Driving Factors of Recent Vegetation Changes in Hexi Region, Northwest China Based on a New Classification Framework

Since other factors (soil properties, topography, etc.) under natural conditions are relatively invariant over one or two decades, climate variables (precipitation and temperature) and human activities are the two fundamental factors driving vegetation changes in global or large-scale areas. However, the combined effects of either single climatic factor and human activities on vegetation changes and the role of human activities itself in a specific region has not been fully discussed. In this study, the Hexi region, a typical dryland consisting of three inland river basins in northwest China was selected as a case area. A new classification framework combining Pearson correlation analysis and residual trend approach was proposed to assess their individual and conjoint contributions of climate variables and human activities in areas of significant vegetation changes. Our results indicated that most of vegetation covered areas in the Hexi region experienced significant changes during the period 2001−2017, and vegetation improvements were widespread except the interior of oases; significant changes in vegetation caused by human activities, precipitation, the interactions of precipitation and human activities, temperature, the interactions of temperature and human activities, the interactions of temperature and precipitation, and the interactions of the three factors accounted for 50.46%, 16.39%, 19.90%, 4.33%, 2.32%, 2.11%, and 4.49% of the total change areas, respectively. Generally, the influence of temperature was relatively weaker than that of precipitation, and the contributions of the interactions of climate variables and human activities on vegetation changes were greater than that of climate contributions alone. Moreover, the results of various investigations, according to the trends and the time of vegetation changes, indicate that decreasing trends of the normalized difference vegetation index (NDVI) in the Hexi region were chiefly attributed to the adjustments of agricultural planting structure while the comprehensive treatment programs implemented in river basins supported a large proportion of vegetation improvements.

[1]  Meixue Yang,et al.  Using the NDVI to identify variations in, and responses of, vegetation to climate change on the Tibetan Plateau from 1982 to 2012 , 2017 .

[2]  Mihretab G. Ghebrezgabher,et al.  Spatial-temporal dynamics of desert vegetation and its responses to climatic variations over the last three decades: a case study of Hexi region in Northwest China , 2016, Journal of Arid Land.

[3]  S. Running,et al.  Contrasting Climatic Controls on the Estimated Productivity of Global Terrestrial Biomes , 1998, Ecosystems.

[4]  Tai-bao Yang,et al.  Trend shifts in satellite-derived vegetation growth in Central Eurasia, 1982-2013. , 2017, The Science of the total environment.

[5]  M. Steinbach,et al.  Terrestrial vegetation dynamics and global climate controls , 2008 .

[6]  Rasmus Fensholt,et al.  Greenness in semi-arid areas across the globe 1981–2007 — an Earth Observing Satellite based analysis of trends and drivers , 2012 .

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

[8]  Le Houérou,et al.  Rain use efficiency: a unifying concept in arid-land ecology , 1984 .

[9]  Tim R. McVicar,et al.  Global changes in dryland vegetation dynamics (1988–2008) assessed by satellite remote sensing: comparing a new passive microwave vegetation density record with reflective greenness data , 2013 .

[10]  Yaowen Xie,et al.  The critical role of local policy effects in arid watershed groundwater resources sustainability: A case study in the Minqin oasis, China. , 2017, The Science of the total environment.

[11]  Rikie Suzuki,et al.  Relationships between meridional profiles of satellite-derived vegetation index (NDVI) and climate over Siberia , 2000 .

[12]  Anming Bao,et al.  Disentangling the relative impacts of climate change and human activities on arid and semiarid grasslands in Central Asia during 1982-2015. , 2019, The Science of the total environment.

[13]  D. L. Seen,et al.  Driving forces of recent vegetation changes in the Sahel: Lessons learned from regional and local level analyses , 2017 .

[14]  Changhui Peng,et al.  Large-scale detection of vegetation dynamics and their potential drivers using MODIS images and BFAST: A case study in Quebec, Canada , 2018 .

[15]  Lara Prihodko,et al.  On regreening and degradation in Sahelian watersheds , 2015, Proceedings of the National Academy of Sciences.

[16]  G. Sun,et al.  Combined effects of climate and land management on watershed vegetation dynamics in an arid environment. , 2017, The Science of the total environment.

[17]  F. van den Bergh,et al.  Limits to detectability of land degradation by trend analysis of vegetation index data , 2012 .

[18]  C. Tucker,et al.  Climate-Driven Increases in Global Terrestrial Net Primary Production from 1982 to 1999 , 2003, Science.

[19]  Liping Di,et al.  Modelling relationships between NDVI and precipitation during vegetative growth cycles , 1994 .

[20]  A. Dai,et al.  Changes in global vegetation activity and its driving factors during 1982–2013 , 2018 .

[21]  Hysteresis Effect of Runoff of the Heihe River on Vegetation Cover in the Ejina Oasis in Northwestern China , 2008 .

[22]  Junfeng Wei,et al.  Spatiotemporal changes of vegetation and their responses to temperature and precipitation in upper Shiyang river basin , 2017 .

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

[24]  Shengjun Wu,et al.  NDVI indicated long-term interannual changes in vegetation activities and their responses to climatic and anthropogenic factors in the Three Gorges Reservoir Region, China. , 2017, The Science of the total environment.

[25]  Zeyu Liu,et al.  Greening and Browning of the Hexi Corridor in Northwest China: Spatial Patterns and Responses to Climatic Variability and Anthropogenic Drivers , 2018, Remote. Sens..

[26]  Andreas Buerkert,et al.  Quantification of aboveground rangeland productivity and anthropogenic degradation on the Arabian Peninsula using Landsat imagery and field inventory data , 2011 .

[27]  Q. Feng,et al.  Public perception of an ecological rehabilitation project in inland river basins in northern China: Success or failure. , 2015, Environmental research.

[28]  Jianlong Li,et al.  Grassland dynamics in responses to climate variation and human activities in China from 2000 to 2013. , 2019, The Science of the total environment.

[29]  Lei He,et al.  Spatio-Temporal Changes of Oases in the Hexi Corridor over the Past 30 Years , 2018, Sustainability.

[30]  Peter B. Adler,et al.  Sensitivity of mean annual primary production to precipitation , 2012 .

[31]  A. Lin,et al.  What drives the vegetation restoration in Yangtze River basin, China: Climate change or anthropogenic factors? , 2018, Ecological Indicators.

[32]  Wei Song,et al.  Changes in ecosystem services associated with planting structures of cropland: A case study in Minle County in China , 2017 .

[33]  Yansui Liu,et al.  Anthropogenic contributions dominate trends of vegetation cover change over the farming-pastoral ecotone of northern China , 2018, Ecological Indicators.

[34]  Wei Zhou,et al.  Quantitative assessment of the individual contribution of climate and human factors to desertification in northwest China using net primary productivity as an indicator , 2015 .

[35]  S. Nicholson,et al.  A comparison of the vegetation response to rainfall in the Sahel and East Africa, using normalized difference vegetation index from NOAA AVHRR , 1990 .

[36]  Shuai Wang,et al.  Ecological effects and potential risks of the water diversion project in the Heihe River Basin. , 2018, The Science of the total environment.

[37]  Yi Y. Liu,et al.  Detecting dryland degradation using Time Series Segmentation and Residual Trend analysis (TSS-RESTREND) , 2017 .

[38]  Kevin P. Price,et al.  Spatial patterns of NDVI in response to precipitation and temperature in the central Great Plains , 2001 .

[39]  Y. Li,et al.  Environmental Restoration in the Shiyang River Basin, China: Conservation, Reallocation and More Efficient Use of Water , 2014 .

[40]  Hao Xu,et al.  Impacts of climate change and human activities on the aboveground production in alpine grasslands: a case study of the source region of the Yellow River, China , 2017, Arabian Journal of Geosciences.

[41]  Ramakrishna R. Nemani,et al.  Global vegetation cover changes from coarse resolution satellite data , 1996 .

[42]  Huimin Lei,et al.  Responses of Natural Vegetation Dynamics to Climate Drivers in China from 1982 to 2011 , 2015, Remote. Sens..

[43]  Yaowen Xie,et al.  Detecting Patterns of Vegetation Gradual Changes (2001-2017) in Shiyang River Basin, Based on a Novel Framework , 2019, Remote. Sens..

[44]  S. Jeon,et al.  Long-term trend and correlation between vegetation greenness and climate variables in Asia based on satellite data. , 2018, The Science of the total environment.

[45]  Heiko Balzter,et al.  Land Degradation Assessment Using Residual Trend Analysis of GIMMS NDVI3g, Soil Moisture and Rainfall in Sub-Saharan West Africa from 1982 to 2012 , 2015, Remote. Sens..

[46]  A. Bao,et al.  Vegetation dynamics and responses to climate change and human activities in Central Asia. , 2017, The Science of the total environment.

[47]  S. Bruin,et al.  Trend changes in global greening and browning: contribution of short‐term trends to longer‐term change , 2012 .

[48]  Xunming Wang,et al.  Temporal and Spatial Variations in the Climate Controls of Vegetation Dynamics on the Tibetan Plateau during 1982–2011 , 2018, Advances in Atmospheric Sciences.

[49]  Yuqing Zhang,et al.  Responses of vegetation to climatic variations in the desert region of northern China , 2019, CATENA.

[50]  R. Fensholt,et al.  Evaluation of Earth Observation based global long term vegetation trends — Comparing GIMMS and MODIS global NDVI time series , 2012 .

[51]  Chengcheng Gang,et al.  Assessing the effects of climate variation and human activities on grassland degradation and restoration across the globe , 2019, Ecological Indicators.

[52]  Xiaoping Zhou,et al.  Distinguishing the vegetation dynamics induced by anthropogenic factors using vegetation optical depth and AVHRR NDVI: A cross-border study on the Mongolian Plateau. , 2018, The Science of the total environment.

[53]  Pol Coppin,et al.  Review ArticleDigital change detection methods in ecosystem monitoring: a review , 2004 .

[54]  Shunlin Liang,et al.  Vegetation dynamics and responses to recent climate change in Xinjiang using leaf area index as an indicator , 2015 .

[55]  Xiangzheng Deng,et al.  Understanding the spatiotemporal variation of urban land expansion in oasis cities by integrating remote sensing and multi-dimensional DPSIR-based indicators , 2018, Ecological Indicators.