Multiple responses of bryophytes in a chronosequence of burnt areas in non-fire prone subtropical cloud forests

Abstract

In non-fire prone ecosystems, like some subtropical humid forests, fire produces habitat destruction and intensifies land degradation by inducing changes in native species composition, soil properties and erosive processes. Bryophytes are key components of the Macaronesian laurel forests playing an important role in regulating water cycling and microclimate. Ecological and taxonomical bryophytes groups have distinct ecological and physiological requirements and may respond in a different way to the same fire events. Therefore, analysing post fire recovery of bryophyte communities represents a key step towards a better understanding of forest fire drivers and post fire management. We investigated how species richness and composition of different ecological and taxonomical bryophyte groups varied in 1158 samples within a fire chronosequence from 5 to 57 years in the best-preserved laurel forest from Canary Islands (Garajonay National Park) analysing communities in terms of differences with comparable surrounding old growth unburnt stands. Epiphyte, terricolous and saxicolous bryophytes were sampled at each plot and the influence of the time since fire was analyzed together with environmental variables (temperature, precipitation, mist precipitation and elevation) and forest structure variables. Our results indicate that there is no general pattern of post fire recolonization, as recolonization varies depending on the ecological and phylogenetic groups considered. Climate and forest structure play an important role in post-fire recolonization, such that time since fire is not the most important variable influencing richness and composition. The results increase the understanding of the processes that shape compositional patterns in groups with high dispersal capacities and high microclimate dependence, such as mosses and liverworts.