Olympic Habitat Development Study
US FOREST SERVICE

 

Station 3 -SKIPS

In spite of all the good things we can achieve by thinning (backtrack to Station 2 if you missed it), there can be several reasons to leave some areas unthinned or "skipped over" during the thinning. These areas were "no entry" areas for equipment in our project. We call these areas "skips" and 10% of the Fresca area within the VDT (variable-density thinning) plots was assigned to skips. The skips varied in size but were about 0.1 to 0.3 ha.¼ to ¾ acre These skips will retain the high density of trees from the original uncut stand and serve 3 basic functions:

•  Preserve legacies,(structures or organisms which carry over from the previous stand) especially large conifer snags. Skips are an important way to preserve tall, well decayed snags, since such structures may be felled in logging operations to provide for worker safety. The presence of large snags is part of the structural complexity associated with older forests (snags are old-growth elements). Old-growth characteristics

    •  Large (>80cm) or old (>200 years) trees
    •  2 or more species with a wide range in ages and sizes
    •  Deep, multi-layered canopy
    •  Large conifer snags
    •  Large diameter and long logs

(For more detailed information, see the link located in Resources.)

Smaller snags, including those from hardwood trees, are also valuable although they usually fall down sooner than larger ones. Large-diameter logs are also most likely to remain intact in skips.

•  Provide areas of dense concentrations of trees. These will provide areas where the trees grow the least (thus helping to provide a wide range in tree growth rates throughout the stand) as well a continuous source of suppression mortality.(a natural process in which smaller trees die to the lack of light or other resources) Suppression mortality is an important resource for decomposing organisms that specialize in recycling woody material.

•  Provide habitat for species associated with slow tree growth (e.g., lichens which can’t attach well on fast growing branches), ones which need higher humidity conditions (such as some amphibians), and those which do not respond well to disturbance. Skips also favor species that are more competitive under low light than in more open environments.


 

Skip areas retain larger numbers of trees; thus, they will be a source of suppression mortality.
Skips retain large snags; an important element for structural complexity. Skip areas retain larger numbers of trees; thus, they will be a source of suppression mortality. Some species of plants may benefit from the lack of ground disturbance in skips, like the shade-loving western trillium (Trillium ovatum).
Skip areas retain larger numbers of trees; thus, they will be a source of suppression mortality.