上海装饰公司营销计划书.doc

(3)随着林木胸径的增大,树冠受损比例也逐渐增大;断枝比例随林木胸径增大而增大,而断梢和失冠则随林木胸径的增大而减小。常绿树与落叶树不同,落叶树种更倾向于断枝,而常绿树种更倾向于断梢。
(4)与灾前相比,灾后大明山常绿阔叶林的叶面积指数下降18~ 41%,导致林内光照的显著增强,表现在林内的散射透光系数增加
42-、,60%,直射透光系数增加42"---56%。大明山常绿阔叶树林林冠状况比较稳定,叶面积指数保持在2左右(+),属于叶面积指数较低的森林。这是中山区常绿阔叶林长期遭受冰冻干扰影响,树冠由半圆球形向狭窄的圆柱形树冠演变的结果。
(5)冰冻干扰是樟科、壳斗科、安息香科、杜英科植物大量更新的主要驱动力,干扰发生后,这些科的属种数普遍增加,特别是樟科植物,其灾后更新种类达11种之多,占林下更新幼苗物种数的 30%,%~
%,%。冰冻干扰后,不同坡位林下更新幼苗的密度均表现为先增后减规律, 7‰2增至
,之后又降至3267-4717株/hm2。(6)随着恢复期的延长,更新幼苗的物种丰富度、多样性指数、
辛普森指数和均匀度指数均表现为递减趋势(2010年上坡除外),但不同年份、不同坡位各指数之间无显著差异。冰冻干扰只增加林下更新幼苗的个体数,对幼苗的物种多样性无显著影响。
(7)不同年份、不同坡位林下更新幼苗的高度级结构存在差异,
万方数据
以V级苗的数量最多,Ⅲ级苗的数量最少。在冰冻干扰后的第一年(2009年),I、II、Ⅲ级苗木极少,甚至缺失;灾后的第二年(2010 年),各级苗木的数量均显著增加,特别是I、II级苗的数量增加最为明显。表明冰冻干扰后林隙增加,林内光、温、水等资源的有效性改善,为种子萌芽和生长提供条件。
关键词:冰冻干扰林冠状况幼苗动态常绿阔叶林大明山
1II
万方数据
EFFECTS OF FROZEN DISTURBANCE ON CANOPY CONDITION AND SEEDLING DYNAMICS OF AN EVERGREEN FOREST IN DAMINGSHAN
ABSTRACT
Forest canopy iS the most direct and active layer interacting with the extemal environment in forest biodiversity in canopy,canopy and climate
change has e one of hotspots in international ecology also
gradually is developed as a the present study,the changes of canopy of an evergreen broad·leaved forest after damaging by frozen rain and snow and its effects on the dynamic of tree seedlings were analyzed by continually surveying in 72 permanent sample plots(each plot Was 400 m)for 4 years in an evergreen broad—leaved forest in Damingshan objectives are to:(1)clarify the effects of ice storm disturbance on canopy munity regeneration;(2)provide
data for deeper understanding the canopy characteristic of evergreen broad—leaved
forest and enriching the Canopy theory in southern subtropics.
1f11e main results are as follows:
(1)A total of 253 8 trees、Ⅳith DBH≥5cm were identified in the 72 permanent sample plots,in which 1 71 4 trees