Fig 1 - uploaded by Hanqin Tian
Content may be subject to copyright.
Source publication
How terrestrial ecosystems respond to future environmental change in the 21st century is critically important for understanding the feedbacks of terrestrial ecosystems to global climate change. The southeastern United States (SEUS) has been one of the major regions acting as a carbon sink over the past century; yet it is unclear how its terrestrial...
Contexts in source publication
Context 1
... Coasts to more than 1,800 m in the Appalachian Mountains. Its longitude ranges from 758 W to 1008 W, and its latitude ranges from 308 N to 378 N. The summer seasons are relatively long, hot, and humid. The major vegetation types in this region are temperate coniferous forest and temperate deciduous forest, grassland, cropland, and shrubland ( Fig. ...
Context 2
... of Agriculture (USDA) Natural Resources Conservation Service, while the tex- ture information of each map unit was estimated using the USDA soil texture triangle (Miller and White 1998). Our contemporary vegetation map v www.esajournals.org shows the distribution of four natural plant functional groups of SEUS before human distur- bances ( Fig. 1), derived from GLC2000 at a resolution of 1 km ( Bartholome and Belward 2005). We reclassified the potential vegetation into ten general plant functional groups and replaced the cropland and urban area in the GLC2000 with the potential vegetation types from Ramankutty and Foley (1998). Water bodies were excluded from the vegetation map ...
Context 3
... ( Fig. 1), derived from GLC2000 at a resolution of 1 km ( Bartholome and Belward 2005). We reclassified the potential vegetation into ten general plant functional groups and replaced the cropland and urban area in the GLC2000 with the potential vegetation types from Ramankutty and Foley (1998). Water bodies were excluded from the vegetation map (Fig. 1). All of these input data were aggregated and re- projected to a spatial resolution at 8 km 3 8 ...
Context 4
... study region, the simulation driven by NCAR-climate conditions under the A1B scenar- io has the largest increase in carbon storage, with a 38% increase from the 2000s to the 2090s, while the simulation driven by GFDL-climate condi- tions under A2 scenario has the smallest increase in carbon storage, with a 16% increase from the 2000s to the 2090s (Fig. ...
Context 5
... nitrogen and elevated CO 2 could affect ecosystem functioning such as carbon fluxes at scales from stomata to regional (Farquhar et al. 1980, Melillo et al. 1993, Cramer et al. 2001, Thornton et al. 2002, Zeng et al. 2005). Over the time period of 2010-2099, we find that climate change contributes less to the increase in total carbon storage (Fig. 11D), as compared with elevated atmospheric CO 2 and N deposition (Fig. 4D). This is consistent with a previous study based on a multi-model analysis (Cramer et al. 2001). In that study, they reported that the global NPP continuously increased through the 2090s and attributed the increase to the CO 2 fertilization effect ( Cramer et al. ...
Context 6
... storage is simulated to increase from the 2000s to the 2090s, which is consistent across climate scenarios and climate models. However, this study does show large discrepancies in magnitude of carbon storage change among climate scenarios and climate models (Fig. 10). Also, the carbon storage differences among the climate scenarios are not consistent with the future policy scenarios. For example, the A2 scenario features the highest elevated CO 2 concentration which has a fertilization effect on vegetation growth; however the greatest simu- lated carbon sequestration occurs under the A1B scenario. ...
Similar publications
This work compares five precipitation datasets for South America, for the period 2000-2004, considering the meridional variation, the variation across the main continental watersheds (Amazonas, Tocantins, São Francisco, Orinoco, Paraná/Prata, in addition to the main Patagônia basins) and across the main vegetation types (tropical evergreen forest,...
We used a land surface model to quantify the causes and extents of biases in terrestrial gross primary production (GPP) due to the use of meteorological reanalysis datasets. We first calibrated the model using meteorology and eddy covariance data from 25 flux tower sites ranging from the tropics to the northern high-latitudes, and subsequently repe...
Citations
... This model has been extensively calibrated against various field data in typical vegetation types including forest, grassland, and cropland from the Chinese Ecological Research Network, the US Long-Term Ecological Research (LTER) sites, and the AmeriFlux network (Tian et al. 2010). The DLEM has been used to simulate the effects of climate variability and change, atmospheric CO 2 , tropospheric ozone, nitrogen deposition, and LULC change on the pools and fluxes of carbon and water in China (Ren et al. 2007, Tian et al. 2011a, b, Lu et al. 2012), the United States (Tian et al. 2010, Song et al. 2013) and North America (Xu et al. 2010 ). The detailed information on how DLEM simulates these processes are available in Tian et al. (2010). ...
In arid and semi-arid regions, grassland degradation has become a major environmental and economic problem, but little information is available on the response of grassland productivity to both climate change and grazing intensity. By developing a grazing module in a process-based ecosystem model, the dynamic land ecosystem model (DLEM), we explore the roles of climate change, elevated CO2, and varying grazing intensities in affecting aboveground net primary productivity (ANPP) across different grassland sites in Mongolia. Our results show that both growing season precipitation totals and average temperature exert important controls on annual ANPP across six sites over a precipitation gradient, explaining 65% and 45% of the interannual variations, respectively. Interannual variation in ANPP, measured as the ratio of standard deviation among years to long-term mean, increased from 9.5 to 18.9% to 23.9-32.5% along a gradient of high to low precipitation. Historical grazing resulted in a net reduction in ANPP across all sites ranging from 2% to 15.4%. Our results further show that grassland ANPP can be maintained at a grazing intensity of 1.0 and 0.5 sheep/ha at wet and dry sites, respectively, indicating that dry sites are more vulnerable to grazing compared to wet sites. In addition, precipitation use efficiency (PUE) decreased while nitrogen use efficiency (NUE) increased across a gradient of low to high precipitation. However, grazing resulted in a net reduction in both PUE and NUE by 47% and 67% across all sites. Our results indicate that seasonal precipitation totals, average temperatures and grazing are important regulators of grassland ANPP in Mongolia. These results have important implications for grassland productivity in semi-arid regions in Central Asia and beyond.
