The Herbivore Assemblage, Herbivory and Leaf Chemistry of the Mangrove Kandelia obovata in Two Contrasting Forests in Hong Kong |
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Authors: | Y F Tong S Y Lee B Morton |
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Institution: | (1) Department of Ecology and Biodiversity, The Swire Institute of Marine Science, The University of Hong Kong, Cape d’Aguilar, Shek O, Hong Kong;(2) Present address: Centre for Aquatic Processes and Pollution, and School of Environmental and Applied Sciences, Griffith University, PMB 50 GCMC, Qld, 9726, Australia |
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Abstract: | The herbivore assemblage, intensity of herbivory and factors determining herbivory levels on the mangrove Kandelia obovata (previously K. candel, Rhizophoraceae) were studied over a 13-month period at two forests with contrasting growing conditions in Hong Kong. Mai
Po was part of an eutrophic embayment in the Pearl River estuary and generally offered more favourable conditions for mangrove
growth, whereas Ting Kok had a rocky substratum and oceanic salinity. Twenty-four insect herbivore species were recorded on
K. obovata, with lepidopteran larvae that consume leaf lamina being the dominant species. While leaf litter production was similar at
the two forests, herbivory level at Mai Po (mean = 3.9% in terms of leaf area loss) was more severe than that at Ting Kok
(mean = 2.3%). Peak herbivory levels were found in summer at both locations (6.5% for Mai Po and 3.8% for Ting Kok). Young
leaves of K. obovata at both locations were generally preferred by the herbivores from the period of late spring to summer. Concentrations of
most feeding deterrents (ash, crude fibre, and total soluble tannins) were significantly higher in both young and mature leaves
at Ting Kok, whereas leaf nutrients (total nitrogen and water) were the same at the two sites. Young leaves at Ting Kok contained
about 30% more tannins than their counterparts at Mai Po. Significant differences in leaf chemistry also existed between young
and mature leaves at either site. The differences were concomitant with the observed patterns of leaf herbivory on K. obovata, and suggest a potential relationship between environmental quality and plant defence against herbivory. |
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Keywords: | Herbivores Kandelia obovata Leaf chemistry Mangrove |
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