Microhabitat affects acorn removal in three sympatric and endangered Neotropical oak species

Abstract

AbstractAcorn removal and predation are processes that can influence forest dynamics and the ecological niche segregation of sympatric oak species. Different factors affect these processes, including differences in acorn germination rate and exposure to predators and/or dispersers. This study evaluated acorn removal and predation patterns in three threatened tropical cloud forest oak species (Quercus germana, Quercus sartorii and Quercus cortesii). Acorns were placed in two accessibility treatments (open to all potential acorn consumers vs. accessible to mice only) and in two types of microhabitat (covered by trunks, shrubs and herbaceous plants vs. uncovered). In addition, acorn germination rate was evaluated in a greenhouse. After 130 days, 76.67 ± 2.45 % of the seeds had been removed and the two accessibility treatments did not differ significantly. Mice were therefore shown as important predators and/or dispersers of acorns. Removal was greater in the covered (93.33 ± 2.04 %) compared to the uncovered (60.00 ± 4.01 %; P < 0.05) microhabitat. Acorn removal and germination were highest for Q. germana (82.00 ± 3.86 %, 91.67 ± 4.41 %, respectively), followed by Q. sartorii (79.00 ± 4.09 %; 50.00 ± 7.64 %) and Q. cortesii (69.00 ± 4.64 %; 13.33 ± 4.41 %); the same trend was recorded in the acorn germination rate (P < 0.05). Our findings suggest that uncovered sites with partial shade might function as regeneration microhabitats where less acorn removal and higher germination occur. The implications of differential acorn trait preferences by rodents for the coexistence of these oak species are discussed.