Macroinvertebrates and buffers : The influence of riparian buffers on stream communities influenced by forest management.

Forest management, including timber harvesting, is the primary land use activity in most of Sweden. However, clear cutting forests (i.e., final felling) can create a number of environmental problems in aquatic ecosystems and their communities. To combat these affects, intact riparian ‘buffer zones’ are typically left along streams and lakes in the Swedish landscape. There are many ideas on how wide a buffer zone has to be, to maintain an optimal ecological and hydrological state of a stream. Not only is the width of buffer zones debated, but also their overall design, including whether un-buffered stream segments could be beneficial. This study aims to test the effects of riparian buffers on macroinvertebrate biodiversity and community composition in streams draining catchments with clear cutting. To do this, I estimated the family richness and a variety of additional metrics from nine streams from southern Sweden in the Jönköping area. Three of the streams had intact buffers (<5 meter), three had no buffers, and three were unharvested (i.e., forested) catchments that served as controls. This study used data and benthic invertebrate samples collected as part of a bigger study, which were picked and manually sorted by the author. Richness ranged from 3 families at one site to as many as 13 at another one. Total abundance ranged between sites from 19820/m2to 27920/m2individuals. Overall, the results showed no significant difference in any of the invertebrate metrics across the three stream types. However, family richness increased among sites as a function of water temperature. The lack of buffer effects reported here may reflect the extremely warm summer of 2018, which caused a massive drought and was the warmest one ever recorded in the parts of Sweden where the invertebrates were collected.