Do different logging strategies influence the abundance of epiphytic chlorolichens?

Abstract

The effects of two logging strategies and edge effects on cover and abundance of the epiphytic chlorolichens Cavernularia hultenii, Platismatia glauca and P. norvegica were studied in an experimentally logged boreal spruce forest. Whether lichen size distribution within the three species was affected by logging regimes was also tested. One hundred and ten branches were sampled at random within: (1) fine-grained clearcuts consisting of 23 cutblocks 0·25 ha each; (2) coarse-grained clearcuts consisting of 3 clearcuts 2·25 ha each; and (3) a control area.

Of the three species studied, C. hultenii was the most vulnerable to logging, with an abundance much lower in logged areas than in the control area. By contrast, P. glauca was equally abundant in the fine-grained area and in the control area, but significantly less abundant in the coarse-grained area where it seems to have been adversely affected by a pronounced edge effect. No such edge effect, however, was noted in the fine-grained area. Juvenile thalli of C. hultenii and P. glauca were less frequent in the coarse-grained area than in the fine-grained and control areas, suggesting that the juvenile stage might be more sensitive to logging than mature thalli. These results indicate that creation of large clearcuts (2·25 ha) may not be in accordance with the goal of maintaining population size in either C. hultenii or P. glauca. However, P. glauca does not seem to be negatively influenced by a fine-grained logging pattern. No effect of logging strategy or distance from the forest edge was observed on P. norvegica. It follows from the above that any management plans aimed at maintaining population size should be based on an understanding of ecology and life history gleaned from the area in question.