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ENVIRONMENTAL CONSEQUENCES in rocky mountain coniferous ...

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Understory<br />

Residue<br />

Vegetation Response to Harvest<strong>in</strong>g and<br />

Management <strong>in</strong> a LarchlFir Forest<br />

Wyman C. Schmidt<br />

Project L .eader and Research Si 1 vi cul turi s t<br />

USDA Forest Service, I ntermountai n Forest<br />

and Range Experiment Station<br />

ABSTRACT<br />

This paper reports the response of understory shrubs and<br />

herbs to comb<strong>in</strong>ations of three si 1 vicul tural harvest-<br />

cutt<strong>in</strong>g systems--cl earcut, she1 terwood, group selection--<br />

and four residues treatments--<strong>in</strong>termediate utilization<br />

of harvest residues followed by broadcast burn<strong>in</strong>g,<br />

conventional-utilization-and-broadcast-burn <strong>in</strong>tense<br />

removal of a1 1 woody residues, and understory-protected<br />

treatments. Volume, cover, and biomass of shrubs and<br />

herbs were evaluated before, and at 2 years and 4 years<br />

after harves ti ng.<br />

A1 1 treatments substantial ly reduced the volume and biomass<br />

of 1 ive shrubs to as little as 3 percent of the preharvest<br />

vol ume on burned treatments. However, a1 1 vegetation<br />

responded rapidly under all treatments, <strong>in</strong> some cases<br />

approach<strong>in</strong>g preharvest levels <strong>in</strong> as few as 4 years. Herbs<br />

responded earlier and more to treatments than did the shrubs.<br />

Total biomass of 1 i ve understory vegetation (not <strong>in</strong>clud<strong>in</strong>g<br />

trees) averaged over 5 000 kglha (4,500 pounds/acre) <strong>in</strong> the<br />

mature forest, reached about half that 2 years after harvest-<br />

<strong>in</strong>g, and about three-fourths of that 4 years after harvest<strong>in</strong>g.<br />

KEYWORDS: Larix oceidentiaZCs, Pseudotsuga rnenziesii, larch/<br />

Douglas-fir, understory vegetation, residues uti 1 i zation,<br />

prescribed burn<strong>in</strong>g , shrubs , herbs, si 1 vi cul tural system

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