Question: What are the impacts of factors controlling patterns of change in woodland field-layer vegetation, through time?

Location: Wytham Woods, Oxford, UK (51°41′ N, 1°19′ W).

Methods: Species occurrence was monitored in 163 permanent plots three times between 1973 and 2002 and related to management compartment and history. The dataset was analysed using a combination of ordination methods, univariate and multivariate analysis of variance and HOF modelling.

Results: The two key findings of this paper are: (1) that the species composition of ancient woodlands (often cited as a conservation goal), may be moving along an ‘undesirable’ trajectory, from a conservation viewpoint; and (2) that the impact of a synergistic effect of changing canopy dynamics, nitrogen deposition and a rising deer population has resulted in an increase in grass species, at the expense of woodland herbs. These findings have significant implications for the practical conservation of similar habitats across Europe.

Conclusions: The analytical methodology presented here allowed detailed assessment of the potential roles of a range of environmental factors controlling change. The methodology may be applicable to other long-term studies of vegetation, and is particularly appropriate for identification of cross-site drivers, such as pollutant load and climate change.

Nomenclature: Stace (1997).