Forest seed dispersal by carnivores in temperate forests and dry
tropical forests
Abstract
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
Fría, 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.