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Our knowledge about the Holocene vegetation changes in southern China has been based on the inference from pollen percentages. However, the relationship between pollen percentages and vegetation is non-linear. This may lead to significant bias in real vegetation cover and limit our understanding of land cover changes and its relation to climate and human activities. Here we quantitatively reconstruct past regional land-cover changes by applying the REVEALS model to four pollen records collected from two study areas in southern and middle subtropical zones. The two study areas, representing the Pearl River Basin (PRB) and Wuyi Mountain (WYM), are located in spatial gradients, thus help to elucidate not only the climate forcing, but also the spatio-temporal spread of agriculture in this region. The REVEALS reconstruction shows a clear difference from original pollen percentages and is considered more realistic in depicting regional vegetation changes. Based on more reasonable reconstruction result by excluding wetland-associated taxa, i.e., Cyperaceae and Alnus , we found a gradual decline of forest covers since the middle Holocene which may be related to the reduced rainfall in response to the weakening East Asian Summer Monsoon. The human impact on the forest cover was identified by an abrupt increase of Poaceae cover at 3500–2700 cal yr B.P. in the PRB area, which appeared later in the WYM mountainous area. Thus, our study reveals a progressive expansion of anthropogenic activities from the coastal lowlands to mountainous areas. [ABSTRACT FROM AUTHOR]

China's forests were severely degraded by human activities during the latter half of the 20th century. Therefore, China enacted ambitious programs of natural forest protection and afforestation to protect and expand forests. Yet it is unclear how the programs, especially the designation of forest reserves, have affected forest cover and fragmentation. We evaluated the effectiveness of China's national forest reserves designated since 1990 in conserving forests, by analyzing four forest metrics (i.e., percentage forest cover, mean forest patch size, mean forest patch radius of gyration, and forest patch cohesion index) derived from a newly produced 30 m annual China land cover dataset from 1990 to 2019. We found that overall forest cover increased and fragmentation decreased from baseline years, when reserves were designated, to 2019 in both reserves and their surrounding areas, and only the increase in forest cover relative to baseline was significantly greater in reserves than in surrounding areas. The designation time of reserves under national protection had no considerable effect on changes in the four metrics, but for zonation, the core zone showed a significantly higher increase in forest patch cohesion index relative to baseline than the buffer and transition zones. Nevertheless, forest cover declined and fragmentation increased in highly forested reserves, suggesting destructive human activities and ineffective management. Thus, forest protection and regeneration programs were moderately successful. We recommend that there is significant improvement needed to ensure greater protection of existing forests and reduction of threats to promote effective management. • The nature reserve program showed effectiveness in conserving forests in China. • There was better protection and recovery of forest cover than reducing fragmentation. • Destructive human activities may cause forest declines in highly forested reserves. [ABSTRACT FROM AUTHOR]

Land cover changes, especially excessive economic forest plantations, have significantly threatened the ecological security of West Dongting Lake wetland in China. This work aimed to investigate the spatiotemporal dynamics of forests in the West Dongting Lake region from 2000 to 2018 using a reconstructed monthly Landsat NDVI time series. The multi-type forest changes, including conversion from forest to another land cover category, conversion from another land cover category to forest, and conversion from forest to forest (such as flooding and replantation post-deforestation), and land cover categories before and after change were effectively detected by integrating Breaks For Additive Seasonal and Trend (BFAST) and random forest algorithms with the monthly NDVI time series, with an overall accuracy of 87.8%. On the basis of focusing on all the forest regions extracted through creating a forest mask for each image in time series and merging these to produce an 'anytime' forest mask, the spatiotemporal dynamics of forest were analyzed on the basis of the acquired information of multi-type forest changes and classification. The forests are principally distributed in the core zone of West Donting Lake surrounding the water body and the southwestern mountains. The forest changes in the core zone and low elevation region are prevalent and frequent. The variation of forest areas in West Dongting Lake experienced three steps: rapid expansion of forest plantation from 2000 to 2005, relatively steady from 2006 to 2011, and continuous decline since 2011, mainly caused by anthropogenic factors, such as government policies and economic profits. This study demonstrated the applicability of the integrated BFAST method to detect multi-type forest changes by using dense Landsat time series in the subtropical wetland ecosystem with low data availability. [ABSTRACT FROM AUTHOR]