陕北黄土高原植被恢复与生态系统服务的时空关系

陕北黄土高原作为退耕还林还草核心区域,是地表格局及植被显著变化的区域之一。评估植被恢复成果及其对生态系统服务的影响,对促进区域生态环境提升具有重要作用。本研究选择植被覆盖度作为指标评估区域植被恢复状况,以碳固定服务、土壤保持服务、生境质量及产水服务作为指标表征区域生态系统服务,分析权衡协同关系及不同尺度的时空变化,同时运用双变量空间自相关分析植被恢复对生态系统服务的影响。结果表明: 2000—2020年,陕北黄土高原植被覆盖度呈波动上升趋势,年均值由31.7%升至47.1%,植被改善显著;研究区碳固定服务、土壤保持服务呈明显上升趋势,生境质量几乎保持不变,产水服务先升后下降总体呈上升趋势,各生态系统服务时空变化存在明显的尺度效应;4种生态系统服务间的关系主要为协同;植被覆盖与生态系统服务之间存在显著的空间依赖性,相关程度存在一定差异,植被覆盖度对土壤保持服务影响最明显,其次为碳固定服务,而植被覆盖增强条件下林草耗水增多则导致区域产水量下降,造成一定的负效应。总的来说,陕北黄土高原地区植被建设已取得显著成效,生态环境得到明显改善。

Spatio-temporal relationship between vegetation restoration and ecosystem services in the Loess Plateau of Northern Shaanxi,China

As the core region of the “Grain to Green” Program, the Loess Plateau of Northern Shaanxi became an example with the most dramatic changes in earth surface pattern and vegetation cover. Evaluating the effectiveness of vegetation restoration is important for promoting regional ecological environment. In this study, the fractional vegetation coverage (FVC) was used as the index to analyze the changes in vegetation coverage in this area. Soil conservation service, carbon sequestration service, habitat quality, and water yield were used to characterize the regional ecosystem services (ESs). The effects of FVC on ESs were analyzed based on the bivariate spatial autocorrelation model. The trade-off synergies and spatio-temporal variations of different scales of those indices were discussed. The results showed that the FVC of the study area presented a fluctuating upward trend from 2000 to 2020, with the annual average value increasing from 31.7% to 47.1%. Carbon sequestration service and soil conservation service were increased, habitat quality was stable. Water yield increased firstly and then decreased, with an overall upward trend. The ESs changes were scale-dependent. There was an obvious synergistic relationship among ESs. There was a significant spatial dependence between FVC and ESs, with some differences in the degree of correlation. FVC had the strongest impact on soil conservation, followed by carbon sequestration service. However, the increase of vegetation coverage and water consumption of forest and grass led to the negative effect of water yield reduction. In gene-ral, FVC in the Loess Plateau of Northern Shaanxi had achieved remarkable success, and the ecological environment had been significantly improved.