THE ECOLOGY OF BETULA SPECIES GROWING ON INDUSTRIAL CUTAWAY PEATLANDS IN IRELAND(ABSTRACT)

摘要

Birch (Betula) is a pioneer species producing relatively large numbers of small, widely dispersed seeds. Its seedlings are intolerant to shade and naturally establish where patches of forest have been destroyed or where soil is bare due to some other disturbance such as peat harvesting. Of the two species native to Ireland, B. pubescens and B. pendula, the former shows more tolerance to cooler, wetter and nutrient poor conditions and is often found growing on peat. B. pendula prefers drier soils but also peat soils to a lesser extent. Overall, little information exists on the distribution and the associated ecological characteristics of feral birch growing on cutaway peat in Ireland. Therefore, it is of interest to study the natural regeneration of Betula species in the context of sustainable forest management and particularly forest biodiversity.An extensive survey of feral Betula species growing on cutaway peat was carried out by combining fieldwork with national forest inventory records. As both species exhibit a variety of growth forms and are known to hybridise to a degree, the morphological study of trees was supplemented by the analysis of the platyphylloside content of the bark in order to adequately identify the species in question. Environmental variables studied included peat type, peat depth, pH, degree of decomposition, sub-peat mineral soil, ground vegetation, tree diameter and height, stocking density and estimated age of the trees. A distribution map integrating the environmental data was produced by using ArcView~R GIS. Multivariate analysis was carried out in order to explain relationships between the establishment and growth of trees and ecological characters. This study will improve our general understanding of the ecology of Betula species on cutaway peatlands, contributing to future management plans for enhanced forest biodiversity in Ireland.