JOURNAL OF NANJING FORESTRY UNIVERSITY ›› 2020, Vol. 44 ›› Issue (3): 119-125.doi: 10.3969/j.issn.1000-2006.201904012

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Spatio‑temporal characteristics of grassland water use efficiency and its response to climate change in northwest China

CHANG Juan1(), ZHANG Zengxin1,2(), TIAN Jiaxi1, CHEN Xi2, CHEN Yizhao1   

  1. 1.Co -Innovation Center for the Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing 210037, China
    2.State Key Laboratory of Hydrology-Water Resources and Hydraulics Engineering, College of Hydrology and Water Resources, Hohai University, Nanjing 210098, China
  • Received:2019-04-08 Revised:2019-11-22 Online:2020-05-30 Published:2020-06-11
  • Contact: ZHANG Zengxin E-mail:changjuan1617@163.com;nfuzhang@163.com

Abstract: Objective

The dynamic changes of water use efficiency (WUE) in northwest China and its response to climate change are important to simulate the changing trends of the WUE under future climate change, which could provide a basis for water resources utilization and ecological environment construction in this region.

Method

The net primary productivity (NPP) and evapotranspiration (ET) data were simulated by the Lund-Potsdam-Jena dynamic global vegetation model (LPJ model) using air temperature, precipitation, cloud cover, and other data from northwest China during 1961-2013. The spatio-temporal dynamic changes of the grassland WUE and its response to climate change were then analyzed via correlation analysis and other methods.

Result

① The average annual NPP value of the grassland was 199.72 g/m2 in northwest China from 1961 to 2013, and the average annual ET value was 233.22 mm. The changes of the NPP and ET showed a spatial decreasing trend from southeast to northwest, and the changes of the NPP and ET for the grassland showed significant upward trends during this period. ② The average WUE per unit area of grassland was 0.61 g/(mm·m2) in northwest China from 1961 to 2013. The spatial distribution of the grassland WUE showed a decreasing trend from the east to the west in northwest China, while the grassland WUE in the northwestern region showed a significant upward trend during the past decades. ③ The grassland WUE in the northwestern China was positively correlated with the air temperature and precipitation, and the positive correlation was dominant. The WUE of the grassland increased significantly with the increase of air temperature and precipitation, and the impacts of air temperature on the grassland WUE was greater than those of precipitation.

Conclusion

The spatial distribution of WUE for the grassland in northwest China decreased from the east to the west. However, the WUE increased significantly, which was highly correlated with climate change and the WUE might increase with the increase of air temperature and precipitation increasing.

Key words: grassland, water use efficiency (WUE), climate change, Lund-Potsdam-Jena dynamic global vegetation (LPJ) model, northwest China

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