A survey of dipterocarp forest in four sites revealed that the incidence of stem canker was relatively low but high localized incidences were recorded. No consistent association was obtained between the presence of mechanical damage and cankers. Cankers occurred more frequently on dipterocarps and less frequently on euphorbs. Field studies and experimental manipulations were used to compare sapling resistance and responsiveness to wounding and stem breakage in relatively nutrient-rich, alluvial forest and relatively nutrient-poor, sandstone ridge forest. Species found on sandstone ridges showed greater resistance to damage (e.g., greater stem flexibility, narrower crowns) than those on alluvial soils. Species common on alluvial soils tended to be more responsive to damage (e.g., faster wound closure rates, more likely to re-sprout). Results from manipulation experiments conducted on pot-grown seedlings were consistent with results from the field studies, where conditions of greater nutrient availability, saplings closed wounds at faster rates, had less flexible stems, more narrow crowns, and lower levels of foliar total phenolics. Species showed differential rezones to resource availability which, in part, may relate to contrasting strategies for investment in passive defence (i.e., resins and phenolics) over investment in growth. Through their narrower crowns, greater whole stem flexibility, and lesser stem taper, tree species characteristic of sandstone ridges had greater resistance to mechanical damage from debris falling from above than congeneric species characteristic of alluvial soils. Tree species characteristic of alluvial soils were more responsive to damage than congeners on sandstone ridges, by producing earlier and longer sprouts following stem snapping and more rapid rates of wound closure following wounding.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:521340 |
| Date | January 2009 |
| Creators | Mohd Salim @ Halim, Jamilah |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=130838 |
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