THE RELATIONSHIP BETWEEN BUTTERFLIES AND ENVIRONMENTAL INDICATOR VALUES - A TOOL FOR CONSERVATION IN A CHANGING LANDSCAPE

We examined relationships between Dutch butterfly species and the Elle nberg indicator values for nutrients, acidity and moisture. Presence/a bsence data on butterflies were obtained from monitoring transects of the Dutch Butterfly Monitoring Scheme. Mean indicator values were calc ulated from vegetation samples of a selection of transect sections. Si ngle and multiple logistic regression models were used to analyse the relationships. Except for the moisture value, the vegetation samples c overed the Ellenberg scales quite well. Significant correlations betwe en moisture and acidity (-) and nutrients and acidity (+) were observe d. Sites that were both acid and nutrient-rich were not observed. Most of the observed significant relationships were unimodal (Gaussian), i n which species show a clear optimum indicator value. Other species sh owed a sigmoidal (linear) response to one or more of the ecological in dicator values. Several species were significantly correlated with all three indicator values. For a small group this was also the case in t he multiple regression model. This was probably caused by multicolline arity of the indicator values, leading to some spurious significant si ngle regression models. We discuss methodical problems and possibiliti es for refinements of the models. The observed relationships between b utterflies and indicator values agreed well with available ecological information. The observed regression models can be used to (a) predict the effects of environmental factors on the butterfly fauna, (b) use changes in the abundances of certain species as indicators of ecologic al processes and (c) determine the sensitivity of butterflies for eutr ophication, acidification and ground-water draining. In conclusion, th e models provide a powerful aid in the conservation of butterflies in a changing environment. (C) 1998 Elsevier Science Ltd. All rights rese rved.