Vertical Stratification and Caloric Content of the Standing Fruit Crop in a Tropical Lowland Forest1

Schaefer, H. Martin; Schmidt, Veronika; Wesenberg, Jens

doi:10.1646/0006-3606(2002)034[0244:vsacco]2.0.co;2

Cited by 23 publications

(31 citation statements)

References 31 publications

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“…G. glabra trees had no specific fruiting season and ripened fruits throughout the year. To assess the overall availability of ripening stages, we counted the fruits from each ripening stage on all trees in the plot once a month (Schaefer et al 2002). G. glabra trees had a mean crop size of 9,103 ± 11,642 (SD) during our observational period, but single large trees may bear up to 150,000 fruits.…”

Section: Study Site and Speciesmentioning

confidence: 99%

The fruits of selectivity: how birds forage on Goupia glabra fruits of different ripeness

Schaefer

2006

J Ornithol

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Although many studies have been published on avian fruit selection, few have addressed the effects of fruit scarcity on the patterns of fruit choice. Here, we compared the consumption of seven bird species for six simultaneously present maturation stages of Goupia glabra fruits. Ripe G. glabra fruits contain more lipids, carbohydrates and energy, and fewer phenols, than unripe fruits. All bird species selected from among ripening stages and removed a higher proportion of ripe fruits than of intermediate or unripe fruits. Importantly, however, fruit choice was flexible in all species. Whether birds preferred or avoided fruits of intermediate ripeness depended on the overall fruit supply. When ripe fruits were scarce, birds showed a higher acceptance of fruits of intermediate ripeness, but still rejected the least ripe fruit stages. In a foraging bout, most birds fed on fruits of the same ripeness. By doing so, birds maximised instantaneous energy gain per time, because search time was longer for riper fruits while energy intake was lower for less ripe fruits. The results suggest that birds select fruits based on fine-scale differences in profitability, but accept less profitable fruits during low fruit abundance. If environmental factors such as overall fruit availability influence avian fruit choice, we suggest that the potential for directional selective pressures on fruit compounds is restricted.

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Section: Study Site and Speciesmentioning

confidence: 99%

The fruits of selectivity: how birds forage on Goupia glabra fruits of different ripeness

Schaefer

2006

J Ornithol

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“…Schaefer et al (2002) found that fruit of various species were most abundant >16 m, rare at 4-12 m, and the caloric content of the standing crop differed among forest strata. They investigated fruit production among trees from species that differed in adult height; we propose to test variation of fruit production within the tree.…”

Section: Introductionmentioning

confidence: 95%

Intratree Variation in Fruit Production and Implications for Primate Foraging

2007

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We tested the hypothesis that fruit quantity and quality vary vertically within trees. We quantified intratree fruit production before exploitation by frugivores at different heights in 89 trees from 17 species fed on by primates in Kibale National Park, Uganda. We also conducted a pilot study to determine if the nutritional value of fruit varied within tree crowns. Depending on the species and crown size, we divided tree canopies into 2 or 3 vertical layers. In 2-layered trees, upper crowns produced fruits that were 9.6-30.1% bigger and 0.52-140 times the densities of those from lower crowns, with one exception. Among 2-layered trees, upper crowns produced a mean of 46.9 fruits/m 3 (median 12.1), while lower crowns produced a mean of 14.1 fruits/m 3 (median 2.5). Among 3-layered trees, upper crowns produced a mean density of 49.9 fruits/m 3 (median 12.5), middle crowns a mean of 16.8 fruits/m 3 (median 6.6), and lower crowns a mean of 12.8 fruits/m 3 (median 1.8). Dry pulp and moisture were systematically greater per fruit in the highest compared to the lowest canopy layers (22.4% and 16.4% respectively in 2-layered trees, 49.7% and 21.8% respectively in 3-layered trees). In 1 tree of Diospyros abyssinica, a pilot nutritional study showed that upper crown ripe fruit contained 41.9% more sugar, 8.4% more crude proteins, and 1.8 times less of the Int potentially toxic saponin than lower crown ripe fruit, but the result needs to be verified with more individuals and species of trees. We discuss the consequences of intratree variations in fruit production with respect to competition among frugivorous primates.

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“…This has been shown for an array of animals, including monkeys (Wrangham and Waterman 1981), mites (Lindo and Stevenson 2007), birds (Schaefer et al 2002), snails (Toth and Pavia 2002), isopods (Honkanen et al 2002), as well as for a variety of insects (Denno and McClure 1983;Carroll and Quiring 1994;Roslin et al 2006). Due to their relatively small size and limited mobility, phytophagous insects may be subjected to especially strong selective pressure to adapt foraging behaviors that increase their ability to eYciently Wnd Communicated by Thomas HoVmeister.…”

Section: Introductionmentioning

confidence: 86%

Intra-tree variation in foliage quality drives the adaptive sex-biased foraging behaviors of a specialist herbivore

et al. 2010

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Some herbivorous insects enhance their fitness using foraging strategies that allow them to find and colonize the best of available resources within heterogeneous plants. The yellowheaded spruce sawfly, Pikonema alaskensis (Roh.) (Hymenoptera: Tenthredinidae), is a common defoliator that oviposits and feeds on the developing foliage of young open-grown black spruce [Picea mariana (Mills) B.S.P.]. While female and male eggs are both laid throughout the crown, most eggs laid in the upper crown are female, and more female than male late-instar larvae disperse acropetally, from the lower and mid-crown to the upper crown, to complete juvenile development. Here we present results from 4 years of manipulative sleeve-cage experiments that were carried out to evaluate the hypothesis that sex-biased oviposition-site selection and acropetal dispersal by P. alaskensis are adaptive responses to intra-tree variation in foliage quality. Survival and proportion of survivors that were female were either the same (2 years) or significantly higher (2 years) for groups placed in the lower or mid-crown during early instars, and then transferred acropetally during late instars to complete development in the upper crown, compared with those forced to feed exclusively in the lower crown. This suggests that females benefited most from acropetal dispersal. Sex ratios of survivors that had been forced to develop exclusively in the upper crown were usually more female biased than those of survivors that developed exclusively in the lower crown, suggesting higher survival for female than for male larvae emerging from eggs laid in the upper crown. Sex-biased egg allocation and larval dispersal appear to increase the survival of P. alaskensis by accounting for differential effects on male versus female larvae of phenology-independent temporal and spatial variations in the quality of foliage within the heterogeneous crown of black spruce.

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Vertical Stratification and Caloric Content of the Standing Fruit Crop in a Tropical Lowland Forest1

Cited by 23 publications

References 31 publications

The fruits of selectivity: how birds forage on Goupia glabra fruits of different ripeness

The fruits of selectivity: how birds forage on Goupia glabra fruits of different ripeness

Intratree Variation in Fruit Production and Implications for Primate Foraging

Intra-tree variation in foliage quality drives the adaptive sex-biased foraging behaviors of a specialist herbivore

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