Areas of longstanding woodland habitat are thought to be capable of acting as refuges for many rare and vulnerable plants. They are also home to a number of species which are largely reliant on this type of old growth forest habitat in order to survive. Expert authors have attempted to group these species into lists of “ancient woodland indicator species” which, when employed in conjunction with historical land use information, can be used to help identify areas of high conservation value old growth woodlands and to assess the biodiversity of forest habitats.
Since few species are entirely restricted to ancient woodland habitat (many are capable of surviving in other semi-natural habitat types where these are present in the landscape), the designation of ancient woodland indicators is not a straightforward task. A subjective decision as to how often a species can occur outside of ancient woodland and still be a valid indicator must be taken. We used classification tree methods to attempt to separate designated ancient woodland indicators from other woodland species based upon their life history traits, identifying the strength of differences between the two groups of species.
Results suggest that despite the element of subjectivity in their derivation, designated ancient woodland indicator species in Britain do, by and large, possess a distinct set of traits. These species are almost exclusively short, perennial plants, usually with a high seed weight. The poor dispersal and competitive ability which is linked to these traits may therefore be partly responsible for the indicator species’ reliance upon ancient woodland habitat. This characteristic profile is also likely to leave ancient woodland indicators vulnerable to future habitat change.
Although ancient woodland indicators are broadly identifiable by their trait profile, a number of cases which do not conform to this trait profile were also highlighted. These species had traits more in common with widely occurring plants of disturbed habitats than other proposed indicator species and may therefore be less reliable as indicators of ancient woodland. Rarer indicator species tended to have the most distinct trait profile, suggesting that these are likely to be the most useful species in identifying ancient woodland habitat.
This article is taken from the recent paper by Kimberley et al in Applied Vegetation Science:
Kimberley, A., Blackburn, G. A., Whyatt, J. D., Kirby, K., Smart, S. M. (2013), Identifying the trait syndromes of conservation indicator species: how distinct are British ancient woodland indicator plants from other woodland species? Applied Vegetation Science. doi: 10.1111/avsc.12047
Adam Kimberley is a second year PhD student at the Centre for Ecology and Hydrology, based at the University of Lancaster. adakim [at] ceh [dot] ac [dot] uk