Effects of single-tree selection harvesting on hymenopteran and saproxylic insect assemblages in the canopy and understory of northern temperate forests  

作　　者：Sandy M. Smith Nurul Islam M. Isabel Bellocq 

机构地区：[1]Faculty of Forestry, University of Toronto, 33 Willcocks St., Toronto, Ontario, M5S 3B3 Canada [2]Departamento de Ecología, Genética y Evolución, FCEN, Universidad de Buenos Aires [3]CONICET. Ciudad Universitaria Pab 2, Piso 4, Buenos Aires 1426, Argentina

出　　处：《Journal of Forestry Research》2012年第2期275-284,共10页林业研究（英文版）

基　　金：funded by the Richard Ivey Foundation;the Haliburton Forest;Wild Life Reserve

摘　　要：Insects respond to changes in microhabitat caused by canopy disturbance, and thus can be used to examine the ecological impacts of harvesting. Single-tree selection harvesting is the most common silvicultural system used to emulate local small-scale natural disturbance and maintain uneven-aged forest structure in temperate forests. Here, we test for differences in richness, abundance, and composition of hymenopteran and saproxylic insect assemblages at four different taxon levels （selected insect orders; and all hymenopteran families, and braconid subfamilies and morphospecies） between the canopy and understory of unharvested and single-tree selection harvested sites in a northern temperate forest from central Canada. Harvesting had no effect on insect assemblage richness, composition or abundance at the three highest taxon levels （order, family and subfamily）. Similarly, richness and abundance at the lowest-taxon level （braconid morphospecies） were similar, although composition differed slightly between unharvested and harvested stands. Insect assemblages were vertically stratified, with generally higher abundance （for Diptera, Hymenoptera, some hymenopteran families and braconid subfamilies） and richness （for braconid morphospecies） in the understory than the canopy. In particular, composition of the braconid morphospecies assemblage showed relatively low similarity between the understory and canopy. Single-tree selection harvesting appears to influence wood-associated insect taxa only subtly through small changes in community composition at the lowest taxon level, and thus is recommended as a conservative approach for managing these northern temperate forests.Insects respond to changes in microhabitat caused by canopy disturbance, and thus can be used to examine the ecological impacts of harvesting. Single-tree selection harvesting is the most common silvicultural system used to emulate local small-scale natural disturbance and maintain uneven-aged forest structure in temperate forests. Here, we test for differences in richness, abundance, and composition of hymenopteran and saproxylic insect assemblages at four different taxon levels （selected insect orders; and all hymenopteran families, and braconid subfamilies and morphospecies） between the canopy and understory of unharvested and single-tree selection harvested sites in a northern temperate forest from central Canada. Harvesting had no effect on insect assemblage richness, composition or abundance at the three highest taxon levels （order, family and subfamily）. Similarly, richness and abundance at the lowest-taxon level （braconid morphospecies） were similar, although composition differed slightly between unharvested and harvested stands. Insect assemblages were vertically stratified, with generally higher abundance （for Diptera, Hymenoptera, some hymenopteran families and braconid subfamilies） and richness （for braconid morphospecies） in the understory than the canopy. In particular, composition of the braconid morphospecies assemblage showed relatively low similarity between the understory and canopy. Single-tree selection harvesting appears to influence wood-associated insect taxa only subtly through small changes in community composition at the lowest taxon level, and thus is recommended as a conservative approach for managing these northern temperate forests.

关 键 词：selection harvesting insect communities canopy insects Jack pine forests forest management high-taxon level insect conserva-tion 

分 类 号：S718.7[农业科学—林学]