基于MOD17 A3的陕北植被净初级生产力变化特征研究

目的]基于MOD17A3数据研究陕北地区植被净初级生产力(NPP)。方法]基于利用2000—2010年MOD17A3数据集的年均NPP数据和GIS技术定量分析了陕北植被NPP的时空变化特征。结果]榆林市东南部及延安市中北部年平均NPP大部在151~250 g C/(m~2·a);延安市中南部年平均NPP大部在300 g C/(m~2·a)以上。延安、榆林市年NPP增加的面积都在90%以上,分别为92.9%、97.8%。2000与2010年的平均NPP相比,大部分地区是增加的,只有少部分地区是减少的。增加幅度在0~50 g C/(m~2·a)的地区为榆林市长城沿线一带,增加幅度在51~90 g C/(m~2·a)的地区为榆林市大部及延安市西北部,增加幅度在91~120 g C/(m~2·a)及120 g C/(m~2·a)以上的主要分布在榆林市东南部及延安市中部;NPP降低的区域主要分布在延安市南部的桥山林区和黄龙林区。结论]通过实施退耕还林等生态建设工程,陕北地区植被状况得到较好的改善。

Variation Characteristics of Vegetation Net Primary Productivity in North of Shaanxi Province Based on MOD17A3

Objective] To study variation characteristics of vegetation net primary productivity in north of Shaanxi Province based on MOD17A3.Method]Based on the annual NPP data and GIS technology from 2000 to 2010, the temporal and spatial variation characteristics of vegetation NPP in Northern Shaanxi were quantitatively analyzed based on MOD17A3.Result]The results showed that the average NPP of the North and South of Yulin was 151-250 g C/(m2· a).The average NPP was more than 300 g C/(m2· a) in the southern part of Yan'an. From Yan'an and Yulin, the increase of NPP in the two cities were 92.9％, 97.8％ respectively.Compared with NPP in 2010, the majority of the region has increased, and only a few areas have been reduced.Rises in 0-50 g C/(m2· a) areas along the Great Wall area of Yulin, increase in 51-90 g C/(m2· a) in northwest region has the most of Yulin and Yan'an, rises in 91-120 g C/(m2· a) and the presence of >120 g C/(m2· a) above the main central southeast of Yulin and Yan'an;The decrease of NPP was mainly distributed in the Bridge Mountain Region and Huanglong Region in the south of Yan'an.Conclusion]The study suggested that through the implementa-tion of a series of ecolog-ical construction projects such as closing hill for forestation and restoring farmland into forestland,the vegetation in these parts was improved.