scholarly journals Worldwide impacts of atmospheric vapor pressure deficit on the interannual variability of terrestrial carbon sinks

2021 ◽  
Author(s):  
Bin He ◽  
Chen Chen ◽  
Shangrong Lin ◽  
Wenping Yuan ◽  
Hans W Chen ◽  
...  
Keyword(s):  
Vapor Pressure ◽  
Interannual Variability ◽  
Environmental Variables ◽  
Vapor Pressure Deficit ◽  
Carbon Sink ◽  
Gross Primary Production ◽  
Terrestrial Ecosystem ◽  
Carbon Sinks ◽  
Terrestrial Carbon ◽  
Climate Conditions

Abstract Interannual variability of the terrestrial ecosystem carbon sink is substantially regulated by various environmental variables and highly dominates the interannual variation of atmospheric carbon dioxide (CO2) concentrations. Thus, it is necessary to determine dominating factors affecting the interannual variability of the carbon sink to improve our capability of predicting future terrestrial carbon sinks. Using global datasets derived from machine learning methods and process-based ecosystem models, this study reveals that the interannual variability of the atmospheric vapor pressure deficit (VPD) was significantly negatively correlated with net ecosystem production (NEP) and substantially impacted the interannual variability of the atmospheric CO2 growth rate (CGR). Further analyses found widespread constraints of VPD interannual variability on terrestrial gross primary production (GPP), causing VPD to impact NEP and CGR. Partial correlation analysis confirms the persistent and widespread impacts of VPD on terrestrial carbon sinks compared to other environmental variables. Current Earth system models underestimate the interannual variability in VPD and its impacts on GPP and NEP. Our results highlight the importance of VPD for terrestrial carbon sinks in assessing ecosystems’ responses to future climate conditions.

scholarly journals Increased atmospheric vapor pressure deficit reduces global vegetation growth

2019 ◽  
Vol 5 (8) ◽  
pp. eaax1396 ◽  
Author(s):  
Wenping Yuan ◽  
Yi Zheng ◽  
Shilong Piao ◽  
Philippe Ciais ◽  
Danica Lombardozzi ◽  
...  
Keyword(s):  
Vapor Pressure ◽  
Vapor Pressure Deficit ◽  
Vegetation Index ◽  
Global Climate ◽  
Gross Primary Production ◽  
Ecosystem Responses ◽  
Climate Conditions ◽  
Vegetation Growth ◽  
Current Century ◽  
Global Vegetation

Atmospheric vapor pressure deficit (VPD) is a critical variable in determining plant photosynthesis. Synthesis of four global climate datasets reveals a sharp increase of VPD after the late 1990s. In response, the vegetation greening trend indicated by a satellite-derived vegetation index (GIMMS3g), which was evident before the late 1990s, was subsequently stalled or reversed. Terrestrial gross primary production derived from two satellite-based models (revised EC-LUE and MODIS) exhibits persistent and widespread decreases after the late 1990s due to increased VPD, which offset the positive CO2 fertilization effect. Six Earth system models have consistently projected continuous increases of VPD throughout the current century. Our results highlight that the impacts of VPD on vegetation growth should be adequately considered to assess ecosystem responses to future climate conditions.

Amazon rainforest increases photosynthesis in reponse to atmospheric dryness

2020 ◽  
Author(s):  
Julia K. Green ◽  
Pierre Gentine ◽  
Yao Zhang ◽  
Joe Berry ◽  
Philippe Ciais
Keyword(s):  
Vapor Pressure ◽  
Vapor Pressure Deficit ◽  
Carbon Sink ◽  
Gross Primary Production ◽  
Remote Sensing Data ◽  
Amazon Rainforest ◽  
Machine Learning Techniques ◽  
Earth System ◽  
System Models ◽  
Earth System Models

<p>Earth system models predict that atmospheric dryness reduces photosynthesis due to its reductive effect on stomatal conductance. However, while this representation may be appropriate in many environments, in the wet Amazonian tropical rainforest, this is not the case. Using remote sensing data combined with machine learning techniques (k-means clustering and artificial neural networks), we show that in the wettest parts of the Amazon rainforest, gross primary production and evapotranspiration continue to increase alongside atmospheric dryness, i.e. vapor pressure deficit, despite reductions in ecosystem conductance. On the other hand, Earth system models have the opposite photosynthetic response to vapor pressure deficit in the wettest part of the Amazon, overestimating its reductive effect on tropical vegetation photosynthesis and evapotranspiration, leading to an exaggerated carbon source to the atmosphere. As vapor pressure deficit is expected to increase with climate change, our study highlights the importance of reframing how we understand and represent the response of ecosystem photosynthesis to atmospheric dryness in the wettest ecosystems, to accurately quantify the future land carbon sink and atmospheric CO2 growth rate.</p>

Moisture and heat advection as drivers of global ecosystem productivity

2020 ◽  
Author(s):  
Dominik L. Schumacher ◽  
Jessica Keune ◽  
Diego G. Miralles
Keyword(s):  
Primary Production ◽  
Interannual Variability ◽  
Carbon Sink ◽  
Gross Primary Production ◽  
Terrestrial Ecosystems ◽  
Ecosystem Productivity ◽  
Climate Conditions ◽  
Source Regions ◽  
Heat And Moisture ◽  
The Impact

<p>Terrestrial ecosystems play a key role in climate by dampening the increasing atmospheric CO<sub>2</sub> concentrations primarily caused by anthropogenic fossil fuel emissions. The capability of the land biosphere to act as a carbon sink largely depends on climate conditions, which determine the energy and water availability required by plants to grow. Even though only a small part of the global land area is covered by vegetation, the impact of extreme dry and wet seasons has been shown to largely drive the global interannual variability of gross primary production. The climate in a certain area can be seen as the balance of different heat and moisture fluxes: local surface–atmosphere fluxes from below, entrainment of heat and moisture from aloft, and ‘horizontal’ advection of heat and moisture from upwind regions. The latter provides a mechanism for remote regions to impact gross primary production downwind, and has received less scientific attention. Here, advection is inferred from a bird’s eye perspective, focussing on the five ecoregions with the largest interannual variability in peak productivity around the globe. Employing the atmospheric Lagrangian trajectory model FLEXPART, driven by ERA-Interim reanalysis data, we track the air residing over ecoregions back in time to deduce the origins of heat and moisture that affect ecosystem gross primary production. Utilizing the evaporative source regions supplying water for precipitation to these ecosystems, as well as the analogous source regions of advected heat, we estimate the contribution of advection to gross primary production. Our findings show that source regions of heat and moisture are not congruent: upwind land surfaces typically supply most of the advected heat, whereas upwind oceans tend to provide more moisture. Moreover, low gross primary production in heat-stressed and water-limited ecosystems is often accompanied by enhanced heat and reduced moisture advection from land regions, exacerbated by upwind land–atmosphere feedbacks. These results demonstrate that anomalies in atmospheric advection can cause ecosystem productivity extremes. Particularly in light of ongoing climate change, we emphasize the potentially detrimental effects of upwind areas that may cause long-lasting impacts on the terrestrial carbon budget, thereby further affecting the climate.</p>

scholarly journals Projected increases in intensity, frequency, and terrestrial carbon costs of compound drought and aridity events

2019 ◽  
Vol 5 (1) ◽  
pp. eaau5740 ◽  
Author(s):  
Sha Zhou ◽  
Yao Zhang ◽  
A. Park Williams ◽  
Pierre Gentine
Keyword(s):  
Vapor Pressure Deficit ◽  
Carbon Sink ◽  
Terrestrial Carbon ◽  
Negative Effects ◽  
Compound Events ◽  
High Vapor ◽  
In Situ Observations ◽  
Earth System Models ◽  
Very High

Drought and atmospheric aridity pose large risks to ecosystem services and agricultural production. However, these factors are seldom assessed together as compound events, although they often occur simultaneously. Drought stress on terrestrial carbon uptake is characterized by soil moisture (SM) deficit and high vapor pressure deficit (VPD). We used in situ observations and 15 Earth system models to show that compound events with very high VPD and low SM occur more frequently than expected if these events were independent. These compound events are projected to become more frequent and more extreme and exert increasingly negative effects on continental productivity. Models project intensified negative effects of high VPD and low SM on vegetation productivity, with the intensification of SM exceeding those of VPD in the Northern Hemisphere. These results highlight the importance of compound extreme events and their threats for the capability of continents to act as a carbon sink.

scholarly journals Interactive Impacts of Fire and Vegetation Dynamics on Global Carbon and Water Budgets using Community Land Model version 4.5

2018 ◽  
Author(s):  
Hocheol Seo ◽  
Yeonjoo Kim
Keyword(s):  
Land Surface ◽  
Vegetation Dynamics ◽  
Carbon Sink ◽  
Vegetation Type ◽  
Water Fluxes ◽  
Carbon Sinks ◽  
Terrestrial Carbon ◽  
Moisture Profile ◽  
Community Land Model ◽  
Model Version

Abstract. Fire plays an important role in terrestrial ecosystems. The burning of biomass affects carbon and water fluxes and the distribution of vegetation. To understand the effect of the interactive processes of fire and ecological succession on land surface carbon and water fluxes, this study utilized the Community Land Model version 4.5 to conduct a series of experiments that included and excluded fire and dynamic vegetation processes. Results of the experiments that excluded dynamic vegetation showed a global increase in net ecosystem production (NEP) in post-fire regions, which has been shown in previous studies with the similar modeling practices. However, inclusion of dynamic vegetation revealed a fire-induced decrease in NEP in some regions. Additionally, the carbon sink in post-fire regions reduced when the dominant vegetation type was changed from trees to grasses. This study shows that inclusion of dynamic vegetation enhances carbon emissions from fire by reducing terrestrial carbon sinks; however, this effect is somewhat mitigated by the increase in terrestrial carbon sinks when dynamic vegetation is not used. Results also show that fire-induced changes in vegetation modify the soil moisture profile because grasslands are more dominant in post-fire regions; this results in less moisture within top soil layers compared to non-burned regions, even though transpiration is reduced overall. These findings are different from those of previous fire model evaluations, that ignore vegetation dynamics, and thus highlight the importance of interactive processes between fire and vegetation dynamics, particularly when evaluating recent model developments with respect to fire and vegetation dynamics.

scholarly journals Sub-grid scale representation of vegetation in global land surface schemes: implications for estimation of the terrestrial carbon sink

2013 ◽  
Vol 10 (10) ◽  
pp. 16003-16041 ◽  
Author(s):  
J. R. Melton ◽  
V. K. Arora
Keyword(s):  
Water Balance ◽  
Environmental Conditions ◽  
Land Surface ◽  
Carbon Balance ◽  
Spatial Representation ◽  
Carbon Sink ◽  
Terrestrial Ecosystem ◽  
Terrestrial Carbon ◽  
Global Land ◽  
Terrestrial Carbon Sink

Abstract. Terrestrial ecosystem models commonly represent vegetation in terms of plant functional types (PFTs) and use their vegetation attributes in calculations of the energy and water balance and to investigate the terrestrial carbon cycle. To accomplish these tasks, two approaches for PFT spatial representation are widely used: "composite" and "mosaic". The impact of these two approaches on the global carbon balance has been investigated with the Canadian Terrestrial Ecosystem Model (CTEM v 1.2) coupled to the Canadian Land Surface Scheme (CLASS v 3.6). In the composite (single-tile) approach, the vegetation attributes of different PFTs present in a grid cell are aggregated and used in calculations to determine the resulting physical environmental conditions (soil moisture, soil temperature, etc.) that are common to all PFTs. In the mosaic (multi-tile) approach, energy and water balance calculations are performed separately for each PFT tile and each tile's physical land surface environmental conditions evolve independently. Pre-industrial equilibrium CLASS-CTEM simulations yield global totals of vegetation biomass, net primary productivity, and soil carbon that compare reasonably well with observation-based estimates and differ by less than 5% between the mosaic and composite configurations. However, on a regional scale the two approaches can differ by > 30%, especially in areas with high heterogeneity in land cover. Simulations over the historical period (1959–2005) show different responses to evolving climate and carbon dioxide concentrations from the two approaches. The cumulative global terrestrial carbon sink estimated over the 1959–2005 period (excluding land use change (LUC) effects) differs by around 5% between the two approaches (96.3 and 101.3 Pg, for the mosaic and composite approaches, respectively) and compares well with the observation-based estimate of 82.2 ± 35 Pg C over the same period. Inclusion of LUC causes the estimates of the terrestrial C sink to differ by 15.2 Pg C (16%) with values of 95.1 and 79.9 Pg C for the mosaic and composite approaches, respectively. Spatial differences in simulated vegetation and soil carbon and the manner in which terrestrial carbon balance evolves in response to LUC, in the two approaches, yields a substantially different estimate of the global land carbon sink. These results demonstrate that the spatial representation of vegetation has an important impact on the model response to changing climate, atmospheric CO2 concentrations, and land cover.

scholarly journals Nested atmospheric inversion for the terrestrial carbon sources and sinks in China

2013 ◽  
Vol 10 (1) ◽  
pp. 1177-1205
Author(s):  
F. Jiang ◽  
H. Wang ◽  
J. M. Chen ◽  
W. Ju ◽  
A. Ding
Keyword(s):  
Atmospheric Transport ◽  
Southern Oscillation ◽  
Carbon Sink ◽  
Carbon Sources ◽  
Measurement Data ◽  
Strong Relationship ◽  
Horizontal Resolution ◽  
Carbon Sinks ◽  
Terrestrial Carbon ◽  
Atmospheric Inversion

Abstract. In this study, we establish a~nested atmospheric inversion system with a focus on China using the Bayes theory. The global surface is separated into 43 regions based on the 22 TransCom large regions, with 13 small regions in China. Monthly CO2 concentrations from 130 GlobalView sites and a Hong Kong site are used in this system. The core component of this system is atmospheric transport matrix, which is created using the TM5 model with a horizontal resolution of 3° × 2°. The net carbon fluxes over the 43 global land and ocean regions are inverted for the period from 2002 to 2009. The inverted global terrestrial carbon sinks mainly occur in Boreal Asia, South and Southeast Asia, eastern US and southern South America (SA). Most China areas appear to be carbon sinks, with strongest carbon sinks located in Northeast China. From 2002 to 2009, the global terrestrial carbon sink has an increasing trend, with the lowest carbon sink in 2002. The inter-annual variation (IAV) of the land sinks shows remarkable correlation with the El Niño Southern Oscillation (ENSO). However, no obvious trend is found for the terrestrial carbon sinks in China. The IAVs of carbon sinks in China show strong relationship with drought and temperature. The mean global and China terrestrial carbon sinks over the period 2002–2009 are −3.15 ± 1.48 and −0.21 ± 0.23 Pg C yr−1, respectively. The uncertainties in the posterior carbon flux of China are still very large, mostly due to the lack of CO2 measurement data in China.

scholarly journals Carbon balance of China constrained by CONTRAIL aircraft CO<sub>2</sub> measurements

2014 ◽  
Vol 14 (18) ◽  
pp. 10133-10144 ◽  
Author(s):  
F. Jiang ◽  
H. M. Wang ◽  
J. M. Chen ◽  
T. Machida ◽  
L. X. Zhou ◽  
...  
Keyword(s):  
Transport Model ◽  
Carbon Sink ◽  
Terrestrial Ecosystem ◽  
Co2 Flux ◽  
Co2 Concentration ◽  
Atmospheric Co2 ◽  
Inversion Method ◽  
Climate Factors ◽  
Terrestrial Carbon ◽  
Atmospheric Co2 Concentrations

Abstract. Terrestrial carbon dioxide (CO2) flux estimates in China using atmospheric inversion method are beset with considerable uncertainties because very few atmospheric CO2 concentration measurements are available. In order to improve these estimates, nested atmospheric CO2 inversion during 2002–2008 is performed in this study using passenger aircraft-based CO2 measurements over Eurasia from the Comprehensive Observation Network for Trace gases by Airliner (CONTRAIL) project. The inversion system includes 43 regions with a focus on China, and is based on the Bayesian synthesis approach and the TM5 transport model. The terrestrial ecosystem carbon flux modeled by the Boreal Ecosystems Productivity Simulator (BEPS) model and the ocean exchange simulated by the OPA-PISCES-T model are considered as the prior fluxes. The impacts of CONTRAIL CO2 data on inverted China terrestrial carbon fluxes are quantified, the improvement of the inverted fluxes after adding CONTRAIL CO2 data are rationed against climate factors and evaluated by comparing the simulated atmospheric CO2 concentrations with three independent surface CO2 measurements in China. Results show that with the addition of CONTRAIL CO2 data, the inverted carbon sink in China increases while those in South and Southeast Asia decrease. Meanwhile, the posterior uncertainties over these regions are all reduced (2–12%). CONTRAIL CO2 data also have a large effect on the inter-annual variation of carbon sinks in China, leading to a better correlation between the carbon sink and the annual mean climate factors. Evaluations against the CO2 measurements at three sites in China also show that the CONTRAIL CO2 measurements may have improved the inversion results.

scholarly journals Ecophysiological Vulnerability to Climate Change in Mexico City’s Urban Forest

2021 ◽  
Vol 9 ◽  
Author(s):  
Victor L. Barradas ◽  
Manuel Esperon-Rodriguez
Keyword(s):  
Climate Change ◽  
Stomatal Conductance ◽  
Vapor Pressure ◽  
Water Potential ◽  
Tree Species ◽  
Environmental Variables ◽  
Vapor Pressure Deficit ◽  
Urban Forest ◽  
Urban Climate ◽  
Vulnerability To Climate Change

Urban forests play an important role in regulating urban climate while providing multiple environmental services. These forests, however, are threatened by changes in climate, as plants are exposed not only to global climate change but also to urban climate, having an impact on physiological functions. Here, we selected two physiological variables (stomatal conductance and leaf water potential) and four environmental variables (air temperature, photosynthetically active radiation, vapor pressure deficit, and water availability) to compare and evaluate the ecophysiological vulnerability to climate change of 15 dominant tree species from Mexico City’s urban forest. The stomatal conductance response was evaluated using the boundary-line analysis, which allowed us to compare the stomatal response to changes in the environment among species. Our results showed differential species responses to the environmental variables and identified Buddleja cordata and Populus deltoides as the least and most vulnerable species, respectively. Air temperatures above 33°C and vapor pressure deficit above 3.5 kPa limited the stomatal function of all species. Stomatal conductance was more sensitive to changes in leaf water potential, followed by vapor pressure deficit, indicating that water is a key factor for tree species performance in Mexico City’s urban forest. Our findings can help to optimize species selection considering future climate change by identifying vulnerable and resilient species.

scholarly journals Sub-grid scale representation of vegetation in global land surface schemes: implications for estimation of the terrestrial carbon sink

2014 ◽  
Vol 11 (4) ◽  
pp. 1021-1036 ◽  
Author(s):  
J. R. Melton ◽  
V. K. Arora
Keyword(s):  
Land Cover ◽  
Water Balance ◽  
Environmental Conditions ◽  
Land Surface ◽  
Carbon Balance ◽  
Carbon Sink ◽  
Terrestrial Ecosystem ◽  
Terrestrial Carbon ◽  
Global Land ◽  
Terrestrial Carbon Sink

Abstract. Terrestrial ecosystem models commonly represent vegetation in terms of plant functional types (PFTs) and use their vegetation attributes in calculations of the energy and water balance as well as to investigate the terrestrial carbon cycle. Sub-grid scale variability of PFTs in these models is represented using different approaches with the "composite" and "mosaic" approaches being the two end-members. The impact of these two approaches on the global carbon balance has been investigated with the Canadian Terrestrial Ecosystem Model (CTEM v 1.2) coupled to the Canadian Land Surface Scheme (CLASS v 3.6). In the composite (single-tile) approach, the vegetation attributes of different PFTs present in a grid cell are aggregated and used in calculations to determine the resulting physical environmental conditions (soil moisture, soil temperature, etc.) that are common to all PFTs. In the mosaic (multi-tile) approach, energy and water balance calculations are performed separately for each PFT tile and each tile's physical land surface environmental conditions evolve independently. Pre-industrial equilibrium CLASS-CTEM simulations yield global totals of vegetation biomass, net primary productivity, and soil carbon that compare reasonably well with observation-based estimates and differ by less than 5% between the mosaic and composite configurations. However, on a regional scale the two approaches can differ by > 30%, especially in areas with high heterogeneity in land cover. Simulations over the historical period (1959–2005) show different responses to evolving climate and carbon dioxide concentrations from the two approaches. The cumulative global terrestrial carbon sink estimated over the 1959–2005 period (excluding land use change (LUC) effects) differs by around 5% between the two approaches (96.3 and 101.3 Pg, for the mosaic and composite approaches, respectively) and compares well with the observation-based estimate of 82.2 ± 35 Pg C over the same period. Inclusion of LUC causes the estimates of the terrestrial C sink to differ by 15.2 Pg C (16%) with values of 95.1 and 79.9 Pg C for the mosaic and composite approaches, respectively. Spatial differences in simulated vegetation and soil carbon and the manner in which terrestrial carbon balance evolves in response to LUC, in the two approaches, yields a substantially different estimate of the global land carbon sink. These results demonstrate that the spatial representation of vegetation has an important impact on the model response to changing climate, atmospheric CO2 concentrations, and land cover.

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