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Water use efficiency of China's terrestrial ecosystems and responses to drought.

Liu Y, Xiao J, Ju W, Zhou Y, Wang S, Wu X - Sci Rep (2015)

Bottom Line: Droughts usually increased annual WUE in Northeast China and central Inner Mongolia but decreased annual WUE in central China. "Turning-points" were observed for southern China where moderate and extreme droughts reduced annual WUE and severe drought slightly increased annual WUE.The cumulative lagged effect of drought on monthly WUE varied by region.WUE is expected to continue to change under future climate change particularly as drought is projected to increase in both frequency and severity.

View Article: PubMed Central - PubMed

Affiliation: Jiangsu Key Laboratory of Agricultural Meteorology, School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing, 210044, China.

ABSTRACT
Water use efficiency (WUE) measures the trade-off between carbon gain and water loss of terrestrial ecosystems, and better understanding its dynamics and controlling factors is essential for predicting ecosystem responses to climate change. We assessed the magnitude, spatial patterns, and trends of WUE of China's terrestrial ecosystems and its responses to drought using a process-based ecosystem model. During the period from 2000 to 2011, the national average annual WUE (net primary productivity (NPP)/evapotranspiration (ET)) of China was 0.79 g C kg(-1) H2O. Annual WUE decreased in the southern regions because of the decrease in NPP and the increase in ET and increased in most northern regions mainly because of the increase in NPP. Droughts usually increased annual WUE in Northeast China and central Inner Mongolia but decreased annual WUE in central China. "Turning-points" were observed for southern China where moderate and extreme droughts reduced annual WUE and severe drought slightly increased annual WUE. The cumulative lagged effect of drought on monthly WUE varied by region. Our findings have implications for ecosystem management and climate policy making. WUE is expected to continue to change under future climate change particularly as drought is projected to increase in both frequency and severity.

No MeSH data available.


Related in: MedlinePlus

The spatial distributions of annual WUE anomalies (%) in 2001 (a), 2006 (b), 2009 (c) and 2011 (d) relative to the 12-year mean over the period 2000-2011 means, respectively. This figure was produced using ArcGIS 10.0.
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f4: The spatial distributions of annual WUE anomalies (%) in 2001 (a), 2006 (b), 2009 (c) and 2011 (d) relative to the 12-year mean over the period 2000-2011 means, respectively. This figure was produced using ArcGIS 10.0.

Mentions: Over the 12-year period from 2000 to 2011, the years of 2001, 2006, 2009, and 2011 were dry years for China28. WUE exhibited different responses to droughts (Figs 4 and S5). In 2001, droughts occurred in most of northern China, such as Inner Mongolia, Northeast China, and North China, and Central China28. Mild autumn drought in the east of Northeast China led to slight increases in annual WUE (less than 4%). Annual WUE also increased in central Inner Mongolia during moderate summer droughts. In northern Inner Mongolia suffered from mild and moderate drought in summer and autumn, however, annual WUE decreased about 16% (Fig. 4). Moderate to severe droughts in North China decreased annual WUE by more than 20%. Severe drought in the north of Northeast China did not result in significant changes in annual WUE likely because the drought led to similar reduction in annual NPP and ET (Figs 4 and S5). In this region, temperature is also a dominant controlling factor of vegetation growth, and the enhancement on NPP and ET by temperature increase during the drought period might partly offset the decrease of NPP and ET induced by water stress. Droughts hitting central China in 2006 were mostly mild28 and mainly occurred in summer and autumn. Annual WUE decreased by more than 16% in northern Central China, central Southeast China, and southern Tibetan Plateau. Moderate summer drought occurred in regions around Chongqing decreased annual WUE by about 8% (Fig. 4). By contrast, annual WUE increased in the north of North China affected by mild autumn drought. In mid drought-hit regions of Inner Mongolia and North China, annual WUE increased by more than 20%. In 2009, mild to moderate droughts affected a large portion of China. Inner Mongolia and Northeast China were hit by droughts in spring and summer while the south of Southwest China was affected by droughts in autumn and winter. These droughts induced a larger decrease in NPP than in ET, leading to a decrease in annual WUE by 16–20% (Fig. 4). In contrast, summer drought-induced reduction in ET was larger than the decline in NPP across the Northwest China, leading to increases in annual WUE (Figs 4 and S5). In Tibetan Plateau, mild to moderate droughts in summer and autumn increased annual WUE in the north and decreased WUE in the southeast (Fig. 4). The drought in 2011 was perhaps the most severe one over the last five decades. The southern half of the country experienced moderate to extreme droughts in spring and winter28. The droughts in Southwest, Central, Southeast, and South China resulted in similar reduction in NPP and ET, and therefore there were no large changes in annual WUE (Figs 4 and S5). The extreme spring and summer droughts hitting Yunnan and Jiangxi provinces caused slight reduction in annual WUE (by ∼10%). Mild and moderate autumn drought occurring in Northeast China and central Inner Mongolia increased annual WUE by ∼8% (Figs 4 and S5).


Water use efficiency of China's terrestrial ecosystems and responses to drought.

Liu Y, Xiao J, Ju W, Zhou Y, Wang S, Wu X - Sci Rep (2015)

The spatial distributions of annual WUE anomalies (%) in 2001 (a), 2006 (b), 2009 (c) and 2011 (d) relative to the 12-year mean over the period 2000-2011 means, respectively. This figure was produced using ArcGIS 10.0.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4562296&req=5

f4: The spatial distributions of annual WUE anomalies (%) in 2001 (a), 2006 (b), 2009 (c) and 2011 (d) relative to the 12-year mean over the period 2000-2011 means, respectively. This figure was produced using ArcGIS 10.0.
Mentions: Over the 12-year period from 2000 to 2011, the years of 2001, 2006, 2009, and 2011 were dry years for China28. WUE exhibited different responses to droughts (Figs 4 and S5). In 2001, droughts occurred in most of northern China, such as Inner Mongolia, Northeast China, and North China, and Central China28. Mild autumn drought in the east of Northeast China led to slight increases in annual WUE (less than 4%). Annual WUE also increased in central Inner Mongolia during moderate summer droughts. In northern Inner Mongolia suffered from mild and moderate drought in summer and autumn, however, annual WUE decreased about 16% (Fig. 4). Moderate to severe droughts in North China decreased annual WUE by more than 20%. Severe drought in the north of Northeast China did not result in significant changes in annual WUE likely because the drought led to similar reduction in annual NPP and ET (Figs 4 and S5). In this region, temperature is also a dominant controlling factor of vegetation growth, and the enhancement on NPP and ET by temperature increase during the drought period might partly offset the decrease of NPP and ET induced by water stress. Droughts hitting central China in 2006 were mostly mild28 and mainly occurred in summer and autumn. Annual WUE decreased by more than 16% in northern Central China, central Southeast China, and southern Tibetan Plateau. Moderate summer drought occurred in regions around Chongqing decreased annual WUE by about 8% (Fig. 4). By contrast, annual WUE increased in the north of North China affected by mild autumn drought. In mid drought-hit regions of Inner Mongolia and North China, annual WUE increased by more than 20%. In 2009, mild to moderate droughts affected a large portion of China. Inner Mongolia and Northeast China were hit by droughts in spring and summer while the south of Southwest China was affected by droughts in autumn and winter. These droughts induced a larger decrease in NPP than in ET, leading to a decrease in annual WUE by 16–20% (Fig. 4). In contrast, summer drought-induced reduction in ET was larger than the decline in NPP across the Northwest China, leading to increases in annual WUE (Figs 4 and S5). In Tibetan Plateau, mild to moderate droughts in summer and autumn increased annual WUE in the north and decreased WUE in the southeast (Fig. 4). The drought in 2011 was perhaps the most severe one over the last five decades. The southern half of the country experienced moderate to extreme droughts in spring and winter28. The droughts in Southwest, Central, Southeast, and South China resulted in similar reduction in NPP and ET, and therefore there were no large changes in annual WUE (Figs 4 and S5). The extreme spring and summer droughts hitting Yunnan and Jiangxi provinces caused slight reduction in annual WUE (by ∼10%). Mild and moderate autumn drought occurring in Northeast China and central Inner Mongolia increased annual WUE by ∼8% (Figs 4 and S5).

Bottom Line: Droughts usually increased annual WUE in Northeast China and central Inner Mongolia but decreased annual WUE in central China. "Turning-points" were observed for southern China where moderate and extreme droughts reduced annual WUE and severe drought slightly increased annual WUE.The cumulative lagged effect of drought on monthly WUE varied by region.WUE is expected to continue to change under future climate change particularly as drought is projected to increase in both frequency and severity.

View Article: PubMed Central - PubMed

Affiliation: Jiangsu Key Laboratory of Agricultural Meteorology, School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing, 210044, China.

ABSTRACT
Water use efficiency (WUE) measures the trade-off between carbon gain and water loss of terrestrial ecosystems, and better understanding its dynamics and controlling factors is essential for predicting ecosystem responses to climate change. We assessed the magnitude, spatial patterns, and trends of WUE of China's terrestrial ecosystems and its responses to drought using a process-based ecosystem model. During the period from 2000 to 2011, the national average annual WUE (net primary productivity (NPP)/evapotranspiration (ET)) of China was 0.79 g C kg(-1) H2O. Annual WUE decreased in the southern regions because of the decrease in NPP and the increase in ET and increased in most northern regions mainly because of the increase in NPP. Droughts usually increased annual WUE in Northeast China and central Inner Mongolia but decreased annual WUE in central China. "Turning-points" were observed for southern China where moderate and extreme droughts reduced annual WUE and severe drought slightly increased annual WUE. The cumulative lagged effect of drought on monthly WUE varied by region. Our findings have implications for ecosystem management and climate policy making. WUE is expected to continue to change under future climate change particularly as drought is projected to increase in both frequency and severity.

No MeSH data available.


Related in: MedlinePlus