Mixed-forest species establishment in a monodominant forest in central Africa: implications for tropical forest invasibility.
BACKGROUND
Traits of non-dominant mixed-forest tree species and their synergies for successful co-occurrence in monodominant Gilbertiodendron dewevrei forest have not yet been investigated. Here we compared the tree species diversity of the monodominant forest with its adjacent mixed forest and then determined which fitness proxies and life history traits of the mixed-forest tree species were most associated with successful co-existence in the monodominant forest.


RESULTS
We sampled all trees (diameter in breast height [dbh]≥10 cm) within 6×1 ha topographically homogenous areas of intact central African forest in SE Cameroon, three independent patches of G. dewevrei-dominated forest and three adjacent areas (450-800 m apart). Monodominant G. dewevrei forest had lower sample-controlled species richness, species density and population density than its adjacent mixed forest in terms of stems with dbh≥10 cm. Analysis of a suite of population-level characteristics, such as relative abundance and geographical distribution, and traits such as wood density, height, diameter at breast height, fruit/seed dispersal mechanism and light requirement-revealed after controlling for phylogeny, species that co-occur with G. dewevrei tend to have higher abundance in adjacent mixed forest, higher wood density and a lower light requirement.


CONCLUSIONS
Our results suggest that certain traits (wood density and light requirement) and population-level characteristics (relative abundance) may increase the invasibility of a tree species into a tropical closed-canopy system. Such knowledge may assist in the pre-emptive identification of invasive tree species.
Institute for Life Sciences, University of Southampton, Southampton, United Kingdom; Ecology and Global Change group, School of Geography, University of Leeds, Leeds, United Kingdom; Conservation Science Group, Department of Zoology, University of Cambridge, Cambridge, United Kingdom.
Kelvin S-H
KS
Peh
Plant Systematic and Ecology Laboratory, Higher Teacher's Training College, University of Yaoundé I, Yaoundé, Cameroon.
Bonaventure
B
Sonké
Institute of Agricultural Research for Development, Yaoundé, Cameroon.
Olivier
O
Séné
Department of Botany and Plant Physiology. University of Buea, Buea, Cameroon.
Marie-Noël K
MN
Djuikouo
African Forest Forum, Nairobi, Kenya.
Charlemagne K
CK
Nguembou
Plant Systematic and Ecology Laboratory, Higher Teacher's Training College, University of Yaoundé I, Yaoundé, Cameroon.
Hermann
H
Taedoumg
Ecology and Global Change group, School of Geography, University of Leeds, Leeds, United Kingdom; Cameroon Biodiversity Conservation Society, Yaoundé, Cameroon.
Serge K
SK
Begne
Ecology and Global Change group, School of Geography, University of Leeds, Leeds, United Kingdom; Department of Geography, University College London, London, United Kingdom.
Simon L
SL
Lewis
D044822:Biodiversity; D002163:Cameroon; D007887:Fabaceae / Q000502:physiology*; D065928:Forests; D058865:Introduced Species