吉林省露水河地区森林景观格局变化

Changes of Forest Landscape Pattern in Lushuihe Watershed of Jilin Province

遥感影像记录的地物信息具有很大的时空延展性,20世纪80年代中期以前传统林业政策在吉林省露水河地区非常盛行,森林经营以采伐为主,从20世纪90年代初开始当地林业经营策略渐趋科学,本文选用研究区1985年及1999年两期遥感影像从景观、类型及斑块3个尺度研究其森林景观格局和斑块变化特征,结果表明:研究区森林景观本底由成熟林转变为中龄针叶林和成熟阔叶林,成熟针叶林受到的破坏最为严重,全区森林景观趋向破碎化,除中龄针叶林外,其它森林景观类型平均斑块变小。区域森林景观要素有部分趋于优化,如森林覆盖率提高了6·37%,中龄针叶林景观类型逐渐占优势,有利于恢复区域地带性植被,大量宜林地绿化成林等。造成这种格局的主要原因是人类对森林产品的采伐,森林群落自身的演替也是造成区域森林景观破碎化的重要因素,但其影响作用较人类活动小,气候变化因素对森林景观变化起促进作用。本文对研究区森林景观格局优化提出了建议。

Although remote sensing image only records time-period information on the land covers on space scales and time scales, it is useful to detect the changes of land covers. Before the middle of 1980s, traditional forest policy featured with deforestation was prevailing in the study area. The forest policies have been modified scientifically since the 1990s. This paper aims to detect the changes of forest pattern and features of forest ecosystem based on RS images in 1985 and 1999. Types of forest landscape in the study area were classified into ripe conifer forest (F1), midlife conifer forest (F2), ripe broadleaf forest (F3), midlife broadleaf forest (F4) and cultivated young forest (F5). Ripe forests include three tree-age groups of traditional forest management. The rate of forest coverage has increased 6.37 percentage points from 88.27% in 1985 to 94.64% in 1999. The dominant forest landscapes were ripe conifer forest and ripe broadleaf forest in 1985, but midlife conifer forest and ripe broadleaf forest in 1999. It indicates that the feature of forest landscape in the study area has changed. Landscape in the study site has transformed from mature forest to midlife conifer forest and mature broadleaf forest. Mature conifer forest was demolished seriously. Except for midlife broadleaf forest, the whole forest landscape tends to be fragmentation and patches of other types of forest landscapes is getting smaller. There were two main reasons for the change of landscape pattern. One is human's frequent deforestation activity and the other is the effect of climate changes and succession of forest community. The impact of the latter is weaker and climate factors only accelerate the change process. The left climax community, broadleaf and Korean pine forest, is isolated and its border is dismembered seriously. Its inner and exterior habitation has differentiated largely and the modes of inflow of material, information and energy have changed greatly. Those forests must be protected so as to construct ecological environment similar to original climax community of broadleaf and Korean pine forest. The overall forest ecological system is moving to a stable status. In addition, many landscape elements tend to rationalization. Many hills are covered with trees with dominance of midlife conifer forests. It is helpful to recover the zonal vegetation-broad leaf and Korean pine forest.