Dynamic of grassland vegetation degradation and its quantitative assessment in the northwest China

Grasslands, one of the most widespread land cover types in China, are of great importance to natural environmental protection and socioeconomic development. An accurate quantitative assessment of the effects of inter-annual climate change and human activities on grassland productivity has great theoretical significance to understanding the driving mechanisms of grassland degradation. Net primary productivity (NPP) was selected as an indicator for analyzing grassland vegetation dynamics from 2001 to 2010. Potential NPP and the difference between potential NPP and actual NPP were used to represent the effects of climate and human factors, respectively, on grassland degradation. The results showed that 61.49% of grassland areas underwent degradation, whereas only 38.51% exhibited restoration. In addition, 65.75% of grassland degradation was caused by human activities whereas 19.94% was caused by inter-annual climate change. By contrast, 32.32% of grassland restoration was caused by human activities, whereas 56.56% was caused by climatic factors. Therefore, inter-annual climate change is the primary cause of grassland restoration, whereas human activities are the primary cause of grassland degradation. Grassland dynamics and the relative roles of climate and human factors in grassland degradation and restoration varied greatly across the five provinces studied. The contribution of human activities to grassland degradation was greater than that of climate change in all five provinces. Three outcomes were observed in grassland restoration: First, the contribution of climate to grassland restoration was greater than that of human activities, particularly in Qinghai, Inner Mongolia, and Xinjiang. Second, the contribution of human activities to grassland restoration was greater than that of climate in Gansu. Third, the two factors almost equally contributed to grassland restoration in Tibet. Therefore, the effectiveness of ecological restoration programs should be enhanced whenever climate change promotes grassland restoration.

[1]  K. Paustian,et al.  GRASSLAND MANAGEMENT AND CONVERSION INTO GRASSLAND: EFFECTS ON SOIL CARBON , 2001 .

[2]  Jennifer Small,et al.  Can human-induced land degradation be distinguished from the effects of rainfall variability? A case study in South Africa , 2007 .

[3]  Roger A. Pielke,et al.  A comparison of regional trends in 1979–1997 depth-averaged tropospheric temperatures , 2000 .

[4]  Wu Wei.  Study on Process of Desertification in Mu Us Sandy Land for Last 50 Years, China , 2001 .

[5]  Xuefeng Cui,et al.  Recent land cover changes on the Tibetan Plateau: a review , 2009 .

[6]  Hao Xin,et al.  A Green Fervor Sweeps the Qinghai-Tibetan Plateau , 2008, Science.

[7]  Xunming Wang,et al.  Roles of climate changes and human interventions in land degradation: a case study by net primary productivity analysis in China’s Shiyanghe Basin , 2011 .

[8]  J. Randerson,et al.  Global net primary production: Combining ecology and remote sensing , 1995 .

[9]  Liu Yunfeng,et al.  Climatic change on the Tibetan Plateau: Potential Evapotranspiration Trends from 1961–2000 , 2006 .

[10]  D. Zhuang,et al.  Multi-scale quantitative assessment of the relative roles of climate change and human activities in desertification – A case study of the Ordos Plateau, China , 2010 .

[11]  Laura Schneider,et al.  Deforestation in the southern Yucatan peninsular region: an integrative approach , 2001 .

[12]  Zhibao Dong,et al.  The relative role of climatic and human factors in desertification in semiarid China , 2006 .

[13]  Jiaguo Qi,et al.  Understanding the coupled natural and human systems in Dryland East Asia , 2012 .

[14]  Z. Nan.  The grassland farming system and sustainable agricultural development in China , 2005 .

[15]  Deyong Yu,et al.  Forest ecosystem restoration due to a national conservation plan in China , 2011 .

[16]  Tao Wang,et al.  The relative role of climate change and human activities in the desertification process in Yulin region of northwest China , 2012, Environmental Monitoring and Assessment.

[17]  S. Sterling,et al.  Human Appropriation of Photosynthesis Products , 2001, Science.

[18]  Helmut Haberl,et al.  Human Appropriation of Net Primary Production , 2002, Science.

[19]  Yong Zha,et al.  Assessment of grassland degradation near Lake Qinghai, West China, using Landsat TM and in situ reflectance spectra data , 2004 .

[20]  Wenying Wang,et al.  The effect of land management on plant community composition, species diversity, and productivity of alpine Kobersia steppe meadow , 2006, Ecological Research.

[21]  Gaoming Jiang,et al.  Restoration and Management of the Inner Mongolia Grassland Require a Sustainable Strategy , 2006, Ambio.

[22]  D. Schimel,et al.  Terrestrial biogeochemical cycles: Global estimates with remote sensing , 1995 .

[23]  G. Asrar,et al.  Distinguishing among tallgrass prairie cover types from measurements of multispectral reflectance , 1986 .

[24]  J. Randerson,et al.  Terrestrial ecosystem production: A process model based on global satellite and surface data , 1993 .

[25]  Hideyuki Shimizu,et al.  Did climate drive ecosystem change and induce desertification in Otindag sandy land, China over the past 40 years? , 2006 .

[26]  Z. Wenquan,et al.  Simulation of maximum light use efficiency for some typical vegetation types in China , 2006 .

[27]  Zhicai Zhang,et al.  Management and land use change effects on soil carbon in northern China's grasslands: a synthesis , 2011 .

[28]  Xuebin Zhang,et al.  Trends in Total Precipitation and Frequency of Daily Precipitation Extremes over China , 2005 .

[29]  Stephen D. Prince,et al.  Evidence from rain‐use efficiencies does not indicate extensive Sahelian desertification , 1998 .

[30]  Stephen D. Prince,et al.  Mapping land degradation by comparison of vegetation production to spatially derived estimates of potential production , 2008 .

[31]  Hiroyuki Yamada,et al.  Weak and Frequent Monsoon Precipitation over the Tibetan Plateau , 2001 .

[32]  E. Kang,et al.  Recent and Future Climate Change in Northwest China , 2007 .

[33]  Le Kang,et al.  Grassland ecosystems in China: review of current knowledge and research advancement , 2007, Philosophical Transactions of the Royal Society B: Biological Sciences.

[34]  J. Ni.  Carbon storage in grasslands of China , 2002 .

[35]  Zhibao Dong,et al.  Modern dust storms in China: an overview , 2004 .

[36]  Dengsheng Lu,et al.  Mapping and monitoring land degradation risks in the Western Brazilian Amazon using multitemporal Landsat TM/ETM+ images , 2007 .

[37]  C. Tucker,et al.  Recent trends in vegetation dynamics in the African Sahel and their relationship to climate , 2005 .

[38]  Jian Sun,et al.  On the Variation of NDVI with the Principal Climatic Elements in the Tibetan Plateau , 2013, Remote. Sens..

[39]  J. Evans,et al.  Discrimination between climate and human-induced dryland degradation. , 2004 .

[40]  S. Carpenter,et al.  Global Consequences of Land Use , 2005, Science.

[41]  A. Hanafi,et al.  Are long-term vegetation dynamics useful in monitoring and assessing desertification processes in the arid steppe, southern Tunisia , 2008 .

[42]  Frank Veroustraete,et al.  Comparison and conversion of AVHRR GIMMS and SPOT VEGETATION NDVI data in China , 2010 .

[43]  Emilio Chuvieco,et al.  Satellite remote sensing analysis to monitor desertification processes in the crop-rangeland boundary of Argentina , 2002 .

[44]  Elias Symeonakis,et al.  Monitoring desertification and land degradation over sub-Saharan Africa , 2004 .

[45]  D. O. Hall,et al.  The global carbon sink: a grassland perspective , 1998 .