POSTDISPERSAL FRUIT AND SEED REMOVAL BY FOREST-DWELLING RODENTS IN A LOWLAND RAIN-FOREST IN MEXICO

This study examined whether postdispersal fruit and seed removal by te rrestrial mammals of common plant species was affected by the type of item, item density (low, medium, high), and habitat (gap, mid-successi on, mature). Fruits of Brosimum alicastrum and Ficus yoponensis (Morac eae), Astrocaryum mexicanum (Palmae), and Nectandra ambigens (Lauracea e), and seeds of Omphalea oleifera (Euphorbiaceae) and Cymbopetalum ba illonii (Annonaceae) were tested at the Los Tuxtlas rainforest in Mexi co. Item removal from 108 experimental patches (N = 2340 fruits or see ds for each plant species tested) after 5 d was lower for F. yoponensi s (6.6%) than for N. ambigens (68.0%), B. alicastrum (67.8%) C. baillo nii (64.0%) and A. mexicanum (60.0%). No seeds of O. oleifera were rem oved. A higher fruit or seed removal was observed from high density th an low density food patches in A. mexicanum, C. baillonii and N. ambig ens, but not in B. alicastrum and F. yoponensis. A higher fruit or see d removal was observed from food patches in mature forest than in gaps in all plant species tested. Similar removal values between open (ope n to all terrestrial mammals) and caged (open to small rodents) fruit and seed patches, abundant rodent live-trapping, and a scarcity of lar ge terrestrial mammals, indicated that forest-dwelling small rodents w ere the main postdispersal removal agents. Differences in plans specie s seedling recruitment resulting from small rodent food choices can pa rtially determine long-term forest floristic composition at the Los Tu xtlas rainforest.