Ecological Requirements of Pseudotsuga Macrocarpa in the Santa Ana Mountains, California
Big-cone Douglas-fir is the most ubiquitous tree in the Santa Ana Mountains and is commonly associated with chaparral. It ranges from canyon bottoms to ridges, with an average stand elevation of 3,280 feet. Slopes of stands vary from 2 to 90° with an average angle of 34.5° Big-cone Douglas-fir occurs on all exposures but is most common on north faces. North-facing slopes support the highest tree densities, but the fastest growth takes place on open level sites with a southern exposure. Big-cone reproduction occurs on a wide variety of sites. Germination is enhanced by above-average rainfall. Greatest seedling densities occur in dense big-cone stands and in burned stands. Seedlings are suppressed by a shading overstory and are most vigorous following fire. An outstanding adaptation of big-cone Douglas-fir is its ability to produce trunk resprouts after it has been burned. Trunk meristems are protected from fire by the tree's thick bark. Although big-cone Douglas-fir is widely distributed in the Santa Ana Mountains, it prefers mesic sites within this semiarid region and is only secondarily confined to less favorable sites by chaparral competition and recurring fires.
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Document Type: Journal Article
Affiliations: Associate Professor, Department of Botany, California State College at Los Angeles
Publication date: 01 February 1969