Spatial patterns of tree recruitment in East African tropical forests that have lost their vertebrate seed dispersers
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Date
2010
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Journal of tropical ecology
Abstract
The direct removal of adult trees by logging affects tree recruitment in tropical rain forests. However,
secondary effects of logging, such as loss of vertebrate seed dispersers may also affect tree recruitment. We studied
the recruitment and spatial distribution of five tree species namely Balanites wilsoniana, Celtis zenkeri, Chrysophyllum
albidum, Cordia millenii and Ricinodendron heudelotii in Kibale, Budongo and Mabira Forests in Uganda. These forests
have been subjected to varying degrees of disturbance leading to changes in their vertebrate seed dispersers. Vertebrate
frugivores of the five tree species were identified. Three 1-ha plots were established around adult trees of the same five
species in each forest and the distance from the juveniles to the nearest adult conspecific was measured to generate
a recruitment curve. Frugivore visitation rates were high in the less disturbed Budongo and Kibale (2.2 and 1.6
individuals h−1 respectively) compared with the highly disturbed Mabira (0.9 individuals h−1). In the frugivoreimpoverished
forest, 70–90% of juveniles established beneath adult conspecifics, whereas in the less-disturbed forests
juveniles were established up to 80 m from adult conspecifics. Shade-tolerant species capable of recruiting beneath
adult conspecifics appeared to maintain their populations without dispersal. Consequently, disturbances leading to
significant loss of vertebrates may alter tree recruitment and spatial distribution with consequences for long-term
population viability of shade-intolerant tropical trees.
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Keywords
Balanites wilsoniana, Celtis zenkeri, Chrysophyllum albidum, Clumped, Cordia millenii, Density, Dispersal, Disturbance, Predation, Ricinodendron heudelotii
Citation
Babweteera, F., & Brown, N. (2010). Spatial patterns of tree recruitment in East African tropical forests that have lost their vertebrate seed dispersers. Journal of tropical ecology, 26(2), 193-203. doi:10.1017/S026646740999054X