Should riparian buffers be part of forest management based on emulation of natural disturbance?

摘要

Riparian communities (those near open water) have often been shown to display high structural and compositional diversity and they have been identified as potentially serving a keystone role in the landscape. Thus, they are the focus of specific management guidelines that attempt to protect terrestrial and aquatic ecosystems. We used a digital forest inventory database for a portion of the boreal mixed-wood forest in Alberta, Canada, to examine whether proximity to a lake affects forest composition, age, or configuration. Two analyses were employed: (1) forest composition (dominant canopy species, proportional composition of different species) and age (decade-of-origin) in bands of 50 m width and varying distance from small lakes were compared to forest in a similar spatial configuration but away from open water and (2) forest composition, dominant canopy species, age, and stand shape metrics were examined along transects emanating out from lakes in two regions, which varied in topography and dominant forest cover. We found no effect of distance from lake on forest age. The proportion of the landscape covered by forest of the predominant canopy species increased with distance from lake, but this was largely due to a corresponding decline in cover of non-forest vegetation rather than a change in forest canopy composition. At the spatial resolution of forest management planning, riparian forests in this region are of similar age and composition as those away from lakes. Since there is no natural analogue for riparian buffer strips around lakes, they may not be justified in the context of ecosystem management following the natural disturbance paradigm. Management of riparian forests should focus on meeting defined management and conservation objectives through, for example, protection of finer scale features of riparian zones and landscape-level planning for allocation of uncut forest