Modelling long-term effects of forest management on epiphytic lichens in northern Sweden

Species-habitat models are important tools in conservation and wildlife management today. Models simulating the long-term ecological consequences of forestry on biodiversity have large potential as guidance for management. In this paper, we evaluated a model, lichen biomass spatially explicit model (LIBSEM) that predicts the temporal and spatial distribution of epiphytic lichens in boreal coniferous forests. We assessed model performance by simulating the standing crop of pendulous lichens (Bryoria spp.) over a 50-year period in a managed forest landscape (Brattaker,4405 ha). We compared the simulated data with independent field data based on sampling of lichen litter in 54 plots stratified by forest age class. Simulated epiphyte standing crop was significantly related to field data but overall model performance was rather poor at the cell level (50 m x 50 m cells) with a modelling efficiency of 12%. Results suggest that the model succeeded better in predicting lichen biomass on the landscape level. We used LIBSEM to assess possible long-term consequences on epiphytes of four management scenarios differing in the length of the rotation cycle. The change in epiphyte biomass was projected over a 200-year period. Results show that an even-aged silvicultural system with a normal rotation (110 years) only can support a low amount of pendulous lichens while short rotation (60 years) is very detrimental to epiphyte communities. Thus, to enhance the abundance of epiphytic lichens it is necessary to use extended rotations, preferably in combination with forest reserves. We conclude that spatially explicit landscape models may act as a guide for managing boreal forests to improve conditions for epiphytes. (C) 2002 Elsevier Science B.V All rights reserved.