Tree death is not always preceded by a visible decline in vigor (canopy dieback) or a progressive loss in crown volume. Identifying early-warning signals of incipient decline can help to implement the necessary measures to prevent tree death. The aim of this work is to understand what functional alterations preceded the massive drought-induced death of adult Pinus canariensis trees in an arid stand

Partitioning of evapotranspiration (ET) is important for understanding surface-atmosphere interactions, hydrological cycle, and plant water use strategy. Here, we applied seven widely used eddy covariance (EC)-based methods and 15-year EC measurements in a winter wheat-summer maize rotation cropland in North China Plain to partition ET into soil evaporation (E) and plant transpiration (T). Then the

Revealing the physiological mechanisms and the implications of changes in spring phenology is crucial for understanding ecosystem productivity and functioning. Previous studies reported an increased vegetation growth associated with warming-induced earlier spring phenology, which can in turn make feedback to the climate systems and increase summer drought. The effects of preseason drought on spring

Photosynthetic light response curves were measured in four cultivars of Humulus lupulus L. (hop) at CO2 concentrations of 415, 500, 600, and 700 μmol CO2 mol−1. Short-term elevated CO2 increased net photosynthesis (An), light-saturated rates of photosynthesis, and quantum yield and decreased the light compensation point and leaf respiration. To illustrate the effects on canopy carbon gain, we used

Intensified interannual variability in precipitation is anticipated to alter soil salinization in coastal wetlands, which may significantly impact the structure and function of ecosystems, especially soil carbon cycling. However, the response patterns and mechanisms of soil respiration to precipitation changes in coastal wetlands remain uncertain. To assess the response pattern of soil respiration

Crop growth condition and production play an important role in food management and economic development. Therefore, estimating yield accurately and timely is of vital importance for regional food security. The long short-term memory (LSTM) model represents a deep network structure to incorporating crop growth processes, which has been proven to accommodate different types and representations of data

Eddy fluxes collected during 2016 to 2019 from eight production-scale multi-purpose winter wheat fields (grain only, graze-grain, and graze-out), managed under conventional till (CT) and no-till (NT), were synthesized to determine seasonality, daily magnitudes, seasonal, and annual budgets of carbon dioxide (CO2) fluxes and evapotranspiration (ET), and to investigate spatio-temporal variability of

Rainfall seasonality and timing are key climatic features affecting crop yield in rainfed agriculture (RFA). We evaluated the dynamics of temporal rainfall attributes – the strength of seasonality, the date of onset, cessation, and duration of the rainy season – over RFA areas across Ethiopia for the period 1981-2010 and explored their impacts on cereal crop production (including maize, teff, sorghum

In open-canopy ecosystems, thermal imaging affords an unprecedented opportunity to resolve concurrent temperatures of overstory vegetation, understory vegetation, and soil across space and time. This simultaneous view of ecosystem components promises a holistic understanding of ecosystem energy status, defines diverse thermal niches, and can provide a full suite of thermal measurements to drive ecosystem

Accurate estimates of cumulative N2O fluxes from agricultural soil are essential for quantifying global N2O emissions and for identifying effective mitigation strategies. This study focuses on the short term temporal variability of N2O fluxes, and on how the accuracy of annual cumulative estimates is affected by different (simulated) measuring frequencies of an automatic system based on the closed

A one-source model type that combines surface renewal (SR) and similarity theories to estimate the sensible heat flux (H) involving the land surface temperature (LST) and low-frequency measurements, HSR-LST, was tested over agricultural surfaces with fractions of ground canopy cover that ranged from 39% up to 97% and canopy heights ranging from 0.2 to 1.8 m. The performance was tested under clear sky

Surface roughness – a key control on land-atmosphere exchanges of heat and momentum – differs between dormant and growing seasons. However, how surface roughness shifts seasonally at fine time scales (e.g., days) in response to changing canopy conditions is not well understood. This study: (1) explores how aerodynamic resistance changes seasonally; (2) investigates what drives these seasonal shifts

Waterlogging severely constrains wheat production after rice cultivation in the middle-lower reaches of the Yangtze River Plain, China. Raised bed planting (RBP) patterns may reduce waterlogging stress and increase wheat productivity. However, the physical mechanisms of resource use in wheat, particularly radiation resource use, are not well understood. The effects of planting patterns on the canopy

In this study, ten-minute meteorological data-sets recorded at Burgos, Spain, are used to develop models of Photosynthetic Active Radiation (PAR) following two different procedures: multilinear regression and Artificial Neural Networks. Ten Meteorological Indices (MIs) are chosen as inputs to the models: clearness index (kt), diffuse fraction (kd), direct fraction (kb), Perez's clear sky index (ɛ)

Separation of water absorption by roots between trees and crops is critical to intercropping in water-limited regions. The current knowledge about interspecific water relationship is in one dimension, i.e., the vertical direction, little is known in both vertical and horizontal directions under different rainfall conditions. Therefore, an experiment was carried out in an apple tree based intercropping

The observation of regional evaporative fraction (EF) over a heterogeneous area is crucial to surface energy balance modeling and satellite-based evapotranspiration (ET) validation over complex areas. However, regional EF observations are often lacking or not directly acquired because the sparse distribution and inadequate spatial representativeness of ground measurements cannot represent the region's

Despite the advances in technologies to derive the maximum rate of Rubisco carboxylation (Vcmax) seasonality at large-scale, factors controlling the temporal dynamics of Vcmax is largely unknown without extensive field measurements at stand scale. In addition, state-of-the-art process-based terrestrial ecosystem models had not accounted the complex canopy structure for estimating radiation interception

The microclimate dynamics under forest crown fundamentally drive plant community responses to global warming. The understory air and soil temperatures are two of the most important components of forest understory microclimate. However, there is rare method to reasonably evaluate the joint effects of forest cover on the understory air and soil temperatures. In this study, we combined a novel three-layer

Ecosystem water use efficiency (WUE), defined as the ratio of gross primary production (GPP) over evapotranspiration (ET), is a crucial variable that describes the tradeoff between ecosystem carbon uptake and water loss. However, the effects of soil moisture on WUE remain unclear. Based on hourly observations from 36 forest eddy-covariance sites globally and two percentile-based statistical models

The growing demand for Heat Pulse Probes (HPPs) to estimate thermal properties and surrogate soil processes comes with a need for improved standards for calibration and validation in reference materials. This study proposed air-free ice as a calibration material to determine the apparent rod spacing (rc) for HPPs. The advantage of using air-free ice as a calibration standard over agar-stabilized water

A clear understanding of the relationship between two photosynthetic capacity parameters, maximum carboxylation rate (Vcmax) and maximum electron transport rate (Jmax), is expected to reveal plant photosynthetic physiology strategies and is critical in determining the carbon and water cycle in the terrestrial biosphere. Increasing evidence in recent suggests the relationship is unstable in spatiotemporal

Potato crops are susceptible to numerous field diseases causing significant losses in the quality and tuber yield. Control measures have a negative impact in soil and water resources affecting also farmers’ health and food security. Hence, a more sustainable agriculture management is a need to preserve ecosystems. Therefore, the objective of this study was to evaluate the response of nine potato cultivars

Although there are ample data on growth trends and climate growth relationships of trees from the leading edge of their distribution at treeline, information from the neighbouring trailing edge of the vegetation belt dominated by alpine shrubs is missing. We expected trees at their upper limit to exhibit unambiguous temperature limitation with a clearly positive growth response to recent warming. On

Global climatic change indicates that some climate systems have passed tipping points, e.g. the inner East Asia; however it's still uncertain when the tipping point of forest mortality could be triggered. Absent rings are early warnings of irreversible mortality. They widely exist in Northern Hemisphere forests, but they're locally rare and under-discussed in previous studies. We reported a tree ring

Lodging is a major limiting factor for the yield, quality and harvesting efficiency of selected crops worldwide. This study presents an efficient, robust and non-destructive assessment of lodging severity for four different grasses for seed production, using images collected by an unoccupied aerial vehicle (UAV) in two field plot experiments across five growing seasons. Canopy texture and height related

As an important part of global semi-arid grassland, adequately understanding the spatio-temporal variability of evapotranspiration (ET) and water balance (WB, defined as precipitation-ET) over the temperate semi-arid grassland of China (TSGC) could advance our understanding of climate, hydrological and ecological processes over global semi-arid areas. Based on the largest number of in-situ ET measurements

Plant phenological processes significantly impact ecosystem function and services across multiple ecological scales and are widely viewed to be among the most sensitive indicators of global environmental change. Remote sensing has crucially expanded our understanding of phenological variability. Yet, we continue to lack a complete mechanistic understanding of phenology and its variability and drivers

Fuel moisture exerts considerable influence on fire behavior and effects but varies substantially spatially and temporally. A portion of the spatial variation in dead surface fuel moisture of woodland and forest ecosystems is likely attributed to differences in stand conditions (i.e. stand density and composition). Existing evidence suggests that the role of stand conditions on dead surface fuel moisture

We present numerical predictions and experimental observations of the drag force on the major branches of a model tree as well as the wind field in its wake. The tree model was mounted on a force sensor in a wind tunnel. The numerical simulations solved both the Reynolds Averaged Navier Stokes and detached eddy simulations, in combination with an immersed boundary model representation of the tree,

As one of the most dynamic aspects of global environmental change, land cover change (LCC) has a profound impact on terrestrial carbon sequestration. However, LCC-induced carbon fluxes are still the most uncertain terms in global and regional carbon budgets. Ecosystem gross primary production (GPP) is the total carbon uptake by vegetation through photosynthesis, serving as a major control on ecosystem

Forests store large amounts of carbon as wood, but this storage potential depends on seasonal radial growth and how it is driven by climate. Therefore, we need a better understanding on how intra-annual radial increment rates determine growth responses to climate variability. There is a large gap of knowledge on the climate windows, i.e. the effective climatic time-window for tree growth, and predictors

Mediterranean forests face an intensification of droughts caused by ongoing climate change. To improve our understanding of tree and forest responses to increasing drought, we explored over nine years, the effects of a 30% rainfall exclusion experiment on the water potential, sap velocity and primary and secondary growth of two co-occurring species (Quercus ilex and Pinus halepensis) in a French Mediterranean

With the intensification and frequency of heat waves and periods of water deficit stress, along with rising atmospheric carbon dioxide [CO2], understanding the seasonal leaf-gas-exchange responses to combined abiotic factors will be important in predicting crop performance in semi-arid production systems. In peanut (Arachis hypogaea L.), the availability of developmental stage physiological data on

Aquaculture ponds are important anthropogenic methane (CH4) sources to the atmosphere. Currently large uncertainties still remain regarding the emission strength of this source type and its relationship with aquacultural farming practices. In this study, the methane flux was measured continuously for four years with eddy covariance (EC) in an aquaculture pond complex in the Yangtze River Delta, China

Different stomatal behaviors among species under drought conditions may affect species-specific seasonal variations in photosynthesis and water use efficiency (WUE), and could enable species to follow differing growth strategies. Here we monitored leaf gas exchange, intra-annual radial growth, leaf stoichiometry, and microclimate of three conifers with contrasting stomatal behaviors (isohydric Picea

The amplification of global warming in the Northern regions results in a higher probability of wildfires in boreal forests. On the forest floor, wildfires have long-term effects on vegetation composition as well as soil and its microbial communities. A large variety of biogenic volatile organic compounds (BVOCs) such as isoprene, monoterpenes, sesquiterpenes have been observed to be emitted from soil

The surface renewal method offers an inexpensive way to estimate the sensible heat flux (H). When combined with measurements of net radiation and soil heat flux, latent heat flux (evapotranspiration) can be estimated indirectly. This study evaluated the performance of two surface renewal models to estimate H in a traditional coffee agroforestry system. The first model (Snyder96) is the commonly used

The Himalayas are experiencing dramatic warming and drought events, which occur at a faster rate than the global average. How will the high-elevation ecosystems cope with such changing conditions? This study aims to combine cambial phenology with quantitative wood anatomy to understand how the growth dynamics affect the trade-off between safety and efficiency of water transport in the Himalayan forests

The long-term increasing trend of annual mean temperature is only one aspect of recent climate change. Other changes in climate, seen in within-year weather patterns relevant to crop production, have also occurred since the late-19th Century. Multivariate analysis combining Principal Components Analysis and K-means clustering applied to temporal meteorological datasets (monthly summaries of rainfall

This paper evaluates the atmospheric controls contributing to actual evapotranspiration (ET) variability and trends across the ecological zones in the data-scarce region of West Africa. Spatial and temporal ET dynamics in the region were analysed using three selected prognostic- and machine learning-based global ET over 1983 to 2012. In addition, the responses of annual actual ET to changes in annual

Investigating ecosystem, soil and aboveground respiration under different agricultural management regimes (i.e., fertilization, crop types and plowing practices) is critical for better understanding the processes of agricultural carbon cycles. The effects of agricultural management regimes on ecosystem respiration and its soil and aboveground respiration components have not been well identified. We

Soil water sources for shrub encroachment in arid and semiarid regions have not been fully understood. This study used stable δ2H and δ18O isotope ratios of plants, soil water and precipitation, coupled with proportional similarity index of species to identify relations between shrub encroachment and water sources for four shrub and grass species at various shrub encroachment stages in a semiarid grassland

During the past three decades, maize yields in China have steadily increased as producers experienced climate changes and utilized improved hybrids and management, etc. Elucidating the relative contributions of these factors to historical yield changes will aid in sustaining or increasing yields in the future. In this study, statistical methods were used to estimate the contribution of incident solar

Phenological transitions determine the timing of changes in land surface properties and the seasonality of exchanges of biosphere-atmosphere energy, water, and carbon. Accurate mechanistic modeling of phenological processes is therefore critical to understand and correctly predict terrestrial ecosystem feedbacks with changing atmospheric and climate conditions. However, the phenological components

Drought is the primary limiting factor for tree growth in arid and semi-arid regions, where it can greatly influence xylem anatomical traits and induce multiple responses to wood development. However, the mechanisms driving xylogenesis and intra-annual density fluctuations (IADFs), as well as the seasonal dynamics of wood development in water-limited environments, are still unclear. In this study,

One challenge in precision nitrogen (N) management is the uncertainty in future weather conditions at the time of decision-making. Crop growth models require a full season of weather data to run yield simulation, and the unknown weather data may be forecasted or substituted by historical data. The objectives of this study were to (1) develop a model-based in-season N recommendation strategy for maize

Although biosphere-atmosphere exchanges of ammonia (NH3) are of great environmental importance regarding, e.g., eutrophication and aerosol-related human health problems, their magnitudes are not well constrained due to the challenges in in-situ measurements of NH3 fluxes. In this paper we introduce a portable, low-power and quantum cascade laser-based open-path analyzer for eddy covariance (EC) measurement

Fluctuations in weather conditions, particularly precipitation and water availability, may strongly affect growth rate patterns and lead to interannual height growth variation. Consequently, height growth models developed using airborne laser scanning (ALS) data collected at short time intervals may over- or underestimate long-term height growth trends and finally result in different growth forecasts

Extreme climatic and weather events are inducing widespread tree mortality in many forest ecosystems worldwide. A severe frost related to the historic cold wave that affected much of North America in early February 2011 triggered extensive tree mortality in the lowland tropical dry forest in northwestern Mexico. In this landscape, we assessed frost-induced vegetation damage using anomalies of the widely