The trend shift caused by ecological restoration accelerates the vegetation greening of China’s drylands since the 1980s

Abstract

Satellite observations since the early 1980s have revealed a trend of “Earth greening” across global terrestrial ecosystems. Dryland vegetation is more sensitive to climate change and human activities. China's drylands are among the largest in extent worldwide, and large-scale ecological restoration of these areas has been implemented since the late 1970s, which has resulted in more complicated but still poorly quantified vegetation dynamics. To figure out the vegetation dynamics and associated driving forces, we provide an assessment of the vegetation dynamics from 1982-2015 using the CO2 fertilization effect function, principal component regression, Residual Trend analysis, and Breaks For Additive Seasonal and Trend methods based on the ERA5 climate factors and GIMMS 3.1 NDVI datasets. This study shows that anthropogenic impacts and CO2 fertilization have jointly led to vegetation greening in China’s drylands since the 1980s, and ecological restoration has accelerated this greening since the 2000s. The results show that the vegetation greening in China’s drylands (41.51% of the study area, +0.60×10-3/yr) is mainly driven by CO2 fertilization (+0.55×10-3/yr) and anthropogenic activities (+0.12×10-3/yr). The anthropogenic effects are especially higher on the Loess Plateau (+1.01×10-3/yr) and the Three-North region (+0.23×10-3/yr). The vegetation dynamics shifts in 6.73% (31.64 Mha) of China’s drylands were directly attributed to anthropogenic impacts around the 2000s. When the anthropogenic effect was intensified, the vegetation dynamics shifted from no change to greening and vice versa, which significantly intensified the vegetation greening since the 1980s. These results capture the processes of ecological programs and provide an assessment of the effects of ecological restoration. This work provides a credible attribution of the vegetation greenness dynamics and trend shifts in China’s drylands, thus facilitating a better understanding of regional environmental change and management.

Changes and influencing factors of ecosystem resilience in China

“…These positive temperature-associated couplings combined with multiple water and biological cycles resulted in high atmospheric moisture demand, which made an active impact to the earlier BPs and widespread reduction in ER after BPs (figure 2). Together, the present spatiotemporal results demonstrated that the relationships between ER and climate conditions varied among different regions and were also influenced by ocean-atmospheric circulations (figure S10) (Kim et al 2019, Wang et al 2022. Our comprehensive analysis provides important findings that help understand the response of ecosystem functions to terrestrial-atmospheric variables.…”

“…This has also been widely used as an alarm system to provide information on when and where changes have occurred using the R packages' bfast' , 'tseries' , and 'rlang' . The shortest segment was set to 0.25 of the total data length to limit the minimum number of observations in each segment (Li et al 2022). The most significant BPs were tested using the Chow test (P < 0.05) (Verbesselt et al 2012).…”

“…In addition to precipitation (ppt), temperature (tmp Therefore, this study investigated the relative contributions of climatic factors, carbon dioxide concentration and anthropogenic factors to annual changes in ER by the relationships between AR(1) and multiple factors. Considering there may exist multicollinearity among these factors, we used the PCR method to separate contributions (Li et al 2022). All explanatory variables were tested for no multicollinearity by variance inflation factor values (VIF < 5).…”

“…where β 0 is the intercept and the significant coefficient β 1 (P < 0.05) reflects the anthropogenic effect (Li et al 2022).…”

The response of geographical processes to landscape restoration: China’s research progress

“…Li et al (2021a) analyzed the effects of 13 large-scale land conservation and restoration programs and found that more than 45% of China’s drylands experienced a significant increase in the normalized difference vegetation index. Since the early 2000s, vegetation greenness has increased by 6.7% (31.6 Mha) in China’s drylands as a direct result of restoration, especially in the Loess Plateau and the so-called Three-North region (Li et al, 2022b). Vegetation cover change in the last two decades in northern China has been especially prominent, where, for example, in Inner Mongolia, annual land cover changes exhibited a net forest increase of more than 190,000 ha during 2001–2014 in the areas where ecological programs have been conducted (Yin et al, 2018; Niu et al, 2019).…”