Stand dynamics of the shade-tolerant conifers Podocarpus nubigena and Saxegothaea conspicua in Chilean temperate rain forest



Abstract. Population structures were used to infer regeneration patterns of the conifers Podocarpus nubigena and Saxegothaea conspicua and associated angiosperm tree species in six stands in the temperate rainforests of the coastal ranges of southern Chile. On poorly-drained, nutrient-poor and high altitude sites, where most of the associated species were fairly shade-intolerant and light-crowned, dense all-aged populations and the presence of numerous saplings beneath the canopy suggested continuous regeneration of both P. nubigena and S. conspicua. On more favourable sites, where several of the associated angiosperms were highly shade-tolerant and densecrowned, both conifers, particularly P. nubigena, were less abundant, and their regeneration from seed appeared to be sporadic. S. conspicua's great longevity (≥ 750 yr) and frequent vegetative reproduction are probably crucial to its persistence in competition with shade-tolerant broadleaved species in undisturbed stands on favourable sites. Results of this study, and a review of related literature on southern temperate forests are not consistent with the hypothesis that heavily-shaded, infrequently-disturbed habitats are an evolutionary refuge for conifers. Sites likely to have high leaf area indices and infrequent disturbance are better exploited by shade-tolerant angiosperms.