Forest dynamics dominated by Podocarpus parlatorei, in a post-grazed Subtropical Montane forest cronosequence

CARILLA, JULIETA

Bariloche

Congreso; VI Southern Connection Congress; 2010

Univ. Nacional del Comahue, CONICET, INTA

Long term monitoring of forest dynamic is an effective tool for detecting and forecasting forest changes. This study aimed to analyze successional trajectory in subtropical montane forest of NW Argentina; from secondary forest, dominated by Alnus acuminata,Crinodendron tucumanum (Aa Ct) and Podocarpus parlatorei (Pp), to old-growth forest dominated by Myrtaceae family species (M o-g). Permanent plots were established at 1800 m, in Sierra San Javier, Tucumán, in 1991 and re-measured in 1996, 2001 and 2007. Compositional, demographic and structural variables were calculated, emphasizing in aboveground biomass (AB) as an approach to quantify forest C stores. Aa Ct forest accumulated AB quickly, reaching 181 tn/ha in few decades, but not persisted, due to Aa short longevity and recruitment dominated by understory species. Pp forests reached high AB values (393 tn/ ha), similar as M o-g (407 tn/ha), but decreased as succession progressed due to large individuals death. Intense intra-specific competition of dominant individuals resulted in low structural changes and growth rates. Despite Pp relatively low growth (0.2 cm yr-1), recruitment and mortality rates, it contributed significantly with forest AB (up to 93% of total AB). M o-g biomass showed different patterns between them. Secondary forest composition tended to converge to more diverse M o-g forest, with slow replacement of pioneers by long-lived species, and potentially high C sequestration and storage capacity.