DataSheet_1_Characterization and attribution of vegetation dynamics in the ecologically fragile South China Karst: Evidence from three decadal Landsat observations.pdf

Plant growth and its changes over space and time are effective indicators for signifying ecosystem health. However, large uncertainties remain in characterizing and attributing vegetation changes in the ecologically fragile South China Karst region, since most existing studies were conducted at a coarse spatial resolution or covered limited time spans. Considering the highly fragmented landscapes in the region, this hinders their capability in detecting fine information of vegetation dynamics taking place at local scales and comprehending the influence of climate change usually over relatively long temporal ranges. Here, we explored the spatiotemporal variations in vegetation greenness for the entire South China Karst region (1.9 million km2) at a resolution of 30m for the notably increased time span (1987-2018) using three decadal Landsat images and the cloud-based Google Earth Engine. Moreover, we spatially attributed the vegetation changes and quantified the relative contribution of driving factors. Our results revealed a widespread vegetation recovery in the South China Karst (74.80%) during the past three decades. Notably, the area of vegetation recovery tripled following the implementation of ecological engineering compared with the reference period (1987-1999). Meanwhile, the vegetation restoration trend was strongly sustainable beyond 2018 as demonstrated by the Hurst exponent. Furthermore, climate change contributed only one-fifth to vegetation restoration, whereas major vegetation recovery was highly attributable to afforestation projects, implying that anthropogenic influences accelerated vegetation greenness gains in karst areas since the start of the new millennium during which ecological engineering was continually established. Our study provides additional insights into ecological restoration and conservation in the highly heterogeneous karst landscapes and other similar ecologically fragile areas worldwide.

植物生长及其随空间与时间的变化，是表征生态系统健康状况的有效指标。然而，在生态脆弱的中国南方喀斯特（South China Karst）地区，对植被变化的特征刻画与归因仍存在较大不确定性：当前多数研究要么采用较为粗糙的空间分辨率，要么仅覆盖有限的时间跨度。鉴于该区域景观高度破碎化，现有研究难以精准捕捉局地尺度上的植被动态细节，也无法充分理解气候变化在较长时间范围内产生的影响。为此，本研究依托三期年代际陆地卫星（Landsat）影像与基于云的谷歌地球引擎（Google Earth Engine）平台，针对总面积达190万平方千米的中国南方喀斯特全域区域，以30米的空间分辨率与显著延长的1987-2018年时间跨度，探究了植被绿度的时空变化特征。此外，本研究对植被变化开展了空间归因分析，并量化了各驱动因子的相对贡献。研究结果显示，过去三十年间，中国南方喀斯特地区整体呈现普遍的植被恢复态势，恢复区域占比达74.80%。值得注意的是，生态工程实施后的植被恢复面积较参考时段（1987-1999年）增至三倍。同时，通过赫斯特指数（Hurst exponent）分析证实，2018年之后的植被恢复趋势仍具备较强可持续性。进一步研究发现，气候变化仅对植被恢复贡献了五分之一的比例，而植被恢复主要归因于造林工程，这表明自新千年以来，随着生态工程的持续推进，人为活动加速了喀斯特地区的植被绿度提升。本研究为全球范围内异质性喀斯特景观及其他类似生态脆弱区域的生态修复与保护工作提供了新的认知视角。