Seed production and survival of four dipterocarp species in degraded forests in Singapore

Abstract

Background: Seed production, germination, and seedling survival are crucial processes during community masting events in dipterocarp-dominated rain forest in South-east Asia.

Aims: We examine how these processes function in fragmented remnants of dipterocarp forest in Singapore.

Methods: Fruits were captured in seed traps and seed fates on the ground were tracked up to 5 months after fruiting for four dipterocarp species during a masting event in 2014; camera traps under each tree recorded seed predators.

Results: Long-tailed macaques were the major seed predators, claiming 34% of pre-dispersal seeds. Insect seed predation, primarily by moth larvae, played a relatively minor role, claiming only 9% of seed pre-dispersal and 0.7% post-dispersal. The mean proportion of seeds that escaped post-dispersal predation but failed to germinate was between 5% and 37% for the four species.

Conclusions: The non-viability of dipterocarp seeds can be at least as great a concern for forest regeneration as the rate of vertebrate pre-dispersal predation.

Keywords:

• degraded forests
• Dipterocarpus
• masting
• predator satiation
• pre-dispersal
• post-dispersal
• seed predation
• seedling survival
• Shorea

Acknowledgements

We would like to thank: Seah Wei Wei, Louise Neo, Jolyn Loh, Reuben Lim, Jon Tan, Koh Choon Yen, Ng Xin Yi, Chua Xin Yi, Letchumi Mani, Ng Wen Qing and Jonathan Ho for helping with fieldwork; Shawn Lum and Lua Hock Keong for showing us more trees, and Ang Wee Foong and Ryan Chisholm for discussions; Samantha Lai of the National Biodiversity Centre for handling our research permit (NP/RP14-031) request to the National Parks Board; Sharon Chan, Chung Yi Fei, and staff from the Central Nature Reserves unit of the National Parks Board for providing feedback and assistance; as well as Francis Brearley and the editors for considering this submission.

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

Notes on contributors

Kwek Yan Chong

Kwek Yan Chong is an ecologist with particular interests in vegetation ecology, invasion ecology, urban ecology, and the forests of tropical Asia.

Rie Chong

Rie Chong and Lorraine Tan were undergraduates when they undertook this project as part of an Undergraduate Research Opportunities Programme in Science offered as an academic enhancement by the Faculty of Science, National University of Singapore.

Lorraine W.A. Tan

Rie Chong and Lorraine Tan were undergraduates when they undertook this project as part of an Undergraduate Research Opportunities Programme in Science offered as an academic enhancement by the Faculty of Science, National University of Singapore.

Alex T.K. Yee

Alex Yee is currently completing his PhD on succession and recovery of secondary vegetation in Singapore. He is also a researcher at the Centre for Urban Greenery and Ecology, National Parks Board of Singapore.

Marcus A.H. Chua

Marcus Chua is a museum officer and curator at the Lee Kong Chian Natural History Museum of the National University of Singapore. His interests are in the ecology and conservation of mammals in human modified landscapes.

Khoon Meng Wong

Khoon Meng Wong is a forest botanist and plant taxonomist with general interests in Southeast Asian ecology and biogeography.

Hugh T.W. Tan

Hugh Tan is a botanist at the National University of Singapore, with broad interests including urban greening, urban agriculture, and propagation and conservation of native plant species.