云南喀斯特关键带植被时空变化特征及气候与人为影响因子解析

Spatio-temporal Variations of Vegetation Coverage and Its Climatic and Human Factors Analysis in the Karst Critical Zone of Southeast Yunnan

受自然环境及人类活动的影响,滇东南喀斯特地区石漠化问题严重,当地生态环境面临巨大压力。基于MODIS-NDVI数据通过像元二分模型提取植被覆盖度FVC,采用回归与残差分析等方法对2000~2016年植被覆盖时空变化特征和趋势进行了分析,并对影响其变化的气候和人为因子进行了解析。研究结果表明:近17年研究区FVC总体呈波动上升的趋势,增长速率为春季(0.005 0/a)>冬季(0.004 3/a)>秋季(0.004 0/a)>夏季(0.000 3/a),年增长速率0.003 6/a。2000年以来FVC呈增加趋势的区域占研究区总面积比例在85%以上,而在市域、县域中心区以减少为主。研究区分别有56.41%、61.47%的FVC与气温、降水因子的相关系数通过0.05的显著性检验,主要呈正相关关系。2000~2016年研究区受人类活动影响持续增加的面积占总面积80.54%,持续减弱的面积占13%,影响不变的面积占6.46%,人类活动对FVC变化的影响呈持续加强的趋势。研究结果将为定量评估喀斯特区域石漠化综合治理工程和生态修复评估提供科学依据。

Influenced by natural environment and human activities, rocky desertification in the karst region of southeast Yunnan is serious, degrade ecosystems have been restored to some extent through a series of ecological conservation projects that started in 2000. In the present study, based on MODIS-NDVI data, the pixel dichotomy model was used to extract fractional vegetation cover(FVC), spatio-temporal variation characteristics of vegetation cover and its climate and human factors from 2000 to 2016 was investigated. Results show that the FVC in the study area showed a general trend of increase in recent 17 years, the growth rate was as follows: spring(0.005 0/a) > winter(0.004 3/a) > autumn(0.004 0/a) > summer(0.000 3/a), and the annual growth rate was 0.003 6/a. Since 2000, the area with an increasing trend of FVC accounted for more than 85% of the total area of the study area, while in the central area of city and county, it was mainly reduced. FVC was positively correlated with temperature and precipitation. From 2000 to 2016, the area affected by human activities in the study area increased continuously accounting for 80.54% of the total area, decreased continuously accounting for 13%, and remained unchanged accounting for 6.46%. The influence of human activities on the change of FVC showed a trend of continuous strengthening. Overall, the rocky desertification control projects play an important role in increasing vegetation cover.