the grassland exhibiting values lower than 4 g kg−1. Observed SOC content was positively correlated with observed plant biomass, and for predicted values, this correlation was strong in the desert steppe and the steppe desert of rocky mountains. Air temperature was the most important factor affecting SOC contents in the RF model. Moreover, the residual error of observations and predictions increased as the grazing intensity varied from none to very severe in the temperate desert steppe, and this RF model may not perform well in plains. The use of the RF model for SOC prediction in Loess Plateau grasslands provides a reference for C storage studies in arid and semi-arid regions, and aboveground biomass and temperature should receive more attention due to increasing C sequestration.

    更新日期:2017-11-22
  • Reviewing our Options: Managing Water-Limited Soils for Conservation and Restoration
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-17
    Eleanor Hobley, Noelia Garcia-Franco, Rico Hübner, Martin Wiesmeier

    The FAO considers around a quarter of global land to be degraded (FAO-ITPS, 2015). Of particular concern are threats to soils in water-limited regions, which are critical to food and economic security in countries across the globe but are under increasing pressure due to human use and climatic forcing. These soils have been used to feed and provide resources and services to human societies for millennia, with earliest land-uses dating back to pre-historic times. With the adoption of modern, frequently unsuitable agricultural practices combined with the population pressures and shifting consumption patterns, soils in water-limited regions have come under threat, resulting in degradation and in worst-case scenarios, desertification. Here we review the current state of soils in water-limited environments and provide a guide to management for conservation and restoration of these fragile soils. Options to manage specific threats to soil functionality, namely erosion, soil salinity, loss of functionality due to landscape homogenisation, degradation of soil organic matter as well as climate vulnerability are presented for specific land-uses using a whole-system approach management framework.

    更新日期:2017-11-17
  • Influence of natural regeneration on fractal features of residue microaggregates in bauxite residue disposal areas
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-17
    Feng Zhu, Qingyu Cheng, Shengguo Xue, Chuxuan Li, William Hartley, Chuan Wu, Tao Tian

    Bauxite residue is often physically degraded, which limits vegetation establishment on the disposal areas. Microaggregate stability is an important physical property due to its significant effect on erosion and surface runoff, however this is rarely reported for bauxite residue. Native plant encroachment on a bauxite residue disposal area in Central China has revealed that natural regeneration may ameliorate the residue and help to support plant growth. Residue samples from five different disposal ages were collected to determine microaggregate stability and identify their fractal features. Following natural regeneration, the aggregate fraction 250-50 μm increased significantly from 27.4% to 40.3%, whilst the silt+clay size aggregate fraction decreased from 58.4% to 30.7%. With increasing disposal age, the residue clay dispersion ratio (CDR) ranged from 7.7% to 22.5%, whilst aggregated silt and clay (ASC) ranged from 15.3% to 19.0% indicating a stable microaggregate structure. The single-fractal dimension (D) of the residues for different disposal ages varied from 2.2 to 2.4. The high pH and salinity of bauxite residue indicated a high value of single-fractal dimension. The multi-fractal parameters of residue microaggregates, including capacity dimension (D0), information dimension (D1) and information dimension/capacity dimension (D1/D0) decreased which resulted in homogeneity following natural regeneration. Correlation analysis revealed that both single- and multi-fractal dimensions had significant correlations with residue microaggregate stability. Our results suggested that natural regeneration may improve microaggregate stability of bauxite residue, and fractal parameters of residue microaggregates may be used to describe residue microaggregate stability and the physical condition of bauxite residue.

    更新日期:2017-11-17
  • SPATIAL PATTERNS OF SEDIMENT CONNECTIVITY IN TERRACED LANDS: ANTHROPOGENIC CONTROLS OF CATCHMENT SENSITIVITY
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-16
    Aleix Calsamiglia, Josep Fortesa, Julián García-Comendador, Manuel E. Lucas-Borja, Adolfo Calvo-Cases, Joan Estrany

    In recent decades the dynamics of global change in developed countries has led to significant alterations in the hydrological and sediment dynamics of terraced land. Agricultural terraces were built to control overland flow and prevent erosion, acting as buffers and barriers throughout the sediment cascading system. Their abandonment and degradation increase the sensitivity of the catchment, promoting the collapse of dry-stone walls and the reworking of stored sediment. In this study, a geomorphometric Index of Connectivity (IC) –derived from high-resolution LiDAR data (0.9 pt m-2, RMSE < 0.2 m)– analysed the spatial patterns of structural connectivity in a small Mediterranean catchment (4.8 km2) characterized by a massive presence of terraces (37% of the surface area). The morphological characteristics of these anthropogenic features generated a dual effect: (1) general disconnectivity between different compartments of the catchment and (2) concentration of water and sediment flows along preferential pathways promoted by a cascade effect of collapse within the terraced areas. The fieldwork found that 73% of wall collapses were located on these pathways that showed high IC values (>Q8). This spatial matching was related to feedback dynamics between structural and functional connectivity, in which the failure of walls increases the concentration of runoff, which in turn accelerates the hydraulic processes causing their collapse. Identifying the most connected pathways within the most vulnerable structures in an integrated analysis could be a cost-effective strategy for establishing priority areas for the management of terraced lands.

    更新日期:2017-11-17
  • Cultivation of Opuntia ficus-indica under different soil management practices: A possible sustainable agricultural system to promote soil carbon sequestration and increase soil microbial biomass and activity
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-10
    Angélica Bautista-Cruz, Tania Leyva-Pablo, Fernando León-González, Raúl Zornoza, Verónica Martínez-Gallegos, Mariela Fuentes-Ponce, Luis Rodríguez-Sánchez

    Monitoring of soil organic carbon (SOC) content, SOC pools, and enzymes involved in SOC degradation and mineralization is needed to elucidate the impact of conversion from forest to agriculture on SOC and properties, and how and which crop system and management practices can contribute to C sequestration, thus climate change mitigation. This study compared the impact of forest conversion to maize (Zea mays L.) and cactus (Opuntia ficus-indica [L.] Mill.) fields with different farming management on SOC content and pools (recalcitrant, labile, and extractable), soil microbial biomass carbon, and enzyme activities involved in the soil C cycle. For this purpose, a site under strong land use changes in Central Mexico with high demographic density was selected. Forest conversion to maize fields decreased the original SOC and the C recalcitrance index (RI). However, land use change from forest to cactus systems maintained SOC content, C RI, and arylesterase activity near the values observed in the original forest. Cactus systems promoted higher soil extractable organic carbon content, related to increases in microbial biomass and β-glucosidase activity. Additionally, cactus cultivation can maintain SOC and a C RI at a similar level to the forest soil, which contributes to sustainability of the agroecosystem and climate change mitigation. Therefore, it could comprise a promising viable option for sustainable crop production systems under temperate subhumid conditions, in turn promoting socioeconomic development and rural growth.

    更新日期:2017-11-10
  • Assessment of ecosystems: a system for rigorous and rapid mapping of floodplain forest condition for Australia's most important river
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-08
    Shaun C. Cunningham, Peter Griffioen, Matt D. White, Ralph Mac Nally

    Methods that provide rapid assessments of changing ecosystems at multiple scales are needed to inform management to address undesirable change. We developed a remote-sensing method in partnership with, and for use by, natural resource managers to predict annually stand condition of floodplain forests along Australia's longest river, the Murray River. A measure of stand condition, which was developed in collaboration with responsible natural resource managers, is a function of plant area index, crown extent, and the percentage live basal area. We surveyed a broad range of spatial and temporal variation in condition, built predictive stand-condition models using satellite-derived variables, and validated predictions with surveys of new sites. A multi-year model using data from two drought years and a year following extensive floods provided better predictions of stand condition than did models based on data for individual years. The model provided good predictions for data collected after the build for 50 sites and for resurveys of build sites in later years (R2 ≥ 0.86). There was limited, temporary improvement in stand condition after the extensive flooding (2010–late 2010) that followed a 13-year (1997–early 2010) drought. Forest condition can be mapped accurately and annually at medium resolution (25 × 25 m) for large areas (100,000s ha) if quantitative ground surveys, satellite imagery, machine learning and future validation are combined. Regular assessments of forest condition can be related to likely causes of change by using regular, rapid assessments, and hence can provide important management information.

    更新日期:2017-11-09
  • Crops and livestock under the sun: obstacles to rural livelihood adaptations to hotter 21st Century temperatures in eastern Senegal
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-07
    Leif Brottem, Bonnie Brooks

    This article evaluates the proposition that farmers in dryland West Africa will be compelled by mid-century to shift household resources from crop to livestock production due to changing climate conditions. The article investigates the prospects for such a livelihood transition in the semi-arid part of eastern Senegal, where downscaled statistical models indicate temperature increases of at least two degrees, which will have substantially negative impacts on crop yields. Based on survey of 448 households and focus groups conducted across an eco-climatological transect, the article presents evidence that this livelihood transition is already underway in many households but is increasingly out of reach for others. It uses statistical and qualitative analysis to argue that the most vulnerable households—crop-dependent smallholders in the geographic area where the livelihood shift is most needed—are the least prepared for it. The article shows that land degradation is both an additional cause of the transition and an obstacle to it. Soil exhaustion, made worse by the lack of opportunities to procure chemical fertilizer, is compelling many to seek to increase their livestock holdings. This strategy is constrained by rangeland degradation, which, made worse by expanding agriculture, reduces the viability of the transition for all but the wealthiest households. Households rely on migration to compensate for shortfalls in production but this option is becoming closed off to those households who do not already have a member abroad. This is shown to raise the vulnerability of households who rely on a degraded resource base for their livelihoods.

    更新日期:2017-11-07
  • Remediation of a Heavy Metals Contaminated Soil Using Mycorrhized and Non Mycorrhized Helichrysum Italicum (Roth) Don
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-07
    Gennaro Brunetti, Claudia Ruta, Andreina Traversa, Giuseppe D’Ambruoso, Waed Tarraf, Francesco De Mastro, Giuseppe De Mastro, Claudio Cocozza

    Four hundred hectares of the inland and hilly part of Apulia Region (Southern Italy) were contaminated by using low quality composts for many years. That territory now belongs to a National Park and needs a sustainable soil restoration. Therefore, a greenhouse experiment was carried out to test the phytoremediation potential of the frugal Helichrysum italicum (Roth) Don, alone and mycorrhized by Septoglomus viscosum. The aims of the research were i) to test if the H. italicum can reduce the soil content of Cd, Co, Cr, Cu, Ni, Pb, and Zn; ii) to identify in which part of the plant those metals are mainly accumulated; iii) to check the role of S. viscosum in promoting the plant growth and the soil phytoremediation. The results showed better plant growth in contaminated soils in comparison to control soils, regardless of the presence of mycorrhiza, probably due to the better soil fertility parameters in contaminated soils. In addition, non-mycorrhized plants from contaminated soil accumulated greater amounts of heavy metals, especially Cr, Cu, Pb, and Zn, in their root system. According to the translocation and bioconcentration factors, the mechanism by which H. italicum incorporated heavy metals was ascribable to a phytostabilization process. In contrast, the application of mycorrhiza in the contaminated soil reduced the uptake of heavy metals by the roots, possibly through an exclusion mechanism, reducing the phytoremediation potential of H. italicum.

    更新日期:2017-11-07
  • Estimating Soil Redistribution Patterns with 137cs Measurements in a Mediterranean Mountain Catchment Affected by Land Abandonment
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-07
    I. Lizaga, L. Quijano, L. Gaspar, A. Navas

    In Mediterranean mountainous environments, the removal of natural vegetation for developing agriculture increased the surface areas prone to erosion in the past centuries. In Southern Pre-Pyrenees, the process was inverted during the middle of the XXth century. This work aims to assess how land use changes after widespread land abandonment affect soil redistribution. For this purpose, 137Cs was used in a 23 km2 catchment that was mostly cultivated at the beginning of the past century. After land abandonment, 16.5% of croplands persisted but afforestation and natural revegetation occupy 83.5% of the catchment area. 137Cs massic activity and related soil properties -stoniness, grain size and organic matter contents- were analysed in 98 bulk core samples. Physiographic characteristics -slope, altitude and solar radiation- at the sampling points were determined by using Geographic Information Systems (GIS). Soil erosion and deposition rates were derived from 137Cs measurements after applying conversion models and were spatially interpolated to estimate the amount of net soil loss. In cropland soils mean erosion (62.6 Mg ha−1year−1) and deposition rates (55.2 Mg ha−1year−1) were significantly higher than in the other land uses. The lowest mean erosion rates (2.4 Mgha−1year−1) were found in natural forests and the lowest mean deposition (2.6 Mg ha−1year−1) in pine afforestation evidencing the soil stabilization achieved in the last decades due to revegetation. A sediment budget with the interpolated rates, result in a specific sediment yield of 4.15 Mg ha−1year−1. These results outline the impact of land use changes on soil redistribution in fragile mountain agroecosystems.

    更新日期:2017-11-07
  • Organic amendments and mulches modify soil porosity and infiltration in semiarid mine soils
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-07
    Lourdes Luna, Nadia Vignozzi, Isabel Miralles, Albert Solé-Benet

    The restoration of soils affected by mining activities depends on the improvement of soil physical quality. This study aimed to determine the medium-term effects of organic amendments and mulches on soil physical properties and soil hydrological response. The experimental restoration was conducted in a homogeneous slope using a factorial design (organic amendments × mulches). The organic amendments consisted of compost from domestic organic residues, sewage sludge from an urban water treatment facility, and a control without amendment. The mulches consisted of gravel, woodchips, and a control without mulch. Modifications of the soil structure induced by the combinations of techniques were quantified by micromorphometric analysis of 2D porosity. Undisturbed soil cores were collected to determine the soil bulk density. Soil hydrological behaviour was determined by rainfall simulations. Samples from natural undisturbed soils surrounding the quarry were also taken as a reference. Restored soils with organic amendments have a higher total porosity than did nonamended substrates. Each restoration treatment combination resulted in a different pore system with very diverse hydrological responses. Organic amendments resulted in infiltration improvement and water erosion reduction. The woodchip mulch was more effective at trapping runoff and sediment, although this type of mulch did not favour vertical water movement towards deeper horizons. Therefore, the use of organic amendments should be encouraged in mine soil restoration and should be strongly recommended for its proven environmental benefits (enhancement of soil structure and infiltration and reduction of soil losses). However, the mulches did not produce the expected results in the tested arid–semiarid area.

    更新日期:2017-11-07
  • Biophysical landscape interactions: Bridging disciplines and scale with connectivity
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-07
    Martine J. Ploeg, Jantiene E.M. Baartman, David A. Robinson

    Landscape composition and land use impact the interactions between soil and vegetation. Differences in micro-behaviour, driven by the interplay of heterogeneous soil and vegetation dynamics, affect emergent characteristics across a landscape. Scaling approaches to understand the drivers of these emergent characteristics have been attempted, but the blueprint of interacting biophysical processes in landscapes is inherently messy and often still unknown. A complicating factor is single disciplinary focus in environmental sciences. Integrated knowledge is vital especially in view of future challenges posed by climate change, population growth, and soil threats. In this paper, we give examples of biophysical interactions that occur across various temporal and spatial scales and discuss how connectivity can be useful for bridging disciplines and scales to increase our understanding.

    更新日期:2017-11-07
  • Land use change uncertainty impacts on streamflow and sediment projections in areas undergoing rapid development: A case study in the Mekong Basin
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-06
    Bikesh Shrestha, Thomas A. Cochrane, Brian S. Caruso, Mauricio E. Arias

    Quantitative understanding of potential changes in streamflow and sediment load is complicated by uncertainty related to land use change projections, which is characterized by a high uncertainty in terms of demand (quantity) and location of changes (spatial distribution). We simulate the Sesan, Srepok, and Sekong Rivers (3S), the most important tributaries of the lower Mekong River, with the Soil and Water Assessment Tool (SWAT) to investigate the implications of conversion of forest to agricultural lands. Multiple land use transitions in the 3S basin are projected using the Land Change Modeler. The uncertainty in land use projection was addressed using an ensemble forecasting approach for 2060, combining (a) three land demand scenarios, (b) two transition potential modeling approaches (i.e., approach to create maps of the likelihood for areas to transition from one land use type to another), and (c) retaining or not protected areas. Land demand leads to the greatest uncertainty in land use change projections. Transition potential modeling approaches do not make much difference in the total change, but can result in spatial variations of change. Retaining protected areas can contribute significantly to uncertainty in land use change projections. Decrease in annual streamflow of the 3S basin varied from 3% to 21%, and changes in annual sediment outflux from the basin ranged from −8% to 249% for simulated scenarios. Land use demand uncertainty results in the highest streamflow and sediment load changes and can thus have major consequences for water and sediment management strategies in areas undergoing rapid development.

    更新日期:2017-11-07
  • Small-scale Geodiversity Regulates Functioning, Connectivity, and Productivity of Shrubby, Semi-arid Rangelands
    Land Degrad. Dev. (IF 9.787) Pub Date : 2016-02-04
    Ilan Stavi, Shimon Rachmilevitch, Hezi Yizhaq

    Geodiversity has recently been attracting increasing attention as a measure of diversity for the physical components of natural environments. It has shown positive relations with biodiversity, as well as with several ecosystem services. Yet, so far, geodiversity studies have focused on relatively large spatial scales, ranging between hillslope, basin, and landform scales. It is proposed that either natural-induced or anthropogenic-induced, small-scale (centimeter-scale to few decimeter-scale) geodiversity has a large impact on the hydrological connectivity and overall functioning of semi-arid rangelands and other shrubby and woody drylands. It is further proposed that greater small-scale geodiversity increases the on-site retention of water and soil resources, decreasing the vulnerability of rangelands to prolonged droughts and climatic changes. Particularly, positive impact of moderate grazing intensity on rangelands functioning is demonstrated by the formation of livestock trampling routes, which transect hillslopes, increase ecosystem geodiversity, and modify the spatial redistribution of scarce water and soil resources at the patch scale. Numerical simulations of a mathematical model for vegetation patterns in water-limited systems show that the trampling routes increase the survivability of vegetation patches under prolonged droughts. In practical terms, the concept of small-scale geodiversity is relevant for the determination, monitoring, and assessment of land degradation, as well as for restoration projects of eroded lands and degraded ecosystems. Copyright © 2015 John Wiley & Sons, Ltd.

    更新日期:2017-11-07
  • Economic Benefits and Costs of Sustainable Land Management Technologies: An Analysis of WOCAT's Global Data
    Land Degrad. Dev. (IF 9.787) Pub Date : 2015-10-07
    Markus Giger, Hanspeter Liniger, Caspar Sauter, Gudrun Schwilch

    Perceived profitability is a key factor in explaining farmers' decision to adopt or not adopt sustainable land management (SLM) technologies. Despite this importance, relatively little is known about the economics of SLM. This paper contributes to the literature by analysing data on costs and perceived cost/benefit ratios of SLM technologies. Data are taken from the World Overview of Conservation Approaches and Technologies technology database and cover 363 case studies conducted in a variety of countries between 1990 and 2012. Based on an in-depth descriptive analysis, we determine what costs accrue to local stakeholders and assess perceived short-term and long-term cost/benefit ratios. Our results show that a large majority of the technologies in our sample are perceived as being profitable: 73% were perceived to have a positive or at least neutral cost/benefit ratio in the short term, while 97% were perceived to have a positive or very positive cost/benefit ratio in the long term. An additional empirical analysis confirms that economic factors are key determinants of land users' decisions to adopt or not adopt SLM technologies. We conclude that a wide range of existing SLM practices generate considerable benefits not only for land users, but for other stakeholders as well. High initial investment costs associated with some practices may, however, constitute a barrier to their adoption; short-term support for land users can help to promote these practices where appropriate. Copyright © 2015 John Wiley & Sons, Ltd.

    更新日期:2017-11-07
  • A Water Rights Trading Approach to Increasing Inflows to the Aral Sea
    Land Degrad. Dev. (IF 9.787) Pub Date : 2015-05-28
    Maksud Bekchanov, Claudia Ringler, Anik Bhaduri

    Tremendous development of irrigation since the 1960s combined with unbalanced water resources management led to the destruction of the ecosystems in the delta zone and the gradual desiccation of the Aral Sea, once the fourth largest freshwater lake of the world. Command-and-control-based water management in the Aral Sea basin inherited from Soviet times did not create any incentives for investing in improved irrigation infrastructure, adopt water-wise approaches, and thus maintain flows into the Aral Sea. This study examined the potential for market-based water allocation to increase inflows to the Aral Sea while maintaining stable agricultural incomes. We find that a water trading system can improve inflows to the Aral Sea but would require significant compensation for agricultural producers. Agricultural producers can use the compensation payments to cope with reduced water supply by improving irrigation and conveyance efficiencies and by developing alternative rural activities such as livestock grazing, agro-processing, and cultivation of low water-consumptive crops. We also find that a water trading system would be more efficient if it includes both trade among irrigation sites and between sites and instream uses. Copyright © 2015 John Wiley & Sons, Ltd.

    更新日期:2017-11-07
  • Issue Information - TOC
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-07

    No abstract is available for this article.

    更新日期:2017-11-07
  • Issue Information - Journal Info page
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-07

    No abstract is available for this article.

    更新日期:2017-11-07
  • Effects of vegetation rehabilitation on soil organic and inorganic carbon stocks in the Mu Us Desert, northwest China
    Land Degrad. Dev. (IF 9.787) Pub Date : 2017-11-06
    Yang Gao, Peng Dang, Qingxia Zhao, Jinliang Liu, Jiabin Liu

    In arid and semiarid areas, the importance of soil inorganic carbon (SIC) is at least as high as that of soil organic carbon (SOC) in affecting the regional carbon budget following vegetation rehabilitation. However, variations in SIC have been uncertain, and few studies have analyzed the interactions between the SOC and SIC pools. We measured SIC, SOC, δ13C-SIC, and δ13C-SOC after planting Mongolian pine (MP) and Artemisia ordosica (AO) on shifting sand land (SL) over 10 years in the Mu Us Desert, northwest China. The results showed that, compared to SL, SIC stocks at 0–100 cm in MP and AO lands significantly increased by 12.6 and 25.8 Mg ha−1, respectively; SOC stocks in MP and AO lands significantly increased by 24.0 and 38.4 Mg ha−1, respectively. Both δ13C-SIC and δ13C-SOC in the 2 plantation lands were significantly lower than those in SL were. All 315 samples exhibited a negatively linear relationship between SIC content and δ13C-SIC (R2 = .70, p < .01) and showed positively linear relationships between SIC content and SOC content (R2 = .69, p < .01) and between δ13C-SIC and δ13C-SOC (R2 = .61, p < .01). The results demonstrated that vegetation rehabilitation on SL has a high potential to sequester SIC and SOC in semiarid deserts. The reduction in δ13C-SIC and the relationship of SIC with δ13C-SIC following vegetation rehabilitation suggested that SIC sequestration is likely caused by the formation of pedogenic inorganic carbon. The relationships between SIC and SOC and between δ13C-SIC and δ13C-SOC implied that the pedogenic inorganic carbon formation may be closely related to the SOC accumulation.

    更新日期:2017-11-06
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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