黄土高原从1999年开始大规模退耕还林(草),植被覆盖发生了较大变化,对黄土高原植被恢复现状和恢复潜力进行评估具有重要意义。本文使用1999-2013年SPOT VEG NDVI数据,采用线性回归、Hurst指数分析法、统计学方法以及地理空间分析技术,对黄土高原植被恢复状况和潜力进行了探讨。结论主要为:(1)1999年退耕还林(草)以来,黄土高原植被覆盖度呈显著上升趋势,黄土高原三分之二地区的植被将会持续改善;(2)植被响应曲线分析表明,黄土区植被覆盖度和干旱指数呈显著的指数关系,且缓坡相关性大于陡坡。土石山区植被响应函数为线性函数,相关系数下降;(3)整个黄土高原地区平均植被恢复潜力为69.75%。植被恢复潜力值东南高而西北低,黄土高原东南地区植被恢复状况较好,其植被恢复潜力指数较小,而植被恢复潜力指数较高的地区主要为北方风沙区及西部丘陵沟壑区;(4)不同降水量条件下,植被恢复速度差别显著,其中降水量在375~575 mm之间的地区,植被恢复最快。植被恢复措施应该"因水制宜",避免因造林带来的土壤干化加剧。研究结果以期为黄土高原生态文明建设提供科学支撑。
The "Grain for Green" project has been initiated in the Loess Plateau since 1999, and would be continuously promoted in the future. Therefore, it is of important significance to assess the vegetation restoration and its potential in the Loess Plateau. In this paper, based on the SPOT VEG NDVI dataset, the trend analysis, Hurst exponent method, statistical methods and geographical spatial analysis technology were adopted. Results showed that NDVI from 1999 to 2013 had a significant upward trend and the vegetation of 2/3 of the area would continue to improve. In loessal areas, the analysis of vegetation response curve indicated that vegetation coverage had a significant exponential relationship with drought index. Such relationship of gentle slope was more obvious than that of steep slope. The best vegetation response function of soil and rock-mountainous areas was linear function. Its correlation coefficient was lower than that of loessal areas. In the future, the average vegetation restoration potential of the Loess Plateau could reach 69.75%, which was high in the southeast and low in the northwest of the plateau. The region with better vegetation restoration would have lower vegetation restoration potential index. The vegetation restoration potential was mainly concentrated in the northern sandy land as well as in the western hilly and gully area. Subsequently, the differences of vegetation restoration rate for this region under different precipitation thresholds were remarkable, among which the area with precipitation of 375-450 mm had fast vegetation restoration. The measures "adaptation to water conditions" should be taken so as to avoid soil drying for afforestation. The results provided scientific support for the construction of ecological civilization on the Loess Plateau.