title: Impacts of logging on density-dependent predation of dipterocarp seeds in a South East Asian rainforest.
abstract: Much of the forest remaining in South East Asia has been selectively logged. The processes promoting species coexistence may be the key to the recovery and maintenance of diversity in these forests. One such process is the Janzen-Connell mechanism, where specialized natural enemies such as seed predators maintain diversity by inhibiting regeneration near conspecifics. In Neotropical forests, anthropogenic disturbance can disrupt the Janzen-Connell mechanism, but similar data are unavailable for South East Asia. We investigated the effects of conspecific density (two spatial scales) and distance from fruiting trees on seed and seedling survival of the canopy tree Parashorea malaanonan in unlogged and logged forests in Sabah, Malaysia. The production of mature seeds was higher in unlogged forest, perhaps because high adult densities facilitate pollination or satiate pre-dispersal predators. In both forest types, post-dispersal survival was reduced by small-scale (1 m(2)) conspecific density, but not by proximity to the nearest fruiting tree. Large-scale conspecific density (seeds per fruiting tree) reduced predation, probably by satiating predators. Higher seed production in unlogged forest, in combination with slightly higher survival, meant that recruitment was almost entirely limited to unlogged forest. Thus, while logging might not affect the Janzen-Connell mechanism at this site, it may influence the recruitment of particular species.
authors: Department of Animal and Plant Science, University of Sheffield, Western Bank Road, Sheffield S10 2TN, UK. bagchi.r@gmail.com
authors: Robert
authors: R
authors: Bagchi
authors: Christopher D
authors: CD
authors: Philipson
authors: Eleanor M
authors: EM
authors: Slade
authors: Andy
authors: A
authors: Hector
authors: Sam
authors: S
authors: Phillips
authors: Jerome F
authors: JF
authors: Villanueva
authors: Owen T
authors: OT
authors: Lewis
authors: Christopher H C
authors: CH
authors: Lyal
authors: Reuben
authors: R
authors: Nilus
authors: Adzley
authors: A
authors: Madran
authors: Julie D
authors: JD
authors: Scholes
authors: Malcolm C
authors: MC
authors: Press
mesh_terms: D000818:Animals; D053958:Dipterocarpaceae / Q000254:growth & development / Q000502:physiology*; D016468:Forestry; D018525:Germination; D060434:Herbivory; D007313:Insecta / Q000502:physiology; D008296:Malaysia; D054817:Pollination; D036226:Seedlings / Q000502:physiology; D012639:Seeds / Q000254:growth & development / Q000502:physiology*; D014197:Trees / Q000502:physiology; D014329:Tropical Climate; D014714:Vertebrates / Q000502:physiology