【摘要】 "三北"防护林体系、退耕还林等林业生态工程实施对黄土高原林草植被建设具有重要积极作用。为探索半干旱黄土区工程实施过程中林草植被的分布规律及其主要影响机制,选取陕北吴起县为典型代表区,基于Landsat系列数据,采用像元二分模型提取吴起县1997、2005、2010和2016年4期遥感影像的植被覆盖度数据,运用相关分析及主成分分析法,研究了植被覆盖度变化趋势及时空分布特征,揭示气象因子及居民区、道路、水系的人文社会因素对林草植被建设的影响机制。结果表明:1) 1997—2016年吴起县植被覆盖度总体呈上升趋势,由东南向西北植被覆盖度逐渐增加。2)植被覆盖度结构得到明显改善,低等级土地面积以转出为主,中高及高等级土地面积以转入为主。3)长时间序列来看,气温对植被覆盖度的影响大于降水,且两者均存在滞后性,冬春季降水量对植被覆盖度有重要影响。4)林草植被主要分布在距居民点500～2 500 m、主要道路0～800 m及主要水系0～400 m的范围内,且对中等级植被覆盖度林草地分布位置的影响最大,对低等级近乎没有影响。更多还原

【Abstract】 [Background]The implementation of forestry ecological engineering such as the Three-North Shelterbelt System and Returning Farmland to Forests has an important and positive effect on the construction of forest and grass vegetation on the Loess Plateau. In order to explore the distribution pattern of forest and grass vegetation and its main influencing mechanism during the implementation of semi-arid loess area,Wuqi county,the first county of conducting China’s Returning Farmland to Forests in northern Shaanxi province,has implemented Returning Farmland to Forests for over 20 years,and was selected as the typical representative area of this study. [Methods] Based on the Landsat series data,the image binary model was used to extract vegetation coverage data of Wuqi county in 1997,2005,2010 and 2016. Then these data were processed by correlation analysis and principal component analysis. The relationship between vegetation coverage and spatio-temporal distribution characteristics and its relationship with climate and forest vegetation location factors were studied. [Results]1) From 1997 to2016,the vegetation coverage of Wuqi county was generally on the rise,and the vegetation coverage from the southeast to the northwest gradually increased. 2) The vegetation coverage structure was significantly improved. The land area with low vegetation coverage was mainly transferred out,and the land area with medium and high vegetation coverage was mainly transferred in. 3) In the long-term sequence,the influence of temperature on vegetation coverage was greater than that of precipitation,and both had hysteresis. Precipitation in winter and spring had an important impact on vegetation coverage. 4) The forest and grass vegetation was mainly distributed in the range of 500-2 500 m from the residential area,0-800 m from the main road and 0-400 m from the main water system,and had the greatest influence on the distribution position of the forest vegetation in the middle level vegetation cover,and no influence in the low level. [Conculsions]Under the background of the implementation of the project of Returning Farmland to Forests,the living environment of vegetation such as temperature and precipitation has gradually become an major factor affecting the coverage of local vegetation.更多还原