No abstract

Dipterocarpaceae, the dominant family of Bornean canopy trees, display the unusual reproductive strategy of strict interspecific mast-fruiting. During 1986-99, more than 50 dipterocarp species dispersed seed only within a 1- to 2-month period every 3 to 4 years during El Nino-Southern Oscillation events. Synchronous seed production occurred across extensive areas and was essential for satiating seed predators. Logging of dipterocarps reduced the extent and intensity of these reproductive episodes and exacerbated local El Nino conditions. Viable seed and seedling establishment have declined as a result of climate, logging, and predators. Since 1991, dipterocarps have experienced recruitment failure within a national park, now surrounded by logged forest.

To examine the interspecific reproductive synchrony of Dipterocarpaceae with vertebrate responses to seed availablity, we monitored the spatiotemporal distribution and phenology of more than 2367 adult dipterocarp individuals of 54 species from March 1985 to January 1993 in the Gunung Palung National Park, West Kalimantan, Indonesia. Seven vegetational formations were sampled along an altitudinal gradient from peat swamp forest (5 m a.s.l. [above sea level]) across lowlands to upper montane zones (1100 m a.s.l.) that encompassed two upland valley complexes in a 15‐km2 area. Four significant reproductive events were documented: (1) a common lowland species reproduced outside of mast events in 1986 and in 1990; (2) a localized lowland “minor” mast event in 1986 in which 24.3% of the adult trees (21 spp.) participated; (3) a major community‐wide mast event (92.8%, 48 spp.) in 1987, just 6 mo after the minor event; and (4) another major community‐wide mast fruiting event after a 4‐yr intermast interval (88%, 48 spp.) in 1991. West Kalimantan export records of illipe nut (Dipterocarpaceae: Shorea section Pachycarpae) from 1968 to 1997 were compiled as a baseline measure of the frequency and relative intensity of dipterocarp mast‐fruiting events in the region (cv = 152%). A “bumper crop” occurred about every 5 ± 2.6 yr (mean ± 1 sd; range 3–9 yr). Fruit production was significantly associated with El Niño–Southern Oscillation (ENSO) events. The 1987 and 1991 mast events monitored were the third and fourth largest export years in the province since 1968. Because of the disputed role of vertebrate seed predators in causing and maintaining mast‐fruiting behavior, the response of seed‐eating vertebrates to this spatiotemporal variation in dipterocarp seed production was examined. Seed of a common, but asynchronous, lowland species was largely consumed by vertebrates. In the 1986 minor mast, 21 dipterocarp species that produced 60 000 seeds/ha (dry mass 46 kg/ha) lost all monitored viable seed to a diversity of resident and nomadic vertebrate seed predators. Timed with dipterocarp seed production in all mast events, nomadic vertebrates increased their populations through both reproduction and regional movement (numerical response). However, in both the 1987 and 1991 mast events, resident vertebrates destroyed only 1.5% and 2.6% of community seed production, and predation was recorded only in the tails of the fruit‐fall distribution. During these community mast events, resident vertebrates switched from dipterocarp seed to feed on fruit and seed from other available species. Nomadic vertebrates arrived late in the fruit‐fall period during both major mast events and, thus, were able to destroy only seed dispersed in the final 1–3 wk of fruit‐fall. Seed escape, and thus regeneration, only occurred in major mast events when all dipterocarp species across large areas participated. Considerable seedling recruitment was recorded in both the 1987 (∼95 000 seedlings/ha) and 1991 (155 824 ± 36 764 seedlings/ha) mast events. Results fr...

To examine the interspecific reproductive synchrony of Dipterocarpaceae with vertebrate responses to seed availablity, we monitored the spatiotemporal distribution and phenology of more than 2367 adult dipterocarp individuals of 54 species from March 1985 to January 1993 in the Gunung Palung National Park, West Kalimantan, Indonesia. Seven vegetational formations were sampled along an altitudinal gradient from peat swamp forest (5 m a.s.l. [above sea level]) across lowlands to upper montane zones (1100 m a.s.l.) that encompassed two upland valley complexes in a 15-km 2 area. Four significant reproductive events were documented: (1) a common lowland species reproduced outside of mast events in 1986 and in 1990; (2) a localized lowland ''minor'' mast event in 1986 in which 24.3% of the adult trees (21 spp.) participated; (3) a major community-wide mast event (92.8%, 48 spp.) in 1987, just 6 mo after the minor event; and (4) another major community-wide mast fruiting event after a 4-yr intermast interval (88%, 48 spp.) in 1991. West Kalimantan export records of illipe nut (Dipterocarpaceae: Shorea section Pachycarpae) from 1968 to 1997 were compiled as a baseline measure of the frequency and relative intensity of dipterocarp mast-fruiting events in the region (CV ϭ 152%). A ''bumper crop'' occurred about every 5 Ϯ 2.6 yr (mean Ϯ 1 SD; range 3-9 yr). Fruit production was significantly associated with El Niñ o-Southern Oscillation (ENSO) events. The 1987 and 1991 mast events monitored were the third and fourth largest export years in the province since 1968.Because of the disputed role of vertebrate seed predators in causing and maintaining mast-fruiting behavior, the response of seed-eating vertebrates to this spatiotemporal variation in dipterocarp seed production was examined. Seed of a common, but asynchronous, lowland species was largely consumed by vertebrates. In the 1986 minor mast, 21 dipterocarp species that produced 60 000 seeds/ha (dry mass 46 kg/ha) lost all monitored viable seed to a diversity of resident and nomadic vertebrate seed predators. Timed with dipterocarp seed production in all mast events, nomadic vertebrates increased their populations through both reproduction and regional movement (numerical response). However, in both the 1987 and 1991 mast events, resident vertebrates destroyed only 1.5% and 2.6% of community seed production, and predation was recorded only in the tails of the fruit-fall distribution. During these community mast events, resident vertebrates switched from dipterocarp seed to feed on fruit and seed from other available species. Nomadic vertebrates arrived late in the fruit-fall period during both major mast events and, thus, were able to destroy only seed dispersed in the final 1-3 wk of fruit-fall. Seed escape, and thus regeneration, only occurred in major mast events when all dipterocarp species across large areas participated. Considerable seedling recruitment was recorded in both the 1987 (ϳ95 000 seedlings/ha) and 1991 (155 824 Ϯ 36 764 seedlings/ha) mast events.Resul...

Physical anthropologists use the term "fallback foods" to denote resources of relatively poor nutritional quality that become particularly important dietary components during periods when preferred foods are scarce. Fallback foods are becoming increasingly invoked as key selective forces that determine masticatory and digestive anatomy, influence grouping and ranging behavior, and underlie fundamental evolutionary processes such as speciation, extinction, and adaptation. In this article, we provide an overview of the concept of fallback foods by discussing definitions of the term and categorizations of types of fallback foods, and by examining the importance of fallback foods for primate ecology and evolution. We begin by comparing two recently published conceptual frameworks for considering the evolutionary significance of fallback foods and propose a way in which these approaches might be integrated. We then consider a series of questions about the importance of fallback foods for primates, including the extent to which fallback foods should be considered a distinct class of food resources, separate from preferred or commonly eaten foods; the link between life history strategy and fallback foods; if fallback foods always limit primate carrying capacity; and whether particular plant growth forms might play especially important roles as fallback resources for primates. We conclude with a brief consideration of links between fallback foods and primate conservation.