Stocking levels and seedling heights on clearcuts in relation to habitat type in the western Cascades of Oregon

Stocking characteristics and heights attained by treeseedlings at ages five and seven were measured on 45 studyunits, representing five habitat types, established onclearcuts in the Abies amabilis zone in the Western Cascadesof Oregon. The study units ranged from six to 30 acres insize, seven to 15 years in age (time elapsed since harvest),and occupied a variety of slope aspects, inclinations, andtopographic positions. A restricted random sampling proce-dure and circular one-milacre plots were employed to collectdata.
Mean post-harvest stocking levels (on a one-milacre ba-sis) ranged from 14.4% in the Abies amabillis-Tsuga merten-siana/Xerophyllum tenax habitat type to 48.3`' in the Abies amabilis/Rhododendron macrophyllum-Vaccinium alaskaense/Cor-
nus canadensis habitat type, and mean advance stocking lev-els ranged from 2.0% in the Abies amabilis/Vaccinium membra-naccum/Xerophyllum tenax habitat type to 16.5% in the Abies/Rhododendron-Vaccinium/Cornus habitat. type. Differences inmean post-harvest stocking among the habitat types werefound to be inversely correlated with differences in meanradiation indices and mean elevations. Differences werealso found among the habitat types in the comparative stock-ing levels of individual tree species. Abies procera (noblefir) stocking was generally less than or equal to that ofPseudotsuga menziesii (Douglas-fir) in habitat types typi-cally positioned on lower-to mid-slopes, but much greaterthan that of Pseudotsuga menziesii in habitat types whichare typically located on or near ridgetops.
Mean heights of tree seedlings were found to vary con-siderably among tree species and habitat types. Pseudotsugamenziesii seedlings generally grow to roughly equivalent orto greater heights than do Abies procera seedlings in allhabitat types. Both Pseudotsuga menziesii and Abics proceraseedlings attained greatest heirhts in the Abies amabilis:Achlvs triphylla habitat type, and lowest heights in an nn-documented Abies amabilis/Rhododendron macroph_yllum-Vaccin-ium membranaceum habitat type.
The structure and composition of successional plant.
communities which developed following clearcutting was alsofound to vary considerably among habitat types. Clearcutsin habitat types typically located on lower-to mid-slopeswere occupied by plant communities often dominated by
shrubs, whereas plant communities dominated by herbs usually-occupied clearcuts located in habitat types typically posi-tioned on or near ridgetops.
The results of this research imply that each habitattype seems best suited for specific silvicultural practices.Habitat type classification and mapping can be a productivetool for foresters involved with the regeneration manage-ment of Abies amabilis zone forests of the Western Cascadesof Oregon.