Land Degradation Assessment in Pakistan based on LU and VCF

Abstract Land degradation is a global environmental issue receiving much attention currently. According to the definition and interpretation of land degradation by relevant United Nations organizations, land use degradation was qualitatively analyzed based on the two periods of land use data in 2001 and 2020, land use transfer matrix and change flow description table in 2001 and 2020. At the same time, here we employed the Vegetation Continuous Fields MODIS data over the span of 21years (2000–2020) to quantitatively estimate vegetation degradation by using the Theil-Sen Median trend and Mann-Kendall non-parametric test. And the land degradation situation in Pakistan was comprehensively evaluated by combining the results of qualitative and quantitative analysis. Major findings of this study indicate: (1) unused land (61.91%), cropland (20.7%) and grassland (15.88%) are the major types of land use in Pakistan. Unused land area decreased during whole period, while other land areas increased, the grassland area changed the most, the cropland area increased the most, and the conversion between grassland and unused land was the most significant. (2) The average vegetation coverage in Pakistan is low, but showed a significant upward trend during whole study period, with a growth rate of 0.0786/a. The vegetation degradation area accounts for only 1.32% and the vegetation improvement area accounts for 28.79%. (3) 2.15% of the land was degraded, of which land use degradation accounts for 1.9% and vegetation degradation only accounts for 0.25%. Land use degradation is mainly due to vegetation loss (53.78%) and withdrawal of agriculture (40.07%). 22.41% of the land has been improved, of which land use improvement accounts for 5.75% and vegetation improvement accounts for 16.66%; The improvement of land use is mainly due to agricultural expansion (48.9%) and vegetation establishment (48.81%). The degradation and improvement of land use in Pakistan are mainly affected by grassland, followed by cropland. The research shows that there are serious phenomena of cropland abandonment, vegetation loss and over agricultural expansion in Pakistan, but thanks to Pakistan's efforts in forest restoration and ecological protection in recent years, the overall vegetation coverage has been significantly improved. At the same time, we found that the regional distribution of land degradation and improvement has obvious spatial similarity, which is mostly distributed in the transition area from northern mountainous area to central plain, central and eastern plain and the Indus River Basin. The distribution of cropland and built-up land is similar in space. Meanwhile, we found that land degradation in Pakistan is significantly affected by human activities. The government and people should devote more energy to optimizing the use of cropland land resources, reasonably reclaiming wasteland for cropland land, and protecting forests and vegetation. This paper provides a new idea for land degradation assessment, and the assessment results can optimize the use of land resources to improve the current situation of land degradation and serve the sustainable development of land resources in Pakistan.