Open access publications in the SLU publication database

Abstract

In many national guidelines and policies regarding protection of freshwater systems from stressors associated with forestry, riparian buffer width is a commonly prescribed strategy, typically with no other refinements of protection measures. In Sweden, the Strategic Management Objectives (SMOs) were developed to ensure that riparian buffers that are left after harvesting sustain important ecosystem attributes in aquatic systems, referred to as objectives, namely shading, biodiversity, reduction of sedimentation, and provision of deadwood and food. However, little specification is given on threshold targets or how to manage riparian zones to effectively provide these objectives. In this paper, we evaluated whether existing riparian buffers of different widths along small, recently harvested (<8 years) streams were able to provide proxies of these targeted objectives, and further compared harvested streams to counterparts situated in mature unharvested production forests (reference) in northern and southern Sweden. The influence of buffer width varied with objective and geographic location. In both regions, canopy cover (proxy for shading) increased with riparian width, and riparian deadwood was highest in no buffer sites. Organic matter (OM; proxy for food) was highest in the northern no buffer streams, while in the south OM increased with buffer width. All other parameters tested had no relationship to buffer width. These differing responses even in streams subjected to similar land-use and management within a close vicinity and region, suggest that the contemporary strategy of prescribing fixed buffer widths and/or stating objectives without defined guidelines for what constitutes an effective riparian buffer is insufficient given the large variability of stream ecosystems across small spatial scales. More comprehensive consideration synergistically accounting for site-specificity and land mosaic planning are needed to develop functionally effective buffers that can mitigate forestry impacts on stream ecosystems.