Temporal persistence of edge effects on bryophytes within harvested forests

Abstract

For the management of forest harvesting it is important to understand the processes that impact the re-colonisation of disturbed forests. Edge effects into disturbed forests have been identified as having important impacts on the re-colonisation of both flora and fauna. In a study system located in southern Tasmania, we investigated whether bryophyte colonisation of harvested forests was impacted by edge effects from a standing mature forest (forest influence) and if this effect persisted through time. We tested this by placing transects across a mature/regeneration forest boundary, then recording bryophyte community composition from the ground and coarse woody debris at set distances from the edge. A chronosequence of harvested forest ages (∼7, ∼27 and ∼45years post harvesting) was used to determine if forest influence persisted through time. Models generated by non-linear canonical analysis of principal coordinates (NCAP) predicted the depth of forest influence, and ‘distances among centroids’ inferred the magnitude of forest influence.Results showed that bryophyte composition in regeneration forests responded to distance from a mature edge. Locations closer to a mature edge had greater similarity in community composition with mature forests. This study also showed that the response of bryophytes to forests influence persisted though time, even after canopy closure. Overall, mature forest species tended to be aided and early seral species restricted by forest influence. However, responses were species-specific and varied with forest age. The colonisation success of mature forest associated species was improved by forest influence; these species are typically at most at risk of being eliminated after disturbance. This result highlights the need to consider edge effects in management. The impact of forest influence on bryophytes therefore has the potential to be used in the design of areas to be harvested.