当前期刊: Ecological Engineering Go to current issue    加入关注   
显示样式:        排序: 导出
  • The impacts of tree stand thinning on groundwater recharge in aridland forests
    Ecol. Eng. (IF 3.406) Pub Date : 2020-01-22
    Edward R. Schenk; Frances O'Donnell; Abraham E. Springer; Lawrence E. Stevens
  • Ecological methods and indicators for recovering and monitoring ecosystems after mining: A global literature review
    Ecol. Eng. (IF 3.406) Pub Date : 2020-01-20
    Walmer Bruno Rocha Martins; Michael Douglas Roque Lima; Udson de Oliveira Barros Junior; Larissa Sousa Villas-Boas Amorim; Francisco de Assis Oliveira; Gustavo Schwartz

    Mining contributes significantly to the world's economy. However, it brings strong environmental impacts, including the destruction of the original vegetation. In this way, the recovery of degraded areas by mining has been a mandatory procedure in many countries. With the objective to review this subject, a bibliometric analysis was carried out using scientific articles published in the period 1990–2018. A total of 700 articles in 171 journals were sampled. Ecological Engineering and Restoration Ecology were the journals with the largest number of articles. There was a significant increase of articles along time approaching the use of geotechnologies and arbuscular fungi. Recovered or recovering ecosystems were studied in 45 countries, mainly in Brazil, Australia, USA, China, and Spain. Coal and bauxite were the most common resources mined. The most frequent recovery methods were: seedling planting, direct seeding, natural regeneration, and hydroseeding, with techniques employed in some of them. In 35.71% of the articles, a small number of species (2–5) were used for the initial plant's establishment. The number of articles decreased as the number of both, plant species used in the initial recovery phase, and ecosystem's age increased. In monitoring, the most important indicators were classified as functional or functional plus structural. From the functional indicators, the Technosols or rebuilt soils were the most evaluated. Future perspectives on forests recovery includes methods tailored to peculiar features (soil and economic) of each ecosystem. For the forest recovery monitoring, the use of geotechnologies, mainly the Unmanned Aerial Vehicles (UAVs), as well as wildlife indicators tend to increase rapidly.

  • Large scale constructed wetlands for phosphorus removal, an effective nonpoint source pollution treatment technology
    Ecol. Eng. (IF 3.406) Pub Date : 2020-01-20
    Hongying Zhao; Tracey Piccone

    The Everglades Stormwater Treatment Areas (STAs) are large-scale freshwater wetlands constructed to reduce total phosphorus (TP) concentrations in runoff to support restoration of the Everglades. TP reduction and retention in STAs occurs through settling, plant growth and accumulation of dead plant material in a layer of peat. This study evaluated the performance of six treatment flow-ways in STA − 2 and STA-3/4, two of the best performing Everglades STAs, through water and TP budget analyses based on over a decade of hydrological, meteorological, and water quality data. STA performance was evaluated by comparing annual and long-term average annual flow-way and treatment cell TP flow-weighted mean outflow (FWMC) concentrations, TP load retention percentage, and TP FWMC reduction percentage. The effects of annual hydraulic loading rate, annual phosphorus loading rate, annual average hydraulic residence time, inflow TP FWMC and annual average water depth on annual flow-way TP FWMC were evaluated. For the six flow-ways studied, a higher frequency of low-level outflow TP annual FWMC was achieved when the annual hydraulic residence time was longer than 14 d, annual hydraulic loading rate was less than or equal to 3.5 cm day−1, the annual water depth was shallower than or equal to 0.65 m, the annual phosphorus loading rate was smaller than or equal to 1.2 g m2 yr−1, or the annual inflow TP FWMC was less than or equal to 100 μg L−1. This study demonstrated that TP settling rate alone is not adequate to evaluate STA treatment performance especially when hydraulic loading rates differ. This study also helped improve understanding of the factors that affected the treatment performance of large-scale constructed wetland flow-ways which consistently retained TP and reduced TP concentrations over a long-term operational period.

  • Trend, seasonality and relationships of aquatic environmental quality indicators and implications: An experience from Songhua River, NE China
    Ecol. Eng. (IF 3.406) Pub Date : 2020-01-17
    Yuanzheng Zhai; Xuelian Xia; Guang Yang; Hong Lu; Guangyu Ma; Guoqiang Wang; Yanguo Teng; Wenzhen Yuan; Sangam Shrestha

    To ensure safety of drinking water and verify effectiveness of environmental protection, it is essential to monitor aquatic environmental quality of rivers regularly, alongside hydrological variables. However, routine surveillance without in-depth analysis may prove insufficient to elucidate the changes, which is established issues receiving much attention. This study aimed to identify the trend, seasonality and relationships among the aquatic environmental quality indicators at a monitoring point of the mainstream of an important large river in Northeast China, the Songhua River. The study also endeavored to discuss the main factors impacting the quality and to verify the effectiveness of management. The aquatic environmental quality data and the hydrometeorological data were collected monthly from 2012 to 2018. Statistical analyses revealed that at the 5% significance level, SO42−, Cl− and total nitrogen (TN) showed an increasing trend over time, while F−, NH3-N and CODCr showed a decreasing trend. Chroma, SO42−, NH3-N, TN, Fe and dissolved oxygen showed relatively obvious seasonal changes. The water quality changed seasonally with the best occurring in summer and the worst in winter. And each season had its own typical indicators controlling the quality class. However, the randomness of the indicator changes cannot be ignored, which indicates the complexities of impacting factors and mechanism. There are both natural and anthropogenic factors and the latter is mainly the sewage discharge from industrial and agricultural production and residential life. The seasonality of natural impacts is obvious, while the trend or the randomness induced by anthropogenic impacts is more obvious. It remains imperative to ensure that the sewage discharge complies with the national discharge requirements and further reduce the discharge amount. It may be necessary for water plants to adjust the purification process according to the changes of river water quality, and for authorities to consider optimizing the existing monitoring program especially considering the monitoring indicators.

  • Microbial characterization of a facultative residual sludge obtained from a biogas plant with ability to degrade commercial B10 diesel oil
    Ecol. Eng. (IF 3.406) Pub Date : 2020-01-14
    Dana Belén Loureiro; Camila Olivera; María Laura Tondo; María Sol Herrero; Lucas Matías Salvatierra; Leonardo Martín Pérez
  • Evaluating wildflowers for use in conservation grass buffers to augment natural enemies in neighboring cornfields
    Ecol. Eng. (IF 3.406) Pub Date : 2020-01-13
    Galen P. Dively; Alan W. Leslie; Cerruti R.R. Hooks

    Adding wildflowers to arable lands is a tactic used to engineer agroecosystems to provide additional ecosystem services by attracting and supporting beneficial arthropods. Two studies were conducted to investigate the ability of wildflowers to influence populations of natural enemies. In the wildflower study, 24 early, mid and late season flowering species native to the USA Mid-Atlantic region were evaluated for their attractiveness to natural enemies and competitiveness with a perennial grass over two years. Insectary values were assigned to each wildflower based on length of flowering and relative attractiveness adjusted for background natural enemy activity. Wildflower species differed significantly in their ability to attract natural enemies, provide floral resources during the growing season, and maintain continued growth and flowering when contiguous with a perennial grass. Over two years, 45.9 to 82.4% of beneficials captured on sticky cards were hymenopteran parasitoids and their abundance was the major driver accounting for differences among wildflower species. At the farm level, we evaluated effects of wildflower addition to grass buffers on natural enemies in adjacent cornfields. Significant increases in taxa richness, abundance, and diversity of beneficial arthropod communities were measured in cornfields adjacent to grass buffers with wildflowers. Taken together, both studies provide evidence that insectary wildflowers can augment natural enemies in crop fields. However, differential attraction, flowering period and competitive abilities of wildflowers should be considered when selecting insectary species to mix with permanent grass buffers.

  • Seed density is as important as limiting similarity, diversity effect, and propagule pressure in plant restoration to control invasion
    Ecol. Eng. (IF 3.406) Pub Date : 2020-01-13
    Chaeho Byun; Minwoo Oh; Eun Ju Lee; Hojeong Kang

    Restoring invasion-resistant plant communities is critical for the successful control of invasive plant species. It is based on ecological principles, such as limiting similarity, and the diversity–invasibility hypothesis, which can be used to select optimal combinations of species and determine appropriate plant density for the effective suppression of invasion due to propagule pressure. However, no attempt has been made to combine these factors in a single research framework. Here, we show for the first time the relative importance of all significant factors, including seed density, limiting similarity, diversity effect, and propagule pressure, in the invasion mechanism of Sicyos angulatus, an invasive plant species. Our results suggest that seed density, rarely explored in previous studies, is as important a determinant of invasion success as limiting similarity, diversity effect, and propagule pressure. Thus, the density-mediated mechanism must be given careful consideration for the restoration of strong invasion-resistant native plant communities.

  • Surface and subsurface material selections influence the early outcomes of boreal upland forest restoration
    Ecol. Eng. (IF 3.406) Pub Date : 2020-01-09
    Shauna Stack; Caren Jones; Jana Bockstette; Douglass F. Jacobs; Simon M. Landhäusser

    Soil is an essential component supporting the growth and maintenance of forests, providing anchorage, water, and nutrients for a diversity of plants. In Canada's boreal forest, surface soils differ widely in their chemical and physical conditions, ranging from coarse to fine textured mineral soils in the uplands to organic soils in the lowlands. Industrial disturbances in the boreal region require the selective salvage of surface and sub-soils from low- and upland areas during open pit mine operations, which can be used to reconstruct different soil profiles by arranging the materials in variable layers and thicknesses. The type of materials and their configuration in the reconstructed soil profile can have a profound effect on early forest establishment in reclaimed areas. We compared the growth of trembling aspen (Populus tremuloides Michx.), jack pine (Pinus banksiana Lamb.), and white spruce (Picea glauca Moench.) on sites that had different reconstructed soils caps using varying surface soil materials (salvaged lowland peat and upland forest floor material (FFM)), placement depths (10 or 30 cm for peat, 10 or 20 cm for FFM), and subsoil material types determined by salvage depth (Bm, BC, and C). Early seedling establishment and growth and soil and climatic parameters were monitored over a five-year period. Generally, seedling growth was greatest on FFM and appeared to be related to phosphorous availability, while peat as a surface soil reduced growth, likely due to delayed soil warming in the spring and cooler soil conditions that potentially limited resource availability. However, the greater water holding capacity of the organic matter in peat also provided a benefit for seedling growth that was apparent during water limiting climatic conditions. The underlying subsoil material also influenced growth, particularly later in establishment when roots occupied the deeper subsoils. Aspen growth was greatest when the subsoil was shallow salvaged and represented a weathered subsoil (Bm) compared to the more deeply salvaged, less weathered subsoils BC and C. Aspen and pine seedlings, with their larger roots systems, may have benefited from small increases in the silt fraction of the subsoils, likely due to the greater water holding capacity of these otherwise coarse textured sandy soils. Spruce regeneration responded marginally to soil treatments because of its overall slow growth-strategy and tolerance to resource limitations. Our results indicate that different soil capping strategies affect the performance of forest regeneration during post-mining site reconstruction, and boreal forest species may vary in responses according to their ecological life strategies.

  • 更新日期:2020-01-09
  • Zokor disturbances indicated positive soil microbial responses with carbon cycle and mineral encrustation in alpine grassland
    Ecol. Eng. (IF 3.406) Pub Date : 2020-01-09
    Junhu Su; Weihong Ji; Huan Li; Tuo Yao; Jianfeng Wang; Zhibiao Nan

    The alpine grassland is a fragile ecosystem sensitive to human disturbance; the Qinghai-Tibetan Plateau alpine grassland is an example with large areas that are currently suffering from degradation. Although subterranean mammals (e.g., the plateau zokor, Eospalax baileyi) are thought to contribute to grassland soil and plant degradation, they are native species and play positive roles in the alpine ecosystem as ecosystem engineers. However, little is known about their effect on soil microbial communities. Using Illumina sequencing of the 16S rRNA gene and the internal transcribed spacer 2 (ITS2) regions, we compared soil prokaryotic and fungal community composition and diversity in areas disturbed by plateau zokors during the grassland recovery process. We found an increase in the number of observed operational taxonomic units (OTUs) of soil prokaryotic and fungal microbes, while the community structure of the microbes became significantly divergent. Soil properties, plant cover, and aboveground biomass explained the majority of the changes in microbial communities, suggesting that the changes in soil and plant characteristics mainly regulate the response of soil microbes to zokor disturbance in alpine grasslands. Zokor disturbances result in positive soil microbial responses in phyla with carbon cycle and mineral encrustation associations, suggesting a positive role for soil microbial community functions. Our findings provide novel evidence that zokors are important ecosystem engineers essential for alpine ecosystem functions.

  • Effects of shading and herb/liana eradication on the assembly and growth of woody species during soil translocation in Southwest China
    Ecol. Eng. (IF 3.406) Pub Date : 2020-01-09
    Gaojuan Zhao; Youxin Shen; Wenyao Liu; Zhenjiang Li; Beilin Tan; Zhimeng Zhao; Juan Liu

    Due to the intensification of human activities and global climate change, large areas of forest have been degraded and converted to other land uses. Soil translocation, which transfers the topsoil of donor forest to the receiving site to allow for the germination and reestablishment of soil seed bank and seedling, is a promising method for restoring vegetation that is similar to the donor forest. However, the lower similarity between the germinated community and donor forest has diminished its application against the ecological restoration and biodiversity compensation. We hypothesized that the exposure of donor forest soil to strong sunlight and early herb/liana competition may block germination and establishment of woody species (trees and shrubs) following soil translocation. To test this, here we investigated the effect of shading and weeding treatment on woody species assembly and seedlings growth at a karst rocky desertification area in southwest China. The results showed that soil translocation in blank control significantly increased the richness and similarity of woody species compared with receiving site. Moreover, soil translocation with shade treatment not only increased the richness and density of species during the germination period, but it also improved the survival and growth of most species—especially Osteomeles anthyllidifolia, Fraxinus malacophylla, Quercus baronii, and Rhamnus parvifolia—when compared with soil translocation in blank control after 18 months. Additionally, although soil translocation with blank control and weeding, and soil translocation with shade and weeding increased neither the number of woody species nor the density of shrubs species, they improved the density and similarity of tree species as well as the similarity of shrub species. We concluded that soil translocation with shade and weeding is likely more effective and helpful to restore the vegetation that is more similar to the donor forest in semi-humid regions of southwest China and comparable regions worldwide. But in practice, only soil translocation with moderate shade is deemed the optimal restoration method because it maintain the “recovery effect” while decrease the labor cost. Nevertheless, we should further assess the longer-term development and stabilization of established vegetation.

  • Transplantation of native species to existing vegetated slopes: Importance of optimal habitat and initial nutrient reserves
    Ecol. Eng. (IF 3.406) Pub Date : 2020-01-08
    Takatoshi Nakamura; Haruto Hirano; Hiroki Jin; Ryouta Zenpou; Rika Ohtani; Takeshi Kiyokawa; Hiroshi Kakuda

    Although ecosystem degradation is often caused by existing slopes vegetated with commercial species, limited data are available for implementing practical approaches for nature restoration by transplanting native species to those vegetated slopes. Existing vegetated slopes are characterized by spatial heterogeneity in the habitat environment and competition with existing vegetation, which affect the behaviors of transplanted native species. In this study, we examined the factors affecting the survival, growth, verticillation, and flowering of Lilium pensylvanicum, a native coastal-meadow species transplanted to a vegetated road slope in Hokkaido, Japan. In the fourth year after transplantation, the number of surviving plantlets was 364 (57% of 640 transplanted plantlets) and the number of plantlets that shifted to verticillate leaves was 181 (50% of the survivors). The flowering plantlets accounted for 9% (n = 34) of the survivors. The generalized linear model showed that plantlet survival is strongly promoted by a larger bulb scale, that is, nutrient reserves. Furthermore, the survival ratio was greatly improved in the drought-prone, stressful habitats with low vegetation coverage, even for plantlets with relatively smaller bulb scales. However, in the moist habitat with high coverage, the survival ratio was greatly decreased regardless of the bulb scale size. Growth, verticillation, and flowering were facilitated by higher soil nutrient availability, such as a lower C/N ratio and thicker soil layer. Therefore, transplanting of native species to vegetated slopes requires the selection of stress-tolerant species with large nutrient reserves and identification of optimal habitats for transplanting, namely stressful environments with reduced vegetation coverage.

  • Growth performance of tropical wetland species (Cyperus involucratus Rottb. and Thalia geniculata L.) in anaerobic digester effluent and their water treatment efficiency
    Ecol. Eng. (IF 3.406) Pub Date : 2019-11-21
    Tararag Pincam; Hans Brix; Arunothai Jampeetong

    Anaerobic digester effluent contains high concentrations of nutrients and other contaminants and has low dissolved oxygen. While there is increased interest nowadays in using constructed wetlands to treat wastewater, the ability of the wetland plants to grow in these stressful conditions is scantily investigated. Hence, this research investigated the growth performance of two tropical wetland species (Cyperus involucratus and Thalia geniculata) in anaerobic digester effluent and assessed their potential for treating the wastewater. Both C. involucratus and T. geniculata grew well in the wastewater probably because of aerenchyma development (28% air-space tissue) in the roots and radial oxygen loss from the roots. The pollutant level in the anaerobic digester effluent was significantly reduced with high removals of BOD (96–100%) and COD (69–73%). The remove of nutrients differed between species. T. geniculata had the better removal of PO4-P (48%), whereas C. involucratus had the better removal of NH4-N (99% in 28 days) and inorganic N (64% in 56 days). The removal of TSS (87–88%), EC (36–38%) and TDS (51–54%) in the systems were not significantly different between the two species. The study suggests that C. involucratus is a good candidate species for N removal in constructed wetlands whereas T. geniculata is better for removal of P.

  • Physicochemical determinants in stabilizing soil aggregates along a hydrological stress gradient on reservoir riparian habitats: Implications to soil restoration
    Ecol. Eng. (IF 3.406) Pub Date : 2019-11-21
    Yiguo Ran; Maohua Ma; Yan Liu; Kai Zhu; Xuemei Yi; Xiaoxiao Wang; Shengjun Wu; Ping Huang

    Stability of soil aggregates, playing a significant role in soil quality, has been greatly impacted by wetting-drying cycles. Yet, determinants in stabilizing soil aggregate structure have been rarely clarified under the hydrological stress. Therefore, under the hydrological stress, this study evaluated the relative importance of soil physicochemical properties in stabilizing soil aggregates on the water level fluctuating zones of the Three Gorges Reservoir riparian at China's Yangtze River. Water stable aggregates of soils (large macroaggregates: > 2 mm, small macroaggregates: 0.25–2 mm, microaggregates: 0.053–0.25 mm, silt- and clay-sized aggregates: 0–0.053 mm) were measured by wet sieving, and soil aggregate stability was evaluated as mean weight diameter (MWD), geometric mean diameter (GMD) and fractal dimension (D) of soil aggregate and soil erodibility parameter (K). Physicochemical properties of the riparian soils were analyzed as total carbon, nitrogen, organic matter, phosphorus and potassium content, C/N ratio, soil mechanical composition, pH, bulk density and moisture content. The results indicated that soil total carbon, nitrogen, organic matter, phosphorus and potassium were highly concentrated in the areas under strong hydrological stress; the pH was mainly alkalinity, pH value and bulk density both decreased along the incremental stress gradient. The findings revealed that the proportion and stability of water stable aggregates were affected by hydrological stress, and stability indices were interpreted by pH, C/N ratio, potassium and silt contents. Aggregates showed the highest and lowest stability under intermediate and strong stress, respectively, however, no significant difference was found between weak and none stress. Finally, our results suggested that the riparian ecosystem may have the ability of autogenic restoration for soil stability. Under intermediate hydrological stress level, autogenic restoration with less human intervention would be recommended for stabilizing the riparian soil. However, under strong hydrological stress, anthropogenic restoration is still needed to stabilize soil structure and reduce soil erosion in the reservoir riparian habitats.

  • Effect of media variation on the removal efficiency of pollutants from domestic wastewater in constructed wetland systems
    Ecol. Eng. (IF 3.406) Pub Date : 2019-11-20
    Magdi Ebrahim Khalifa; Yasmeen Gaber Abou El-Reash; Mohamed I. Ahmed; Fady W. Rizk

    Constructed Wetlands (CWs) are a group of effective and environmentally safe wastewater treatment systems that combine chemical, physical and biological treatment processes. These processes regulate the removal of inorganic, organic and biological pollutants from wastewater. This work presents a pilot field study carried out at Samaha wastewater treatment plant located at Al-Dakahlia province, Egypt. The present study addresses the use of some field wastes (e.g. plastic, rubber and polystyrene foam) as low cost alternative substrates to the common media in the constructed wetlands. It was noticed that after mixing the traditional used media (gravel, plastic or rubber) with polystyrene foam, the removal efficiency of pollutants was remarkably enhanced. The removal efficiency was followed by noticing the levels of biological oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), ammonia and phosphate in the treated wastewater. Data obtained indicated that, the removal efficiency of COD increased from 71% to 88% while for BOD and the total suspended solids, it was enhanced from 72 to 88% and from 83 to 88.5% respectively. For ammonia, the removal percentage increased from 66 to78% and phosphate reduction raised from 78% to 85%, while a slight modification of total coliform from 98.4–98.6% was found. The effect of flow rate on the removal efficiency is also studied and obtained results proved that the efficiency is inversely proportional to the flow rate and the best flow rate in this work was 2 m3/day. This improvement in removal efficiency was established based on comparison with regular treatment efficiency reported at Samaha wastewater treatment plant.

  • 更新日期:2020-01-04
  • A watershed scale assessment of phosphorus remediation strategies for achieving water quality restoration targets in the western Everglades
    Ecol. Eng. (IF 3.406) Pub Date : 2019-11-22
    Yogesh P. Khare; Ghinwa Melodie Naja; Rajendra Paudel; Christopher J. Martinez

    Watershed scale models have become important tools to assess the effectiveness of regional and farm level remediation strategies for ecological restoration. The Everglades is an ecologically unique and complex system posing numerous challenges to water managers in South Florida. The Feeder Canal Basin (FCB) in Hendry County, Florida, drains 277 km2 of land into the central Everglades. During 2008–2017, the average annual total phosphorus (TP) concentration at the FCB outflow was approximately 89 μg/L, almost an order of magnitude higher than the restoration target for the Everglades marshes. This study aimed at evaluating remediation strategies - Best Management Practices (BMPs) and Stormwater Treatment Areas (STAs) to achieve TP targets for ecosystem restoration using an integrated modeling framework with a top-down approach. The baseline regime was modeled using the Watershed Assessment Model with multi-gage calibration (2000−2003) and validation (2004–2010). With the model performing satisfactory to very good for all gage locations, results indicated that row crops, groves & orchards, and improved pastures were largely responsible for TP concentrations and/or loads. BMP scenario results showed that TP loads could be reduced by 8% to 24% at the FCB outlet under minimal or very aggressive BMPs, respectively, indicating the need for additional water quality improvement projects to meet restoration targets. A preliminary design of two STAs, using the Dynamic Model for Stormwater Treatment Areas, estimated that a total of 52 km2 and 11.3 km2 of STAs will be required to achieve the TP concentration targets. The analysis framework employed in this study can be replicated in other watersheds to provide a holistic picture of remediation measures required to achieve water quality targets.

  • Closing the loop - Recovery of nutrients and energy from wetland biomass
    Ecol. Eng. (IF 3.406) Pub Date : 2019-11-22
    Piotr Banaszuk; Andrzej K. Kamocki; Agnieszka Wysocka-Czubaszek; Robert Czubaszek; Slawomir Roj-Rojewski

    The aim of our research was to estimate the amount of energy, C, N and P that potentially could be extracted from the plant biomass harvested annually in the Narew National Park (NE Poland). We found that the conversion of biomass through anaerobic digestion (AD) delivers not only power and heat but also ensures the recovery of nutrients and organic matter for their reuse in agriculture. The most productive community with the highest biomass yield was reed bed of Phragmites australis (9.78 ± 1.66 t d.w. ha−1). It was followed by Phalaridetum and tall sedge communities with Carex elata and C. gracilis (6–7 t d.w. ha−1), rushes of Glyceria maxima (3.61 ± 0.63 t d.w. ha−1), and sedge moss communities with C. lasiocarpa (~1 t d.w. ha−1). Annual vegetation management would result in ~33·103 t d.w. of biomass. The primary net energy output was related to the productivity of the vegetation and ranged from ~17 GJ ha−1 for the sedge moss communities to 160 GJ ha−1 for Phragmitetum australis. The methane potential of the studied species was low and varied between 89 Nm3 t−1 d.w. for Phragmites and 188 NL kg−1 d.w. for Glyceria maxima. Consequently, the unit related net gain of energy in CH4 ranged between 23 and 30 GJ ha−1 for the perennial grasses and tall-sedge communities, and 3.5 GJ ha−1 for the low-productivity sedge-moss communities. As a result of low energy inputs for harvesting, the wetland biomass exhibited a favorable energy balance. The annual potential of CH4 for the whole studied valley section was 3286 ± 439·103 m3 resulting in net electricity potential of ~9.1 GWh and waste heat –32.3 TJ. An “average” hectare of wetland could power 1.2 household and provide 1010.4 ± 169.4 kg of C, 117.8 ± 19.6 kg of N, and 11.9 ± 2.0 of P applied do crop soils along with a digestate.

  • Increased soil aggregate stability is strongly correlated with root and soil properties along a gradient of secondary succession on the Loess Plateau
    Ecol. Eng. (IF 3.406) Pub Date : 2019-11-24
    Lie Xiao; Kehan Yao; Peng Li; Ying Liu; Enhao Chang; Yi Zhang; Tiantian Zhu

    The stability of soil aggregates is an indicator of restoration of soil in degraded ecosystems. A multitude of factors such as properties of plant roots and soil have been suggested to contribute to aggregate stability, but little information is available on the relative importance of these factors in temperate grass zones. We examined how root and soil properties modified aggregate stability along a gradient of secondary succession grassland on the Loess Plateau in China. We selected three cropland abandoned for 3, 10, and 16-year and measured the distribution of aggregates, mean weight diameter (MWD), bulk and aggregate-associated soil organic carbon (SOC) and glomalin-related soil protein (GRSP) contents, root biomass density, root length density, and specific root length (SRL). Compared with 3-year site, the amount of large macroaggregates (>2 mm) and aggregate stability (indicated by MWD) at 16-year site increased by 25.6% and 8.5%. The higher MWD contributed the most to the accumulation of SOC in large and small macroaggregates and to the accumulation of GRSPs in microaggregates (<0.25 mm). SRL was significantly positively correlated with MWD. Redundancy analysis (RDA) showed that soil and plant variables together explained 89.1% of the aggregate distribution variation. Partial RDA further revealed that soil variables solely explained 6.4% of the variation, plant root variables explained 47.9% of the variation, and interaction of soil and plant variables accounted for 34.8% of the variation. Our study indicated that increased soil aggregate stability during plant secondary succession depended on both plant roots and aggregate-associated SOC and GRSPs, and plant root exerted a stronger influence on soil aggregate stability than soil. Allowing secondary succession may be a promising strategy for restoring degraded ecosystems on the plateau.

  • Impacts of combined land-use and climate change on streamflow in two nested catchments in the Southeastern United States
    Ecol. Eng. (IF 3.406) Pub Date : 2019-11-25
    Chen-Ling J. Hung; L. Allan James; Gregory J. Carbone; John M. Williams
  • Prediction of spatial distribution of invasive alien pests in two-dimensional systems based on a discrete time model
    Ecol. Eng. (IF 3.406) Pub Date : 2019-12-06
    Jian Gao; Changgui Gu; Huijie Yang; Tongfeng Weng

    Preventing and managing the invasion of alien species poses significant challenges. In this article, we studied the population density of invasive alien pests based on a discrete time model, and found a new type of pattern and a new type of pattern formation mechanism. This new pattern is caused by the uncertainty of two states in the system (caused by chaos), which is different from the Turing instability. At last, the formation conditions of the irregular speckle pattern were quantitatively analyzed. We believe that the findings of this paper can provide theoretical guidance for the prevention and management of the invasion of alien pests.

  • 更新日期:2020-01-04
  • An exploration of plant characteristics for plant species selection in wetlands
    Ecol. Eng. (IF 3.406) Pub Date : 2019-11-25
    Junjie Liu; Bin Dong; Yuanlai Cui; Wangzi Zhou; Fangping Liu

    Plants are a major component of constructed wetlands (CWs) but arriving at a reasonable choice of plants is a challenge. In this study, surface flow CWs planted with eight different species of plants were investigated to explore the relationship between plant characteristics, including density, height, leaf area index, evapotranspiration (ET) and plant coefficient (the ratio of the actual plant ET to a reference ET), and the treatment performance of these plants in purifying water. Of the five plant characteristics, only the plant coefficient was found to be negatively correlated with kv (first-order removal rate) for nitrogen and phosphorus. The interpretation of this relationship requires caution, as the negative relationship may be caused by the water consumed by ET in the long term. The relationship between ETc (actual ET of a plant), plant coefficient and the removal load explain the two contradictory effects of ET on the removal load. Considering treatment performance and plant coefficient, the plant most recommended for use in CWs is Iris sibirica and that which is the least recommended is Nelumbo nucifera Gaertn. The combination of treatment performance and plant coefficient provides a robust approach to the selection of plants for areas with a high ET.

  • Improving denitrification in an aquaculture wetland using fish waste - a case study
    Ecol. Eng. (IF 3.406) Pub Date : 2019-11-25
    Mathis von Ahnen; Per Bovbjerg Pedersen; Johanne Dalsgaard

    Cost-efficient, end-of-pipe, nitrate removal techniques are called for by the commercial aquaculture industry. This case study examined how simple flow manipulations improved the denitrification performance of a 19,007 m2 (13,305 m3) constructed, free water surface (FWS) wetland treating aquaculture effluent. The wetland consisted of two separate streams with a common outlet: one stream treating nitrate-rich but carbon deficient effluent from the production unit at a hydraulic retention time (HRT) of 1.5 days (wetland stream 1); and a second stream treating carbon-rich, fish sludge-based effluent at a HRT of 41.0 days (wetland stream 2). During the course of the study (May–July 2017), three increasing proportions (40, 49 and 56%) of nitrate-rich effluent were re-directed from wetland stream 1 to the sludge-fed wetland stream 2 aiming at improving heterotrophic denitrification conditions in wetland stream 2 and consequently nitrogen removal in the wetland as a whole. Inlet C/N ratio in wetland stream 2 decreased from 1086 ± 57 to an average of 234 ± 56 (p < .05), and the area-based, total nitrogen (TN) removal rate in this wetland section increased significantly from 0.1 ± 0.01 to 8.4 ± 1.4 g/m2/d at the highest manipulated flow. In comparison, the flow manipulations had no effect on TN removal rates in wetland stream 1 averaging 1.4 ± 0.2 g/m2/d throughout the study. For the wetland as a whole, the TN removal rate increased from 1.4 ± 0.2 to 3.9 ± 0.8 g TN/m2/d. The flow manipulations furthermore improved the removal rates of total phosphorous and dissolved organic matter in the wetland as a whole. The study demonstrates that denitrification in a constructed aquaculture wetland may be improved by combining sludge-based and nitrogen-rich effluents in right proportions and leading it through an anoxic section of the wetland.

  • Optimizing the formulation of coal gangue planting substrate using wastes: The sustainability of coal mine ecological restoration
    Ecol. Eng. (IF 3.406) Pub Date : 2019-11-28
    Tao Du; Dongmei Wang; Yujie Bai; Zezhou Zhang

    With the development of China's coal industry, coal gangue has become one of the most extensive solid wastes. The collection of soil from other places for land reclamation has become a commonly used technology for ecological restoration of coal-mining areas in China. The purpose of this study was to use coal gangue as a new type of planting substrate component, with the goal of replacing soil to solve the increasing shortage of land resources. The formulation of the substrate was optimized using an orthogonal experiment with four factors: coal gangue (g)-to-soil (g) ratio (1000:0, 750:250, 500:500), maize straw content (0, 25, and 50 g kg−1), fly ash content (0, 75, and 150 g kg−1), and water retention agent content (0, 1, and 2 g kg−1).The results showed that coal gangue significantly improved the chemical properties (organic matter, total N, total P, available N, available P and available K) of the substrate (P < .01) at a dosage of 1000 g and increased alfalfa growth and improved the soil nutrient ratio at a dosage of 500 g. In addition, maize straw significantly affected the physical properties (bulk density, total porosity, capillary porosity, soil moisture content and permeability coefficient) of the substrate (P < .01) at 50 g and was most beneficial to plant growth (P < .01) at 25 g. Fly ash caused certain changes in the physical and chemical properties of the substrate and thus affected plant growth; the water retention agent showed a lesser effect. After the orthogonal experiments, we used a model to comprehensively analyze the effects of the four factors on 21 parameters to determine the optimum ratios of the components, which were as follows: a coal gangue-to-soil ratio of 1:1 (500 g:500 g), a maize straw content of 50 g kg−1, a fly ash content of 37 g kg−1, and a water retention agent content of 1 g kg−1. The findings of this study will provide a theoretical and technical basis for the ecological restoration of coal mining areas and the resource utilization of coal gangue.

  • 更新日期:2020-01-04
  • Complementing energy production with nutrient management: Anaerobic digestion system for algal turf scrubber biomass
    Ecol. Eng. (IF 3.406) Pub Date : 2019-11-28
    Freddy Witarsa; Andrea Yarberry; Peter May; Patrick Kangas; Stephanie Lansing
  • Optimal selection of hydraulic indexes with classical test theory to compare hydraulic performance of constructed wetlands
    Ecol. Eng. (IF 3.406) Pub Date : 2019-11-27
    Junjie Liu; Bin Dong; Wangzi Zhou; Zhongdong Qian

    Residence time distributions (RTDs), obtained from tracer experiments, are one of the main tools for investigating the hydraulic performance of constructed wetlands. However, the existence of various hydraulic indexes derived from RTDs has led to inconsistency in their application for comparing the hydraulic performance. In this work, eight hydraulic indexes were initially selected based on their popularity, and then divided into three categories: hydraulic efficiency indexes (HEIs) (λm, λe, λp, and MI), short-circuiting indexes (SIs) (t5 and t10), and mixing indexes (MIs) ( σ2 and Morril index). Then, the hydraulic indexes were optimized for compatibility, discrimination, difficulty, and their mutual relationships between different categories. The results showed large inconsistencies among HEIs, and small inconsistencies among SIs and MIs. Among the four HEIs, λe performed best in terms of compatibility, discrimination, and difficulty. Among SIs, t5 and t10 differed little in the three aforementioned aspects. Among MIs, the Morril index performed better than σ2 in terms of discrimination and difficulty. The significant correlation between short-circuiting flow and hydraulic efficiency highlights the necessity of reducing short-circuiting flow. Within each category, λe, t10, and the Morril index are recommended to quantify hydraulic efficiency, short-circuiting flow, and mixing flow, respectively. This study brings clarity to the application of hydraulic indexes and provides uniform standards for the quantification of hydraulic performance.

  • Which water bird groups need greater habitat conservation measures in a wetland ecosystem?
    Ecol. Eng. (IF 3.406) Pub Date : 2019-12-19
    Saeideh Maleki; Nicolas Baghdadi; Vahid Rahdari

    One important issue in wildlife conservation is the identification of the groups of species that need greater conservation measures. In this regard, maps of habitat degradation are useful tools. However, water bird habitat mapping in wetland ecosystem is difficult due to the large extent and complexity of wetlands and the narrow boundary between the habitats of different groups. In this paper, the capabilities of synthetic aperture radar (SAR) data were applied to overcome these limitations and to provide a practical scheme to conserve water bird habitats. The significance of this paper is the novel application of the SAR capabilities for water bird habitat conservation. These data were used to separate the habitat of the three water bird groups and to determine the destroyed habitats that should be protected for water birds in wetlands with unstable conditions. Using Sentinel-1 (S1) data, habitat maps for the water birds were created during the inundation period in the Hamoun-e-Hirmand. These habitats included the shrub swamps, flooded meadows, and open water. Based on the four-month flooded period of the wetland and the S1 image archive, habitat maps were created for six dates. The SAR backscattering coefficients of these three habitat classes were first analyzed to investigate the potential of the S1 images to differentiate between the habitat classes. A support vector machine (SVM) was then developed to separate the habitat classes. The accuracy of the six produced maps was calculated to be between 81% and 87.5%, which confirmed the ability of the S1 images to differentiate between water bird habitat classes. Based on the habitat degradation analysis, Anatidae, Charadriiformes, Ciconiiformes, Gruidae, Pelecanidae and the diving ducks need greater conservational measures in their feeding habitats (flooded meadow and open water). This paper introduced S1 data as an effective tool for mapping the habitats of each group of water birds in a wetland.

  • Propagule types and environmental stresses matter in saltmarsh plant restoration
    Ecol. Eng. (IF 3.406) Pub Date : 2019-11-27
    Qun Zhang; Shiyun Qiu; Yi Zhu; Xinhong Cui; Qiang He; Bo Li

    Restoration of degraded saltmarshes has attracted global attention, which makes disentangling the factors that determine target species success critically important. The pioneer plant Scirpus mariqueter in the Yangtze River estuary saltmarshes is rapidly declining due to plant invasion. It needs to be protected and restored, but the effects of environmental factors and propagule types on its restoration success are unclear. We examined the environmental niche of three propagule types (seedlings, corm shoots and plantlets) of Scirpus mariqueter under water level, salinity and nitrogen treatments in a greenhouse experiment. We found that water level was the most critical environmental factor limiting plant performance, followed by salinity. Nitrogen addition inhibited propagule growth in intermediate water level and salinity treatments. There were significant three-way interactions between water level, salinity, and nitrogen addition: Scirpus mariqueter performed best in treatments of low salinity + low to intermediate water levels + high nitrogen. Corm shoots outperformed plantlets and seedlings. Our results suggest that planting corm shoots under intermediate salinity and high water level conditions will enhance the restoration success of Scirpus mariqueter in the saltmarshes of the Yangtze River Estuary.

  • Invasion and ecological effects of exotic smooth cordgrass Spartina alterniflora in China
    Ecol. Eng. (IF 3.406) Pub Date : 2019-11-28
    Weiqing Meng; Rusty A. Feagin; Rachel A. Innocenti; Beibei Hu; Mengxuan He; Hongyuan Li

    Smooth cordgrass (Spartina alterniflora) was introduced to China in December 1979 to buffer against tides and to accelerate coastal wetland accretion. Since then, its propagation and natural dispersal have allowed this exotic plant to rapidly expand throughout coastal China with generally negative ecological effects. In 2003 S. alterniflora was labeled as an invasive plant in China, and it now covers ~50,000 ha. In this review, we first summarize the mechanisms of spread and spatial distribution of S. alterniflora, and how its physiological characteristics and strong adaptability to the available niche space in China's wetlands have enabled its spread and competition with native plants. Then we review the effects of S. alterniflora on ecosystem function in terms of habitat conversion and the alteration of biodiversity, soil carbon flux and sequestration, and various processes of nutrient regulation. We conclude that we need a long-term and context-dependent perspective, in order to maximize the benefits and minimize the costs of S. alterniflora within each of China's unique provinces.

  • Temporal variation pollution source and decontamination characteristics of the Myriophyllum spicatum treatment pond
    Ecol. Eng. (IF 3.406) Pub Date : 2019-11-28
    Jinfeng Xue; Haicai Li; Jiazhi Du; Mingyue Zhou; Yang Mei
  • Ecological effects of fire severity and time since fire on the diversity partitioning, composition and niche apportionment models of post-fire understory vegetation in semi-arid oak forests of Western Iran
    Ecol. Eng. (IF 3.406) Pub Date : 2019-12-03
    Hadieh Moradizadeh; Mehdi Heydari; Reza Omidipour; Arash Mezbani; Bernard Prévosto

    Monitoring and evaluating changes of the various characteristics of ecosystems after disturbances are essential to protect the services provided by each ecosystem. In the present study, different ecological characteristics including structure, composition and diversity at different post-fire times (one, five and ten years) in low and high fire severities were investigated in semi-arid oak (Quercus brantii L.) forests of western Iran. One hundred twenty-six 1.5 × 1.5 m plots were sampled in 14 patches (12 burned and 2 unburned). Alpha and beta diversity indices as well as species abundance distribution models of ecological niche apportionment were produced. The results showed that the distribution pattern of species, composition and diversity were influenced by the severity and time since fire. Based on Tokeshi's niche apportionment models, the low severity and short post-fire time generated a pattern with higher heterogeneity (MacArthur fraction; MF) than high severity and short post-fire time (dominance decay; DD). In contrast, long-term effects were less pronounced. Non-metric multidimensional scaling (NMDS) showed that there are different patterns of vegetation composition in low and high fire severities. The plant composition of the studied areas at low severity but with a longer time period since fire was more similar to the control area. In contrast, in the high fire severity, unburned and burned plots with different times since fire did not occupy overlapping areas in the ordination space. Severe fires also increased the alpha diversity at all spatial scales whereas the beta diversity only increased at the largest scale. Change of plant diversity pattern with time was more homogenous in low fire severity and more patchy in high fire severity. We concluded that the changes in the structure, composition and diversity of the post-fire vegetation were influenced both by fire severity and time since fire and that restoration actions to promote vegetation recovery should be adapted accordingly.

  • Do the dominant plant species impact the substrate and vegetation composition of post-coal mining spoil heaps?
    Ecol. Eng. (IF 3.406) Pub Date : 2019-12-03
    Agnieszka Kompała-Bąba; Edyta Sierka; Marcin K. Dyderski; Wojciech Bierza; Franco Magurno; Lynn Besenyei; Agnieszka Błońska; Karolina Ryś; Andrzej M. Jagodziński; Gabriela Woźniak
  • An example of multi-habitat restoration: Conceptual assessment of benefits from merging shellfish-reef and boulder-reef restorations
    Ecol. Eng. (IF 3.406) Pub Date : 2019-12-25
    K. Liversage

    Multi-habitat restoration should be considered for conservation of habitat-types that are ecologically-related and regularly co-occur. Multi-habitat restoration has been used to a limited extent for marine habitats including oysters, mangroves and seagrass. Recent increases in research and understanding of shellfish-reefs and boulder/cobble-reefs means they should likewise be considered for integrated restoration. Importantly, boulders have recently been used as the foundation for several large-scale oyster-reef restorations. These would benefit from improved recognition that multiple distinct habitat-types are involved each associated with distinct knowledge pools. These habitat-types mostly have similar restoration objectives, they often co-occur pre-disturbance, and they share varied taxa. These linkages mean that opportunities may be missed if restorations are only considered separately in contexts where an integrated approach is feasible; restoration of one habitat may benefit from concurrent restoration of the other and the sum of benefits from integration may outweigh the sum from restorations done separately. Here, I discuss concepts concerning five potential synergies: 1) boulders provide natural hard-substrata that initiates shellfish recruitment, 2) boulders produce beneficial hydrological heterogeneity, increasing recruitment of some shellfish species, 3) shellfish generate self-sustaining supplies of novel hard-substrata habitat used by boulder/cobble species thus expanding the original restoration site footprint, 4) large shellfish populations strengthen valuable ecological functions in boulder habitats, and 5) boulders and shells together increase overall diversity of available hard-substrata types, and thus of associated specialist species. Not only restoration outcomes, but also objectives and planning can be improved by integrating knowledge from both habitat-types to encompass these five synergies.

  • Variation in contaminant removal efficiency in free-water surface wetlands with heterogeneous vegetation density
    Ecol. Eng. (IF 3.406) Pub Date : 2019-12-03
    Nima Sabokrouhiyeh; Andrea Bottacin-Busolin; Matteo Tregnaghi; Heidi Nepf; Andrea Marion

    The interaction between flow and vegetation in constructed wetlands plays a major role in determining wetland performance. In this study, a two-dimensional depth-averaged model was used to simulate flow, mass transport and contaminant removal in a conceptual free-water surface (FWS) wetland with heterogeneous vegetation patterns. The main objectives of this study were (1) to quantify the effectiveness of FWS wetlands with different vegetation patterns in reducing pollutant load, and (2) to identify optimal vegetation distributions that maximize contaminant removal. Simulations were performed for different random vegetation fields characterized by imposed mean, variance and correlation lengths of stem density. The wetland was assumed to receive water from a stream and to deliver it back to the same stream according to an imposed head drop. The simulations show that the concentration reduction efficiency increases monotonically with average stem density, whereas mass removal has a peak for an intermediate value of average stem density. The ensemble average of the total mass removal decreases for increasing stem density variance and correlation length, because the presence of vegetation patches with significantly different stem density promotes preferential flow paths. Preferential flow paths parallel to the mean flow direction were found to reduce the hydraulic efficiency of wetlands by producing short-circuiting, whereas, for the same mean stem density, alternating stripes of stem density perpendicular to the flow direction provided higher concentration and mass reduction. By providing a quantitative understanding of the impact of spatial vegetation heterogeneity, the results provide useful guidelines for design and maintenance of constructed wetlands for wastewater treatment.

  • In-situ measurements of turbulent flow over intertidal natural and degraded oyster reefs in an estuarine lagoon
    Ecol. Eng. (IF 3.406) Pub Date : 2019-12-04
    Vasileios Kitsikoudis; Kelly M. Kibler; Linda J. Walters

    Oysters are ecosystem engineers that form reefs with rough surfaces. The complex surface of a reference-condition reef contains clusters of live oysters that protrude into and interact with flows. A degraded oyster reef contains fewer live oyster clusters and subsequently has different bed roughness. Such morphological differences may translate to varied hydrodynamic function, with influence to local and larger-scale flow fields and sediment transport, as well as larval recruitment and long-term reef sustainability. The objective of this study is to compare a degraded and a reference-condition intertidal oyster reef, and assess how differences in structure (reef morphology and roughness) influence near-bed hydrodynamic function within the roughness sublayer defined by oysters. Sediment entrainment and bed deformation were observed only on the reference oyster reef, despite that mean velocities were lower than those at the degraded reef. This was attributed to slightly finer bed material and higher turbulent kinetic energy, k, at the reference reef (k = 29.2 ± 4.5 cm2/s2 with mean velocity 11.5 ± 0.6 cm/s at 1 cm above the bed) compared to the degraded reef (k = 22.6 ± 4.2 cm2/s2 with mean velocity 16.1 ± 1.7 cm/s at 1 cm above the bed). At 1 cm above the bed, shear turbulence production at the degraded reef was significantly larger than turbulence dissipation rate, while at the reference reef this pattern was observed only for time periods with low turbulent kinetic energy. For measurements 5 cm above the bed at the reference reef, shear turbulence production and turbulence dissipation rates exhibited a relatively balanced pattern, with dissipation exceeding shear production for the time period with elevated turbulence. Four bed shear stress calculation methodologies converged over the degraded oyster reef but deviated considerably at the reference oyster reef. The drag coefficient associated with bed shear stress at the reference reef was almost two times greater than that at the degraded reef and almost an order of magnitude greater than those observed at sand and mud beds.

  • Use of Cylindrical Bristle Clusters as a novel multispecies fish pass to facilitate upstream movement at gauging weirs
    Ecol. Eng. (IF 3.406) Pub Date : 2019-12-09
    Daniella Montali-Ashworth; Andrew S. Vowles; Gustavo de Almeida; Paul S. Kemp

    Globally, gauging weirs are commonly installed in rivers to monitor flows. They have widespread negative impacts on the upstream movement of fish due to the barriers created by the unfavourable hydraulic conditions on the downstream face. There is a need to develop simple low-cost solutions to enhance multi-species fish passage, while not impacting the ability of these structures to gauge flow or increasing their potential to accumulate debris. This study investigated the use of an array of Cylindrical Bristle Clusters (CBCs), mounted on the downstream face of Crump weirs, to improve upstream passage of multiple species of fish while maintaining gauging accuracy. The simplicity and modularity of the design helps improve cost effectiveness and ease of installation. Laboratory tests with roach (Rutilus rutilus) showed that the passage efficiency of a Crump weir was increased from 0% (control) to ≈30% when retrofitted with CBCs. Swim path analysis indicated fish utilised low velocity zones in the wake of clusters to facilitate passage. Time taken to pass the weir and length of the swim path were greatest under the highest cluster density, where manoeuvrability was most constrained. Following these promising experimental results, the fish pass efficiency of a weir retrofitted with a staggered array of CBCs, was evaluated in the field. Upstream passage of a number of non-salmonid fish, including chub (Squalius cephalus) and roach, was monitored using Passive Integrated Transponder telemetry at a 7 m long, 1.2 m wide, Crump weir with a 1:5 downstream slope. Overall passage efficiency, considering all species, increased from 2% to 14% when the fish pass was installed, and for chub from 0 to 52%. Debris accumulation was minimal during the test period. Assessment of the impact of a variety of CBC array densities on gauging was also undertaken. As predicted using theory, there was no effect on gauging when arrays were placed downstream of the point at which flow regime changes from sub- to supercritical. This study highlights the potential for a staggered array of CBCs to improve the upstream passage of multiple species of fish at gauging weirs, common barriers to fish migration throughout the world, without affecting the accuracy of flow gauging.

  • The use of small-Unmanned Aerial Systems for high resolution analysis for intertidal wetland restoration schemes
    Ecol. Eng. (IF 3.406) Pub Date : 2019-12-06
    Jonathan Dale; Niall G. Burnside; Conor J. Strong; Heidi M. Burgess

    Coastal and estuarine wetlands provide a range of important ecosystem services, but are currently being damaged and degraded due to human activities, reduced sediment supply and sea level rise. Managed realignment (MR) is one approach used to compensate for the loss of intertidal habitat, however saltmarshes in MR sites have been recognised to have lower biodiversity than natural environments. This has been associated with differences in the physical functioning including the sediment structure, reduced hydraulic connectivity, and lower topographic variability such as the abundance of intertidal creek networks. Intertidal morphology, including creek networks, play an important role in supporting and regulating saltmarsh environments through the supply of sediment, nutrients and water, and in draining intertidal marshes. However, there is a lack of empirical data on the formation and evolution of topographic features and variability in saltmarsh environments. This is likely to be due to creek networks in natural marshes already being in a state of quasi-equilibrium, making MR sites an ideal environment to investigate creek development. However, traditional remote sensing techniques (such as LiDAR) tend to be relatively expensive, infrequent and at a coarse resolution meaning small, but important (cm-scale), changes are often missed. This study advances the ability to detect these small scale changes by demonstrating the suitability and potential applications of using the emerging photogrammetric method Structure-from-Motion (SfM) on images taken using a small-Unmanned Aerial System (sUAS). Three surveys from a rapidly changing, near-breach site were taken at the Medmerry Managed Realignment Site in July 2016, September 2017 and July 2018. A suitable degree of confidence was found between the modelled surface and independent check points (vertical root-mean-square-errors of 0.0245, 0.0704 and 0.1571 for 2016, 2017 and 2018 respectively). DSMs of Difference (DoD) analysis was performed to evaluate elevation change, with areas experiencing up to 85 cm of accretion between 2016 and 2018. However, when considering the error associated with both surveys, between 2016 and 2017, only 34.39% of the survey area experienced change above the level of detection (LoD). In contrast, 76.97% experienced change greater than the LoD between 2017 and 2018. Stream order analysis classified the creek networks into five orders in 2016 and four orders in 2017 and 2018, with 2016 having a higher abundance (291 in 2016 compared to 117 (2017) and 112 (2018)) and density (0.44 m/m2 in 2016 compared to 0.27 m/m2 in both 2017 and 2018) of creek networks. These results provide an innovative high resolution insight into the evolution of restored intertidal wetlands, and suggest that SfM analysis of images taken using a sUAS can be a useful tool with the potential to be incorporated into studies of MR and natural saltmarsh sites. sUAS analysis can, therefore, advance the management of these environments to ensure the provision of ecosystem services and to protect against future anthropogenic activity, sea level rise and climate change.

  • Seasonal performance of stormwater biofiltration system under tropical conditions
    Ecol. Eng. (IF 3.406) Pub Date : 2019-12-11
    Andreas Aditya Hermawan; Amin Talei; Babak Salamatinia; Lloyd H.C. Chua

    Urbanization rates are increasing in developing countries such as Malaysia. In the tropics, flooding is a major concern, due to high rainfall intensities. In addition to flooding, pollution caused by contaminants contained in urban runoff are also of concern. Biofiltration system as one of the technologies in on-site stormwater treatment, has gained its popularity as part of Water Sensitive Urban Design measures. To date however, studies on tropical biofiltration system are limited in number and scope. This study aims to assess the effect of wetting and drying on performance, since such systems are constantly subject to wetting and drying cycles. In this study, a set of sand-based filter columns were prepared with three different native plant species including Cordyline fruticosa (CF), Graptophyllum pictum (GP), and Cyperus alternifolius (CA). Ten wetting and drying regimes were conducted including 5 wet weather simulations (0, 0, 1, 2, 3 dry days) followed by 5 dry weather simulations (5, 7, 10, 14, 21 dry days). To aid the plants survivability during the dry period, submerged zone was installed in all columns, simulating groundwater table. The results showed that all three plants could survive throughout both wet and dry periods with minimum stress. The overall treatment performance of all column types was satisfactory as the heavy metal concentration reduction was 90% and above while total dissolved phosphorus (TDP) reduction was up to 94%. Although total dissolved nitrogen (TDN) reduction was not as high as TDP (up to 58% reduction), the effluent TDN concentration still met the required receiving water quality standard. Overall, effluent concentration from CF, GP, and CA columns satisfied the requirement of class IIB recreational water standard in Malaysia. It was also concluded that plant CA comparatively performed better than the others in terms of both survivability and pollutants removal aspects.

  • Downstream passage behavior of potamodromous fishes at the fish protection and guidance system “Flexible Fish Fence”
    Ecol. Eng. (IF 3.406) Pub Date : 2019-12-13
    Heidi Kammerlander; Lisa Schlosser; Bernhard Zeiringer; Günther Unfer; Achim Zeileis; Markus Aufleger

    Using an outdoor experimental channel, this study evaluates downstream passage behavior of potamodromous fish species at an innovative fish protection and guidance system, the Flexible Fish Fence (FFF). Under variation of the spacing between the cables, the exposition angle and the approach velocity, the fish protection and the guidance efficiency are investigated. Experiments were carried out using wild born and PIT-tagged chubs (Squalius chephalus), graylings (Thymallus thymallus), brown trouts (Salmo trutta) and rainbow trouts (Oncorhynchus mykiss) with body lengths between 100 and 200 mm. The results show that fish protection efficiency is predominately dependent on the cable spacing and varies strongly between fish species. While all fish (100%) are prevented from passing through the FFF at 10 mm spacing, it is far less effective at 20 mm spacing (83% of chubs, 59% of trouts and 26% of graylings). The effects of the exposition angle, the approach velocity, and the fish length are identified using multinomial logistic regression models: fish protection efficiency increases significantly with increasing fish length and increasing approach velocity (particularly for the highest angle) for chubs and trouts. Increasing flow velocity induces cable vibrations presumably triggering avoidance behavior. Unfavourable hydraulic conditions at the bypass entrance (approach velocity of 0.65 m s-1, velocity changes or turbulences) negatively affect the bypass efficiency for all fish species, pointing out that the design of bypasses for downstream migration is of major relevance.

  • Evaluating the performance of conservation practices under climate change scenarios in the Miyun Reservoir Watershed, China
    Ecol. Eng. (IF 3.406) Pub Date : 2019-12-20
    Jiali Qiu; Zhenyao Shen; Xiaoshu Hou; Hui Xie; Guoyong Leng
  • Lake recovery from eutrophication: Quantitative response of trophic states to anthropogenic influences
    Ecol. Eng. (IF 3.406) Pub Date : 2019-12-23
    Chunxue Yu; Zuoyong Li; Zhihao Xu; Zhifeng Yang

    Lake eutrophication is a serious environmental problem worldwide, caused by both natural processes and anthropogenic influences. For effective lake eutrophication management, a variety of models have been designed to investigate the complex interrelationship between physical, chemical and biological factors and processes in lakes. However, these models are inconvenient for predictions of lake eutrophication in practical application. To date, very few studies have focused on lake eutrophication in terms of anthropogenic influences (such as sewage emissions and agricultural practices), which are more readily regulated than natural processes. Effective lake eutrophication prediction models should base primarily on facile controlled or predictable indicators. Therefore, to meet this requirement, we designed simple predictive models to determine the interrelationship between the trophic states of lakes and nutrient inputs, which is a direct measurement to characterize anthropogenic influences. Lake Taihu (China) was used as a representative eutrophic water body to assess the accuracy of the proposed predictive models. Firstly, to comprehensively understand the role of nutrient input indicators (NIIs) during eutrophication, Pearson correlation coefficient analysis was conducted on 7 NIIs and 38 types of algae. Secondly, based on the NIIs identified with high correlation coefficients, we modified three commonly used growth models (Gompertz, logistic and Richards) to describe the lake's trophic state. A particle swarm optimization algorithm (PSOA) was used to optimize model variables. Results showed that the mean absolute percentage errors of the optimized Gompertz, logistic and the Richards models were 2.95%, 2.88% and 2.17%, respectively. Finally, these optimized models were used to predict lake eutrophication under several different nutrient input scenarios. Two adjustment scenarios revealed remarkably satisfied trophic states (including roughly oligotrophic and even ultra-oligotrophic) by the 2030s. Our results show that these established models are a simple way to support lake restoration projects by setting realistic and effective targets.

  • Effects of ecological construction on the transformation of different water types on Loess Plateau, China
    Ecol. Eng. (IF 3.406) Pub Date : 2019-11-24
    Binhua Zhao; Zhanbin Li; Peng Li; Yuting Cheng; Bei Gao

    Water is the most essential resource for the ecological and biological survival of organisms as well as being an important strategic socio-economic factor. Stable isotopes of δD and δ18O in water are important indicators of hydrological and ecological process. In this study, temporal and spatial variations in δD and δ18O and transformations between three water bodies (precipitation, stream water, and groundwater) under ecological construction were studied in two contrasting watersheds of the Wuding River, China. In order to understanding the spatial and temporal variation of stable isotopes and water transmission times (WTT) under ecological construction, a total of 1028 water samples were collected from the 30 sites, and 79 precipitation samples were collected at the weather station. The results show that variation range of three water bodies occurred in the order precipitation > stream water > groundwater, the local meteoric water line was above the level of the last two, and the isotopic composition of stream water and groundwater in controlling watershed is more enriched than that in natural watershed. WTT from precipitation to stream water in Jiuyuangou were 1.53 times those of Peijiamao. Similarly, WTT from precipitation to groundwater was about 7.6 times than that form precipitation to stream water. Supply ratios exhibited obvious seasonal variation. Precipitation and groundwater recharged stream water mostly in the dry season, while precipitation and stream water recharged groundwater during the wet season. Overall, this study shows that ecological construction measures extend WTTs and enhance water evaporation and fractionation. The results of this research are significant as they enhance our understanding of water transformation on the Loess Plateau under ecological construction.

  • Growing wheat in Biosphere 2 under elevated CO2: observations and modeling.
    Ecol. Eng. (IF 3.406) Pub Date : 2001-09-07
    F N Tubiello,T Mahato,T Morton,J W Druitt,T Volk,B D Marino

    Spring wheat (Triticum aestivum L., cv. Yecora Rojo) was grown in the intensive agricultural biome (IAB) of Biosphere 2 during the l995-l996 winter/spring season. Environmental conditions were characterized by a day/night temperature regime of 27/17 degrees C, relative humidity (RH) levels around 45%, mean atmospheric CO2 concentration of 450 ppmv, and natural light conditions with mean intensities about half of outside levels. Weekly samples of above-ground plant matter were collected throughout the growing season and phenological events recorded. A computer model, CERES-Wheat, previously tested under both field and controlled conditions, was used to simulate the observed crop growth and to help in data analysis. We found that CERES-Wheat simulated the data collected at Biosphere 2 to within 10% of observed, thus suggesting that wheat growth inside the IAB was comparable to that documented in other environments. The model predicts phenological stages and final dry matter (DM) production within l0% of the observed data. Measured DM production rates, normalized for light absorbed by the crop. suggested photosynthetic efficiencies intermediate between those observed under optimal field conditions and those recorded in NASA-Controlled Ecological Life-Support Systems (CELSS). We suggest that such a difference can be explained primarily in terms of low light levels inside the IAB, with additional effects due to elevated CO2 concentrations and diffuse light fractions.

  • Considerations in miniaturizing simplified agro-ecosystems for advanced life support.
    Ecol. Eng. (IF 3.406) Pub Date : 1996-01-01
    T Volk

    Miniaturizing the Earth's biogeochemical cycles to support human life during future space missions is the goal of the NASA research and engineering program in advanced life support. Mission requirements to reduce mass, volume, and power have focused efforts on (1) a maximally simplified agro-ecosystem of humans, food crops, and microbes; and, (2) a design for optimized productivity of food crops with high light levels over long days, with hydroponics, with elevated carbon dioxide and other controlled environmental factors, as well as with genetic selection for desirable crop properties. Mathematical modeling contributes to the goals by establishing trade-offs, by analyzing the growth and development of experimental crops, and by pointing to the possibilities of directed phasic control using modified field crop models to increase the harvest index.

  • A Constructed Wetland for Treatment of an Impacted Waterway and the Influence of Native Waterfowl on its Perceived Effectiveness.
    Ecol. Eng. (IF 3.406) Pub Date : 2019-10-22
    Brian R McMinn,Sara Klemm,Asja Korajkic,Kimberly M Wyatt,Michael P Herrmann,Richard A Haugland,Jingrang Lu,Eric N Villegas,Craig Frye

    A constructed, variable-flow treatment wetland was evaluated for its ability to reduce microbial loads from the Banklick Creek, an impacted recreational waterway in Northern Kentucky. For this study, levels of traditional (Escherichia coli and enterococci measured by culture and molecular techniques) and alternative fecal indicators (infectious somatic and F+ coliphage, Clostridium spp. and Clostridium perfringens by culture), potential pathogens (molecular signal of Campylobacter spp.) as well as various microbial source tracking (MST) markers (human fecal marker HF183 and avian fecal marker GFD) were monitored during the summer and early fall through five treatment stages within the Banklick Creek Wetland. No difference in concentrations of traditional or alternative fecal indicators were observed in any of the sites monitored. Microbial source tracking markers were employed to identify sources of fecal contamination within the wetland. Human marker HF183 concentrations at beginning stages of treatment were found to be significantly higher (P value range: 0.0016-0.0003) than levels at later stages. Conversely, at later stages of treatment where frequent bird activity was observed, Campylobacter and avian marker (GFD) signals were detected at significantly higher frequencies (P value range: 0.024 to <0.0001), and both signals were strongly correlated (P = 0.0001). Our study suggests constructed wetlands are an effective means for removal of microbial contamination in ambient waters, but reliance on general fecal indicators is not ideal for determining system efficacy or assessing appropriate remediation efforts.

  • A mangrove creek restoration plan utilizing hydraulic modeling.
    Ecol. Eng. (IF 3.406) Pub Date : 2017-12-12
    Darryl E Marois,William J Mitsch

    Despite the valuable ecosystem services provided by mangrove ecosystems they remain threatened around the globe. Urban development has been a primary cause for mangrove destruction and deterioration in south Florida USA for the last several decades. As a result, the restoration of mangrove forests has become an important topic of research. Using field sampling and remote-sensing we assessed the past and present hydrologic conditions of a mangrove creek and its connected mangrove forest and brackish marsh systems located on the coast of Naples Bay in southwest Florida. We concluded that the hydrology of these connected systems had been significantly altered from its natural state due to urban development. We propose here a mangrove creek restoration plan that would extend the existing creek channel 1.1 km inland through the adjacent mangrove forest and up to an adjacent brackish marsh. We then tested the hydrologic implications using a hydraulic model of the mangrove creek calibrated with tidal data from Naples Bay and water levels measured within the creek. The calibrated model was then used to simulate the resulting hydrology of our proposed restoration plan. Simulation results showed that the proposed creek extension would restore a twice-daily flooding regime to a majority of the adjacent mangrove forest and that there would still be minimal tidal influence on the brackish marsh area, keeping its salinity at an acceptable level. This study demonstrates the utility of combining field data and hydraulic modeling to aid in the design of mangrove restoration plans.

  • Large-scale controls on potential respiration and denitrification in riverine floodplains.
    Ecol. Eng. (IF 3.406) Pub Date : 2013-04-09
    Nina Welti,Elisabeth Bondar-Kunze,Gabriel Singer,Michael Tritthart,Sophie Zechmeister-Boltenstern,Thomas Hein,Gilles Pinay

    Restoration measures of deteriorated river ecosystems generally aim at increasing the spatial heterogeneity and connectivity of these systems in order to increase biodiversity and ecosystem stability. While this is believed to benefit overall ecological integrity, consequences of such restoration projects on biogeochemical processes per se (i.e. ecosystem functioning) in fluvial systems are rarely considered. We address these issues by evaluating the characteristics of surface water connection between side arms and the main river channel in a former braided river section and the role and degree of connectivity (i.e. duration of surface water connection) on the sediment biogeochemistry. We hypothesized that potential respiration and denitrification would be controlled by the degree of hydrological connectivity, which was increased after floodplain restoration. We measured potential microbial respiration (SIR) and denitrification (DEA) and compared a degraded floodplain section of the Danube River with a reconnected and restored floodplain in the same river section. Re-establishing surface water connection altered the controls on sediment microbial respiration and denitrification ultimately impacting potential microbial activities. Meta-variables were created to characterize the effects of hydrology, morphology, and the available carbon and nutrient pools on potential microbial processing. Mantel statistics and path analysis were performed and demonstrate a hierarchy where the effects of hydrology on the available substrates and microbial processing are mediated by the morphology of the floodplain. In addition, these processes are highest in the least connected sites. Surface water connection, mediated by morphology regulates the potential denitrification rate and the ratio of N2O to N2 emissions, demonstrating the effects of restoration in floodplain systems.

  • Macroecology Meets Macroeconomics: Resource Scarcity and Global Sustainability.
    Ecol. Eng. (IF 3.406) Pub Date : 2014-06-03
    James H Brown,Joseph R Burger,William R Burnside,Michael Chang,Ana D Davidson,Trevor S Fristoe,Marcus J Hamilton,Sean T Hammond,Astrid Kodric-Brown,Norman Mercado-Silva,Jeffrey C Nekola,Jordan G Okie

    The current economic paradigm, which is based on increasing human population, economic development, and standard of living, is no longer compatible with the biophysical limits of the finite Earth. Failure to recover from the economic crash of 2008 is not due just to inadequate fiscal and monetary policies. The continuing global crisis is also due to scarcity of critical resources. Our macroecological studies highlight the role in the economy of energy and natural resources: oil, gas, water, arable land, metals, rare earths, fertilizers, fisheries, and wood. As the modern industrial technological-informational economy expanded in recent decades, it grew by consuming the Earth's natural resources at unsustainable rates. Correlations between per capita GDP and per capita consumption of energy and other resources across nations and over time demonstrate how economic growth and development depend on "nature's capital". Decades-long trends of decreasing per capita consumption of multiple important commodities indicate that overexploitation has created an unsustainable bubble of population and economy.

  • Rhizospere Redox Cycling and Implications for Rhizosphere Biotransformation of Selected Polychlorinated Biphenyl (PCB) Congeners.
    Ecol. Eng. (IF 3.406) Pub Date : 2014-05-27
    Richard E Meggo,Jerald L Schnoor

    Theoretically, sequential cycles of dechlorination followed by aerobic bio-oxidation are desirable to achieve complete degradation of a mixture of higher and lower chlorinated PCBs. In this research, soil was artificially contaminated with polychlorinated biphenyls (PCBs) in mixture and as single congeners, aged, and planted with two different plant species. Alternating redox cycles were created in the root zone of plants by flooding and draining the soil. Over 32 weeks, switchgrass (Panicum virgatum) and poplar (Populus deltoids x nigra DN34) planted systems that were exposed to alternate cycles of flooding performed better in reducing parent PCBs than planted systems that were not cycled (p<0.05). The cycled systems also had a higher mass of PCB transformation products than the uncycled systems. Multiple cycles were necessary to achieve significant differences between the cycled and uncycled treatments.

  • Enhanced Polychlorinated Biphenyl Removal in a Switchgrass Rhizosphere by Bioaugmentation with Burkholderia xenovorans LB400.
    Ecol. Eng. (IF 3.406) Pub Date : 2014-09-24
    Yi Liang,Richard Meggo,Dingfei Hu,Jerald L Schnoor,Timothy E Mattes

    Phytoremediation makes use of plants and associated microorganisms to clean up soils and sediments contaminated with inorganic and organic pollutants. In this study, switchgrass (Panicum virgatum) was used to test for its efficiency in improving the removal of three specific polychlorinated biphenyl (PCB) congeners (PCB 52, 77 and 153) in soil microcosms. The congeners were chosen for their ubiquity, toxicity, and recalcitrance. After 24 weeks of incubation, loss of 39.9 ± 0.41% of total PCB molar mass was observed in switchgrass treated soil, significantly higher than in unplanted soil (29.5 ± 3.4%) (p<0.05). The improved PCB removal in switchgrass treated soils could be explained by phytoextraction processes and enhanced microbial activity in the rhizosphere. Bioaugmentation with Burkholderia xenovorans LB400 was performed to further enhance aerobic PCB degradation. The presence of LB400 was associated with improved degradation of PCB 52, but not PCB 77 or PCB 153. Increased abundances of bphA (a functional gene that codes for a subunit of PCB-degrading biphenyl dioxygenase in bacteria) and its transcript were observed after bioaugmentation. The highest total PCB removal was observed in switchgrass treated soil with LB400 bioaugmentation (47.3 ± 1.22 %), and the presence of switchgrass facilitated LB400 survival in the soil. Overall, our results suggest the combined use of phytoremediation and bioaugmentation could be an efficient and sustainable strategy to eliminate recalcitrant PCB congeners and remediate PCB-contaminated soil.

Contents have been reproduced by permission of the publishers.
上海纽约大学William Glover