Ecological Relationships of Bristlecone Pine

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Abstract
Functional relationships between bristlecone pine (P. longaeva Bailey) growth characteristics and environmental factors were investigated near Wheeler Peak and Bastian Peak in east-central Nevada [USA]. Because of bristlecone pine''s intolerance to shading it constituted only a small percentage of the total tree cover on sites favoring good growth rates and dense timber stands. On such sites limber pine (P. flexilis James) and Engelmann spruce (Picea engelmanni Parry ex Engelm.) dominated the stands. On harsher sites bristlecone pine often formed essentially pure, although sparse, stands. Regression analyses (both simple and multiple) and analyses of variance revealed that bristlecone pines are faster growing, taller, straighter and less sensitive to climatic fluctuations on sites where moisture conditions are favorable. Organic C, clay and mean air temperature accounted for 83% of the variation in mean annual growth rates of bristlecone pine. Organic C and mean air temperature accounted for 55% of the variation in mean sensitivity (a measured of annual variation in ring width) of the trees. Maximum tree age is associated with harsh growing conditions which result in slow growth rates and dense, highly resinous wood.