Serotiny and life history of Pinus contorta var. latifolia

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Abstract
Mature serotinous and nonserotinous trees of P. contorta Dougl. var. latifolia Engelm. in the Bitterroot Watershed of western Montana [USA] do not differ in most life-history characteristics (reproductive or vegetative). No differences between trees of the 2 cone types were found in height, basal area, basal area growth rates over the lives of the trees or crown ratio. Cone number, weights of individual cones and seeds, and estimates of reproductive effort were similar in serotinous and non-serotinous trees. Reproductive characteristics were either independent of tree age, or related similarly in trees of the 2 cone types. Nonserotinous trees may, however, have more seeds per cone than serotinous trees. This difference in seed numbers may be adaptive if serotinous trees invest relatively heavily in cone materials to protect seeds (which are retained in cones for many years), while nonserotinous trees (which shed seeds each year) invest relatively heavily in seeds. Trees of the 2 cone types differ mainly in the particular types of disturbance favoring their regeneration, but they often grow in the same stands where there are similar selective pressures on most aspects of their biology. Gene flow between them probably homogenizes all but those differences maintained by strong selective pressures.