Browsing in treefall gaps: crossinteractions between large-bodied browsers and forest regeneration in French Guiana forests


Labex CEBA – April 2018 for 1 year


Cécile Richard-Hansen - ONCFS/DRE

Scientific Partnership

  • Marijke Kujik & Rens Vaessen : Université Utrecht , Ecology & Biodiversity

For UMR EcoFog :

Presentation of the project

Since Redford’s “empty forest” early warning about defaunation consequences on tropical forests, many studies uncovered several processes involved in complex interactions between the neotropical large fauna and forest structure and functioning, or modelled consequences of their disappearance. Most of these studies focus on the alteration of seed dispersal, seed survival, and seedling recruitment processes. The impact of direct predation of browsers on forest regeneration has received much less attention.
We propose here to have a deeper insight in this process, particularly focusing on the role of treefall gaps in these interactions. We hypothesize that browsers particularly use them for feeding, because they are dominated by plants with nutritious and palatable leaves. Large neotropical herbivores (ungulates) have a frugivore-folivore diet, and browse mainly young leaves, on small trees up to the sapling stage. They may have a non-negligible and selective impact on the growth and survival rates of some species or functional groups of species, after the most critical survival stage of seedling to sapling transition. BROWSE, which will be the first step of a longer study, will focus on (1) comparing browsing intensity within and outside treefall gaps, and (2) to investigate the degree of selectivity of large browsers within treefall gaps. For the first question, all browsing signs will be counted in paired plots located within and outside treefall gaps. Second, within treefall gap plots, all browsed species, as well as all 20-150cm-high plants in a 10m radius around them, will be identified and measured to test for selectivity, and collected for further analyses. Functional traits will be obtained from existing databases and other ongoing studies. Plots’ frequentation will be checked by video camera traps, to identify the species browsing, and document feeding and selecting behavior. Our results will contribute to understanding of tree regeneration processes in tropical forest, and especially of the understudied ecological role of large browsers in these processes. It will also enhance our currently very poor knowledge of the ecology of these hunted and endangered species, and provide baseline data for hunting and forest management.

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