Abstract

Species composition of tree recruitment in mixed forests is a determining factor related to the canopy structure. This work determines if the mixed forests of Nothofagus pumilio and N. betuloides present transitions towards forest types with the dominance of one of these species or are a stable system, by the analyses of its natural regeneration dynamics. Three forest types were selected (pure N. pumilio, pure N. betuloides and mixed stands) in two contrasting landscapes (coast and mountain) in Tierra del Fuego, Argentina. Forest structure and microclimate (air temperature, soil moisture) were evaluated for each stand (n=12), while seed production and natural tree regeneration were monitored annually (2014-2019). Data were analysed with ANOVAs, general linear models and multivariate techniques. Seedling recruitment of N. pumilio and N. betuloides was proportional to seed production with significant inter-annual variability. Nothofagus pumilio was more successful than N. betuloides in seedlings recruitment in every forest type and landscape. Forest structure and microclimate also played important roles in the dynamics of mixed Nothofagus forests. Multivariate analyses revealed a stronger effect of the landscape rather than canopy composition. Our results show a tendency in mixed Nothofagus forests towards a transition to pure N. pumilio forests, mainly due to greater success in its regeneration strategy.