Postdispersal fruit and seed removal by forest-dwelling rodents in a lowland rainforest in Mexico
VICTOR SÁNCHEZ-CORDERO a1 c1 and ROBERTO MARTÍNEZ-GALLARDO a1 p1
a1 Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México. Apartado Postal 70-153, México, D.F. 04510 MEXICO.
This study examined whether postdispersal fruit and seed removal by terrestrial mammals of common plant species was affected by the type of item, item density (low, medium, high), and habitat (gap, mid-succession, mature). Fruits of Brosimum alicastrum and Ficus yoponensi (Moraceae), Astrocaryum mexicanum (Palmae), and Nectandra ambigens (Lauraceae), and seeds of Omphalea oleifera (Euphorbiaceae) and Cymbopetalum baillonii (Annonaceae) were tested at the Los Tuxtlas rainforest in Mexico. Item removal from 108 experimental patches (N = 2340 fruits or seeds for each plant species tested) after 5 d was lower for F. yoponensis (6.6%) than for N. ambigens (68.8%), B. alicastrum (67.8%), C. baillonii (64.0%) and A. mexicanum (60.0%). No seeds of O. oleifera were removed. A higher fruit or seed removal was observed from high density than low density food patches in A. mexicanum, C. baillonii and N. ambigens, but not in B. alicastrum and F. yoponensis. A higher fruit or seed removal was observed from food patches in mature forest than in gaps in all plant species tested. Similar removal values between open (open to all terrestrial mammals) and caged (open to small rodents) fruit and seed patches, abundant rodent live-trapping, and a scarcity of large terrestrial mammals, indicated that forest-dwelling small rodents were the main postdispersal removal agents. Differences in plant species seedling recruitment resulting from small rodent food choices can partially determine long-term forest floristic composition at the Los Tuxtlas rainforest.(Accepted July 27 1997)
Key Words: Ecology; fruits; forest-dwelling rodents; granivory; terrestrial mammals; Mexico; postdispersal; rainforest; seeds.
c1 e-mail: firstname.lastname@example.org.
p1 Current address: Facultad de Ciencias, Universidad Autónoma de Baja California, Km. 103 Carretera Tijuana-Ensenada, Ensenada, Baja California, 22800 MEXICO.