Long‐term outcomes of forest restoration in an urban park

Creating, restoring, and sustaining forests in urban areas are complicated by habitat fragmentation, invasive species, and degraded soils. Although there is some research on the outcomes of urban reforestation plantings during the first 5 years, there is little research on longer term outcomes. Here, we compare the successional trajectories of restored and unrestored forest sites 20 years after initiating restoration. The sites are located within the Rodman's Neck area of Pelham Bay Park, in the northeast corner of the Bronx in New York City (NYC), U.S.A. Compared with unrestored sites, we saw improvements in species diversity, greater forest structure complexity, and evidence of the regeneration and retention of native tree species in restored sites. In addition, we found differences in restoration outcomes depending on the level of intervention: clearing exotic shrubs and vines and planting native trees and shrubs improved tree diversity and canopy closure to a greater extent than clearing exotics alone, and the mechanical removal of invasive plants after the native plantings further improved some measures of restoration, such as tree species diversity and native tree regeneration. The results of this study suggest that the goal of a sustainable forest ecosystem dominated by native trees and other plant species may not be achievable without continued human intervention on site. In addition, these results indicate that the restoration approach adopted by NYC's reforestation practitioners is moving the site toward a more desirable vegetative community dominated by native species.     

Mutualisms with the wreckage of an avifauna: the status of bird pollination and fruit dispersal in New Zealand

Worldwide declines in bird numbers have recently renewed interest in how well bird?plant mutualisms are functioning. In New Zealand, it has been argued that bird pollination was relatively unimportant and bird pollination failure was unlikely to threaten any New Zealand plants, whereas dispersal mutualisms were widespread and in some cases potentially at risk because of reliance on a single large frugivore, the kereru (Hemiphaga novaeseelandiae). Work since 1989, however, has changed that assessment. Smaller individual fruits of most plant species can be dispersed by mid-sized birds such as tui (Prosthemadera novaezelandiae) because both fruits and birds vary in size within a species. Only one species (Beilschmiedia tarairi) has no individual fruits small enough for this to occur. Germination of 19 fleshy-fruited species, including most species with fruits >8 mm diameter, does not depend on birds removing the fruit pulp. The few studies of fruit removal rates mostly (7 out of 10) show good dispersal quantity. So dispersal is less at risk than once thought. In contrast, there is now evidence for widespread pollen limitation in species with ornithophilous flowers. Tests on 10 of the 29 known native ornithophilous-flowered species found that in 8 cases seed production was reduced by at least one-third, and the pollen limitation indices overall were significantly higher than the global average. Birds also frequently visit flowers of many other smaller-flowered native species, and excluding birds significantly reduced seed set in the three species tested. So pollination is more at risk than once thought. Finally, analyses of both species numbers and total woody basal area show that dependence on bird pollination is unexpectedly high. Birds have been recorded visiting the flowers of 85 native species, representing 5% of the total seed-plant flora (compared with 12% of those with fleshy fruit) and 30% of the tree flora (compared with 59% with fleshy fruit). A higher percentage of New Zealand forest basal area has bird-visited flowers (37% of basal area nationally) than fleshy fruit (31%). Thus, bird pollination is more important in New Zealand than was realised, partly because birds visit many flowers that do not have classic ?ornithophilous? flower morphology.     

Rain forest provides pollinating beetles for atemoya crops

Small beetles, usually species of Nitidulidae, are the natural pollinators of atemoya (Annona squamosa L. x A. cherimola Mill. hybrids; custard apple) flowers but commercial atemoya growers often need to carry out labor-intensive hand pollination to produce enough high-quality fruit. Because Australian rain forest has plant species in the same family as atemoya (Annonaceae) and because many rain forest plants are beetle pollinated, we set out to discover whether tropical rain forest in far north Queensland harbors beetles that could provide this ecosystem service for atemoya crops. Orchards were chosen along a gradient of increasing distance from tropical rain forest (0.1-24 km). We sampled 100 flowers from each of nine atemoya orchards and determined the identity and abundance of insects within each flower. To assess the amount of pollination due to insects, we bagged six flowers per tree and left another six flowers per tree accessible to insects on 10 trees at an orchard near rain forest. Results indicated that atemoya orchards < or = 0.5 km from rain forest were predominantly visited by five previously unrecognized native beetle pollinators that are likely to originate in tropical rain forest. These native beetles occurred reliably enough in crops near rain forest to have a positive effect on the quantity of fruit produced but their contribution was not great enough to satisfy commercial production needs. Management changes, aimed at increasing native beetle abundance in crops, are required before these beetles could eliminate the need for growers to hand pollinate atemoya flowers. Appreciation of the value of this resource is necessary if we are to develop landscapes that both conserve native biodiversity and support agricultural production.     

Fruit type,life form and origin determine the success of woody plant invaders in an urban landscape

The spread of alien plant species is a critical ecological event worldwide, but the forces that control this spread are not well documented. Alien plant species are well known to disrupt ecological services of native ecosystems, change the composition of native habitats, and often lead to the extirpation of native flora and fauna. Here, we report on life history patterns of plant species with rapidly spreading and declining ranges in North America’s major urban region. We tested for differences in life history traits between the 466 native and alien woody flora of the New York metropolitan area. We also examined the relationship between life history traits and change in distribution in the New York metropolitan area between 1900 and 2000. Native and alien species of the New York metropolitan area differ with respect to pollination vector and breeding system. However, pollination vector and breeding system are not associated with success, defined here as increasing range spread in the urban environment; instead, fruit type (dispersal), life form and origin are important determinants of success. Alien species that are deciduous trees, shrubs or vines with fleshy fruit are the most successful in increasing their distribution in this urban landscape. Newly introduced species with these characteristics are expected to have a better chance at establishing in similar urban landscapes and should be targets for intensive management. The ability to predict which alien species will become invasive is also a valuable tool for the prevention of invasions by newly introduced plant species.     

Relative abundance of an invasive alien plant affects native pollination processes

One major characteristic of invasive alien species is their occurrence at high abundances in their new habitat. Flowering invasive plant species that are visited by native insects and overlap with native plant species in their pollinators may facilitate or disrupt native flower visitation and fertilisation by forming large, dense populations with high numbers of flowers and copious rewards. We investigated the direction of such a proposed effect for the alien invasive Rhododendron ponticum in Irish habitats. Flower visitation, conspecific and alien pollen deposition, fruit and seed set were measured in a self-compatible native focal plant, Digitalis purpurea, and compared between field sites that contained different relative abundances of R. ponticum. Flower visitation was significantly lower at higher alien relative plant abundances than at lower abundances or in the absence of the alien. Native flowers experienced a significant decrease in conspecific pollen deposition with increasing alien abundance. Heterospecific pollen transfer was very low in all field sites but increased significantly with increasing relative R. ponticum abundance. However, lower flower visitation and lower conspecific pollen transfer did not alter reproductive success of D. purpurea. Our study shows that indirect interactions between alien and native plants for pollination can be modified by population characteristics (such as relative abundance) in a similar way as interactions among native plant species. In D. purpurea, only certain aspects of pollination and reproduction were affected by high alien abundances which is probably a result of high resilience due to a self-compatible breeding system. Native species that are more susceptible to pollen limitation are more likely to experience fitness disadvantages in habitats with high relative alien plant abundances.     

The impacts of pollination mode,plant characteristics and local density on the reproductive success of a scarce plant species, <Emphasis Type="Italic">Salix arbuscula</Emphasis>

Pollination failure represents one stage at which sexual reproduction of plants may be limited. It is therefore important to understand the pollination mechanism of the plant and how this may be affected by plant and population characteristics. This study examined the reproductive biology of a scarce montane willow species, Salix arbuscula, as part of a programme to determine ecological strategies for the conservation of montane willow scrub, an endangered habitat in the UK. The relative importance of insect and wind pollination, and the role of plant characteristics including plant size, catkin length, number of flowers and local density in determining reproductive success (number of fruit set) were investigated in three populations. Insect exclosures were used to determine the pollination mechanism. Our results suggest that S. arbuscula is predominantly insect-pollinated. In naturally pollinated plants, catkins with a higher proportion of ripe fruit were longer. Plants with more than two males in the local area and unbrowsed plants had a higher proportion of ripe fruit per catkin. The extent of wind pollination was very low, but differed between populations. The success of wind-only pollination was dependent on the number of males nearby, indicating that local density is more important in this type of pollination. Pollination mechanism and fruit set varied between the three populations observed, demonstrating the importance of multi-site comparisons. The number of males in the surrounding area had a positive effect on fruit set in both types of pollination, suggesting that Allee effects are likely to be operating in this species.     

Do frugivorous birds concentrate their foraging activities on those alien plants with the most abundant and nutritious fruits in the South African Mediterranean-climate region?

Alien plants with abundant and nutritious fruits may compete more effectively for avian dispersal services than native shrubs. This premise was examined by comparing daily foraging activity (visitation frequency, foraging bird number and foraging period) by four frugivorous bird species of different size on fruits of two native and two alien shrub species co-occurring at four different sites. Also, the quantities of seeds consumed daily by each of the four birds species from fruits of the four shrub species were measured and compared with the numbers of fruits and seeds, and the mass of fruits present in the shrub canopies as well as with their fruit monosaccharide concentrations. The quantities of seed consumed daily by four different size bird species (Columba arquatrix, Colius striatus, Pycnonotus capensis, Zosterops pallidus subsp capensis) were positively correlated with the numbers of seeds per m² of canopy area and with fruit mass and fruit monosaccharide content per m² of canopy area, as well as with the monosaccharide concentration of individual fruits, except in the C. arquatrix (African olive pigeon). All four bird species displayed the highest daily visitation frequencies on fruits of the alien Solanum mauritianum which were more abundant and nutritious than fruits of the other alien Lantana camara and fruits the natives Olea europaea subsp africana and Chrysanthemoides monilifera. They also all consumed greater quantities of seed daily from fruits of the alien S. mauritianum than from fruits of the other shrub species. These results corroborate proposals that frugivorous birds concentrate their foraging activities on those alien plants with the most abundant and nutritious fruits.     

Increased relative abundance of an invasive competitor for pollination, Lythrum salicaria, reduces seed number in Mimulus ringens

When exotic plant species share pollinators with native species, competition for pollination may lower the reproductive success of natives by reducing the frequency and/or quality of visits they receive. Exotic species often become numerically dominant in plant communities, and the relative abundance of these potential competitors for pollination may be an important determinant of their effects on the pollination and reproductive success of co-occurring native species. Our study experimentally tests whether the presence and abundance of an invasive exotic, Lythrum salicaria L. (Lythraceae), influences reproductive success of a co-flowering native species, Mimulus ringens L. (Phrymaceae). We also examine the mechanisms of competition for pollination and how they may be altered by changes in competitor abundance. We found that the presence of Lythrum salicaria lowered mean seed number in Mimulus ringens fruits. This effect was most pronounced when the invasive competitor was highly abundant, decreasing the number of seeds per fruit by 40% in 2006 and 33% in 2007. Reductions in the number of seeds per fruit were likely due to reduced visit quality resulting from Mimulus pollen loss when bees foraged on neighboring Lythrum plants. This study suggests that visit quality to natives may be influenced by the presence and abundance of invasive flowering plants.     

Effects of invasive alien kahili ginger (Hedychium gardnerianum) on native plant species regeneration in a Hawaiian rainforest

Questions: Does the invasive alien Hedychium gardnerianum (1) replace native understory species, (2) suppress natural regeneration of native plant species, (3) increase the invasiveness of other non‐native plants and (4) are native forests are able to recover after removal of H. gardnerianum. Location: A mature rainforest in Hawai'i Volcanoes National Park on the island of Hawai'i (about 1200 m a.s.l.; precipitation approximately 2770 mm yr^?1). Study sites included natural plots without effects of alien plants, ginger plots with a H. gardnerianum‐dominated herb layer and cleared plots treated with herbicide to remove alien plants. Methods: Counting mature trees, saplings and seedlings of native and alien plant species. Using non‐parametric H‐tests to compare impact of H. gardnerianum on the structure of different sites. Results: Results confirmed the hypothesis that H. gardnerianum has negative effects on natural forest dynamics. Lower numbers of native tree seedlings and saplings were found on ginger‐dominated plots. Furthermore, H. gardnerianum did not show negative effects on the invasive alien tree species Psidium cattleianum. Conclusions: This study reveals that where dominance of H. gardnerianum persists, regeneration of the forest by native species will be inhibited. Furthermore, these areas might experience invasion by P. cattleianum, resulting in displacement of native canopy species in the future, leading to a change in forest structure and loss of other species dependent on natural rainforest, such as endemic birds. However, if H. gardnerianum is removed the native Hawaiian forest is likely to regenerate and regain its natural structure.     

Breeding system and pollination ecology of a potentially invasive alien Clematis vitalba L. in Ireland

Aims Invasive alien plants can greatly affect native communities and ecosystem processes but only a small fraction of alien plant species become invasive. Barriers to establishment and invasion include reproductive limitations. Clematis vitalba L. has been a popular horticultural species for the past century and is widely distributed and can be highly invasive. In Ireland, it is considered naturalized and potentially invasive. Despite this, little is known about its reproductive biology.Methods We carried out manipulative field experiments in Ireland and compared fruit and seed set from a number of pollination treatments, namely cross-pollination, geitonogamy, autogamy and natural pollination. We also recorded floral visitation to C. vitalba through a series of timed observations.Important findings We found that C. vitalba is capable of uniparental reproduction via geitonogamy and autonomous selfing, albeit at a reduced rate compared with outcrossing treatments. Clematis vitalba was visited by at least 10 native pollinator taxa, with hoverflies dominating visitation. Neither fruit set nor seed set in our study population was pollen limited. Given the lack of reproductive constraint, C. vitalba may easily spread in suitable habitats. This is of concern in Ireland, given its prevalence in some of the country's most floristically diverse regions.     

Changes in plant community of Seasonally Semideciduous Forest after invasion by Schizolobium parahyba at southeastern Brazil

The recognition of a species as invasive is generally accepted when it comes from another continent or even from another country, but requires strong evidences of negative impacts to support control actions when the invasive species comes from another region in the same country. Schyzolobium parahyba – the ‘guapuruvu’, is a Brazilian tree native from the evergreen type of the Atlantic Forest, which has been recorded as invader in a number of remnants of the Seasonally Semideciduous Forest – SSF. We hypothesized that this giant and fast growing invasive tree changes the structure and composition of the understory, thus impairing the forest dynamics. We assessed the invasive population in the whole fragment, and, within the portion invaded, we sampled the regenerating plant community 1) under the largest alien trees, 2) under a native species with similar ecology (Peltophorum dubium), and 3) randomly in the forest. Density, basal area and richness under S. parahyba were remarkably lower than under the equivalent native species or in the understory as a whole. Floristic composition of the plant community was also distinct under S. parahyba, possibly due to increased competition for soil water. Even though the alien species has occupied, as yet, a small proportion of the forest fragment, it dominates the overstory and threatens the regeneration processes under its canopy. In view of our findings, we recommend extirpation of the species from SSF, as well as avoiding cultivation of the species away from its native range.     

Effects of habitat disruption on the activity of nectarivorous bats (Chiroptera: Phyllostomidae) in a dry tropical forest: implications for the reproductive success of the neotropical tree Ceiba grandiflora

In the tropical dry forest of the central Pacific coast of Mexico the pollination and reproductive success of the bombacaceous tree Ceiba grandiflora was negatively affected by habitat disruption. Two of the three bat species that function as effective pollinators for this species ( Glossophaga soricina and Musonycteris harrisoni) visited flowers found in trees in disturbed habitats significantly less than trees found in undisturbed habitats. A similar pattern was observed for the effective bat pollinator, Leptonycteris curasoae; however the difference was not significant. The three nectarivorous bats that functioned as effective pollinators of C. grandiflora also visited flowers to exclusively feed on pollen by biting or pulling off an anther (see Fig. S1 of Electronic Supplementary Material). The number of pollen grains deposited on stigmas from flowers in undisturbed areas was significantly greater than from flowers in disturbed habitats. The greater visitation rate and the greater number of pollen grains deposited on flowers from trees in undisturbed forest resulted in a significantly greater fruit set for trees in these areas. Our study demonstrates the negative effect that habitat disruption has on bat pollinators in tropical dry forest ecosystems and documents the negative consequences for the plants they pollinate.     

Restoration of Plant–Pollinator Interactions: Pollination Neighborhood and Asymmetric Pollen Flow Between Restored Habitats in a Beetle‐Pollinated Aroid

Two processes globally threatening natural ecosystems are changes in land use and deforestation. Two methods used to restore threatened ecosystems are: (1) unassisted forest regeneration, which promotes the establishment of plants and fauna arriving from surrounding habitats and (2) assisted restoration, which involves the reconstruction of forests by planting native or exotic trees. Functional attributes, such as plant–pollinator interactions, are essential for ecosystem recovery. Unfortunately, information regarding the effect of restoration on pollination systems is limited. Forty years ago, a tropical cloud forest in Colombia was restored through unassisted forest regeneration, as well as by establishing monospecific plantations of the exotic Chinese ash Fraxinus chinensis. The understories of both restoration strategies were colonized by the beetle‐pollinated aroid Xanthosoma daguense. Using isolation‐by‐distance and multi‐strata mark‐recapture models, I estimated in each restoration strategy two fundamental pollination processes: (1) the magnitude of X. daguense pollination neighborhood and (2) the directionality of pollen flow among plants colonizing both restoration strategies. In addition, I recorded pollinator visits and fruit production for X. daguense in each restored habitats. The pollination neighborhood of X. daguense in the ash plantation is two times larger than its pollination neighborhood in natural regeneration. Inflorescences in the ash plantation donated 10 times more pollen to inflorescences in natural regeneration. Plants in natural regeneration produced two times more infructescences and more fruits than plants in ash plantation. Results show that the selection of different restoration strategies can alter two major components of plant–pollinator interactions in plants colonizing restored habitats, pollination neighborhoods, and pollen flow within the population.     

外来树种的耗水特征及其对环境水资源的影响

外来树种常被作为"先锋树种"广泛引种，在荒山造林和水土保持方面发挥了积极作用；然而，不少外来树种具有高耗水和强抗旱的水分利用特性，耗水量大、水分消耗快，若不加甄别地引种会影响甚至危害本土森林生态系统的健康。目前，部分被引种的外来树种已造成入侵；同时，在当前水资源缺乏的形势下，外来树种的引种安全问题已成为全球关注的生态环境问题。本文综述了外来树种在生态系统、整树、叶片及枝条水平的耗水特性，分析了外来树种对引种地水资源的影响。前期的研究结果显示，被引种的外来树种在生态系统及整树水平的耗水量普遍高于乡土树种，但对水资源的影响却因受控于多个因素如环境、气候、植物个体等而不尽相同；同时还显示，外来树种在叶片和枝条水平的耗水特性更多地体现了其应对环境变化的水分利用策略。研究还就提高外来树种耗水特性研究的准确性和提升外来树种危害风险的预警能力方面，提出了若干研究方向，旨在为森林管理者和政府部门平衡外来树种的经济效益和生态效应提供借鉴和指导，以期降低外来树种引种风险，增进生态安全。     

Comparison of the ecology and evolution of plants with a generalist bird pollination system between continents and islands worldwide

Thousands of plant species worldwide are dependent on birds for pollination. While the ecology and evolution of interactions between specialist nectarivorous birds and the plants they pollinate is relatively well understood, very little is known on pollination by generalist birds. The flower characters of this pollination syndrome are clearly defined but the geographical distribution patterns, habitat preferences and ecological factors driving the evolution of generalist‐bird‐pollinated plant species have never been analysed. Herein I provide an overview, compare the distribution of character states for plants growing on continents with those occurring on oceanic islands and discuss the environmental factors driving the evolution of both groups. The ecological niches of generalist‐bird‐pollinated plant species differ: on continents these plants mainly occur in habitats with pronounced climatic seasonality whereas on islands generalist‐bird‐pollinated plant species mainly occur in evergreen forests. Further, on continents generalist‐bird‐pollinated plant species are mostly shrubs and other large woody species producing numerous flowers with a self‐incompatible reproductive system, while on islands they are mostly small shrubs producing fewer flowers and are self‐compatible. This difference in character states indicates that diverging ecological factors are likely to have driven the evolution of these groups: on continents, plants that evolved generalist bird pollination escape from pollinator groups that tend to maintain self‐pollination by installing feeding territories in single flowering trees or shrubs, such as social bees or specialist nectarivorous birds. This pattern is more pronounced in the New compared to the Old World. By contrast, on islands, plants evolved generalist bird pollination as an adaptation to birds as a reliable pollinator group, a pattern previously known from plants pollinated by specialist nectarivorous birds in tropical mountain ranges. Additionally, I discuss the evolutionary origins of bird pollination systems in comparison to systems involving specialist nectarivorous birds and reconstruct the bird pollination system of Hawaii, which may represent an intermediate between a specialist and generalist bird pollination system. I also discuss the interesting case of Australia, where it is difficult to distinguish between specialist and generalist bird pollination systems.     

Biological invasion into the nested assemblage of tree–beetle associations on the oceanic Ogasawara Islands

Invasion by alien organisms is a common worldwide phenomenon, and many alien species invade native communities. Invasion by alien species is especially likely to occur on oceanic islands. To determine how alien species become integrated into island plant–insect associations, we analyzed the structure of tree–beetle associations using host plant records for larval feeding by wood-feeding beetles (Coleoptera: Cerambycidae) on the oceanic Ogasawara Islands in the northwestern Pacific Ocean. The host plant records comprised 109 associations among 28 tree (including 8 alien) and 26 cerambycid (including 5 alien) species. Of these associations, 41.3% involved at least one alien species. Most native cerambycid species feed on host trees that have recently died. Alien trees were used by as many native cerambycid species (but by significantly more alien cerambycid species) as were native trees. Native cerambycid species used as many alien tree species (but significantly more native tree species) as did alien cerambycids. Thus, we observed many types of interactions among native and alien species. A network analysis revealed a significant nested structure in tree–cerambycid associations regardless of whether alien species were excluded from the analysis. The original nested associations on the Ogasawara Islands may thus have accepted alien species.     

Breakdown of the species-area relationship in exotic but not in native forest patches

We studied the pattern of bird species richness in native and exotic forest patches in Hungary. We hypothesized that species-area relationship will depend on forest naturalness, and on the habitat specialization of bird species. Therefore, we expected strong species-area relationship in native forest patches and forest bird species, and weaker relationship in exotic forest patches containing generalist species. We censused breeding passerine bird communities three times in 13 forest patches with only native tree species, and 14 with only exotic trees in Eastern Hungary in 2003. Although most bird species (92%) of the total of 41 species occurred in both exotic and native forests, the species-area relationship was significant for forest specialist, but not for generalist species in the native forests. No relationship between bird species and area was found for either species group in the forest with exotic tree species. The comparison of native versus exotic forest patches of similar sizes revealed that only large (>100 ha) native forests harbor higher bird species richness than exotic forests for the forest specialist bird species. There is no difference between small and medium forest patches and in richness of generalist species. Thus, the species-area relationship may diminish in archipelago of exotic habitat patches and/or for habitat generalist species; this result supports the warning that the extension of exotic habitats have been significantly contributing to the decline of natural community patterns.     

Implications of newly-formed seed-dispersal mutualisms between birds and introduced plants in northern California,USA

I examined the role of bird dispersal in invasiveness of three non-native plant species in California, USA: Triadica sebifera, Ligustrum lucidum, and Olea europaea. I selected these species because their invasiveness in California is uncertain, but a survey of ornithologists highlighted them as likely bird-dispersed. I quantified bird frugivory of these plants, compared them with a native species (Heteromeles arbutifolia), and explored the management implications of dispersal mutualisms for these and other incipient invasive plants. Fruit removal by birds was sufficient to permit spread for all study species. Seed dispersers (rather than seed predators) and pulse feeders (flocking species with potential for long distance dispersal) performed most fruit removal for the non-native species, a pattern indicative of an effective dispersal regime. The number of fruiting trees per stand was a significant predictor of bird visitation. Founding population size may thus be important in management of invasive, bird-dispersed plants. Disperser-defined niches were relatively narrow because a few disperser species performed the majority of fruit removal from study trees, but each fruit species was consumed by a variety of potential dispersers. This results in strong pairwise niche overlap between some plant species. Ordinated by bird use, study site-species combinations clustered more by geographic location than by plant species, emphasizing the opportunistic nature of bird foraging. None of the non-native focal plant species appears dispersal limited, and all have formed novel mutualisms in California. It is possible that these plants are now in lag phases preceding bird-mediated invasion. Consideration of bird dispersal when evaluating invasiveness is therefore an imperative.     

Effects of floral display and plant abundance on fruit production of Ryncholaelia glauca (Orchidaceae)

Flowering plant density can increase number of visits and fruit set in multi-flowering plants, however this aspect has not been studied on few flower species. We studied the effects of individual floral display and plant density on the fruit production of the epiphytic, moth-pollinated orchid, Ryncholaelia glauca, in an oak forest of Chavarrillo, Veracruz, Mexico. Species is non-autogamous, and produced one flower per flowering shoot each flowering season. We hypothesized that orchids with more flowering shoots and those on trees with clumps of conspecific should develop more fruits than isolated ones. R. glauca population flowers synchronouly, and individual flowers last up to 18 days, with flowers closing rapidly after pollination. Individuals produced few flowers per year, although some plants developed flowers in both seasons and fewer of them developed fruits both years. There was no relationship between flower number per orchid, or per host tree, with the number of fruits developed per plant. Host trees with flowering and fruiting orchids were randomly dispersed and the pattern of distribution of flowering and fruiting plants was not related. Apparently, pollinators visit the flowers randomly, with no evidence of density dependence. The fruit set of R. glauca was as low as fruit set of multi-flowered orchids moth pollinated, suggesting that fruit set on moth pollinated orchids could be independent of the number of flowers displayed.