Seed predation during general flowering events of varying magnitude in a Malaysian rain forest

Abstract

Summary 1The lowland dipterocarp forests of Southeast Asia exhibit interspecifically synchronized general flowering (GF) and mast fruiting at irregular multi-year intervals of 1 to 11 years. The predator satiation hypothesis (PSH) posits that GF events enhance seed survival by reducing the survival, reproduction and population sizes of seed predators between GF events, and then satiating the reduced seed predator populations during GF events. 2 Three GF events of different magnitudes occurred in Pasoh Forest Reserve, Peninsular Malaysia, during 2001, 2002. We exploited this natural experiment to test two predictions of the PSH. The first prediction was that seed survival should increase with the magnitude of the GF event. The second prediction was that seed predation should decrease with time since the previous GF event. 3 A reproductive survey of all ( c . 900) dipterocarp trees ≥ 30 cm d.b.h. in a 50 ha plot showed that flowering pervasiveness (the proportion of dipterocarp species participating) was high and similar in all three GF events. However, relative flowering magnitudes (measured by an index of individual tree participation and flowering intensity in Shorea species) were 2, 5 and 8 for the 2001, 2002 and 2005 GF events, respectively. 4 The percentage of Shorea seeds surviving pre-and post-dispersal predation increased with the magnitude of GF events, which is consistent with the first prediction. 5 Pre-dispersal insect seed predators consumed 12.9%, 11.2% and 3.4% of Shorea seeds in the 2001, 2002 and 2005 GF events, respectively, which is consistent with both predictions. 6 Pre-dispersal seed predation by primates (mainly leaf monkeys) increased from 11.9% to 38.6% then fell to 9.3% in the 2001, 2002 and 2005 GF events, respectively. 7 Predator satiation occurred only at population and community levels. At the individual tree level there was no relationship between the percentage of seeds surviving pre-and post-dispersal seed predation and variation in seed crop size or seed density beneath the tree. This suggests that attempts to test the PSH on the scale of individual trees may miss key community level effects. 8 Our results suggest a more significant role of pre-dispersal seed predation in the evolution of reproductive synchrony than was recognized in the original statement of the PSH.

Long‐term changes in liana loads and tree dynamics in a Malaysian forest

“…4C). As expected, interannual variation associated with weak general flowering events in 2002, 2005, and 2010 was large (Sun et al 2007), and correlations between year and levels of reproduction were insignificant for lianas and trees (jrj , 0.465, P . 0.15 for the six measures of reproduction in Fig.…”

Temporal and spatial variability in seedling dynamics: a cross-site comparison in four lowland tropical forests

“…All four sites have a network of seed traps used in studies of phenology that are arrayed in a stratified random design along each site's trail network (Chen 2007, Norden et al 2007, Persson 2006, Wright & Calderon 1995. We placed three 1-m 2 seedling plots (or 2-3 plots at Nouragues) 2 m from each seed trap in the three directions away from the trail.…”

Abundance of insect seed predators and intensity of seed predation on Shorea (Dipterocarpaceae) in two consecutive masting events in Peninsular Malaysia

“…Insect seed predation lowers the total seed crop in the community, which reduces the capacity of the community to satiate post-dispersal seed predators (Sun et al 2007). Therefore, insect seed predation might have a strong impact on recruitment of dipterocarps and may play an important role in promoting masting behaviour in dipterocarps.…”

“…The (Sun et al 2007). A strong masting event occurred 65 mo before M01 in March 1996 (Numata et al 2003).…”

“…Although many animals, both vertebrates and invertebrates, eat dipterocarp seeds (Curran & Leighton 2000, Sun et al 2007, pre-dispersal seed predation by insects is a major mortality factor for dipterocarp seeds (Nakagawa et al 2005, Sun et al 2007. Insect seed predation lowers the total seed crop in the community, which reduces the capacity of the community to satiate post-dispersal seed predators (Sun et al 2007).…”