Resumo

VALLEJO, MARTHA ISABEL  e  GALEANO, GLORIA. Short-term temporal changes in the spatial patterns of nine species of common plants in an Andean cloud forest in southwestern Colombia. Caldasia [online]. 2009, vol.31, n.1, pp.77-98. ISSN 0366-5232.

The changes in the spatial distribution of nine common species of an Andean cloud forest were analyzed between two censuses carried out in a 25-ha plot. In the first census in 1997, all woody stems with DBH =1 cm were tagged, measured and plotted. After five years, a second census was made and data of mortality and recruitment were recorded. Through spatial statistical tests using Ripley's K (t) function, the patterns of distribution were detected in each species, as well as the relationship between two types of events: big trees (DBH = 10 cm) vs. small trees (DBH < 10 cm) and surviving individuals vs. dead individuals. The random mortality hypothesis was tested to determine if the tendency to over dispersion of the big trees can be attributed to the selective mortality of the small trees. The results corroborate findings of other studies about the aggregation tendency for the smallest size classes, but not for those with DBH = 10 cm, which had a random pattern at small scales. Otoba lehmanii (Myristicaceae) and Matisia bolivarii (Bombacaceae) clearly supported the density and/or distance hypothesis proposed separately by Janzen and Connell, but it was inferred that the processes that led to the over dispersion of the big trees were different. The pattern in O. lehmanii was attributed to distance-dependent processes related to light requirements, and in M. bolivarii to density-dependent processes due to pathogen attack in early stages. Finally, the contribution of this research to the discussion on the neutral theory of biodiversity and biogeography is discussed.

Palavras-chave : Community ecology; plant ecology; random mortality hypothesis; Ripley's K-function; spatial patterns.

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