Introduction to the project: Biotic Interactions in Tropical Rain Forest (BITRF)
The BITRF project is a three-year programme of research funded by the BES under its Overseas Research Programme. The project is implemented by a consortium of British and Malaysian institutions for ecological research at Sepilok Forest Reserve in Sabah, Malaysia.
The aim of our research is to determine the importance of biotic factors to the regeneration and distribution of tropical trees in the family Dipterocarpaceae. In the aseasonal lowland forests of Southeast Asia, dipterocarps can account for 10 % of all tree species, 40 % of all understorey trees and 80 % of all emergent trees. The centre of dipterocarp diversity is the Malesian island of Borneo, where there are more than 250 species in total and 20 species typically coexisting within a given two ha of lowland forest. Dipterocarps are also commercially important. In the Malaysian state of Sabah, forestry based on dipterocarps provides 70 % of total government revenue, and in Malaysia as a whole forestry employs about 150,000 people.
Our guiding hypotheses are that biotic interactions play a major role in determining the early regeneration success of dipterocarps, and that we can use the interactions between the biotic and abiotic environments to predict the habitat distribution of the adult trees. Our approach is to test observational and experimental techniques to test an integrated set of specific hypotheses addressing the importance of biotic mortality agents, ectomycorrhizas, invertebrate herbivores, fungal pathogens and plant-plant competition for dipterocarp regeneration.
Consortium members
Programme Coordinator
David Burslem Department of Plant and Soil Science, Aberdeen University
Other UK Principal Investigators
Steve Compton Centre for Ecology and Evolution, Leeds University
Jaboury Ghazoul Centre for Environmental Technology, Imperial College London
Sue Hartley School of Biological Sciences, University of Sussex
Michelle Pinard Department of Agriculture and Forestry, Aberdeen University
Malcolm Press Department of Animal and Plant Sciences, Sheffield University
Julie Scholes Department of Animal and Plant Sciences, Sheffield University
Malaysian Collaborators
Lee Su See Forest Research Institute of Malaysia
Reuben Nilus Ecology Section, Forest Research Centre, Sabah
Noreen Lee Chemistry Section, Forest Research Centre, Sabah
Chey Van Lun Entomology Section, Forest Research Centre, Sabah
BITRF staff and students
Kalan Ickes Postgraduate Research Assistant, Aberdeen University (1999/2000)
Colin Maycock Postdoctoral Research Fellow, Aberdeen University (2001-)
Reuben Nilus PhD student, Aberdeen University
Markus Eichhorn PhD student, University of Leeds
Francis Brearley PhD student, Sheffield University
Richard Thewlis PhD student, Imperial College London
Jamilah Mohammed Salim PhD student, Aberdeen University
Study site
The programme is located at the Forest Research Centre Sabah (FRCS) at Sepilok and the adjacent Sepilok Forest Reserve (SFR). The FRCS has staff and laboratories dedicated to forestry (e.g. forest pathology, entomology and soils), as well as an extensive herbarium collection and nursery facilities. The SFR is a 4420 ha patch of lowland dipterocarp and heath forest on the east coast of Sabah, owned and managed by the FRCS for forest protection and research. Logging in the SFR was banned in 1957, and extensive areas have never been exploited. The FRCS maintains sample plots in the SFR that were established from the mid-1950s. Therefore, long-term data on the composition and dynamics of the forests are available. Sepilok has a mean annual rainfall of about 3100 mm with no month receiving less than 125 mm on average, (although there is distinct seasonality in rainfall distribution and occasional severe droughts (the latest occurred in 1997-8)).
There is marked variation in forest composition within SFR corresponding to parent material and soils. Sandstone underlies more than 50 % of the SFR and forms prominent scarps and ridges dominated by forests of slow-growing, shade-tolerant dipterocarps such as Dipterocarpus acutangulus, Shorea multiflora and S. beccariana. These forests contrast in their species composition and nutrient status with those on low mudstone and sandstone hills and alluvial flats, in which the relatively fast-growing dipterocarps Parashorea tomentella and S. johorensis are dominant. Long-term sample plots are located in both forest types. A number of dipterocarp species are known to fruit every year at Sepilok (e.g. Parashorea tomentella and Dryobalanops lanceolata).
Specific hypotheses
The programme comprises five specific hypotheses that address the key processes involved in the regeneration of dipterocarp trees and the determination of adult species composition.
H1: Density-dependent ovule- seed- and seedling mortality contributes to interspecific differences in seedling and tree abundance and distribution (Dr Jaboury Ghazoul, Mr Richard Thewlis)
H2: Ectomycorrhizas enhance the probability of dipterocarp seedling survival, and interact with irradiance and nutrient supply to determine seedling performance in different environments (Professor Malcolm Press, Dr Julie Scholes, Mr Francis Brearley)
H3: The availability of resources (C, N) for chemical defence of dipterocarp seedlings against herbivory is greater in canopy gaps than in the forest understorey (Dr Sue Hartley, Dr Steve Compton, Mr Markus Eichhorn)
H4: Fungal wound pathogens affect the distribution and regeneration of dipterocarp species (Dr Michelle Pinard, Ms Jamilah Mohammed Salim)
H5: The interaction between biotic factors (as outlined above) and abiotic factors (i.e. availability of light and nutrients) determines differential adult distribution in relation to soil type at Sepilok Forest Reserve (Dr David Burslem, Dr Colin Maycock, Mr Kalan Ickes, Mr Reuben Nilus)
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