Flowering and seeding patterns in pure and mixed Nothofagus forests in Southern Patagonia

TORO MANRÍQUEZ, MÓNICA; MESTRE, LUCIANA; LENCINAS, MARÍA VANESSA; PROMIS, ÁLVARO; MARTÍNEZ PASTUR, GUILLERMO; SOLER, ROSINA

Ecological Processes

SPRINGER

Año: 2016 vol. 5 p. 1 - 12

Introduction:Variationin reproductive phenology among species is an important mechanism formaintaining species coexistence. In mixed forests, the impact of limiting(biotic and abiotic) factors on tree reproductive success regulates themaintenance of species in balanced proportions or the conversion towardsmonospecific forests. This study offer a significant first approach to thereproductive phenology of mixed forests, assessing flowering, seeding and lossfactors on reproductive success in three forest types (pure deciduous Nothofagus pumilio (Np), evergreen Nothofagus betuloides (Nb) and mixed (M) forests), comparingalso between two geographical locations (coast and mountain), during onegrowing season.Results:Floweringfalling started early in Np. Seed fall occurred first and more concentrated inNp, while in Nb, it was progressive during autumn. Phenology in M combined bothpatterns, but with better reproductive performance of both species. Seedproduction was greater in Nb (42,900,000 ha−1)than in Np (710,000 ha−1),while M presented intermediate values (31,900,000 ha−1).Abortion was greatest in Np (19% of female flowers and 10% of immature fruits),while fruit predation was low (7?9%)in all forest types. Empty seed was the main loss factor, but with low netvalues for each species in M. Regarding geographical location, sea proximitygenerated a quick starting of the growing season in coast compared to mountainsites. However, we detected forest types × location interactions in floweringand seeding patterns (e.g. in male flower production and in empty and viableseeds), with differences in species response according to location.Conclusions: Both deciduous and evergreen species havereproductive advantages in mixed compared to pure forests. However, mixed weremore similar to pure evergreen forests in their reproductive traits and theincidence of the limiting factors. The study of only one growing season doesnot allow us to conclude whether mixed forests are stable communities, but wecontribute to understand the roles of reproductive phenology in mixed forestdynamics.