Modern forest management and the decline of the Woodland Brown (Lopinga achine) in Central Europe

Abstract

The Woodland Brown (Lopinga achine) is a characteristic flagship species for forests. Although it has experienced a dramatic decline, our knowledge concerning the reasons for the population loss is scarce. In this paper: (i) we analyze its habitat preferences on a regional scale in the Bavarian Alps; and (ii) we attempt to determine potential drivers of the decline on a national scale across Germany.Vegetation structure, microclimate and host-plant availability were the most crucial factors explaining habitat selection. Forests with a light canopy on south-facing slopes were the preferred woodland type in the study area. They had a medium-high and dense herbaceous layer rich in low-competitive sedges. Carex alba appeared to be the main host plant. Dense stands of C. alba are necessary to fulfill the eggs’ humidity requirements and to enable ease of access by the larvae. The preference for extraordinarily light forests on warm south-facing slopes most likely reflects a compensation for the cold mountain climate near the altitudinal range limit.Within Germany, L. achine populations have become extinct in regions with a mild climate, while most of the remaining colonies are restricted to areas with cold winters. However, the explanatory power of the model was very low. As the disappearance of the species coincides temporally with the abandonment of coppicing and wood pasture, we assume that the cessation of this management technique was the major driver of the range retraction. In most of the Central European habitats, long-term survival of L. achine strongly depends on suitable forest management.