Volume Of Snags Research Articles

Relationships between riparian buffer widths and the effects of logging on stream habitat, invertebrate community composition and fish abundance

Impacts from the logging of Eucalyptus forest on stream habitat, macroinvertebrate abundance and diversity, and fish abundance were surveyed in Tasmania, Australia. Forty-five pairs of sites from 34 streams of ≥2.5 km² catchment area were each sampled once during summer in the period 1990-92. Each site pair consisted of an 'impacted' site downstream of a logging treatment and an upstream or closely matched 'paired control' site. Site pair treatments encompassed two logging methods (cable and conventional) with a range of riparian buffer strip widths (0-50 m) and included unlogged controls. Differences between site pair variables were used as test statistics for the detection of logging impacts. Logging significantly increased riffle sediment, length of open stream, periphytic algal cover, water temperature and snag volume. Logging also significantly decreased riffle macroinvertebrate abundance, particularly of stoneflies and leptophlebiid mayflies, and brown trout abundance. All effects of logging were dependent on buffer strip width and were not significantly affected by coupe slope, soil erodibility or time (over one to five years) since logging. All impacts of logging were significant only at buffer widths of <30 m. Minimum buffer widths for eliminating logging impacts on stream habitats and biota are discussed.

Coarse woody debris in mixed-conifer forests, Sequoia National Park, California

The decay rate of Abiesconcolor (Gord. & Glend.) Lindl. logs and cover, mass, and volume of logs and snags in six midelevational forest stands of Sequoia National Park, California, are reported. Based on a chronosequence, Abiesconcolor boles have a decay rate-constant of 0.05 year−1 and a half-life of 14 years. A decay classification system was developed for Abiesconcolor, Calocedrusdecurrens (Torr.) Florin, Pinusjeffreyi Grev. & Balf., and Pinuslambertiana Dougl. logs. Dimensions taken from maps of six permanent plots were combined with decay-class information to estimate volume, mass, and projected cover of logs and snags. Total mass ranged from 29 Mg ha−1 in a Pinusjeffreyi forest to 400 Mg ha−1 in a Sequoiadendrongiganteum (Lindl.) Buchh. dominated stand. Volume, projected cover, and nitrogen storage exhibited patterns similar to mass, ranging from 84 to 1160 m3 ha−1, 3.1 to 9.3%, and 41 to 449 kg ha−1, respectively.