气候变化和生态建设对秦岭—淮河南北植被动态的影响

论文基于2000—2019年秦岭—淮河南北MODIS-NDVI植被覆盖数据,对中国南北过渡带植被时空变化进行分析,并探讨植被动态变化驱动因素。结果表明：① 在趋势变化上,2000—2019年秦岭—淮河南北植被显著恢复。其中,秦巴山区植被恢复面积占比最高,其次是巫山山区和关中平原;植被退化区面积占比仅为6.4%,主要分布于长三角城市群。② 在气候因素上,NDVI变化与气温显著相关(P<0.05)面积占比为9.1%,低于降水(13.1%)和日照时数(14.5%)显著区域,无显著相关区域分布面积最广,说明在关键生长季(5—9月),区域水热条件较好,植被年际波动受气候变化影响区域较少。③ 在驱动因素上,受气候因素和生态建设驱动绿化占比分别为19.2%和30.0%,其中,生态建设驱动绿化区与秦巴山区、大别山生态修复工程,川东、长江中下游撂荒地空间格局一致,说明耕地转为生态用地是区域植被快速恢复的主要原因。研究结果对量化湿润—半湿润地区植被驱动因素,优化生态建设评估模型具有启示意义。

Coupling effects of climate change and ecological restoration on vegetation dynamics in the Qinling-Huaihe region

Using the Terra Moderate Resolution Imaging Spectroradiometer (MODIS) Normalized Difference Vegetation Index (NDVI) data (MOD13Q1) and land cover data, and the observed daily temperature, precipitation, and sunlight hours data obtained from 196 meteorological stations in the north and south of the Qinling-Huaihe region, this study explored the spatiotemporal characteristics of the vegetation dynamics in the region. It also analyzed the effects of the driving forces of climate change and human activities (such as urbanization and ecological restoration programs) on vegetation restoration and degradation between 2000 and 2019. As China's north-south transitional zone, the Qinling-Huaihe region has experienced overall greening (54.6% significant NDVI increase at P<0.05) and partial degradation (6.4% significant NDVI decrease at P< 0.05) from 2000 to 2019. The area of vegetation restoration was mainly in the Qinling-Daba Mountains, which are characterized by multi-dimensional zonal structures and biological diversity; and the percentage of NDVI increase was 96.7%. The other areas of restoration were the Qinba Mountains, Wushan Mountains and the Guanzhong Plain, which are all key implementation areas of ecological restoration programs. In terms of vegetation degradation, there was an NDVI decrease of 6.4%, which was mainly concentrated in the Yangtze River Delta urban agglomeration and sporadically spread across other rapid urbanization areas. With regard to the impacts of climatic factors on vegetation dynamics, the areas of NDVI change affected by temperature only accounted for 9.1% of the total area of the region, which is lower than the areas affected by precipitation (13.1%) and sunlight (14.5%). It indicates that the areas with significant (P<0.05) correlation between climatic factors and NDVI are limited. The reason is that there are the good hydrothermal conditions and irrigation facilities in the study region, climatic factors are not the primary limiting factors of vegetation growth. With regard to the driving forces of vegetation change, among the areas of significant greening (54.6%), 19.2% and 30.0% were identified to be related to climate change and ecological restoration programs, respectively. Ecological engineering had an influence on the vegetation dynamics of the Qinling-Huaihe region. The spatial pattern of significant restoration was consistent with the ecological restoration programs, such as the Qinling-Daba Mountains ecological protection and restoration and the Dabie Mountains ecological restoration programs. These findings enrich our understanding of the relationship between vegetation expansion, climate change, and human activities in the subtropical and warm-temperate zones of China.