scholarly journals Twentieth-Century Droughts and Their Impacts on Terrestrial Carbon Cycling in China

2009 ◽  
Vol 13 (10) ◽  
pp. 1-31 ◽  
Author(s):  
Jingfeng Xiao ◽  
Qianlai Zhuang ◽  
Eryuan Liang ◽  
Xuemei Shao ◽  
A. David McGuire ◽  
...  
Keyword(s):  
Twentieth Century ◽  
Carbon Cycling ◽  
Carbon Balance ◽  
Carbon Sink ◽  
Ring Width ◽  
Terrestrial Ecosystems ◽  
Terrestrial Carbon ◽  
Terrestrial Ecosystem Model ◽  
Terrestrial Carbon Sink ◽  
Drought Effects

Abstract Midlatitude regions experienced frequent droughts during the twentieth century, but their impacts on terrestrial carbon balance are unclear. This paper presents a century-scale study of drought effects on the carbon balance of terrestrial ecosystems in China. The authors first characterized the severe extended droughts over the period 1901–2002 using the Palmer drought severity index and then examined how these droughts affected the terrestrial carbon dynamics using tree-ring width chronologies and a process-based biogeochemistry model, the Terrestrial Ecosystem Model (TEM). It is found that China suffered from a series of severe extended droughts during the twentieth century. The major drought periods included 1920–30, 1939–47, 1956–58, 1960–63, 1965–68, 1978–80, and 1999–2002. Most droughts generally reduced net primary productivity (NPP) and net ecosystem productivity (NEP) in large parts of drought-affected areas. Moreover, some of the droughts substantially reduced the countrywide annual NPP and NEP. Out of the seven droughts, three (1920–30, 1965–68, and 1978–80) caused the countrywide terrestrial ecosystems to switch from a carbon sink to a source, and one (1960–63) substantially reduced the magnitude of the countrywide terrestrial carbon sink. Strong decreases in NPP were mainly responsible for the anomalies in annual NEP during these drought periods. Changes in heterotrophic respiration happened in the same direction, but mostly with smaller magnitude. The results show that severe extended droughts had significant effects on terrestrial carbon cycling in China, although future studies should consider other important processes such as drought-induced mortality and regrowth, land-use change, disturbances (e.g., fire), human management (e.g., fertilization and irrigation), and environmental pollution (e.g., ozone pollution, nitrogen deposition). These drought effects are of particular importance in light of projected widespread summer drying in midlatitude regions during the twenty-first century. Future droughts could lead to a reduced terrestrial carbon sink or even a source and exert a positive feedback to the global climate system.

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 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.

scholarly journals Recent pause in the growth rate of atmospheric CO2 due to enhanced terrestrial carbon uptake

2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Trevor F Keenan ◽  
I. Colin Prentice ◽  
Josep G Canadell ◽  
Christopher A Williams ◽  
Han Wang ◽  
...  
Keyword(s):  
Growth Rate ◽  
Carbon Sink ◽  
Large Fraction ◽  
Terrestrial Ecosystems ◽  
Anthropogenic Emissions ◽  
Terrestrial Carbon ◽  
Vegetation Models ◽  
Terrestrial Carbon Sink ◽  
Global Vegetation ◽  
Global Carbon

Abstract Terrestrial ecosystems play a significant role in the global carbon cycle and offset a large fraction of anthropogenic CO2 emissions. The terrestrial carbon sink is increasing, yet the mechanisms responsible for its enhancement, and implications for the growth rate of atmospheric CO2, remain unclear. Here using global carbon budget estimates, ground, atmospheric and satellite observations, and multiple global vegetation models, we report a recent pause in the growth rate of atmospheric CO2, and a decline in the fraction of anthropogenic emissions that remain in the atmosphere, despite increasing anthropogenic emissions. We attribute the observed decline to increases in the terrestrial sink during the past decade, associated with the effects of rising atmospheric CO2 on vegetation and the slowdown in the rate of warming on global respiration. The pause in the atmospheric CO2 growth rate provides further evidence of the roles of CO2 fertilization and warming-induced respiration, and highlights the need to protect both existing carbon stocks and regions, where the sink is growing rapidly.

scholarly journals The carbon budget of terrestrial ecosystems in East Asia over the last two decades

2012 ◽  
Vol 9 (9) ◽  
pp. 3571-3586 ◽  
Author(s):  
S. L. Piao ◽  
A. Ito ◽  
S. G. Li ◽  
Y. Huang ◽  
P. Ciais ◽  
...  
Keyword(s):  
Climate Change ◽  
Carbon Cycle ◽  
East Asia ◽  
Carbon Storage ◽  
Carbon Balance ◽  
Carbon Sink ◽  
Regional Scale ◽  
Terrestrial Ecosystems ◽  
Carbon Accumulation ◽  
Terrestrial Carbon

Abstract. This REgional Carbon Cycle Assessment and Processes regional study provides a synthesis of the carbon balance of terrestrial ecosystems in East Asia, a region comprised of China, Japan, North and South Korea, and Mongolia. We estimate the current terrestrial carbon balance of East Asia and its driving mechanisms during 1990–2009 using three different approaches: inventories combined with satellite greenness measurements, terrestrial ecosystem carbon cycle models and atmospheric inversion models. The magnitudes of East Asia's terrestrial carbon sink from these three approaches are comparable: −0.293±0.033 PgC yr−1 from inventory–remote sensing model–data fusion approach, −0.413±0.141 PgC yr−1 (not considering biofuel emissions) or −0.224±0.141 PgC yr−1 (considering biofuel emissions) for carbon cycle models, and −0.270±0.507 PgC yr−1 for atmospheric inverse models. Here and in the following, the numbers behind ± signs are standard deviations. The ensemble of ecosystem modeling based analyses further suggests that at the regional scale, climate change and rising atmospheric CO2 together resulted in a carbon sink of −0.289±0.135 PgC yr−1, while land-use change and nitrogen deposition had a contribution of −0.013±0.029 PgC yr−1 and −0.107±0.025 PgC yr−1, respectively. Although the magnitude of climate change effects on the carbon balance varies among different models, all models agree that in response to climate change alone, southern China experienced an increase in carbon storage from 1990 to 2009, while northern East Asia including Mongolia and north China showed a decrease in carbon storage. Overall, our results suggest that about 13–27% of East Asia's CO2 emissions from fossil fuel burning have been offset by carbon accumulation in its terrestrial territory over the period from 1990 to 2009. The underlying mechanisms of carbon sink over East Asia still remain largely uncertain, given the diversity and intensity of land management processes, and the regional conjunction of many drivers such as nutrient deposition, climate, atmospheric pollution and CO2 changes, which cannot be considered as independent for their effects on carbon storage.

scholarly journals The Significance of the Erosion-induced Terrestrial Carbon Sink

BioScience ◽  
2007 ◽  
Vol 57 (4) ◽  
pp. 337-346 ◽  
Author(s):  
Asmeret Asefaw Berhe ◽  
John Harte ◽  
Jennifer W. Harden ◽  
Margaret S. Torn
Keyword(s):  
Carbon Sink ◽  
Terrestrial Carbon ◽  
Terrestrial Carbon Sink

Saturation of the Terrestrial Carbon Sink

2007 ◽  
pp. 59-78 ◽  
Author(s):  
Josep G. Canadell ◽  
Diane E. Pataki ◽  
Roger Gifford ◽  
Richard A. Houghton ◽  
Yiqi Luo ◽  
...  
Keyword(s):  
Carbon Sink ◽  
Terrestrial Carbon ◽  
Terrestrial Carbon Sink

scholarly journals Field-experiment constraints on the enhancement of the terrestrial carbon sink by CO2 fertilization

2019 ◽  
Vol 12 (10) ◽  
pp. 809-814 ◽  
Author(s):  
Yongwen Liu ◽  
Shilong Piao ◽  
Thomas Gasser ◽  
Philippe Ciais ◽  
Hui Yang ◽  
...  
Keyword(s):  
Field Experiment ◽  
Carbon Sink ◽  
Terrestrial Carbon ◽  
Co2 Fertilization ◽  
Terrestrial Carbon Sink

CO2 stabilization, climate change and the terrestrial carbon sink

2000 ◽  
Vol 6 (7) ◽  
pp. 817-833 ◽  
Author(s):  
Andrew White ◽  
Melvin G. R. Cannell ◽  
Andrew D. Friend
Keyword(s):  
Climate Change ◽  
Carbon Sink ◽  
Terrestrial Carbon ◽  
Terrestrial Carbon Sink

scholarly journals Soil nitrogen cycle unresponsive to decadal long climate change in a Tasmanian grassland

2019 ◽  
Vol 147 (1) ◽  
pp. 99-107 ◽  
Author(s):  
Tobias Rütting ◽  
Mark J. Hovenden
Keyword(s):  
Climate Change ◽  
Atmospheric Carbon Dioxide ◽  
Carbon Sink ◽  
Vegetation Type ◽  
Terrestrial Ecosystems ◽  
Soil N ◽  
Mineral N ◽  
N Dynamics ◽  
Terrestrial Carbon Sink ◽  
Soil Nitrogen Cycle

AbstractIncreases in atmospheric carbon dioxide (CO2) and global air temperature affect all terrestrial ecosystems and often lead to enhanced ecosystem productivity, which in turn dampens the rise in atmospheric CO2 by removing CO2 from the atmosphere. As most terrestrial ecosystems are limited in their productivity by the availability of nitrogen (N), there is concern about the persistence of this terrestrial carbon sink, as these ecosystems might develop a progressive N limitation (PNL). An increase in the gross soil N turnover may alleviate PNL, as more mineral N is made available for plant uptake. So far, climate change experiments have mainly manipulated one climatic factor only, but there is evidence that single-factor experiments usually overestimate the effects of climate change on terrestrial ecosystems. In this study, we investigated how simultaneous, decadal-long increases in CO2 and temperature affect the soil gross N dynamics in a native Tasmanian grassland under C3 and C4 vegetation. Our laboratory 15N labeling experiment showed that average gross N mineralization ranged from 4.9 to 11.3 µg N g−1 day−1 across the treatment combinations, while gross nitrification was about ten-times lower. Considering all treatment combinations, no significant effect of climatic treatments or vegetation type (C3 versus C4 grasses) on soil N cycling was observed.

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