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Regeneration strategy and spatila distribution pattern of Neobalanocarpus heimii in the lowland dipterocarp forest of Pasoh, Peninsular Malaysia

Elouard C., Blanc L.. 2003. In : Okuda Toshinori (ed.), Manokaran N. (ed.), Matsumoto Yoosuke (ed.), Niiyama Kaoru (ed.), Thomas Sean C. (ed.), Ashton Peter S. (ed.). Pasoh : ecology of a lowland rain forest in Southeast Asia. Berlin : Springer, p. 273-284.

Neobalanocarpus heimii (King) Ashton (chengal) is one of the most dominant species in the Pasoh Forest Reserve (Pasoh FR). This tree presents an uncommon phenological behaviour from the other Dipterocarpaceae species of this region. In general, this species fruits every year with population synchrony unlike other species having mast fruiting behaviour. Fruit production and seedling dynamics were monitored during 34 weeks in plots established under four mother trees. Fruit production was continued throughout the survey, and fruiting patterns varied among the studied mother trees. Fruit dispersal did not extend >16 m from the mother tree trunk; most of the fruits, heavy and wingless, fall close to the trunk. Fruit predation was high and mainly related to insect infestation, causing losses of 23 to 37% of the crop. Pre-dispersal mortality by infestation before fruit fall was considerable through fruit dispersal. Seedling mortality, identified as post-dispersal mortality, ranged from 31 to 52%. Cause of mortality was due to abiotic factors, mainly compaction of the soil (probably related to water stress). Additional losses of seedlings came from fungal infection (20-28%) and insect predation (21-32%). Seedling and sapling dynamics were monitored using another approach. Spatial distributions of seedlings and saplings in four height classes, were compared around ten mother-trees. Survival was quantified in relation to the distance to the mother tree. A spacing-distance mechanism was identified, with a higher number of seedlings and saplings at the edge of the mother tree canopy, confirming the Janzen-Connell theory. Tree spatial distribution was analyzed at a larger scale. Immature trees were aggregated whereas mothers trees exhibited a random distribution. The changes in the spatial structure appears consistent with the sapling spacing-distance mechanism. (Résumé d'auteur)

Mots-clés : distribution géographique; fruit; régénération naturelle; dissémination des graines; dipterocarpaceae; malaisie

Thématique : Physiologie végétale : croissance et développement; Physiologie végétale : reproduction

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