Ecological Risks Arising from the Impact of Large-scale Afforestation on the Regional Water Supply Balance in Southwest China

Abstract

Ecological degradation impedes sustainable development in Southwest China, and artificial afforestation has been a key strategy of the Government of China to effectively curb it. However, the water consumed by large-scale afforestation has a huge impact on water supply in Southwest China, which also arise a new challenge causing severe drought here recently. In order to determine the impact of artificial afforestation on the region, this study conducts spatiotemporal, abrupt change, and correlation and regression analyses. Results show that although water resources fluctuate, they exhibit a general declining trend. Especially after 2000, water resources showed a significant downward trend. In terms of spatial tendency, there has been an obvious decrease in water resources in the Sichuan Basin, the mountainous region of eastern Chongqing, and the Yunnan-Guizhou Plateau. Due to extensive afforestation and vegetation cover growth, there has been an increase in most trends of forest-shrub ecosystems, resulting in substantially enhanced evapotranspiration effects. The uptake of water by afforestation in Southwest China could reach 40.42 billion m 3 , which is equivalent to 10.69% of its annul available water supply (1980-2015). Generally, afforestation disrupts the water balance of the region. This study recommends substituting afforestation for natural restoration or, at the very least, selecting vegetation that requires less water for the restoration of the ecological environment of Southwest China, which provide scientific method for regional sustainable development. The IPCC Fifth Assessment Report on climate change stated that global surface temperatures rose by 0.85 °C from 1880 to 2012 (from 0.65 °C to 1.06 °C, respectively). Global warming leads to frequent extreme weather and climate events and impacts both the water supply and the ecological environments of numerous countries 1,2. Severe droughts are caused by a decrease in precipitation, which leads to shortages in water supplies, and such droughts are harmful to life, production, and ecology. Moreover, events such as these have dual attributes, that is, natural attributes and social attributes. This is an important factor which restricts the sustainable development of societies 3. Since the twenty-first century, drought events in Southwest China have moved into a period of "high incidence". With increases in interannual and annual variation in rainfall in Southwest China, the frequency of droughts have increased, and years of serious and catastrophic drought events in different regions and during different seasons have subsequently increased 4. Thus, strengthening research on drought characteristics and causes in Southwest China as well as the level of response, providing a scientific basis for decisions on disaster prevention and mitigation, have important practical implications 5,6. Since 2010, there have been many serious drought events reported in Southwest China, including Yunnan, Guizhou, and Sichuan provinces and the municipality of Chongqing, which...

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“…RMBmn, compared to 2 to 5 times the pollutant discharge fee previously (Xiao, Xiao et al 2020) Currently, the Yellow river is the only river in the northern part of China to meet the Ten Target of 70% in Grade I-III water quality (Yang, Yao et al 2020).…”

Identifying Ecological Security Patterns Based on Ecosystem Services Is a Significative Practice for Sustainable Development in Southwest China

“…In the process of regional development which requires stable natural resources and eco-environmental support, population growth and economic development have led to tremendous pressure on natural ecosystems, causing degradation such as water shortages, soil erosion, carbon loss, biodiversity loss, and habitat fragmentation (Xu et al, 2019). A comprehensive understanding of the effects of ecosystem changes and corresponding security considerations is necessary for establishing regional environmental management policies (Pǎtru-Stupariu et al, 2020;Xiao Y. et al, 2020). With the aim to protect the fragile ecosystem, reduce natural disasters, and curb ecosystem degradation, local and central governments of China have recently launched a series of ecological policies and projects, such as the Slope Land Conversion Project (SLCP), China's Natural Forest Protection Project (NFPP) (Zinda and Zhang, 2018), Artificial Afforestation, the River Shelterbelt Project (Xiao Y. et al, 2020), and Retire Livestock and Restore Grassland (RLRG) (Wang Y.X.…”

“…A comprehensive understanding of the effects of ecosystem changes and corresponding security considerations is necessary for establishing regional environmental management policies (Pǎtru-Stupariu et al, 2020;Xiao Y. et al, 2020). With the aim to protect the fragile ecosystem, reduce natural disasters, and curb ecosystem degradation, local and central governments of China have recently launched a series of ecological policies and projects, such as the Slope Land Conversion Project (SLCP), China's Natural Forest Protection Project (NFPP) (Zinda and Zhang, 2018), Artificial Afforestation, the River Shelterbelt Project (Xiao Y. et al, 2020), and Retire Livestock and Restore Grassland (RLRG) (Wang Y.X. et al, 2018).…”

“…Grassland degradation caused by livestock grazing increased in the late 1990s as several disasters occurred, including Yangtze River floods, the Yellow River running dry increasingly often, and dust-storms and sand-storms originating in western rangelands, which directly damaged ecological security (Harris, 2010). Southwest China, which is rich in biodiversity and has a wide range of ecosystem services (ESs), is a strong support for the sustainable development of the local human wellbeing (Xiao Y. et al, 2020). This area is also one of the key components of the ecological security shelter (ESS) for biodiversity hotspot conservation.…”