Causes of Desertification in China

To understand the factors that determine whether mitigation programs can contribute to desertification control in desertified areas of China a pooled regression model based on panel data to calculate the relative roles of climate change from 1983 to 2012 was used

Desertification is the result of complex interactions among various factors, including climate change and human activities. However, previous research generally focused on either meteorological factors associated with climate change or human factors associated with human activities, and lacked quantitative assessments of their interaction combined with long-term monitoring. Thus, the roles of climate change and human factors in desertification remain uncertain.

To understand the factors that determine whether mitigation programs can contyribute to desertification control and vegetation cover improvements in desertified areas of China, and the complex interactions that affect their success, we used a pooled regression model based on panel data to calculate the relative roles of climate change and human activities on the desertified area and on vegetation cover (using the normalized-difference vegetation index, NDVI, which decreases with increasing desertification) from 1983 to 2012. We found similar effect magnitudes for socioeconomic and environmental factors for NDVI but different results for desertification: socioeconomic factors were the dominant factor that affected desertification, accounting for 79.3% of the effects.

Climate change accounted for 46.6 and 20.6% of the effects on NDVI and desertification, respectively. Therefore, desertification control programs must account for the integrated effects of both socioeconomic and natural factors.

Drylands cover about 54 million km2, which amounts to 40% of the global land area, and are especially common in Asia and Africa, where they account for 58.5% of the world’s dryland area. These regions have suffered from climate change, unfavorable hydrologic conditions, changes in vegetation composition, loss of soil services, and desertification; the combination of these effects has generated many adverse consequences, including sandstorms that threaten ecosystem services and human life.

In recent years, more and more of the sandstorms that form in desert areas have swept into modern cities in areas such as northwestern China, Africa, the western United States, and Australia. In arid, semi-arid, and dry sub-humid regions, land degradation that results in a loss of vegetation cover is caused by several factors, including climatic change and human activities, and has been defined as desertification . As desertified areas expand, the area of livable habitat will decrease, and poverty will be exacerbated. Desertification has become a crucial environmental problem at a global scale, and has begun to affect the survival and socioeconomic development of humankind.

Research has suggested that both climate and human activities play important roles in the process of desertification, which is complicated and includes complex interactions between human and natural factors (e.g., climate). Because of this complexity, past research has generally focused on either simple climate factors or on human activities rather than trying to account for both factors simultaneously. Some studies concluded that climate change affected the soil quality, vegetation cover, species composition, and hydrologic cycles in drylands, and has therefore led to expansion of the desertified area.

Others have argued that unsustainable traditional practices such as grazing, logging, and exploitation of underground water have created enormous pressures on ecosystems, leading to desertification. Such human activities can eliminate the vegetation cover that protects the soil against erosion by water and strong winds. However, without an understanding of how the interactions among the abovementioned factors affect desertification, it is difficult to reconcile the different research results. This creates a high risk of misunderstanding the current situation and adopting ineffective policies and programs to combat desertification.

Source: Nature

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