Epiphytic macrolichens in managed and natural forest landscapes: a comparison at two spatial scales

To maintain biodiversity in managed forests we must understand how forestry affects Various organisms across a wide range of spatial and temporal scales. We compared landscape structure, forest structure, and species richness and abundance of epiphytic macrolichens in three pairs of natural and managed boreal forest landscapes. Study landscapes (2500 ha) were located within and adjacent to three of the largest forest reserves in Sweden (Reivo; Muddus, Jelka). The structural heterogeneity within landscapes was higher in managed forests whereas within-stand structural heterogeneity was higher in natural landscapes. Species richness of macrolichens at the stand level (sample plot) was 23% higher in natural forests but there was no difference at the landscape level. Most (86%) of the common species were more frequent in natural landscapes. Lichen abundance (estimated by lichen litter) was two times higher in natural than in managed landscapes, 5.6 and 2.7 kg ha(-1) forest (pooled data), respectively. Both species richness and abundance were negatively related to cutting lever (number and basal area of cut stumps) and positively related to stand variables (stand age, stem density and basal area). Lichen-rich forest stands were more numerous but covered a smaller area and were more isolated in managed landscapes. This may in turn have important consequences for dispersal of lichen propagules to second-growth forests. In conclusion, the results suggest that effects of forestry on epiphyte diversity and abundance are strongly related to the spatial scale (stand or landscape). To enhance biodiversity in managed forests we must increase structural heterogeneity at the whole range of spatial and temporal scales.