The potential for sustainable management of semi-natural woodlands in southern England using uneven-aged silviculture

Abstract

Summary This paper describes an investigation into the potential use of uneven-aged silviculture in woodlands which have historically been managed using coppice with standards. The study is presented in two parts: the first examines criteria to help decide whether the structure of a woodland is suitable for uneven-aged silviculture, the second proposes two methods of implementation. Three woodlands were selected for the study and data on stand structure and natural regeneration were recorded for nine different strata within these areas. Three criteria were chosen to help decide which stands were suitable for uneven-aged silviculture, these related to basal area, size distribution of trees, and the amount, height and species of natural regeneration. Data from the nine woodland strata were compared with the criteria and only one satisfied all of them. The woodlands had an adequate basal area and generally a good distribution of diameters. However, the main constraints were the failure of seedlings of the desired species to develop into saplings, and a lack of information on the use of neglected coppice to produce canopy trees. It was concluded that the criteria were useful but could not be used in isolation from silvicultural judgement. The two methods of implementation were the reverse-J diameter distribution and the frame tree method. The reverse-J method is a traditional approach to uneven-aged silviculture in which the diameter distribution is manipulated to resemble an ‘ideal’ structure. To determine a suite of ‘ideal’ reverse-J diameter distributions, data from the strata were investigated using a negative exponential function. The second approach, the frame tree method, is a more flexible approach compared with the reverse-J method, and could be used to produce a greater variety of uneven-aged stand structures. Neither of the approaches has been validated and both pose many questions which can probably only be answered by practical implementation.