近20年吉林中东部地区林地的时空变化及成因浅析

Dynamic Changes of Forest in Mid-east Jilin Province in the Past 20 Years.

在遥感(RS)与地理信息系统(GIS)技术的支撑下,以土地利用动态变化模型、景观模型对吉林省中东部山地丘陵区20年来林地面积的时空变化特征进行了定量或半定量的分析。结果表明:①1980年～1995年期间森林面积在减少,斑块数量增加,而相应指标在1995年～2000年期间都呈现相反趋势;②该区的林地动态变化存在明显的区域差异,无论是从土地利用类型相对变化率模型还是从林地分布重心变化情况来看都表明:通化与吉林地区的森林面积变化较大,而白山、延边地区的变化较小。经数据分析与文献调研得知,大量的采伐与人口增长对耕地的需求是林地在1980年～1995年期间减少的直接原因;而国家相应林业政策的出台是1995年～2000年期间林地面积得以增加的直接原因。

Based on RS and GIS technology, data of Landsat-MSS in 1980 and Landsat-TM in 1990 and 2000 were acquired. All those data were registered by topographic map, and then interpreted interactively on ERDAS environment. Spatial database of study area were established. Finally, the spatial and temporal change of woodland area in mountainous mid-east part of Jilin province was analyzed quantitatively or semi-quantitatively in the past two decades. Dynamic change model of land-use and landscape indices were applied in the process of analyzing the spatial and temporal change of woodland in study area. The results showed that: 1) During the year 1980～1995, the area of woodland reduced 22.1×10~4hm^2, while the number of patches increased 69 during 15 years, and the average increasing ratio was 4.6 patches per year; but during the year of 1995～2000, all the corresponding indices showed a reverse trend; 2) There was obvious regional difference for the woodland dynamic change, result from either relative change ratio of land-use or centrobaric change of forest showed that: the area of woodland changed a lot in Tonghua and Jilin region, while it changed quite little in Baishan and Yanbian region, which were the result of imbalance between economic growth and population increase in those districts, however, the areal imbalance of primary forest in those districts should not be neglected. By analysis those spatial data, it can be deduced that limber production and reclamation was the main reason for woodland decrease in 1980～1995, and new policy for forestry protection was the reason for woodland increase during the year of 1995～2000. The paper also addressed that there are drawbacks for data source and interpreters for obtaining accurate information for study the dynamics of forest in the study area, and quantitative models for analyzing forest dynamics may not be the most proper ones.