Study Reveals Significant "Land Debt" in Asian Drylands

A new study published in Journal of Remote Sensing on Oct. 10 has shed new light on the ecological health of Asian drylands, revealing a complex and at times contradictory picture of degradation and recovery. The study highlights a substantial "land debt" despite some promising signs of improvement.

For years, much of the global focus on dryland degradation has centered on the net loss of healthy land, particularly in Central Asia. However, this study, led by Prof. CHEN Yaning from the Xinjiang Institute of Ecology and Geography of the Chinese Academy of Sciences, goes further. It quantifies the delicate balance between degradation and environmental improvement, a critical metric for global policy goals such as the UN's Sustainable Development Goal 15.3.1, which aims for Land Degradation Neutrality (LDN).

By integrating a Regional Ecohealth Assessment (REHA) model with the LDN framework, the researchers effectively bridge the gap between scientific findings and the practical needs of policymakers. Using extensive remote sensing data on land use patterns, soil moisture levels, and vegetation dynamics, they meticulously tracked ecological health across Asian drylands from 2000 to 2020.

Their analysis uncovered a distinct two-phase trend. Initially, regional ecohealth showed a persistent decline until 2012. However, this was followed by an accelerating phase of improvement, offering a glimmer of hope. Despite this positive trajectory, the study warns that a significant ecological deficit remains.

Applying the LDN paradigm, the researchers estimated that approximately 22% of the total land area across Asian drylands, equating to a staggering 196 million hectares, experienced net degradation over the two-decade period. This loss was partially offset by improvements across 13% of the area (119 million hectares), resulting in a net land debt of around 8% of Asian drylands, or 76.9 million hectares – an area roughly four times the size of Kyrgyzstan, degrading at an average rate of 3.8 million hectares annually.

One of the study's key findings is the stark contrast in ecological performance among different sub-regions. Drylands in East Asia, particularly Chinese provinces, showed substantial and widespread improvement trends. In contrast, degradation continued to prevail across Central Asia. Notably, Kazakhstan's ecological health deteriorated from "ordinary" to "poor" levels in its northwestern and eastern regions.

The drivers behind these contrasting dynamics are multifaceted. Land use changes, including alterations in cropping patterns, aridification processes, and afforestation efforts, impacted an estimated 9.1% of Asian drylands (approximately 79.3 million hectares). These pressures were further exacerbated by climate variability. Regions experiencing above-average temperature anomalies, particularly in western Central Asia, exhibited more pronounced degradation.

"While achieving LDN is still within reach, it demands a nuanced and site-specific strategy," said Dr. Patient Mindje Kayumba, first author of the study. He advocates for a management framework centered on a "land balance pyramid," which prioritizes preventing new degradation, reducing ongoing environmental damage, and reversing existing harm.

"Safeguarding intact ecosystems while actively restoring degraded areas through targeted interventions, tailored to the specific root causes and local conditions, is paramount for the sustainable future of drylands." said Kayumba. "For countries like Kazakhstan, grappling with an escalating ecological debt from persistent degradation, this necessitates a resolute focus on implementing reduction strategies within its most affected northwestern and eastern regions to avert further environmental losses."

This study provides a crucial evidence base for policymakers, conservationists, and restoration initiatives, underscoring the imperative to synergize regional monitoring with targeted, local-scale actions to advance sustainable dryland management by 2030.

Read the full article: https://doi.org/10.34133/remotesensing.0897

Contact

LONG Huaping

Xinjiang Institute of Ecology and Geography

E-mail: longhp@ms.xjb.ac.cn

Web: http://english.egi.cas.cn