Plants can be classified into functional groups depending on their ecological roles. Life history and functional trait analyses can be used in the definition of groups, and help us understand how species persist in their habitat, withstand a variety of climatic conditions and use and manage environmental resources. In trees, how resources are allocated and stocked internally will significantly affect growth, regeneration, defence and recovery mechanisms. Therefore, resource management in trees should be a major factor influencing their ecological role and niche occupation in a community, but no explicit hypothesis has yet been formulated linking resource supply and stocks with functional group construction in a mixed tropical forest.

Resources are available following photosynthesis, and are supplied to tree organs in the form of non structural carbohydrates (NSC). NSC differs between species and organs, but apart from seasonal differences, no unifying hypothesis has been put forward explaining why NSC levels differ for the same organ among species.

In sapwood, NSC, are stored in ray and axial parenchyma cells (RAP). An individual may need to rapidly mobilise NSC for drought recovery, wound repair, resprouting and fast growth. Certain species might need to mobilise NSC quickly to colonise newly available space after a disturbance. Conversely, late successional species can require large quantities of NSC for defence against natural enemies to maintain their position in the canopy. Also, taller tree species with a high axial parenchyma (AP) tissue fraction have wider vessels, with most of the AP packed around vessels, to help maintain hydraulic conductivity. In tropical species, highly diverse patterns of RAP and vessel size can be found, and we hypothesize that these patterns reflect species successional stage. Work in French Guiana provides an excellent opportunity to investigate diverse relationships and will enable us to test the relationship between resource supply and stocks, and functional grouping of species.

We will examine anatomical wood traits, including RAP volume and vessel size and density on 50 tree species at Paracou, Guiana. NSC will be measured in leaves (supply) and sapwood (stocks). We expect that NSC stocks are correlated with RAP volume and that specific relationships occur with vessel traits. Links between supply, stock and traits should help our mechanistic understanding of how trees manage resources with regard to their ecological strategy in a context of forest succession.