Seeding and natural regeneration in unmanaged and silvopastoral managed Nothofagus antarctica forests in South Patagonia

ROSINA M. SOLER ESTEBAN; GUILLERMO MARTÍNEZ PASTUR

Nairobi

Congreso; II World Congress of Agroforestry; 2009

Cattle raising is one of the major economical activities in South Patagonia, and silvopastoral systems was proposed to manage Nothofagus antarctica (ñire) forests. Actually, silvopastoral were applied in old-growth forests, but in the near future the managed forests will include secondary forest structures too. Beside this, the proposed thinnings of the silvopastoral systems significantly affects seeding and natural regeneration cycles. To design of sustainable agro-forestal management in South Patagonia requires knowledge of key aspects of seed production. The aim was determine the changes of seeding and natural regeneration in unmanaged and silvopastoral managed Nothofagus antarctica forests. Ten traps per stand (n=8) were monthly collected to analyze seed quality and quantity in old-growth (OG), secondary forests (SF), recent silvopastoral plots (RSS) and long-term silvopastoral use plots (LTS) stands. Natural regeneration was studied in 5 plots (1 m2) per stand. Data were compared using simple ANOVAs and multivariate analysis.Seeding processes and natural regeneration were significantly affected by stand age and silvopastoral management. Seeds were decreased in number (F=33.10 p<0.001), weight (F=4.05 p=0.010) and viability (F=4.05 p=0.005), but percentage of empty seeds was increased (F=8.06 p<0.001). Seedling number (F=3.88 p=0.016), mean age (F=4.34 p=0.0104) and height (F=2.86 p=0.050) were also affected. Multivariate analysis related OG and LTS compared to SF and RSS groups. Seeding and natural regeneration changed along the natural forest cycles (SF compared to OG), and were significantly impacted by the silvopastoral management (RSS), but values were recovered over time (LTS). The proposed silvopastoral management impact over the reproductive cycles in a short-term period, being necessary to develop silviculture strategies to assure the regeneration of the stands in a long-term period.