Long-term effects of selective logging on dipterocarp populations in the Pasoh Forest Reserve, Malaysia

Abstract

Background: Selective logging alters tree growth, mortality and recruitment, and the subsequent population dynamics of trees. However, little information is available on how tree populations reduce local extinction in logged forests.

Aims: We evaluated the effects of selective logging on tree performance and population dynamics of five dominant dipterocarp species in the Pasoh Forest Reserve, Malaysia.

Methods: We used demographic data derived from a forest that was selectively logged in 1958 as well as those from an unlogged primary forest and constructed population transition matrix models to project the population dynamics.

Results: The dipterocarp species studied showed minor differences in mortality and diameter growth, but there was a large difference in recruitment between logged and unlogged forest; populations in the logged forest had 10 times slower recruitment rates into the smallest size class than those in the primary forest. Population size structures differed between the two forest types but, despite a large difference in the recruitment rates, there were only minor differences in both asymptotic- and matrix-projected population growth rates.

Conclusions: A single selective logging event had only minor impacts on the growth rates of dipterocarp trees in the Pasoh forest. But at the same time it had a large impact on the size structure of the dipterocarp populations through a reduction in recruitment showing that the impacts of selective logging are still seen on dipterocarp population after 50 years.

Keywords:

• demography
• life table response experiment
• mortality
• Shorea
• succession
• tropical rain forest

Acknowledgements

The 50 ha forest plot in the Pasoh Forest Reserve is an ongoing project of the Malaysian Government and was directed by the Forest Research Institute of Malaysia through its former Director-General, Dato’ Dr Salleh Mohd. Nor. This was initiated under the leadership of N. Manokaran, P.S. Ashton and S.P. Hubbell. Supplementary funding was provided by the National Science Foundation (USA), the Conservation, Food and Health Foundation, Inc. (USA), the United Nations, through its Man and the Biosphere program; UNESCO-MAB grants, UNESCO-ROSTSEA, and by the continuing support of the Smithsonian Tropical Research Institute and the Center for Global Environmental Research (CGER) at the National Institute for Environmental Studies (NIES), Japan. We wish to thank profoundly Mr Abd W. bin Nali, Mr A. bin Awang, Mr Abd S. bin Latif, Mr Mohd. Y. bin Hitam, Mr S. bin Mohd. Som and Mr Z. bin Ahmad of Forest Research Institute Malaysia, Kuala Lumpur, for their assistance with the field surveys and collection of tree census data at the Pasoh Forest Reserve. The present study was part of a joint research project between the Forest Research Institute of Malaysia (FRIM) and the National Institute for Environmental Studies (NIES) and Universiti Putra Malaysia (UPM). The FRIM Pasoh Research Committee kindly allowed this research (#FRIM394/627/2/739).

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplemental data

Supplemental data for this article can be accessed here.

Additional information

Funding

The research was supported financially by the Global Environment Research Program, Ministry of Environment, Japan [Grant No. D1005].

Notes on contributors

Toshihiro Yamada

Toshihiro Yamada, Toshinori Okuda and Abd Rahman Kassim originally formulated the idea; Toshinori Okuda conducted field research; Toshihiro Yamada and Yu Moriwaki performed data and matrix analyses; Toshihiro Yamada wrote the manuscript; Toshinori Okuda and Abd Rahman Kassim provided editorial advice. Our main interests are tropical forest ecology, management, and conservation.