Land degradation and restoration in the arid and semiarid zones of China: Quantified evidence and implications from satellites

Abstract

Quantified information on land degradation and restoration is needed to support policies for sustainable ecosystem management and socioeconomic development. The arid and semiarid zones of China (ASZC) have experienced significant land degradation, and in response to such degradation, multiple ecological projects were implemented. In this study, remote sensing was used to identify degrading areas and where the degraded areas have been restored from 1990 in this ecologically sensitive region. Specifically, we integrated datasets from the ChinaCover and Moderate Resolution Imaging Spectroradiometer products to characterize changes in vegetation, ecosystems, and environmental conditions. The results confirmed that deforestation, desertification, grassland degradation, wetland loss, and the encroachment upon farmlands were notable in the ASZC. Agricultural activity has cultivated extensive areas of natural ecosystems (46,474 km 2 ). The expansion of built-up lands in terms of national policies has destroyed large areas of natural (5,487 km 2 ) and agricultural (4,138 km 2 ) ecosystems and continually results in negative impacts on ecological conservation. China has restored some lands (7,732 km 2 from farmlands and 24,904 km 2 from barren lands) and improved ecosystems, as characterized by increases in the normalized different vegetation index, leaf area index, net primary productivity, and gross primary productivity values in the ASZC, especially after the implementation of many ecological projects. However, it is also necessary to document the conclusions and lessons from these projects to guide future ecological policies and projects in the context of the substantial new challenges facing the protection of this ecologically sensitive environment. KEYWORDS ecological restoration, land cover, land degradation, MODIS, the arid and semiarid zones of China

Recovery of species richness lags behind functional recovery in restored grasslands

“…Temperate grasslands harbour high biodiversity and are also among the most threatened ecosystems in the world (Dengler, Janišová, Török, & Wellstein, ; Hoekstra, Boucher, Ricketts, & Roberts, ; Ren & Zhou, ). The overwhelming majority of natural grasslands in Eurasia and North America have been tilled and converted into croplands (Habel et al, ; Mao, Wang, Zeng, Luo, & Zhang, ; Samson & Knopf, ; Wesche et al, ), whereas extensively used seminatural grasslands of NW and central Europe have also suffered serious reductions both in area and biodiversity (Török & Dengler, ). A reverse trend, that is, land abandonment, has also become a major driver of landscape change in the past decades due to social economic changes, such as the collapse of the socialist block (Hobbs & Cramer, ).…”

Incorporating the Plant Phenological Trajectory into Mangrove Species Mapping with Dense Time Series Sentinel-2 Imagery and the Google Earth Engine Platform

“…S2, a European Space Agency (ESA) land monitoring mission, has two matching satellites that provide high resolution optical imagery. Sentinel-2A and Sentinel-2B, which operate with the MultiSpectral Instrument (MSI), were successfully launched on June 2015 and March 2017, respectively, and provide important means to augment Earth-observation capabilities [21][22][23][24]. These satellites revisit the same place every 2-5 days.…”

Tracking spatial–temporal landscape changes of impervious surface areas, bare lands, and inundation areas in China during 2001–2017

“…Land degradation describes permanent changes in the capability of lands to support human activities (Abel & Blaikie, ). Land degradation could be possibly associated with three kinds of landscape changes engaging vegetation loss: urbanization, devegetation, and inundation (Chuai et al, ; Mao et al, ; Pekel, Cottam, Gorelick, & Belward, ). Mapping and quantifying large scale land degradation caused by landscape changes are very important for regional sustainable environment management (Burrell, Evans, & Liu, ).…”

“…It is recognized that urbanization and desertification have resulted in substantial land degradation in the past few decades, even in the wet region in China (Chuai et al, 2018;Mao et al, 2018). However, there is limited spatiotemporal explicit information on devegetation (a process from vegetated land to permanent bare lands, desertification in arid/semiarid regions) and their driving forces at the national scale (Feng, Ma, Jiang, Wang, & Cao, 2015).…”