19 February 2024

A new index details the decline of desertification in China

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In the 21st century, the share of China’s grasslands experiencing severe and moderate desertification has dropped from 52 percent to 37 percent. This is revealed in a new survey by the Beijing Academy of Sciences

by Matteo Cavallito

 

A group of researchers has developed a new index to better understand and counter the phenomenon of global grassland desertification. The tool, called the Desertification Difference Index (DDI), was created by scientists at the Aerospace Information Research Institute (AIR) of the Chinese Academy of Sciences (CAS) and is described in a study published in the journal Remote Sensing.

The research, according to a statement from the Academy, focused on extracting information in Xilingol, the Inner Mongolia Autonomous Region in northern China, “offering insights into the spatial and temporal dynamics of desertified grasslands (DGLs).”

A new model

Grassland desertification stands as an ecological concern globally,” the study states. It is crucial for desertification prevention and control to comprehend the variation in area and severity of desertified grassland (DGL), clarify the intensities of conversion among DGLs of different desertification levels, and explore the spatial and temporal driving factors of desertification.”

The Desertification Difference Index, the authors explain, is constructed from surface indicator known as albedo-EVI that encompasses two dimensions: the measure of light radiation reflectivity (albedo, precisely) and the enhanced vegetation index (EVI) for monitoring plant biomass.

“Subsequently, intensity analysis, the Geo-detector model (or, according to the authors, “a statistical method for exploring spatial heterogeneity and its driving factors”, ed.), and correlation analysis were applied to analyze the dynamics and driving factors of desertification.”

Desertification has declined since the turn of the century

The index made it possible to assess the change in the phenomenon by showing a decline in desertification during the 21st century. “Temporally, the degree of DGL decreased, with the proportion of severely and moderately desertified areas decreasing from 51.77% in 2000 to 37.23% in 2020,” the study observes. “While the proportion of nondesertified and healthy areas increased from 17.85% in 2000 to 37.40% in 2020.”

The authors were also able to observe the role of different factors involved in the processes. “Meteorological factors and soil conditions primarily drive the spatial distribution of DDI, with evapotranspiration exhibiting the most significant influence (q-value of 0.83), while human activities dominate interannual DDI variations.” This issue, the researchers point out, highlights “the need for comprehensive prevention and control measures.”

Climate and agriculture influence the phenomenon

In Asia, the region prone to desertification extends from the central part of the continent to northeastern China. This territory covers more than 1.2 million square kilometers. Currently, the Academy of Sciences reminded last year, more than 60 percent of this area is managed under traditional pastoral and agricultural systems. Within this framework, the impacts of desertification on agriculture and grazing affect the lives of more than 47.9 million people.

Over the years, Beijing has worked to counter this phenomenon with various initiatives. These include the Grain for Green program, which provides compensation for farmers who plant trees on their soils and undertake to restore degraded land.

That program, explained a study published in 2023 in the journal Nature, would play a relatively modest role in actually improving the situation. Encouraging the increase in vegetation cover from 2000 onward, the scholars explained, would have been mainly other factors. These included, in particular, increased rainfall and fertilization practices.