scholarly journals Primary production in forests and grasslands of China: contrasting environmental responses of light- and water-use efficiency models

2012 ◽  
Vol 9 (11) ◽  
pp. 4689-4705 ◽  
Author(s):  
H. Wang ◽  
I. C. Prentice ◽  
J. Ni
Keyword(s):  
Primary Production ◽  
Water Use Efficiency ◽  
Water Use ◽  
Net Primary Production ◽  
Upper And Lower Bounds ◽  
Co2 Response ◽  
Data Set ◽  
Use Efficiency ◽  
Vegetation Models ◽  
Environmental Responses

Abstract. An extensive data set on net primary production (NPP) in China's forests is analysed with the help of two simple theoretically derived models based on the light use efficiency (LUE) and water use efficiency (WUE) concepts, respectively. The two models describe the data equally well, but their implied responses to [CO2] and temperature differ substantially. These responses are illustrated by sensitivity tests in which [CO2] is kept constant or doubled, temperatures are kept constant or increased by 3.5 K, and precipitation is changed by ±10%. Precipitation changes elicit similar responses in both models. But NPP in South China, especially, is reduced by warming in the LUE model, whereas it is increased in the WUE model. The [CO2] response of the WUE model is much larger than that of the LUE model. It is argued that the two models provide upper and lower bounds for this response, with the LUE model more realistic for forests. The differences between the two models illustrate some potential causes of the large differences (even in sign) in the global NPP response of different global vegetation models to temperature and [CO2].

scholarly journals Primary production in forests and grasslands of China: contrasting environmental responses of light- and water-use efficiency models

2012 ◽  
Vol 9 (4) ◽  
pp. 4285-4321 ◽  
Author(s):  
H. Wang ◽  
I. C. Prentice ◽  
J. Ni
Keyword(s):  
Primary Production ◽  
Water Use Efficiency ◽  
Water Use ◽  
South China ◽  
Net Primary Production ◽  
Gross Primary Production ◽  
Stomatal Closure ◽  
Co2 Response ◽  
Data Set ◽  
Use Efficiency

Abstract. An extensive data set on net primary production (NPP) in China's forests is analysed with two semi-empirical models based on the light use efficiency (LUE) and water use efficiency (WUE) concepts, respectively. Results are shown to be broadly consistent with other data sets (grassland above-ground NPP; globally extrapolated gross primary production, GPP) and published analyses. But although both models describe the data about equally well, they predict notably different responses to [CO2] and temperature. These are illustrated by sensitivity tests in which [CO2] is kept constant or doubled, temperatures are kept constant or increased by 3.5 K, and precipitation is changed by ±10%. Precipitation changes elicit similar responses in both models. The [CO2] response of the WUE model is much larger but is probably an overestimate for dense vegetation as it assumes no increase in runoff; while the [CO2] response of the LUE model is probably too small for sparse vegetation as it assumes no increase in vegetation cover. In the LUE model warming reduces total NPP with the strongest effect in South China, where the growing season cannot be further extended. In the WUE model warming increases total NPP, again with the strongest effect in South China, where abundant water supply precludes stomatal closure. The qualitative differences between the two formulations illustrate potential causes of the large differences (even in sign) in the global NPP response of dynamic global vegetation models to [CO2] and climate change. As it is not clear which response is more realistic, the issue needs to be resolved by observation and experiment.

scholarly journals Water use efficiency of net primary production in global terrestrial ecosystems

2015 ◽  
Vol 124 (5) ◽  
pp. 921-931 ◽  
Author(s):  
Lei Xia ◽  
Fei Wang ◽  
Xingmin Mu ◽  
Kai Jin ◽  
Wenyi Sun ◽  
...  
Keyword(s):  
Primary Production ◽  
Water Use Efficiency ◽  
Water Use ◽  
Net Primary Production ◽  
Terrestrial Ecosystems ◽  
Use Efficiency

The Effect of Droughts on Ecosystem Water-Use-Efficiency in Europe

2021 ◽  
Author(s):  
Christian Poppe Teran ◽  
Bibi Naz ◽  
Roland Baatz ◽  
Harrie-Jan Hendricks-Franssen ◽  
Nikolaos Nikolaidis ◽  
...  
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Weather Conditions ◽  
Reanalysis Data ◽  
Ecosystem Dynamics ◽  
Drought Indices ◽  
Weather Extremes ◽  
Data Set ◽  
Ecosystem Water Use Efficiency ◽  
Use Efficiency

<div> <p>Hydrological extremes in Europe, such as droughts, are expected to increase in frequency and severity with advancement of climate change. The consequences for ecosystem functioning and processes, including biomass production and evapotranspiration, have not yet been thoroughly mapped. </p> </div><div> <p>Ecosystem water use efficiency (WUE) describes the amount of carbon assimilated as biomass per unit of water. WUE was examined for various case studies and global assessments, yet disagreements in the methodologic approach and uncertainties hinder generic understanding of WUE variability. As a link between the carbon cycle, water cycle and vegetation states, disclosure of WUE courses across European ecosystems enables important estimates of past, present and future ecosystem dynamics. </p> </div><div> <p>Here we generated a long-term and high resolution observational and reanalysis data-set of WUE over Europe by interpolation of high level observation products (GLASS, CRU TS v4) and reanalysis data sets (ERA5-Land, COSMO-REA6, ESSMRA) to a 3 x 3km grid. This European Drought and Water Use Efficiency data-set (EDWUE) contains variables for calculating WUE using three different approaches, as well as indicators of meteorological and agricultural droughts.  </p> </div><div> <p>Drought effects on WUE will be analyzed to investigate the sensitivity of ecosystem processes to extreme weather conditions at regional and local scale by comparison of WUE and drought indices time-series. Spatiotemporal analyses of the EDWUE data-set across European ecosystems will discover differences in patterns and potential trends of WUE between regions and decode the dependencies on ecosystem composition, geographical characteristics, and climate and occurring weather extremes. Intercomparisons between the different WUE calculations will allow to draw conclusions on the roots of particular WUE dynamics.</p> </div>

scholarly journals Quantifying Soil Moisture Impacts on Water Use Efficiency in Terrestrial Ecosystems of China

2021 ◽  
Vol 13 (21) ◽  
pp. 4257
Author(s):  
Xingming Hao ◽  
Jingjing Zhang ◽  
Xue Fan ◽  
Haichao Hao ◽  
Yuanhang Li
Keyword(s):  
Soil Moisture ◽  
Water Use Efficiency ◽  
Water Use ◽  
Land Surface ◽  
Net Primary Production ◽  
Terrestrial Ecosystems ◽  
Sensitivity Coefficient ◽  
Analytical Framework ◽  
Average Value ◽  
Use Efficiency

Soil moisture (SM) significantly affects the exchange of land surface energy and the stability of terrestrial ecosystems. Although some conclusions have been drawn about the effects of SM on the ecosystem water use efficiency (WUE), the influence mechanism and the quantitative assessment framework of SM on WUE are still unclear. This study provides an analysis framework for the feedback relationship between SM and WUE based on the dependence of the evaporation fraction on SM and output datasets from remote sensing and the Global Land Data Assimilation System. The results show that the range of WUE of terrestrial ecosystems of China was0.02–19.26 g C/kg H2O in the growing season with an average value of 1.05 g C/kg H2O. They also show a downward trend in43.99% of the total area. In the evapotranspiration (ET) pathway, SM negatively affected WUE, and the sensitivity coefficient ranged from −18.49 to −0.04. In the net primary production (NPP) pathway, the sensitivity coefficient ranged from −68.66 to 43.19. Under the dual effects of the ET and NPP pathways, the influence of SM on WUE was negative in 84.62% of the area. Variation in SM led to significant WUE variability. Generally, the percentage change in WUE (ΔWUE) ranged from 0% to 190.86%, with an average value of 28.02%. The maximum ΔWUE ranged from 0% to 758.78%, with an average value of 109.29%. The WUE of forest ecosystems showed strong resistance to SM variation, whereas that of non-forest vegetation was more sensitive to SM variation. This analytical framework provides a new perspective on the feedback relationship between WUE and SM in terrestrial ecosystems.

Variation of gross primary production, evapotranspiration and water use efficiency for global croplands

2020 ◽  
Vol 287 ◽  
pp. 107935
Author(s):  
Zhipin Ai ◽  
Qinxue Wang ◽  
Yonghui Yang ◽  
Kiril Manevski ◽  
Shuang Yi ◽  
...  
Keyword(s):  
Primary Production ◽  
Water Use Efficiency ◽  
Water Use ◽  
Gross Primary Production ◽  
Use Efficiency

scholarly journals Water-Use Efficiency of the Terrestrial Biosphere: A Model Analysis Focusing on Interactions between the Global Carbon and Water Cycles

2012 ◽  
Vol 13 (2) ◽  
pp. 681-694 ◽  
Author(s):  
Akihiko Ito ◽  
Motoko Inatomi
Keyword(s):  
Carbon Cycle ◽  
Primary Production ◽  
Water Use Efficiency ◽  
Water Use ◽  
Ecosystem Management ◽  
Water Budget ◽  
Terrestrial Ecosystems ◽  
Terrestrial Biosphere ◽  
Use Efficiency ◽  
Water Cycles

Abstract Carbon and water cycles are intimately coupled in terrestrial ecosystems, and water-use efficiency (WUE; carbon gain at the expense of unit water loss) is one of the key parameters of ecohydrology and ecosystem management. In this study, the carbon cycle and water budget of terrestrial ecosystems were simulated using a process-based ecosystem model called Vegetation Integrative Simulator for Trace Gases (VISIT), and WUE was evaluated: WUEC, defined as gross primary production (GPP) divided by transpiration; and WUES, defined as net primary production (NPP) divided by actual evapotranspiration. Total annual WUEC and WUES of the terrestrial biosphere were estimated as 8.0 and 0.92 g C kg−1 H2O, respectively, for the period 1995–2004. Spatially, WUEC and WUES were only weakly correlated. WUES ranged from <0.2 g C kg−1 H2O in arid ecosystems to >1.5 g C kg−1 H2O in boreal and alpine ecosystems. The historical simulation implied that biospheric WUE increased from 1901 to 2005 (WUEC, +7%; WUES, +12%) mainly as a result of the augmentation of productivity in parallel with the atmospheric carbon dioxide increase. Country-based analyses indicated that total NPP is largely determined by water availability, and human appropriation of NPP is also related to water resources to a considerable extent. These results have implications for 1) responses of the carbon cycle to the anticipated global hydrological changes, 2) responses of the water budget to changes in the terrestrial carbon cycle, and 3) ecosystem management based on optimized resource use.

scholarly journals Dramatic increase in water use efficiency with cumulative forest disturbance at the large forested watershed scale

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Krysta Giles-Hansen ◽  
Xiaohua Wei ◽  
Yiping Hou
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Mountain Pine Beetle ◽  
Sustainable Forest Management ◽  
Net Primary Production ◽  
Forest Disturbance ◽  
Watershed Scale ◽  
Clear Cut ◽  
Use Efficiency ◽  
Induced Changes

Abstract Background Forest disturbance induced changes in the coupling of forest carbon and water have important implications for ecosystem functioning and sustainable forest management. However, this is rarely investigated at the large watershed scale with cumulative forest disturbance. We used a combination of techniques including modeling, statistical analysis, and machine learning to investigate the effects of cumulative forest disturbance on water use efficiency (WUE, a proxy for carbon and water coupling) in the 19,200 km2 Chilcotin watershed situated in the central interior of British Columbia, Canada. Harvesting, wildfire, and a severe Mountain Pine Beetle (MPB) infestation have gradually cumulated over the 45-year study period, and the watershed reached a cumulative equivalent clear-cut area of 10% in 1999 and then 40% in 2016. Results Surprisingly, with the dramatic forest disturbance increase from 2000 to 2016 which was mainly due to MPB, watershed-level carbon stocks and sequestration showed an insignificant reduction. This resilience was mainly due to landscape-level carbon dynamics that saw a balance between a variety of disturbance rates and types, an accumulation of older stand types, and fast growing young regenerated forests. Watershed-level carbon sequestration capacity was sustained, measured by Net Primary Production (NPP). A concurrent significant decrease in annual evapotranspiration (ET), led to a 19% increase in WUE (defined as the ratio of NPP to ET), which is contrary to common findings after disturbance at the forest stand-level. During this period of high disturbance, ET was the dominant driver of the WUE increase. Conclusions We conclude that disturbance-driven forest dynamics and the appropriate scale must be considered when investigating carbon and water relationship. In contrast to the stand-level trade-off relationship between carbon and water, forested watersheds may be managed to maintain timber, carbon and water resources across large landscapes.

The role of Evapotranspiration and Water Use Efficiency in Agriculture in Portugal

2020 ◽  
Author(s):  
José Vaz ◽  
Célia M. Gouveia ◽  
Isabel F. Trigo
Keyword(s):  
Climate Variability ◽  
Primary Production ◽  
Water Use Efficiency ◽  
Water Use ◽  
Reference Evapotranspiration ◽  
Gross Primary Production ◽  
Growth Monitoring ◽  
Climate Variability And Change ◽  
Wine Production ◽  
Use Efficiency

<p>Understanding climate variability and change and its impacts on natural systems is becoming more and more important as changes in earth surface condition near surface air temperature and precipitation. Over Portugal, the observed warming trends have been found to be asymmetric with respect to seasonal and diurnal cycles, with greatest warming occurring for the minimum temperature and during winter and spring. These observed trends exert strong influences on agriculture systems, affecting production viability through changes in winter hardening, frost occurrence, growing season lengths and heat accumulation for ripening potential.</p><p>Remote sensing technology has been developing steadily and its products can provide many applications in agriculture, namely crop identification, crop growth monitoring and yield prediction. Recently the LSA SAF team set up a strategy to generate long term data records from Meteosat Second Generation satellite series (2004 to present), releasing Land Surface Temperature (LST), Reference Evapotranspiration (ETREF) and Vegetation parameters (FAPAR, LAI and FVC) using a stable set of input data and algorithm, which would be suitable for climate variability and change detection studies. On the other hand, a new product to characterize the ecosystem processes, the Gross Primary Production (GPP), is under production since 2018.</p><p>In this work we propose to computed Water Use Efficiency (WUE), as the ratio between Gross Primary Production (GPP) and Reference Evapotranspiration (ETREF), using LSA-SAF Products. WUE translates the exchanges of carbon and water gross fluxes, between natural ecosystem and the atmosphere, allowing to monitor the adaptability of the ecosystems to climate change. The role played by Evapotranspiration and Water Use Efficiency for different crops in Portugal is evaluated, namely on Wine Production for Douro Region. Results for 2018 and 2019 highlights the vulnerability of the different sectors of Douro Region to dry and wet conditions, namely helping to analyze the impact of droughts on Douro wine production.</p><p>Acknowledgements: This study was performed within the framework of the LSA-SAF, co-funded by EUMETSAT This work was partially supported by national funds through FCT (Fundação para a Ciência e a Tecnologia, Portugal) under projects CLMALERT (ERA4CS/0005/2016).</p>

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