Understanding the influence of frament size on biodiversity and ecosystem functions is capable of retaining predictable and functional ecological communities for effective conservation management and maintenance of tropical forest ecosystem stability.
With an aim to test the small island effect (SIE) in the species–area relationship, Dr. Lan QIE of XTBG and National University of Singapore used dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae) in a tropical land-bridge island system and evaluated its effects on species richness and community composition.
Dung beetles are key bioindicators and are important for ecosytem functioning.
The research was conducted in Lake Kenyir, a hydroelectric reservoir in the state of Terengganu, north-eastern Peninsular Malaysia (5°00′ N, 102°48′ E; 145 m a.s.l.) formed by the damming of the upper tributaries of the Terengganu River in 1986.
The researchers sampled dung beetles using human dung baited pitfall traps on 24 land-bridge islands and three mainland sites in the tropical forests of Peninsular Malaysia. They used regression tree analyses to test for the SIE, as well as species traits related to local rarity, as an indication of extinction vulnerability.They employed generalized linear models (GLMs) to examine determinants for species richness at different scales and compared the results with those from conventional linear and breakpoint regressions. Community analyses included non-metric multidimensional scaling, partial Mantel tests, nestedness analysis and abundance spectra.
The researchers highlight the stochastic nature of dung beetle community composition on small islands and argue that this results in reduced ecosystem functionality. A better understanding of the minimum fragment size required for retaining functional ecological communities will be important for effective conservation management and the maintenance of tropical forest ecosystem stability.
The research observation has been published in Journal of Biogeography, 38(2011): 792-804. DOI: 10.1111/j.1365-2699.2010.02439.x
