The evaluation of woodland status by means of botanical indicator species.

The aims of this study were to evaluate the use of botanical species as indicators of antiquity and environmental continuity and also to provide greater understanding of the processes responsible for the formation of woodland plant communities. In order to address this, the research was undertaken along four main themes: 1) Plant colonisation rates. 2) Plant species lists for woodland sites. 3) The impact of surveyor effort and strategy in devising species lists for sites. 4) The response of a typical woodland plant to management. 5) Plant communities in an area of Scottish pine forestIn particular, this study has focussed on the determination of indicator species. Some of the problems of surveying woodlands have also been raised. These problems include a lack of thorough surveys in secondary woodland habitats, and also the difficulty of comparing woodlands when they have been surveyed for different lengths of time, at different times of the year and different recording methods employed. The rate at which species are recorded during surveys has been studied in detail using three non-linear equations, which can be used to predict the number of species missed for a given survey. The results of investigating differences between species lists of different types of woodlands have shown that geology and age are the two most important factors affecting species composition of woodland within the study area (mainly South Yorkshire). The best method for determining indicator species appeared to be a simple comparison procedure between ancient and secondary woodland, with species split into two groups depending upon their percentage occurrence in ancient woodland (>90% and 75-90%) after compensating for unequal numbers of woodlands in the two categories. In addition recommendations have been made as to the number of indicator species required to be confident that a site is ancient. The findings of this study and the conclusions reached will help refine the surveyand evaluation procedure for conserving and maintaining the woodland resource.