Restoration of native woodland in former conifer plantations

Abstract

The majority of Irish forests are plantations of exotic conifer species, with semi-natural woodlands occupying less than 1% of Ireland. Recent land-use changes, in particular the expansion of National Parks and Nature Reserves, provide opportunities for the restoration of native woodlands to areas formerly occupied by conifer plantations. Woodland restoration, however, has received little research attention in Ireland. The main objectives of this project are; i) to determine in what situations natural succession will be sufficient to establish native woodlands, and ii) to identify where more intensive management options, such as tree planting, will be successful. Twenty-one pairs of 400m2 permanent plots were established in or near the Wicklow Mountains and Killarney National Parks. One plot of each pair was fenced to exclude large herbivores. In each plot, vegetation was surveyed in eleven Im" quadrats, and the growth and survival of 72 planted sessile oaks (Quercus petraea) and downy birches (Betula pubescens) and also of naturally regenerating trees was measured annually over three years. Vegetation development was slow over the first few years after felling, but older clearfelled sites developed fairly stable heath vegetation. Acid grassland developed on clearfells with better soils, while rush-dominated communities occurred on wet soils. Early vegetation development was strongly influenced by the soil seed bank, but large herbivores appeared to have little effect.