Tropical rain forests only cover around six percent of the world’s land area and contain around 70 % of the world´s animals and plants. Tropical rainforests have been, and still are, negatively affected by human activities. These activities lead to forest degradation which has negative impacts on production and biodiversity. Between 1970-1980 forests in Borneo, Sabah, Malaysia, was subjected to intense logging. In 1982 and 1983 Sabah was exposed to a prolonged drought followed by wildfires which further ruined the already damaged forests. In 1998 the Yayasan Sabah Group and IKEA started a forest rehabilitation project in the degraded forest in the Kalabakan region in Yayasan Sabah Concession Area in Malaysia. The main aim of the program is to improve the biodiversity status in the degraded tropical rain forest within the project area. To improve or accelerate the regeneration in the rehabilitation areas, enrichment plantings are used. Information about tropical tree species traits is limited, which complicate the rehabilitation work. Functional traits for plants are traits that affect growth, reproduction and survival and hence the plants fitness to the environment. Tree species used to be grouped after their demand for light and growth pattern. Light demanding pioneer species often have low wood densities and fast growth and shade tolerant climax species tend to have high wood densities and slow growth. However, the pioneer-climax classification is considered as a continuum. The objectives of this study were to investigate how different canopy cover affected tree species traits for 34 tree species in an enrichment planted tropical secondary rain forest, and if tree species growth response to increased light after a shade adjustment was related to tree species specific wood densities. The results indicated that tree individuals with least available light generally had smaller dbh (diameter in breast height) and lower tree heights compared to tree individuals with higher light availability. The maximum measured ...