基于MODIS的罕山次生林区森林覆盖面积动态变化分析

Analysis on the Dynamic Change of Forest Coverage Area in Hanshan Secondary Forest Region Based on MODIS

【目的】为了探讨森林生态系统在气候变化条件下的响应,对罕山次生林区的土地利用类型调查、动态监测以及对生态系统连续性的研究具有参考意义,可为今后罕山次生林区的森林生态系统的研究提供参考依据。【方法】以内蒙古罕山次生林区为研究对象,选取2003年、2007年、2011年、2015年、2019年共5期中分辨率成像光谱仪(MODIS)数据,进行支持向量机分类法的监督分类,共分为林地、草地及耕地、沙地、水体、居民点及裸地5种地物类别,并分别统计每期的5种地物类别的像元数及面积等信息。【结果】(1)2003—2019年林地逐渐向草地及耕地转变;(2)研究区内森林覆盖变化最剧烈的地区是罕山次生林区北部地区,其次是中部地区,最后是南部地区;(3)研究区内森林覆盖面积自2003—2019年逐年减少,且每年以2.04%的速度在降低。【结论】罕山次生林区总体上森林覆盖面积呈现出减少趋势,且以北部地区变化程度最为严重,此研究结果能为加强当地生态建设和植被恢复提供理论依据。

【Objective】In order to explore the response of forest ecosystems under the conditions of climate change,it has reference significance for land use type survey,dynamic monitoring and the study of ecosystem continuity in Hanshan secondary forest area,it can provide a reference for the future study of the forest ecosystem in the Hanshan secondary forest area.【Method】Taking the Hanshan secondary forest area in Inner Mongolia as the research object,selecting the data of five periods of medium resolution imaging spectrometer(MODIS)in 2003,2007,2011,2015,and 2019,to carry out the supervised classification of support vector machine classification.It is divided into five types of ground features:woodland,grassland and arable land,sandy land,water,residential areas,and bare land,and statistics on the number of pixels and area of the 5 types of ground features in each period.【Result】(1)From 2003 to 2019,forest land gradually changed to grassland and cultivated land;(2)The most dramatic change in forest cover in the study area was the northern part of the Hanshan secondary forest region,followed by the central region,and finally the southern region;(3)The forest coverage area in the study area has been decreasing year by year from 2003 to 2019,and it is decreasing at a rate of 2.04%every year.【Conclusion】The forest coverage area of the Hanshan secondary forest area generally shows a decreasing trend,and the degree of change is the most serious in the northern region.The results of this study can provide a theoretical basis for strengthening local ecological construction and vegetation restoration.