Age–size–habitat relationships for Polylepis australis: dealing with endangered foreset ecosystems

SUAREZ, MARIA LAURA; RENISON, DANIEL; MARCORA, PAULA; HENSEN, ISABELL

BIODIVERSITY AND CONSERVATION

Springer

Año: 2008 vol. 17 p. 2617 - 2625

0960-3115

Assessing tree ages is important for the understanding of forest recruitmentpatterns and tree growth. However, little experience exists in the subtropics and accurateaging usually involves potentially damaging techniques such as tree coring or even the useof entire cross sections, which is not recommendable in endangered species or ecosystems.We provide an example of how age may be predicted on the basis of tree size and site conditions,using Polylepis australis of Central Argentina. Our study was conducted in twoentire river basins where 96 independent trees were successfully cored for age analysis.Site and tree characteristics were registered and tree age determined through standard dendrochronologicaltechniques. The multiple regression procedure selected tree circumferenceand proportion of rock under the tree canopy as signiWcant variables explaining 48%of the variation in number of growth rings. Trees surrounded by rock clearly grew slowerthan those surrounded by a higher proportion of soil and vegetation. A comparison with aone site study shows that the ability to predict P. australis age is clearly reduced when geographicalrange is extended but the explanatory power of our model is still high enough forcertain applications and within the range of other one site studies. We suggest that tree sizeand site characteristics may be used to predict age in other subtropical mountain forestswith a well marked growth season.