基于3S技术的宁波市东部区域常绿阔叶林动态初步研究

利用3S技术,对宁波1974～2009年间6个时相的Landsat卫星遥感数据进行土地利用和植被类型分类,提取相邻年份不同植被类型与常绿阔叶林转化的区域,并计算每种类型对常绿阔叶林的转化率.研究结果表明,自然演替规律和经济利益驱动是促成常绿阔叶林37年间动态变化的主要原因；在不受人为影响的条件下,它最易与常绿一落叶阔叶混交林和针叶阔叶混交林相互转化.在此基础上,测算每个时期转入为常绿阔叶林的植被类型与同时期保持为常绿阔叶林类型的距离,并计算5个时期的总平均值.将其按植被类型排序为:针叶阔叶混交林＞常绿落叶阔叶混交林＞毛竹林＞针叶林＞园地＞灌丛＞农田.分析结果显示,种源传播和用地历史是影响退化常绿阔叶林群落次生演替方向的关键因素.

Preliminary study on dynamics of evergreen broad-leaved forest in Eastern Ningbo using 3S methods

This paper classified land use and vegetation types of Ningbo with Landsat remote sensing data of 6 times (1974～2009) using 3S methods, extracted the regions of different vegetation types which turn into evergreen broad-leaved forest in each period and calculated transformation rate of every type for evergreen broad-leaved forest. Results showed that physical succession rules and economic benefits are the main causes of evergreen broad-leaved forest dynamic changes in the past 37 years. It is likely to conversed with coniferous and broad-leaved mixed forest and evergreen and deciduous broad-leaved mixed forest without considering human influence. On this basis, we measured the distance between vegetation types turned into evergreen broad-leaved forest in each period and the type remained evergreen broad-leaved forest in the same period, calculated total average value of five periods, and ordered them by vegetation types: coniferous and broad-leaved mixed forest>evergreen and deciduous broad-leaved mixed forest>bamboo>coniferous forest>tea plantations and orchards>shrub>farmland, it is found that seed spread and land use history are key factors which affected direction of degraded evergreen broad-leaved forest community’s secondary succession.