Crop size,plant aggregation,and microhabitat type affect fruit removal by birds from individual melastome plants in the Upper Amazon

We studied the efficiency (proportion of the crop removed) and quantitative effectiveness (number of fruits removed) of dispersal of Miconia fosteri and M. serrulata (Melastomataceae) seeds by birds in lowland tropical wet forest of Ecuador. Specifically, we examined variation in fruit removal in order to reveal the spatial scale at which crop size influences seed dispersal outcome of individual plants, and to evaluate how the effect of crop size on plant dispersal success may be affected by conspecific fruit abundance and by the spatial distribution of frugivore abundance. We established two 9-ha plots in undisturbed terra-firme understory, where six manakin species (Pipridae) disperse most seeds of these two plant species. Mean levels of fruit removal were low for both species, with high variability among plants. In general, plants with larger crop sizes experienced greater efficiency and effectiveness of fruit removal than plants with smaller crops. Fruit removal, however, was also influenced by microhabitat, such as local topography and local neighborhood. Fruit-rich and disperser-rich patches overlapped spatially for M. fosteri but not M. serrulata, nonetheless fruit removal of M. serrulata was still much greater in fruit-rich patches. Fruit removal from individual plants did not decrease in patches with many fruiting conspecifics and, in fact, removal effectiveness was enhanced for M. fosteri with small crop sizes when such plants were in patches with more conspecifics. These results suggest that benefits of attracting dispersers to a patch balanced or outweighed the costs of competition for dispersers. Spatial pattern of fruit removal, a measure of plant fitness, depended on a complex interaction among plant traits, spatial patterns of plant distribution, and disperser behavior.     

Factors affecting seed rain beneath fleshy-fruited plants

We investigated factors affecting seed rain beneath nine fleshy-fruited fruiting plant species growing in a 1-ha plot of planted Pinus thunbergii in central Japan. We tested whether the numbers of seeds and seed species dropped by birds beneath fruiting plants were correlated with the number of fruits removed by birds from the plants. Most of fruiting plant species with high fruit removal had significantly high seed rain. Both the numbers of seeds and seed species dropped were significantly, positively correlated with the number of fruits removed across for all fruiting plant species. Therefore, fruit removal predicted the difference among heterospecific fruiting plants in seed rain. We also tested whether the number of fruits removed from fruiting plants by birds was related with fruit crop size, fruit size, and height of the plants, and the numbers of fruits and fruit species of neighboring plants near the plants. Most of fruiting plant species with high fruit crop size had significantly high fruit removal. The number of fruits removed was significantly, positively correlated with both the fruit crop size and the number of neighboring fruits across the nine fruiting plant species. However, the effect of the neighboring fruit density on fruit removal was lower remarkably than that of fruit crop size. Therefore, fruit crop size best predicted the differences among heterospecific fruiting plants in fruit removal. We suggest that fruiting plant species with high fruit crop size and high fruit removal contribute to intensive seed rain beneath them. This revised version was published online in June 2006 with corrections to the Cover Date.     

Fruit removal and postdispersal survivorship in the tropical dry forest shrub Erythroxylum havanense: ecological and evolutionary implications

We studied the relationship between the removal rate and the spatiotemporal availability of ripe fruits of the tropical deciduous shrub Erythroxylum havanense in western Mexico. We also evaluated the effects of dispersal on seed survival during the first stages of establishment. Fast and early dispersal should be favored in E. havanense, since propagules have more time to grow and accumulate resources before the beginning of the severe dry season. In general, high rates of fruit removal imply faster and earlier dispersal. Thus, plants producing large crops should benefit from high removal rates, which will increase the probability of successful establishment by their progeny. To characterize both individual and population fruiting patterns, we made daily counts of fruits on 51 plants arranged in six clumps of different sizes. The daily number of fruits removed per plant was higher for plants with larger initial crop sizes and larger numbers of ripe fruits on a given day, but decreased as clump size increased. Additionally, we monitored postdispersal survival and germination in an experiment manipulating seed density, distance from adult plants, and seed predation. Early establishment was independent of density or distance, and vertebrate seed predation was the main agent of seed mortality. Our results indicate that the critical variable with respect to fruit removal is the number of fruits a plant produces, large plants having higher dispersal rates. Large plants are also more likely to have more seeds escaping postdispersal seed predation.     

Fruit fate,frugivory, and fruit characteristics: a study of the hawthorn,Crataegus monogyna (Rosaceae)

Summary The fate of fruits from a population of European hawthorn (Crataegus monogyna) in western Oregon, USA, was examined over a two-year period. Only one frugivore, the American robin (Turdus migratorius) foraged on the C. monogyna fruits, making this an unusually straightforward fruit-frugivore system. Dispersal efficiency was low, with an average 21% of seeds being dispersed (carried away from parent plants) each year; the most common fate of fruits was to simply fall. Robins dropped 20% of the fruits that they picked, and defecated/regurgitated 40% of the fruits (seeds) that they swallowed, beneath parent plants. One trait, gruit abundance, strongly affected the probability of bush visitation by robins, bushes with larger fruit displays being preferred. Both absolute dispersal success (number of seeds) and dispersal efficiency (proportion of seeds; success per propagule) were also found to be correlated most strongly with initial fruit abundance. Individual plant fecundity and fruit quality were found to vary little between years; as a result, dispersal efficiencies for individual plants were also annully consistent. Larger (older) plants produced more fruits and therefore had higher fitness. These results suggest that the optimal fruiting strategy for C. monogyna is therefore to get as big as possible as quickly as possible by delaying fruiting until later in life.     

Positive relationship between fruit removal by animals and seedling recruitment in a tropical forest

Fleshy-fruited plants rely on animal frugivores to disperse their seeds, and seed removal by frugivores may leave an imprint on seedling recruitment. However, to what extent plant–frugivore interactions are related to seedling recruitment has rarely been quantified at the community level, especially in species-rich tropical forests. In this study, we tested the effect of different plant traits on fruit removal by frugivores and tested the relative importance of fruit removal, plant traits and abiotic factors for seedling recruitment. We quantified plant–frugivore interactions of 22 fleshy-fruited plant species consumed by 56 diurnal frugivore species, and counted the number of seedlings that emerged along an elevational gradient in the Colombian Andes. We measured a set of plant traits (i.e., crop size; fruit size; seed load and mass; fruit nutritional contents), estimated the density of adult plants and recorded relevant abiotic factors (light, temperature and humidity). We found that fruit removal by frugivores was positively associated with crop size, but negatively associated with fruit length and unrelated to seed load and fruit nutritional content. Seedling densities were positively related to the density of adult plants, seed mass and fruit removal by animals. We found no relationship between abiotic factors and seedling recruitment. Our results indicate that fruit abundance and morphology are important determinants of fruit removal and that fruit removal is positively associated with seedling recruitment accounting for effects of species abundance and plant traits. We conclude that plant traits shape fruit removal and seedling recruitment at the community level, while these two crucial processes of forest regeneration are directly linked by seed dispersal of animals.     

Allometric allocation in fruit and seed packaging conditions the conflict among selective pressures on seed size

Selective pressures on seed size could vary among the different stages of plant life cycles, so no simple relation could explain a priori its evolution. Here, we determined the relationships between seed size and two fitness components—seed dispersal and survival from predation—in a bird-dispersed tree, Crataegus monogyna. We interpret these relationships in relation to the patterns of mass allocation to fruit and seed components. Selection patterns were assessed at two levels (1) selection pressures on the parent tree; comparing seed dispersal efficiency among individual plants and (2) selection pressures at the individual seed level; comparing seed size variation (i) before and after dispersal, and (ii) before and after postdispersal seed predation. Dispersal efficiency (percentage of seed crop dispersed) was positively correlated with fruit mass and fruit width. Differences in crop size did not offset this effect, and larger seeds were overrepresented in the seed rain relative to the seed pool before dispersal. However, the advantage of larger seeds during the dispersal stage was cancelled later by an opposite selection pressure exerted by seed predators. As a result, smaller seeds had a higher probability of surviving postdispersal seed predation, establishing an evolutionary conflict imposed by the need for dispersal and the danger of being predated. Birds and rodents preferentially selected highly profitable fruits and seeds in terms of the relative proportion of their components. Larger fruits had a higher pulp to seed proportion than smaller ones, and all seeds had the same proportion of coat relative to the embryo-plus-endosperm fraction. Hence, although predator pressures were stronger than disperser ones, larger seeds invested proportionally less in structural defense than in dispersal.     

Seasonal variation in fleshy fruit use and seed dispersal by the Japanese black bear (<Emphasis Type="Italic">Ursus thibetanus japonicus</Emphasis>)

Fruit use by the Japanese black bear (Ursus thibetanus japonicus) and seed clumping in bear scat were studied in central Japan using fecal analyses. Between May and November 2003 and 2004, the life form and fruit size of plants consumed by bears and the species composition and intactness of seeds contained in scat were examined in five transects (approximately 10 km × 10 m) in broad-leaved deciduous forests. In 2003, scats with seeds were found only in the autumn, when fruiting trees and shrubs were abundant. In 2004, scats with seeds occurred intermittently from the summer, when fruiting plants were rare, up to the autumn. Yearly and seasonal variation in fruit use reflects the opportunistic foraging behavior of Japanese black bears. Seven of the nine plant species detected in scats had medium-sized fruits (6–15 mm width), whereas the other two species had relatively large fruits (20–100 mm width). In total, 14,492 seeds were detected, of which 97.6% were intact; the remainder were damaged. Intact seeds of one or two species were found in each scat. The number of intact seeds per scat ranged from 1 to 5476. Japanese black bears seldom digest ingested seeds, thereby contributing to the seed dispersal of their food plants, including species with fruits that are too large to be swallowed by frugivorous birds.     

Tree dispersal strategies in the littoral forest of Sainte Luce (SE-Madagascar)

Zoochory is the most common mode of seed dispersal for the majority of plant species in the tropics. Based on the assumption of tight plant-animal interactions several hypotheses have been developed to investigate the origin of life history traits of plant diaspores and their dispersers, such as species-specific co-evolution, the low/high investment model (low investment in single fruits but massive fruiting to attract many different frugivores versus high investment in single fruits and fruit production for extended periods to provide food for few frugivores), and the evolution of syndromes which represent plant adaptations to disperser groups (e.g. birds, mammals, mixed). To test these hypotheses the dispersal strategies of 34 tree species were determined in the littoral forest of Sainte Luce (SE-Madagascar) with the help of fruit traps and tree watches. The impact of fruit consumers on the seeds was determined based on detailed behavioral observations. Phenological, morphological and biochemical fruit traits from tree species were measured to look for co-variation with different types of dispersal. No indication for species-specific co-evolution could be found nor any support for the low/high investment model. However dispersal syndromes could be distinguished as diaspores dispersed by birds, mammals or both groups (mixed) differ in the size of their fruits and seeds, fruit shape, and seed number, but not in biochemical traits. Five large-seeded tree species seem to depend critically on the largest lemur, Eulemur fulvus collaris, for seed dispersal. However, this does not represent a case of tight species-specific co-evolution. Rather it seems to be the consequence of the extinction of the larger frugivorous birds and lemurs which might also have fed on these large fruits. Nevertheless these interactions are of crucial importance to conserve the integrity of the forest.     

Pollinators and Reproductive Success of the Wild Cucurbit Cucurbita maxima ssp. andreana (Cucurbitaceae)

Abstract: We studied the reproductive success and pollinators of Cucurbita maxima ssp. andreana in different disturbed habitats where it grows naturally. Data were obtained from three populations. One grew within a soybean crop, the other within a corn crop, and the third in an abandoned crop field. Cucurbita maxima ssp. andreana is an annual vine with a flowering period from December to April. Male flowers appear first, thereafter female and male flowers appear together. Flower lifetime (9 h) was similar in male and female flowers. The pollinator guild was comparable for the three populations but some differences in the frequency of the insect species were observed. Native bees were the main pollinators in the population in the abandoned field, while beetles pollinated the populations in crop fields. These differences were not linked with the pre-emergent reproductive success, fruit and seed set, or fruit quality. This is a self-compatible plant. Fruit and seed set and fruit traits (total mass, width and length of fruits, number of seeds per fruit, and seed mass) did not show significant differences between hand-cross and hand-self pollinated flowers. This wild cucurbit is a generalist with respect to pollinator guild, and flower visitors seem to be highly efficient in pollen transference. Cucurbita maxima ssp. andreana is well adapted to disturbed habitats because plants ripened fruits successfully, regardless of the group of insects visiting flowers.     

Water limitation effect on seed development and germination in Trigonella coerulea (Fabaceae)

The annual garden spice legume Trigonella coerulea was subjected to controlled drought conditions to investigate the influence of resource limitation on flowering, seed production and germination. Limitations in water availability significantly reduced plant height and the number of fruits produced. However, treatments had no significant effect on seed set within the fruit. Fruit number per plant, rather than seed number per fruit was affected by resource limitation. Plants growing under water deficiency had higher flower abortion rates. Simultaneously, the size and germination rate of the seeds were decreased. In terms of reproductive success T. coerulea was not able to adapt reproduction to water shortage. Increase in moisture had no significant effect on seed quantity and quality when compared to the control.     

Determinants of fruit removal in <Emphasis Type="Italic">Geonoma pauciflora</Emphasis>, an understory palm of neotropical forests

Competition for seed dispersers is supposedly a selective force that drives the evolution of plant reproductive traits. In the understory of tropical forests, such competition should be especially severe among bird-dispersed plant species because (i) the production of copious fruit crops is limited by low light availability; (ii) there usually is a high density of fleshy fruited plants, and (iii) understory frugivorous birds are not abundant. In this paper, we took advantage of a high-density population of Geonoma pauciflora, a bird-dispersed palm species growing in the understory of the Brazilian Atlantic forest, to investigate the influence of plant traits and its immediate neighborhood on fruit removal. Intrinsic (crop and fruit sizes) and extrinsic traits (related to light availability) affected the fruit removal of G. pauciflora. Crop size had a greater influence than fruit size on the absolute number of fruits removed, whereas none of the investigated traits influenced decisively fruit removal efficiency (i.e., the proportion of an individual’s crop removed). The influence of light availability was mostly indirect, through its positive influence on fruit production. A significant positive spatial autocorrelation in removal efficiency occurred among neighboring plants within a 7-m radius, which is indicative of facilitation among neighboring individuals. The consequence of such positive spatial autocorrelation in removal efficiency for clonal plants such as G. pauciflora is that by attracting a frugivore a given ramet may promote the removal of fruits of other ramets, thus enhancing the reproductive output of the genet as a whole.     

Seed size selection by olive baboons

Seed size is an important plant fitness trait that can influence several steps between fruiting and the establishment of a plant’s offspring. Seed size varies considerably within many plant species, yet the relevance of the trait for intra-specific fruit choice by primates has received little attention. Primates may select certain seed sizes within a species for a number of reasons, e.g. to decrease indigestible seed load or increase pulp intake per fruit. Olive baboons (Papio anubis, Cercopithecidae) are known to select seed size in unripe and mature pods of Parkia biglobosa (Mimosaceae) differentially, so that pods with small seeds, and an intermediate seed number, contribute most to dispersal by baboons. We tested whether olive baboons likewise select for smaller ripe seeds within each of nine additional fruit species whose fruit pulp baboons commonly consume, and for larger seeds in one species in which baboons feed on the seeds. Species differed in fruit type and seed number per fruit. For five of these species, baboons dispersed seeds that were significantly smaller than seeds extracted manually from randomly collected fresh fruits. In contrast, for three species, baboons swallowed seeds that were significantly longer and/or wider than seeds from fresh fruits. In two species, sizes of ingested seeds and seeds from fresh fruits did not differ significantly. Baboons frequently spat out seeds of Drypetes floribunda (Euphorbiaceae) but not those of other plant species having seeds of equal size. Oral processing of D. floribunda seeds depended on seed size: seeds that were spat out were significantly larger and swallowed seeds smaller, than seeds from randomly collected fresh fruits. We argue that seed size selection in baboons is influenced, among other traits, by the amount of pulp rewarded per fruit relative to seed load, which is likely to vary with fruit and seed shape.     

Crop Size and Fruit Neighborhood Effects on Bird Visitation to Fruiting Schefflera morototoni Trees in Puerto Rico1

Studies of zoochorous seed dispersal systems often consider crop size, yet seldom consider the kinds and amounts of fruits surrounding parent plants (the fruit neighborhood) when attempting to explain among‐plant variation in fruit removal. We studied avian frugivory at 24 Schefflera morototoni trees from February to May 1998 in central Puerto Rico. The number of fruits removed by avian seed dispersers per visit was similar among focal trees (typically 2–4). In contrast, visitation rate was highly variable (range: 0–71 visits per 4 h). We used multiple regression analyses to evaluate the relative roles of crop size (focal tree ripe fruit abundance) and fruit neighborhood variables (measured within 30 m of focal trees) in affecting visitation to focal trees by avian frugivores. Visitation rate was positively related to crop size (although this variable was only significant in one of four regression models considered) and negatively related to the presence or abundance of conspecific fruits, suggesting that trees competed intraspecifically for dispersers. Relationships between visitation and heterospecific fruits were mixed—some kinds of fruits appeared to enhance visitation to focal trees, while others seemed to reduce visitation. In most regression models, neighborhood variables had larger effects on visitation than focal tree fruit crop size. Our results highlight the important effects of local fruiting environments on the ability of individual plants to attract seed dispersers.     

Facultative ripening in Hamelia patens (Rubiaceae): effects of fruit removal and rotting

Summary In Costa Rica individual Hamelia patens trees produce fruit throughout the year and experience dramatic changes in rates of fruit removal and rotting. During some moths, most fruits rot because they are not removed. Rotting fruits increase the probability that other fruits on the same infructescence will rot. When removal rates are high, fruits are taken as soon as their seeds become viable but before the fruit is completely ripe. Experimental removal of fruits produced significantly higher ripening rates than on control infructescences. This response allows Hamelia to ripen more fruit and increase the number of fruits taken when dispersers are abundant (e.g., during migration). The proximate mechanism of this response probably includes reallocation of energy conserved when partially ripe fruits are removed. Responding to fluctuating disperser populations likely increases dispersal success and may function as the ultimate cause.     

Consequences for seed distributions of intra-crop variation in wing-loading of wind-dispersed species

We used a computer simulation to quantify how intra-crop variation in wing-loading in a wind-dispersed species affects the seed distribution around a parent plant. We used a data set of seed distributions generated from a previous field study using artificial fruits varying in seed mass or fruit area dispersed from a tower into a tropical forest. For this study, the spatial distribution from each hypothetical parent's fruit crop of 1000 was calculated by randomly drawing locations of dispersed fruits from the previous data base. Three parents with contrasting fruit crops were used to test two hypotheses: 1) Increasing within-parent variance in wing-loading (= weight/area), while maintaining the mean, will lead to an increase in the area and uniformity of the seed distribution, without changing the mean dispersal distance. 2) Decreasing within-parent mean wing-loading, (which also decreases variance), will lead to an increase in mean dispersal distance, area, and uniformity of the seed distribution. The hypotheses were tested under four wind speeds.Increasing variance in wing-loading resulted in increasing the area and uniformity of density of the seed distribution without changing mean dispersal distance. Decreasing mean and variance in wing-loading resulted in increasing the area and uniformity of density of the seed distribution, as well as increasing the mean dispersal distance. Similar results occurred whether the differences in wing-loading arose by altering seed mass or fruit area. The effect of wind speed was consistently greater than the effect of parent. Generally, the same pattern of parent effects on seed distributions occurred, regardless of wind condition.The effects on seed distributions differed for alterations in mean versus variance, specifically in whether mean dispersal distance was increased. How selection may act on intra-crop mean and variance in wing-loading will depend on additional factors, e.g. the relative importance of distance, area, and density on seedling recruitment and the relative costs for crop size and seedling establishment of making fruit crops of a given mean and variance.     

Birds and guelder rose <Emphasis Type="Italic">Viburnum opulus</Emphasis>: selective consumption and dispersal via regurgitation of small-sized fruits and seeds

The evolution of fleshy fruit size, in particular in bird-dispersed plants, is believed to be influenced by the size of seed-dispersing vertebrates through gape limitation. Also, it has been demonstrated that seed size correlates positively with fruit size, especially in single- or few-seeded fruits. However, there is little evidence of current selection pressure by disperser birds on fruit and seed size within populations of a particular plant species. In the present study, this aspect was investigated in guelder rose Viburnum opulus (Caprifoliaceae) fruit consumption by birds in an area in NW Spain. Guelder rose fruits are sub-globose drupes that can exceed 11 mm in width, with a single hard seed of up to 8.5 mm in width. Most of the seeds were dispersed by the robin Erithacus rubecula (gape width < 8 mm) and a small thrush, the song thrush Turdus philomelos (gape width < 11 mm), which swallowed the fruits whole, and some were destroyed by the bullfinch Pyrrhula pyrrhula. Most of the seeds were regurgitated rather than defecated by disperser birds, probably because seed size limited gut processing. The mean size of the ingested seeds was smaller than the mean diameter of Turdus droppings, which in turn was smaller than the mean size of the seeds of the fruits available on the plants. As winter progressed, only larger fruits and seeds remained on the plants (seed and fruit size were positively correlated), and the size of ingested seeds increased. Thus, the largest fruits were consumed less by seed-dispersing birds and were exposed to seed-predators (bullfinches and climbing rodents) for longer. Selection pressure on smaller guelder rose seeds must therefore be effective in the dispersal stage in the study area.     

Effects of fruit thinning on fruit and seed features of <Emphasis Type="Italic">Cistus ladanifer</Emphasis>

Fruit and seed features are the result of reproductive allocation decisions which ultimately depend on both plant availability of resources and total number of developing fruits. In this study, we manipulated fruit load in Cistus ladanifer plants by removing 0, 25 or 75% of developing fruits. Fruit features (total fruit weight, fruit-wall weight, total seed weight per fruit and seed number per fruit) were unaffected by fruit thinning, nevertheless mean seed weight increased in treated plants independently of thinning intensity. This reduced compensation was unrelated to plant size and had no consequences on fruit predation by insects. From these results it could be suggested that not only availability of resources but also morphological constraints could affect seed size in Cistus ladanifer. On the other hand, this change in seed weight could have important consequences since in this species heavy seeds perform better after fire events but light ones are advantageous in between fire recruitments.     

Spatial–temporal distribution of ornithochorous seeds from an Elaeagnus umbellata community dominating a riparian habitat

The dispersal efficiency and potential distribution of ornithochorous seeds of Elaeagnus umbellata in a riparian habitat were evaluated to clarify this species' establishment site in relation to the disturbance regime of the floodplain. Fruit removal by avian frugivores was monitored using fruit bags, and the spatial distribution of excreted seeds was quantified by seed traps set randomly on a gravel bar as an isolated seed source in the Yoshino River throughout an autumn fruiting season. Although more than 45% of the fruits remained on the twigs in the fruit bags, almost all fruits on the control twigs without fruit bags were exploited by the beginning of January. The fruit removal rate and seed dispersal distance were positively correlated with an increase in wintering bird species and their abundance. Intact bird‐dispersed seeds of E. umbellata were trapped within a 400‐m range and damaged seeds were limited to traps set within 50 m from the seed source. Frugivore behavior, such as feces excretion on rocks near water drinking sites and perching on surrounding woodland, greatly influenced the spatial and temporal dispersal pattern of the seed rain. In the present study, the avian frugivores showed upstream seed dispersal; thus, in years with stochastic autumnal floods, secondary dispersal via hydrochory downstream may be facilitated. The intensive seed dispersal in E. umbellata indicates that the present distribution of parent trees in the restricted elevation range of the gravel bars is the result of survival through disturbance, rather than seed dispersal limitation.     

Influence of type of avian frugivory on the fitness ofPistacia terebinthus L.

Summary The fruits ofPistacia terebinthus, a circum-Mediterranean tree/shrub, are consumed by an array of bird species that differ in feeding methods and in relative frequencies of visits to plants. In this study I document interindividual variation in the proportion of fruits consumed by three types of frugivores: legitimate dispersers, pulp-consumers and seed predators. The results show that the relative frequencies of each kind of frugivore notably influence the final reproductive output (absolute number of viable seeds dispersed) and in fact prevail over the effects of pre-dispersal factors acting on plant fitness. Those relative frequencies are not associated with any of the plant traits related to fitness, such as fruit crop size and the number of viable seeds produced, suggesting that the type of avian frugivory exerts a negligible, if not null, selective pressure on such plant attributes. Plant specialization to attract the most effective seed dispersers seems to be precluded, given the small scale at which the high variation in seed dispersal success takes place.     

Pollination efficiency and reproductive patterns in relation to local plant density,population size,and floral display in the rewarding Listera ovata (Orchidaceae)

Pollination efficiency and reproductive success vary strongly among populations of most animal‐pollinated plant species, depending on their size and local density, whereas individual plants within populations experience varying levels of reproductive output as a result of differences in floral display. Although most orchid species have been shown to be severely pollination limited, few studies have investigated the impact of the above‐mentioned factors on pollination success and reproduction, especially in rewarding species. In this study, the impact of population size, local density of flowering plants, and floral display on the rates of pollinia export and fruit production was investigated in 13 natural populations of the rewarding terrestrial orchid Listera ovata. In addition, an emasculation experiment was set up to examine how floral display and local density of flowering plants affected the relative importance of cross‐ vs. geitonogamous pollination in determining fruit set. In the studied populations, pollination efficiency, pollen removal, and fruit set increased with increasing population size until a threshold value of 30–40 flowering plants was reached, above which pollination efficiency and reproductive output decreased again. On average, plants with large floral displays showed higher proportional pollinia removal and fruit set compared with smaller plants. Fruit production was also significantly and positively related to local plant density, whereas emasculation did not affect the relationship between local plant density and fruit set, suggesting that geitonogamous pollination did not affect the outcome of female function. The results of this study are discussed in the light of the flowering mechanism of the species and its generalized pollination system. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 157 , 713–721.