SEED PREDATORS, DRUPE PREDATION RATES AND THEIR EFFECTS ON THE REGENERATION DYNAMICS OF Olea .......

A close examination of data acquired during the 1960s forest inventory on the undergrowth demonstrates the absence of Olea welwitschii seedlings. The goal of this study was to figure out why Olea welwitschii doesn't regenerate inside the forest, and to look at the roles of predispersal and postdispersal drupes, as well as seed predation intensities, as precipitators of regeneration failure. Predation tests on seeds and drupes were undertaken on two levels. Predation of pre-dispersal seed and drupes was investigated at the first stage. Under the canopy of five randomly selected Olea fruiting trees, rectangular seed/drupe traps made of meshed fabric with a collecting surface of 0.25 m2 were randomly arranged to cover all four quadrants. The second level investigated post-dispersal predation by sampling seeds and drupes under the crowns of four randomly selected fruiting trees. Five 1m2 quadrats were randomly placed on the ground within each quadrant to cover at least 10% to 30% of the total canopy area. Seed/drupe predation was studied using 30 (l m2) quadrats with equal amounts of seeds and drupes, which were reviewed every 12 hours for a month to see if there were any changes in seed and drupe predation rates. Setting up 50 m long transects with the base of the fruiting trees as the starting point, the effects of density and distance were investigated. At five fruiting trees, two transects were made in two separate directions, north/south and east/west. At a five-meter spacing along each transect, eleven sampling stations were set up. To evaluate changes in small mammal predator density, a trapping grid was placed under the crowns of five fruiting Olea adults and away from the crowns. The results of predation on predispersal drupes were determined from a pooled sample of all drupes collected. There were a total of 1386 drupes collected. Insect holes were found in 3% of the samples. A detailed look at the size and weight of the drupes assaulted found that smaller drupes (70%) were attacked more frequently than larger ones (30 percent ). Overall, there were more little drupes (89%) than huge drupes that fell to the forest floor (11 per cent). Distance from the parent trees decreased drupe and seed density, while distance from the parent trees had a substantial effect on drupe and seed predation rates. Seeds were extracted at higher rates under the parent crowns, regardless of density, while drupes were disregarded by the predators. Praomys jacksoni, a rodent species, was caught. The bulk of the animals were caught under fruiting Olea adults (3.71 each trapping night) rather than farther out from the adult trees (0.61 per trapping night; Z=8.724, p0.01). Only 10% of the intact seeds showed signs of insect/rodent attack, out of a total of 18,000 seeds evaluated for pathogen assaults. The density of Drupes had a significant impact on fungal infection rates (2=55.867, p0.001). The findings clearly show that density has no bearing on the predation of Olea drupes and drupes. The lack of evidence of higher drupe predation rates in large clumps suggests that either large clumps are no simpler to discover for predators than tiny clumps, or that predators destroy all drupes they find regardless of clump size. Patchiness in the activity patterns of drupe eaters appears to influence the likelihood of drupe and seed predation.

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