Natural regeneration dynamic of mixed Nothofagus forests in southern Patagonia: influence of canopy composition and landscape

Abstract

Species composition of tree recruitment in mixed forests is a determining factor related to thecanopy 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 speciesor are a stable system, by the analyses of its natural regeneration dynamics. Three foresttypes were selected (pure N. pumilio, pure N. betuloides and mixed stands) in two contrastinglandscapes (coast and mountain) in Tierra del Fuego, Argentina. Forest structure andmicroclimate (air temperature, soil moisture) were evaluated for each stand (n=12), while seedproduction and natural tree regeneration were monitored annually (2014-2019). Data wereanalysed with ANOVAs, general linear models and multivariate techniques. Seedlingrecruitment of N. pumilio and N. betuloides was proportional to seed production with significantinter-annual variability. Nothofagus pumilio was more successful than N. betuloides inseedlings recruitment in every forest type and landscape. Forest structure and microclimatealso played important roles in the dynamics of mixed Nothofagus forests. Multivariate analysesrevealed a stronger effect of the landscape rather than canopy composition. Our results showa tendency in mixed Nothofagus forests towards a transition to pure N. pumilio forests, mainlydue to greater success in its regeneration strategy