Dispersão de sementes de espécies florestais por caprinos

Abstract

The reestablishment of vegetation cover plays a fundamental role in the recovery of degraded areas in anthropized places. Multiple strategies should be employed to ensure effective recovery of biodiversity at affected sites. The objective of this work was to evaluate the possibility of germination and dispersion of seeds of forest species by goat feces. Initially, we collected 12 species and selected six of them based on their germination potential. The species Apuleia leiocarpa (Vogel) JFMacbr., Samanea saman (Jacq.) Merr., Pseudosamanea guachapele (Kunth) Harms, Mimosa caesalpiniifolia Benth., Acacia angustissima (Mill.) Kuntze and Guazuma ulmifolia Lam. For the passage of seeds through the digestive tract, we used five goats of the Saanen breed. Their age was between three and four years and weight between 45 and 50 kg. Two experiments were carried out: the first with the total collection of feces and germination of the seeds in the laboratory, the second with collection through sampling and germination in the laboratory and in the field, in a pasture area. We provided two hundred seeds of each species for each animal simultaneously and collected the fecal material daily for three days in the first experiment and four days in the second. The seeds recovered in the faeces of the goats were taken to the Laboratory of Legumes of Embrapa Agrobiology, where they were separated and counted to create the curve of excretion and set germination tests. We used autoclaved Petri dishes in a BOD germination chamber with a constant temperature of 28 ° C and a 12-hour photoperiod. We used randomized blocks in the first experiment and completely randomized in the second one with three replicates each. The factorial arrangement was composed of three types of scarification (control, sulfuric acid and digestive tract) and six forest species, resulting in 18 treatments. We evaluated the number of germinated, dead and dormant seeds every week for one month. The analysis of variance indicated a significant interaction between species and scarification factors in the two experiments. The Scott-Knott test indicated that the seeds of the species S. saman and P. guachapele (in the first and second experiments, respectively), after being excreted by the animals, had a germination rate higher than the control, at 5% of meaningfulness. We found scarification with sulfuric acid to be the best treatment for all species in both experiments. In the field part of the second experiment, we observed the emergence of 62 seedlings belonging to five of the species studied. We did not observe the germination of G. ulmifolia seeds in the field experiment. The passage of seeds through the digestive tract of the animals did not prevent the germination of the seeds of the tested species and in some cases increased their potential. Goats have the ability to disperse effectively the seeds of the forest species studied.