Composition, Structure and Regeneration Characteristics of the Open Woodlands of the New Forest, Hampshire

Abstract

The study was carried out to provide the basis for an evaluation of the impact of human activities on tree regeneration in the New Forest woodlands. Five woodland types are distinguished on the basis of ground flora, using cluster analysis techniques. The species composition and size distribution characteristics of the primary and secondary canopies of each type are examined. Finally, the regeneration patterns, both for the woodlands as a whole and for each type, are described and discussed in relation to the composition and structure of the woodlands. Regeneration rates are low throughout the woodlands but appear to match broadly with the principal variations in the light regime of the woodland floor. This is reflected in the spatial distributions of seedlings of the different species. Other influences are also apparent, in particular that of Ilex aquifolium understoreys. In some instances the understorey contributes to the shade pressure on seedlings, whilst in others it appears to act as a nursery for certain species, probably by protecting against browsing. Introduction The New Forest contains perhaps the most extensive area of lowland forest in Britain and appears, moreover, to represent a link in the chain extending back to the original forest cover of the region (Rose & James, 1974). Yet the New Forest woodlands have been moulded by human influence over many centuries and that influence is just as strong, perhaps even stronger, today. When we consider changes in woodland communities in areas such as the New Forest, the central question that must be considered is: to what extent is the regeneration of the tree species controlled by human activities? The results of studies carried out on the impacts of human activities on open woodland regeneration in the New Forest are reported in Morgan (1987). However, evaluation of these impacts required an understanding of the broad patterns of tree regeneration in the woodlands at present, with particular reference to the effect of woodland structure and composition on the form and extent of regeneration. Accordingly, a survey of all the main open woodlands was carried out and the results are reported in this paper. The findings are further discussed in Morgan (1987) where a model of the interaction of the regeneration system and human activities in the New Forest open woodlands is outlined. For the purposes of this study, regeneration is defined as reproduction by seed. This is appropriate for the main tree species in the New Forest. However holly (Ilex aquifolium), an important sub-canopy species, appears to reproduce largely by vegetative means within woodland areas. In practice it was not always possible to differentiate established seedlings from vegetative shoots, therefore regeneration counts for Ilex include both seedling and vegetative individuals.