粤东北山地生态系统植被及其碳储量时空变化

Spatiotemporal variations in vegetation and carbon storage of mountainous ecosystems in Northeastern Guangdong Province

根据遥感影像和实测土壤(选择林地、草地、耕地和建设用地等28个样地,采集112个土壤样品)有机碳含量数据,运用Sen氏趋势分析、Hurst指数、偏相关分析和InVEST模型等方法,探究粤东北山地生态系统植被及其碳储量时空变化特征。研究结果表明:1)研究区植被覆盖度较高,归一化植被指数(NDVI)变化范围为0.14~0.95,平均值为0.79。2000-2021年全域植被覆盖度呈上升趋势,空间分布存在差异,除梅州市区外,其他地区NDVI均有不同程度的增加,其中山地NDVI增加显著,且随海拔先上升后下降。研究区未来植被变化可能存在下降趋势(Hurst指数<0.5);2)2000-2020年研究区碳储量呈现减少趋势,共计减少1.33 Tg。土地利用变化,尤其林地、草地转化为耕地和建设用地是研究区碳储量减少的主要原因。研究结果可为我国亚热带生态系统碳汇功能变化研究提供基础数据。

Based on remote sensing images and measurements of soil organic carbon content(including 28 sample sites,112 soil samples from forests,grasslands,croplands,and construction lands),methods including Sen's trend analysis,Hurst exponent,partial correlation analysis,and the InVEST model were employed to investigate the spatiotemporal variations in vegetation and carbon storage of the mountainous ecosystem in northeastern Guangdong province.The results show that:(1)The research area exhibits relatively high vegetation coverage,with a Normalized Difference Vegetation Index(NDVI)ranging from 0.14 to 0.95 and an average value of 0.79.From 2000 to 2021,the vegetation coverage of the study region increased.Apart from the city area of Meizhou,the rest showed varying degrees of NDVI increase,especially in mountainous areas,where it showed a trend of rising and subsequently declining with elevation.The Hurst exponent(<0.5)implies a potential declining trend in vegetation changes in the study area.(2)From 2000 to 2020,the carbon storage in the study area displayed a decreasing trend,amounting to a total reduction of 1.33 teragrams(Tg).Land use changes,particularly the conversion of forests and grasslands into agricultural and urban areas,are the primary reasons for the decrease in carbon storage in the study area.The conclusions can serve as fundamental data for investigating the changes in carbon sequestration functionality within subtropical ecosystems in China.