 |
Biotic Interactions in Tropical Rain Forest - Update on progress (August 2001)
Our research in Sepilok Forest Reserve, Sabah Malaysia is now in full swing and some fascinating results are beginning to emerge. The reciprocal transplant experiment (RTE) illustrated in a previous Bulletin piece (Feb 2001; 32:1) has now been fully established: seedlings of five dipterocarp species have been planted at sites on resource-rich alluvial soils and resource-poor sandstone soils, in both gaps and in the understorey and half of the transplanted seedlings have been given additional nutrients.
An Insect herbivore tackles a dipterocarp seedling in a gap site.
|
The five species include two specialists of alluvial soils (Parashorea tomentella and Hopea nervosa), two specialists of sandstone soils (Shorea multiflora and Hopea beccariana) and one species that does not occur on either soil type (Shorea fallax). The seedlings are being monitored for survival and growth in response to soil type, nutrient and light availability and rates of herbivory and infection by fungal pathogens are being recorded.
The experiment was a major undertaking, with 10 gaps created and several thousand seedlings collected, transplanted, watered and fertilised! However, all this effort is already bearing fruit with differences in seedling growth rates and susceptibility to herbivory becoming apparent after only 6 months of the treatments.
- Seedling growth is faster, and mortality lower, on alluvial than sandstone soils and growth is faster in gap than understorey environments. Species that are specialists of alluvial soils appear to grow fast under all conditions - future monitoring will determine whether this trait trades-off against high survival under low resource availability and investigate the physiological correlates of differential growth rates.
- Seedlings in gaps were more damaged than those in the understorey; this difference was much greater for the species that are alluvial specialists than for the sandstone species. Soil type also had a significant effect on herbivory, but again results were species-specific, with two species showing the greatest damage on alluvial soils and one on the sandstone soils. Generally, the alluvial specialist species were more damaged than the sandstone specialists and when the alluvial species were grown on alluvial soils, they received much more damage than when they were grown on sandstone soils, especially in the gaps.
The tree nursery at the Forest Research centre in Sepilok. The growth, allocation to defence and resistance to pathogens of dipterocarp seedlings under different light and nutrient regimes is being measured.
|
|
Now that results are coming in, both from this large field experiment and from several other experiments underway in both the field and in nurseries, we are planning to present some preliminary findings at a special session of the BES winter meeting in Warwick in December. In addition, we are very pleased that during the first year we have established collaborative links with five ecological researchers from UK, Canada and USA who will be undertaking related research at Sepilok.
|
Home
Introduction to the project
