Large-scale forest conservation and restoration programs significantly contributed to land surface greening in China

Abstract

China has implemented a portfolio of large-scale forest conservation and restoration programs (FCRPs) to advance the sustainable management of forests. However, the contributions of these programs to forest recovery and land surface greening were generally evaluated on a local scale, which hindered the systematic planning of FCRPs. In this study, we analyzed the spatiotemporal patterns of tree cover change before and after the intensification of FCRPs using Mann-Kendall test and Theil-Sen's slope estimator. With the improved phenology-based residual trend analysis (P-RESTREND) method, we derived the spatiotemporal patterns of human-induced tree cover (TCH) change on the national scale. Then, we calculated effectiveness index of FCRPs at the provincial level, based on which the effectiveness levels for the 31 provinces of mainland China were classified. Our study showed that the area of forested lands with a significant greening trend was almost five times larger in the post-intensification phase (1999–2015) than in the pre-intensification phase of FCRPs (1982–1998). More than 29.9% of the forested lands were significantly improved in tree cover by human activities in the post-intensification phase. Provinces with high effectiveness level were generally distributed in humid areas, whereas the majority of provinces with low and moderate-low effectiveness levels were spread in arid and semi-arid regions. We concluded that the implementation of FCRPs had contributed greatly to the land surface greening in China. Moreover, the effectiveness of FCRPs in forest recovery was heterogeneous at the provincial level and was driven by multiple natural and socioeconomic factors.

Unveiling the driver behind China’s greening trend: urban vs. rural areas

“…In addition to spatiotemporal changes, we also detected the timing and trend shifts of greenness time series to reveal abrupt changes in vegetation during 2000-2020. Our results showed that the year when the turning point of greenness trend occurred spanned from 2005 to 2014 and exhibited heterogeneity across urban and rural areas (figure 6(a)), although previous studies tend to set the same year for the turning points of greenness trends for all regions of China (Ma et al 2019, Zhao et al 2022.…”

“…Urban and rural areas together form the fabric of China's landscape ecology while exhibiting distinct vegetation patterns due to different anthropogenic activities. In recent decades, China has undergone rapid urbanization, accompanied by a large number of people moving from rural to urban areas (Zhao et al 2022, Zhang et al 2022a. This process has been shown to cause a substantial loss in vegetation productivity in urban areas via the expansion of impervious surfaces (He et al 2014, Liu et al 2020b.…”

“…This process has been shown to cause a substantial loss in vegetation productivity in urban areas via the expansion of impervious surfaces (He et al 2014, Liu et al 2020b. Since 2012, when China began incorporating 'Ecological Civilization' into national plans and constitution (Xu et al 2017, Zhao et al 2022, Zhang et al 2022a, urban green spaces has been promoted on a large scale. However, the role of urban greening projects in improving vegetation coverage remains ambiguous.…”

“…Large-scale afforestation activities in rural areas since the 1990s have also been remarkable. Several studies have shown that such afforestation efforts have made significant contributions to improving vegetation density and carbon storage in China (Ma et al 2019, Shi et al 2020, Yang et al 2021, Zhao et al 2022. However, vegetation degradation still persists in some rural areas.…”

“…Besides, previous studies on the temporal trends of vegetation dynamics in China have typically focused on two types of change: phenological change (seasonal dynamic) driven by short-term climate fluctuations (Wang et al 2011, Nguyen et al 2020 and gradual changes (interannual dynamics) (Yao et al 2018, Wang andFriedl 2019). However, abrupt changes, which are often associated with landuse disturbances such as deforestation, afforestation, and extreme climate conditions in both urban and rural areas, have been largely overlooked (Chen et al 2014, Zhao et al 2022. In addition, the factors and mechanisms driving vegetation responses to climate variability and anthropogenic disturbance are still poorly understood across spatial gradients in urban and rural areas (Zhang et al 2022b).…”