Changes in forest floor bryophyte (moss and liverwort) communities 4 years after forest harvest

Abstract

Forest harvest presents a potential threat to forest floor bryophyte communities primarily through alteration of the microclimate and disturbance of substrates on the forest floor. Management, including harvest, applied at the landscape scale creates patches of disturbance of differing severities at the spatial scale experienced by bryophytes. Presumably, bryophyte diversity in managed landscapes is best conserved by forest harvest techniques that minimize community change, thereby allowing disturbed communities to reassemble to approach predisturbance composition. We monitored bryophyte community reassembly by sampling quadrats established in a 54-ha management block of Acadian forest in New Brunswick, before and after harvest. Quadrats were either in unharvested areas, or experienced a range of disturbance severities from removal of some or all canopy, to forest floor disturbance with complete canopy removal. Bryophyte communities showed compositional change over 4 years, even in areas that were not harvested. Although species richness was maintained or recovered 4 years after harvest, changes in species composition were significant in all disturbance classes with greatest change related to forest floor disturbance. In particular, liverworts were lost in areas with forest floor disturbance. We suggest that the simplest method to reduce immediate species loss, and presumably promote conservation of bryophyte communities within managed forest landscapes, is to utilize techniques that reduce the area of forest floor and associated substrates that are physically disrupted.Key words: bryophyte, community change, disturbance, forest harvest, monitoring.

Substrate Form Determines the Fate of Bryophytes in Riparian Buffer Strips

“…Fenton et al 2003). The moss species had both a higher survival rate and a higher establishment rate after logging than did the liverworts (Fig.…”

“…Several studies have shown that bryophyte cover declines after clear-cutting (e.g., Hannerz and Hånell 1997, Fenton et al 2003, and a forest fire kills most bryophytes in dry and mesic sites (K. Hylander, personal observation). The response of bryophyte populations to alternative timber-harvesting methods, such as shelterwood log-FIG.…”

Slope Aspect Modifies Community Responses to Clear-Cutting in Boreal Forests

“…Mosses and liverworts may respond differently because most moss species are less shade adapted and drought sensitive than the majority of liverworts (Marschall and Proctor 2004). Hence, moss richness is less affected by exposure (Fenton et al 2003, Å stro¨m et al 2005, Hylander et al 2005. Furthermore, forest species, and species associated with convex substrates such as logs, stumps, and tree bases, are more prone to local extinction following clear-cutting .…”

Diversité et résilience végétales des pessières noires à lichens de la forêt boréale québécoise deux années après perturbations sylvicoles /

“…D'après les bioindicateurs mesurés, les peuplements étudiés semblent garder leur différence initiale en termes de recouvrement, sauf pour l'épinette noire, où la différence initiale entre les DS et les PM ne s'est pas maintenue deux années après perturbations sylvicoles. (Fenton et al 2003;Fenton et Frego 2005;Frego 2007), fortement abondants dans les PM (Bergeron 1996). Ces espèces ont une capacité de reproduction lente, sont très sensibles à l'ouverture du couvert arborescent, à l'augmentation brusque de la charge radiative, leur abondance est ainsi fortement inhibée par les travaux sylvicoles (Fenton et al 2003).…”

“…(Fenton et al 2003;Fenton et Frego 2005;Frego 2007), fortement abondants dans les PM (Bergeron 1996). Ces espèces ont une capacité de reproduction lente, sont très sensibles à l'ouverture du couvert arborescent, à l'augmentation brusque de la charge radiative, leur abondance est ainsi fortement inhibée par les travaux sylvicoles (Fenton et al 2003). De plus, le stress induit par l'irradiation solaire et le stress hydrique affecte négativement la survie des mousses présentes sur les parterres forestiers (Brumelis et Carleton 1989).…”