Abstract

ESCALANTE, Ernesto; PANDO, Valentín; SARAVIA, Pedro  and  BRAVO, Felipe. Survival and growth of big-leaf mahogany (Swietenia macrophylla King) seedlings in two provenance trials in Bolivia. Ecología en Bolivia [online]. 2012, vol.47, n.1, pp.37-52. ISSN 1605-2528.

The conservation of Bolivian big-leaf mahogany (Swietenia macrophylla King.) forests requires of provenance trials to identify potential seed sources. Survival and early growth of seedlings are regarded as key variables in provenance trials. Two provenance trials were installed in an open secondary forest. Five Bolivian mahogany provenances, which belong to the pre-Andean Amazon (A and SC), Chiquitano-Amazon transitional (B and CH) and the Amazon (C) ecoregions, were evaluated. Mixed models with repeated measurement data were used to analyze survival rate, height growth and root collar diameter of seedlings, as well as seedling vigour. After 12 months of plantation, survivorship of all provenances was much lower at site 1 than at site 2. Height growth was relatively uniform among provenances and sites, ranging from 33-47 cm and from 63-101 cm, respectively. After 19 months at site 2, the provenances from Chiquitano-Amazon transitional (B=84%, N=288) and pre-Andean Amazon (SC=79.5%, N=288) showed the highest survival rates, whereas differences in height growth varied from 150 to 216 cm. In general, root collar diameter growth was lower at site 1 than at site 2. Among provenances, B and CH were significantly different in diameter growth after 4 months at site 1, however, no differences were observed at 12 months among all provenances. At site 2, diameter growth showed that provenances B and CH did better after 4 months while CH did better after 12 and B after 19. In summary, the provenance B from Chiquitano-Amazon transitional showed better characteristics than the rest of tested provenances (84% survival, 135.1 cm/year height growth and 34.7 mm/year root-collar diameter). Our findings provide useful information on survival and growth performance of Bolivian mahogany in plantations on secondary forests.

Keywords : Ecoregion; Height growth; Root collar diameter; Survival rate; Tropical timber species.

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