Flowering and seeding patterns in unmanaged and managed Nothofagus pumilio south Patagonian forests

Quelle: Forstarchiv 79: 2, 60-65 (2008)
Autor(en): Martínez Pastur G, Lencinas M V, Peri P, Cellini J M

Abstract: Regeneration is the success key for the silvicultural treatment implemented in natural seed produced forests. Most of the studies assumed that regeneration is limited by environmental factors and herbivory, but few considered other limiting factors, such as effects on the flowering and seeding processes as bird or insect foraging. A whole cycle approach is necessary to understand the bottlenecks in the regeneration processes. The aim of this work was to analyze the flowering and the seeding patterns in managed and unmanaged Nothofagus pumilio forests, including a predispersion insect and bird foraging analysis, and the abscised biomass production over a growing season. Our results showed that a high percentage of pollinated flowers produces fruits (68-79%), independently to the seed rain production and the forest management of the stand (2.2 to 14.7 million ha-1). The premature abscission of fruits was the main loss factor (13-25%), while biotic factors (insect and bird foraging) were not greatly (less than 5%). A large percentage of empty seeds was observed in all the treatments (21-32%), which was significantly greater in primary unmanaged stands. More studies are necessary to explain the causes of these two main loss factors and self-incompatibility studies to quantify its influence in empty seed production, as well as to extend this kind of studies in long periods of time to include seeding years with different seed rain production.

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