Carnivores participate in forest disturbance recovery by dispersing the seeds that pass through their digestive systems. The objective of this study was to evaluate the capacity of mammals for Juniperus deppeana seed dispersal with an experimental evaluation of endozoochory and diploendozoochory, through indices of recovery, viability, changes in testas, and retention of seeds in the digestive tract. Juniperus deppeana fruits were collected in the Sierra Fría Natural Protected Area, Aguascalientes, Mexico, and were administered in the diet of gray fox (Urocyon cinereoargenteus), coati (Nasua narica) and domestic rabbits (Oryctolagus cuniculus) these three mammals represented the endozoochory. For the diploendozoochory, seeds excreted by rabbits were incorporated into the diets of bobcat (Lynx rufus) and cougar (Puma concolor) in a local zoo. The seeds present in the scats were collected, and recovery rates and retention times were estimated; viability was estimated by X-ray optical densitometry, and testa thicknesses and surfaces were checked by scanning electron microscopy. The results showed a recovery of seeds greater than 70% in all the animals; the retention time was < 24 h in the endozoochory, but the time was longer (24-96 h) in the diploendozoochory (P < 0.05). Seed viability (x ̵̅ ± SD) was decreased in rabbits (74.0 ± 11.5 %) compared to fruits obtained directly from the canopy (89.7 ± 2.0 %), while gray fox, coati, bobcat and puma did not affect viability (P < 0.05). An increase in the thickness of the testas was also observed in seeds excreted from all mammals (P < 0.05). Through evaluation, our results suggest that mammalian endozoochory and diploendozoochory contribute to dispersal of J. deppeana by maintaining viable seeds with adaptive characteristics in the testa to promote resilience and forest restoration. In particular, felines (predators) can provide an ecosystem service through scarification and seed dispersal.
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.