| Popis: |
The mechanisms of forest seed dispersal and regeneration of various altered forest ecosystems are complemented by the action of carnivores. The objective of this study was to evaluate the role of endozoochoric and diploendozoochoric mammals in the dispersal, scarification, and germination of seeds in two different forest ecosystems: temperate forest (TF) and dry tropical forest (DTF). A direct search and scat collection were carried out to determine dispersing agents and the abundance and richness of seeds in the Protected Natural Area, Sierra Fria, Aguascalientes, Mexico. Viability was evaluated by means of X-rays and a germination test using an optical densitometry. In addition, thickness measurements and observations were made on the surfaces of the testas by a scanning electron microscopy. In the TF, four plant species were dispersed, mainly Arctostaphylos pungens (P < 0.05), by four mammals, where the gray fox dispersed the highest average (66.8 ± 68.2; P < 0.05) and diploendozoochory was detected in bobcat scats associated with rabbit hair (Sylvilagus floridanus). The DTF presented higher abundance and richness of species, where Myrtillocactus geometrizans had the highest abundance (2680 ± 4423) and the coati (P < 0.05) dispersed the highest number of seeds (8639 ± 12203). In both types of forest, endozoochory and diploendozoochory did not affect the viability, the thickness of the testas, or the germination of any species of seeds. These results suggest that dispersing carnivores adapt to the abundance and richness of seeds in the forests they inhabit, thus developing an important ecological function by dispersing, scarifying and promoting the selective germination of seeds with thick testas in TF and thin testas in DTF. |
