福建天宝岩国家级自然保护区长苞铁杉林林窗的物种构成和边缘效应分析

Analyses on species composition and edge effect of forest gap of Tsuga longibracteata forest in Tianbaoyan National Nature Reserve of Fujian

在福建天宝岩国家级自然保护区内的长苞铁杉(Tsuga longibracteata W.C.Cheng)纯林和长苞铁杉-阔叶树混交林中选择处于不同发育阶段的24个林窗,对各林窗中心区、边缘区和非林窗区的物种数、个体数、ShannonWiener指数(D)和Simpson指数(C)进行分析,并据此对各林型林窗的边缘效应指数ED和EC进行比较。结果表明:2种林型林窗的物种数和个体数均随林窗的发育进程逐渐增加,且在林窗的不同区域也有一定差异,总体上在林窗边缘区最高、在非林窗区最低;混交林林窗各区域的物种数和个体数均高于长苞铁杉纯林。2种林型林窗不同发育阶段及不同区域间的D和C值存在一定差异;2种林型林窗的中心区和非林窗区的D值均随发育进程逐渐增大,而林窗边缘区的D值则在发育前期最高,且各发育阶段林窗中心区和边缘区的D值均高于非林窗区;纯林林窗不同区域的C值在发育中期最低,发育前期和后期略高;而混交林林窗中心区和非林窗区的C值则随发育进程逐渐减小,林窗边缘区的C值则随发育进程逐渐增大。2种林型林窗的ED值均随发育进程逐渐减小,EC值则随发育进程逐渐增大;其中,林窗发育前期的ED和EC值与发育中期和后期的ED和EC值差异显著(P<0.05),且混交林林窗不同发育阶段的ED值均高于纯林,而其EC值则低于纯林。综合分析结果显示:长苞铁杉纯林和长苞铁杉-阔叶树混交林的林窗均具有明显的边缘效应,且边缘效应的强度与林窗面积和林型相关;混交林林窗的边缘效应一定程度上高于纯林,表明混交林的林窗更有利于林分更新和树木生长。

In Tsuga longibracteata W. C. Cheng pure forest and T. longibracteata-broadleaved tree mixed forest in Tianbaoyan National Nature Reserve of Fujian, 24 forest gaps at different developmental stages were selected, and species number, individual number, Shannon-Wiener index （D） and Simpson index （C） in central, marginal and non-forest gap zones of these forest gaps were analyzed, and hereby, edge effect index E~ and Ec of forest gap of different stands were compared. The results show that numbers of species and individuals in forest gap of two stand types increase gradually with development process of forest gap, and there is also a certain difference in different forest gap zones, as a whole, those are the highest in marginal zone of forest gap and the lowest in non-forest gap zone. Numbers of species and individuals in different forest gap zones of mixed forest are higher than those of T. longibracteata pure forest. There is a certain difference in D and C values among different developmental stages and different zones of forest gap of two stand types. D value in central and non-forest gap zones of forest gap of two stand types increases gradually with development process, while that in marginal zone of forest gap is the highest at early stage, and D values in central and marginal zones of forest gap at different developmental stages are higher than those in non-forest gap zone. C value in different zones of forest gap of pure forest is the lowest at middle stage, and slightly higher at early and later stages, while C value in central and non-forest gap zones of mixed forest decreases gradually and that in marginal zone of forest gap increases gradually with development process. With development process, ED value of forest gap of two stand types decreases gradually and Ec value increases gradually, in which, E~ and Ec values at early stage are significantly different to those at middle and later stages （P〈0.05）. E~ value of forest gap at different developmental stages of mixed forest is higher than that of pure forest, while its Ec value is lower than that of pure forest. The comprehensive analysis result indicates that there are obvious edge effects of forest gaps of T. longibracteata pure forest and T. longibracteata-broadleaved tree mixed forest, and the strength of edge effect is related to forest gap area and stand type. Edge effect of forest gap of mixed forest is higher than that of pure forest in some degree, indicating that forest gap of mixed forest is more beneficial to stand renewing and tree growing.