Abstract

GUERRERO-RODRIGUEZ, Sandra Bibiana; PAZ-CAMACHO, Erika Andrea  and  PARRADO ROSSELLI, Ángela. Effect of human disturbance on seed and seedling distribution of the Andean Oak (Quercus humboldtii Bonpl., Fagaceae) in the Colombian Eastern Cordillera. Colomb. for. [online]. 2010, vol.13, n.1, pp.163-180. ISSN 0120-0739.

Animals affect the spatial occupation patterns of tropical forest plants throughout the seed disper sal they perform. Therefore, changes in vertebrate populations by human disturbance might affect re generation dynamics of plant species. We studied differences in the spatial distribution of seeds and seedlings of the Andean oak (Quercus humboldtii) between two nearby forests with contrasting levels of anthropogenic influence in the Colombian Andes. Density and spatial distribution of seedlings were evaluated in 490 and 484 1 m² plots located in a 28 ha area, in the high and low disturbed site, respectively. In each plot, all seedlings found were sampled and classified into three age categories. Density and spatial distribution of seeds were evaluated in 0.25m² subplots placed in the same plots described above. Results showed a higher number and density of seedlings in the high disturbed site, as well as a marked decrease in seedling density as age increases. Distances to the nearest neighbour were shorter in the high disturbed site for all seedlings and each age category, in contrast to the low disturbed site. Indexes of spatial distribution indicate an aggregated pattern in the most disturbed site, while a uniform pattern in the low disturbed one. Seeds also exhibited an aggregated pattern in the high disturbed site and a higher seed predation by invertebrates. Results seemed to be a conse quence of forest fragmentation and a decrease of vertebrate seed dispersers, seed predators and her bivores associated to the regeneration processes of the species. These results provide important infor mation for the forest management and restoration activities, since in order to maintain plant popula tions in the long term, presence and viable populations of seed dispersers should be also maintained.

Keywords : Colombian Andes; seed dispersal; spatial distribution; Cachalú Biological Reserve; caviomorph rodents.

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