Distribution of three dwarf mistletoe species within their host tree crowns

Abstract

We examined the distribution of dwarf mistletoes within the crowns of Douglas-firs, ponderosa pines, and lodgepole pines. Stand structure and host species had no effect on the proportion of trees within each dwarf mistletoe rating (DMR) class, nor did it affect the distribution of dwarf mistletoe within crown thirds for a given DMR. Dwarf mistletoe tended to infect the lower third of the crown first in all three species. Regardless of DMR, dwarf mistletoe usually intensified in the lowest crown third before doing so in the other thirds. These results are consistent with the distributions of dwarf mistletoe among crown thirds assumed in the Forest Vegetation Simulator for even-aged stands and are also appropriate for uneven-aged stands of Douglas-fir, ponderosa pine, and lodgepole pine. Relationships between percentage of plot infection and DMR and dwarf mistletoe index were strong. Copyright © 2010 by the Society of American Foresters.