The Number of Species of Insects Associated with British Trees: A Re-Analysis

Abstract

An updated list of numbers of phytophagous insects and mites associated with 28 British tree species or genera is presented with revised estimates of the abundance of the trees. Difficulties assessing species-area relationships for insects on trees are discussed and a new relationship calculated. The problems that arise when making comparisons between species-area relationships for subsets of the insect community are explored. The contribution of the taxonomic isolation of different trees to variations in insect species richness was analyzed using a number of approaches, none of which yielded a strong effect. When a number of variables: Log tree abundance, time present in Britain, whether or not trees were evergreen or coniferous, taxonomic relatedness, tree height and leaf length were included in a stepwise multiple regression analysis of insect species richness, all but coniferousness contributed significant F values. These variables accounted for 82% of the variation in insect species richness between British trees. When the regression analysis was repeated but halted after the entry of the last significant F value, log abundance, time and evergreenness emerged as the best set of predictor variables for the numbers of insect species on British trees and accounted for 74% of the variation.