The Sicamous Creek Silvicultural Systems project is a large-scale experiment with three 30-ha replicates of five treatments: 10-ha clearcut with surrounding 20-ha leave strip, array of nine 1-ha patch cuts, array of .fifty-five 0.1-ha patch cuts, individual-tree selection partial cut, and uncut control. Use of harvest treatments, edges, and habitat features by martens was studied at the Sicamous Creek site, using winter track transects and snow-tracking of individuals.
A total of 594 tracks were detected on 87 km of transects over two winters, and 84.4 km of individual tracks were followed. All harvested treatments removed approximately 33% of timber volume, but reduced marten use by over 60% compared to the uncut controls, except the 0.1-ha patch cut arrays, which reduced use by only 33%. Martens strongly avoided 1- and 10-ha openings, but they used 0.1-ha openings. Leave strips of different sizes were used approximately equally, but less than contiguous uncut forest.
Martens responded positively to edges in units with openings, with increased use of forested leave strips within 20 m of openings. However, the reduced use of blocks with openings, and of leave strips compared to contiguous uncut forest, suggested a possible larger-scale negative effect of openings.
Martens preferred wetter site types and areas with canopy cover >30%. In areas with canopy cover <20%, marten used sites that had considerably higher-than-average densities of structures that allowed subnivean access, mainly small trees 2-5 m tall, projecting logs, and lower branches of larger trees.
The results of this study should be used cautiously until they are verified in other areas, but they suggest some options to help maintain martens in managed forests:
- Arrays of small patch cuts (0.1 ha in size) or similar group-selection systems are probably the harvest systems with the least impact on martens.
- Aggregated harvest units should be considered if the alter-native is dispersed clearcuts or extensive uniform partial cutting.
- Marten habitat quality will be improved by stand management that promotes patches of dense canopy, protects wetter sites, and retains numerous structures (especially trees 2-5 m tall and projecting logs) for subnivean access.
- Further information should be obtained on the overall effect of edges.
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Updated October 24, 2008