The effect of buffer strip width and selective logging on streamside plant communities.

BACKGROUND: Riparian forests surrounding streams host high biodiversity values, but are threatened by clear-cut logging. Narrow buffer strips of about 15 m are commonly left between the stream and the clear-cut, but studies suggest that the buffer width should be at least 30 m to protect riparian plant communities. Moreover, selective logging is often allowed on the buffer strips in order to increase economic gain. We used an experiment of 43 riparian sites where buffer strip width and selective logging within the strip were manipulated and supplemented with unlogged control sites. We report the short-term changes in the community composition of vascular plants and mosses near the stream (0-15 m distance).

RESULTS: 15-meter buffers are not enough to protect the vascular plant communities from changes caused by a clear-cut irrespective of the selective logging on the buffer strip. For moss communities 15-m buffers were not enough if they were selectively logged. Relative to the control sites, we observed no significant changes in community composition of vascular plants or mosses in the sites with 30-m buffer strips, whether selectively logged or not.

CONCLUSIONS: We conclude that buffer strips of 15 m are not sufficient to protect streamside plant communities even in the short term, but that buffers of 30 m should be left on both sides of the stream. Selective logging appears not to have effects on buffers that are at least 30 m wide. Thus, it may be more reasonable to increase buffer width and to allow selective logging on the wider buffer in order to compensate for the economic losses than to leave all trees on a narrow and ecologically insufficient buffer.