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1.
One common goal of habitat restoration and reconstruction is to reinstate the biodiversity found at intact reference sites. However, few researchers have examined whether these practices reinstate communities of flower‐visiting insects. This is unfortunate, as anthropogenically mediated declines in flower visitors, including bees (the primary pollinators for most terrestrial ecosystems), beetles, flies, and butterflies, have been reported worldwide. Biodiversity declines may be especially severe in North America's tallgrass prairie, a once‐vast grassland that has experienced severe destruction and degradation due to agricultural conversion. As such, we assessed the structure of forb and flower‐visiting insect communities as a whole and two subsets of the flower visitor community—bees and phytophagous beetles—across five tallgrass prairie remnants and five reconstructed prairies (former crop fields) in Kansas from 2013 to 2015. Remnant prairies had significantly higher forb diversity and differed significantly in forb composition, compared to reconstructed prairies. Despite the dissimilarities in forb community structure, there were no differences in flower visitor diversity or abundance between remnants and reconstructed prairies. However, when considered separately, bee communities exhibited significantly greater variability in composition on reconstructed prairies, likely due to the abundance of generalist bee species visiting non‐native legumes at two reconstructed prairies. Our work provides evidence that prairie habitat reconstruction is a valuable tool for reestablishing flower‐visiting insect communities and also emphasizes the considerable role that non‐native species may play in structuring grassland plant–bee interactions.  相似文献   

2.
Loss of insect pollinators due to habitat fragmentation often results in negative effects on plant reproduction, but few studies have simultaneously examined variation in the bee community, site characteristics and plant community characteristics to evaluate their relative effects on plant reproduction in a fragmented habitat. We examined the reproduction of a common tallgrass prairie forb, Amorpha canescens (Fabaceae), in large (>40 ha) and small (<2 ha) prairie remnants in Iowa and Minnesota in relation to the diversity and abundance of its bee visitors, plant population size, and species density of the forb flowering community. We found significant positive effects of the diversity of bees visiting A. canescens on percent fruit set at a site in both years of the study and in 2002 an additional significant positive effect of plant species density. Abundance of bees visiting A. canescens had a significant positive effect on percent fruit set in 2002, but was only marginally significant in 2003. In 2003 but not 2002, the plant species density at the sites had a significant negative effect on the diversity and abundance of bees visiting A. canescens, indicating community-level characteristics can influence the bee community visiting any one species. Site size, a common predictor of plant reproduction in fragmented habitats did not contribute to any models of fruit set and was only marginally related to bee diversity one year. Andrena quintilis, one of the three oligolectic bee species associated with A. canescens, was abundant at all sites, suggesting it has not been significantly affected by fragmentation. Our results show that the diversity of bees visiting A. canescens is important for maintaining fruit set and that bee visitation is still sufficient for at least some fruit set in all populations, suggesting these small remnants act as floral resource oases for bees in landscapes often dominated by agriculture.  相似文献   

3.
Livestock grazing is a widespread grassland disturbance and can negatively impact biodiversity. Pollinators constitute a vital component of grassland ecosystems, but the impact of grazing on pollinator diversity has seldom been evaluated in North America. We assessed vegetation structure, and pollinator and flowering plant abundance, richness, diversity, and community composition in four pairs of spring-grazed/ungrazed sites in south-central British Columbia, Canada. We also investigated whether pollinator or floral communities differed between the two threatened shrubsteppe habitat types we sampled—antelope-brush and big sagebrush shrubsteppe. Pan-trapping surveys captured 5907 bees, flies, beetles, wasps and butterflies constituting 253 species. We found that the percent cover of shrubs and bare soil increased with grazing, while the height of grasses and forbs decreased. In contrast, pollinator and flowering plant abundance, richness, diversity, and community composition were not significantly affected by grazing. Flowering plant and pollinator community composition did differ significantly between shrubsteppe habitats. Our results indicate that grasslands in North America, when managed responsibly, can maintain pollinator and flowering plant diversity under grazing pressure. The continued effort of land managers to balance ecological integrity and economic viability will be important for the conservation of grassland pollination systems.  相似文献   

4.
Restoration efforts often focus on plants, but additionally require the establishment and long‐term persistence of diverse groups of nontarget organisms, such as bees, for important ecosystem functions and meeting restoration goals. We investigated long‐term patterns in the response of bees to habitat restoration by sampling bee communities along a 26‐year chronosequence of restored tallgrass prairie in north‐central Illinois, U.S.A. Specifically, we examined how bee communities changed over time since restoration in terms of (1) abundance and richness, (2) community composition, and (3) the two components of beta diversity, one‐to‐one species replacement, and changes in species richness. Bee abundance and raw richness increased with restoration age from the low level of the pre‐restoration (agricultural) sites to the target level of the remnant prairie within the first 2–3 years after restoration, and these high levels were maintained throughout the entire restoration chronosequence. Bee community composition of the youngest restored sites differed from that of prairie remnants, but 5–7 years post‐restoration the community composition of restored prairie converged with that of remnants. Landscape context, particularly nearby wooded land, was found to affect abundance, rarefied richness, and community composition. Partitioning overall beta diversity between sites into species replacement and richness effects revealed that the main driver of community change over time was the gradual accumulation of species, rather than one‐to‐one species replacement. At the spatial and temporal scales we studied, we conclude that prairie restoration efforts targeting plants also successfully restore bee communities.  相似文献   

5.
Recent reports of pollinator declines have stirred interest in investigating the impacts of habitat exploitation on the conservation of pollinator and plant communities. An important prerequisite to tailor conservation action is to understand the drivers and patterns of species-rich communities, and how they change in space and time during a whole season. To account for this, we surveyed wild bees and flowering plants using standardized transects in 11 natural habitat fragments of an IUCN important plant area along the coast of Israel. We used phylogeny- and taxon-based methods of community structure analyses to study the assembly processes of bee communities, and investigated the effects of several landscape parameters on bee diversity using generalized linear models (GLMs). Our results illustrate that natural habitat sites comprised significantly higher species richness compared to disturbed habitat sites, and show that even the smallest habitat fragments harbored unique bee assemblages, with significant species replacement (turnover) found in both space and time. Our GLMs indicated that flower diversity, and semi-natural habitat within 500 m of habitat fragments were important drivers of bee diversity, but we found no evidence for a species—area relationship among sites. Finally, we document a case of phylogenetic overdispersion despite low species richness, which highlights the importance of accounting for phylogenetic diversity rather than only species richness to reach a more fine-grained understanding of pollinator diversity. This, in turn, is pivotal to developing conservation actions to protect these essential pollinators and their interaction with rare and endemic plant species in this highly threatened ecosystem.  相似文献   

6.
1.  The evaluation of restoration measures is an important task of conservation biology. Inland sand dunes and dry, oligotrophic grasslands have become rare habitat types in large parts of Central Europe and their restoration and management is of major importance for the preservation of many endangered plant and insect species. Within such habitats, it is important to restore key ecosystem services, such as pollination networks. As wild bees are the most important pollinators in many ecosystems, they represent a suitable key group to evaluate restoration measures. Furthermore, the recent decline of many bee species and the potential ecological and economic consequences are currently topics of strong scientific interest.
2.  We studied the succession of bee communities in response to restoration measures of sand dunes and sand grasslands and compared these communities with those of old sand dune complexes.
3.  Our results show that wild bees respond rapidly to restoration measures indicated by a high species richness and abundance. The community structure of bees at restoration sites converged only slightly to those of the target sites. A higher similarity was found between bee communities at the restoration sites (sand dunes and grasslands), indicating that their close proximity was an important determinant of species overlap. Environmental factors such as the number of entomophilous plant species and moisture had a strong influence on wild bee species composition.
4.   Synthesis and applications . The restoration of inland sand dune complexes provides opportunities for colonization by a diverse wild bee community. Although it is difficult to establish a given target community, restoration measures gave rise to a high pollinator diversity and abundance, suggesting that community function can be re-established.  相似文献   

7.
Natural small, xeric hill prairies in forested landscapes throughout the Midwest United States often contain high diversity and unique species of some organisms because of their unusual landscape context and microclimate. We measured the diversity, richness, and abundance of the bee communities of five hill prairies located in northeastern Iowa and we compared these to values for large prairie preserves in northwestern Iowa, using a Monte Carlo resampling approach to standardize sampling effort between habitat types. We also measured the diversity and richness of the flowering forb communities at the hill prairies and we quantified percentage of the landscape at a 1 km radius in different landscape elements. Bee diversity at the five hill prairies spanned the range of diversity values for large prairies preserves, so although the hill prairies are small (<5 ha), their bee communities are not uniformly depauparate compared to larger western prairie preserves. Bee diversity was significantly related to flowering forb diversity, and may have been influenced by landscape features within 1 km—particularly the percentage of agricultural row crops and open water, which may negatively affect bee diversity at the sites. Iowa’s hill prairie bee communities were largely composed of widespread eastern species, although about 10% of the bee species have more northern or western ranges and appear to be taking advantage of the region’s unique habitat features. Given the dependence of the bee communities on the plant diversity of the sites, management of the plant community to maintain its diversity will also likely benefit bee diversity.  相似文献   

8.
North American Midwestern oak (Quercus spp.) savannas are rare fire‐dependent ecosystems that can support high levels of biodiversity and are the focus of considerable restoration effort due to widespread fire suppression. Due to the predominance of understory forbs in oak savannas, many of which require insect pollination, restoration practices should be evaluated for their potential impacts on pollinator communities. We evaluated bee community responses during the first 2 years of experimental restoration of fire‐suppressed oak savanna in southern Michigan. We used unmanaged references and two different restoration methods (burning only and burning with thinning) to examine the effects of restoration intensity on the abundance, diversity, and functional groups of bees. We found that thinning and burning rapidly increased bee abundance, richness, and Shannon's diversity, relative to unmanaged references, whereas burn‐only restoration largely failed to do so. Thinning and burning also resulted in a distinct bee community after two seasons, while bee communities in burn‐only restoration plots were similar to those from unmanaged references. Differences in bee diversity and community structure between treatments may be due to the influence of restoration on nesting resources, which is reflected in the differential captures of various nesting guilds. Overall, oak savanna restoration by thinning and burning had positive effects on bee diversity, while burning alone only increased bee abundance. We thus illustrate how restoration strategies that typically target plants have broader‐reaching biodiversity benefits. Although restoring savannas through burning alone may eventually shift bee communities, coupling thinning with burning will influence pollinator communities over the shorter term.  相似文献   

9.
Native pollinators are increasingly needed on conventional farms yet rarely fostered via management. One solution is habitat restoration in marginal areas, but colonization may be constrained if resident pollinator richness is low or if restored areas fail to provide sufficient floral or nesting resources. We quantified restoration outcomes for native bees, and associated resources, on three conventional farms with forb‐grass prairie plantings on marginal areas of varying sizes, in a heavily farmed region of central North America. We tested bee abundance and richness in restored prairie versus the dominant habitats of the region—crops, forest remnants, and edges of fields and roads. Restored prairie supported 2× more species (95 of 119 total species) and 3× more bees (72% of captured individuals) compared to the other cover types. All richness and abundance differences among habitat types were associated with higher floral resources in restored prairie. Thirty percent of the bee species were unique to prairie, consistent with long‐distance dispersal but begging the question of origin given the absence of prairie regionally. Our results suggest that road and field edges may be the source, as these areas had more floral and nesting resources than forest or crop fields combined and supported 55% of all species despite covering only approximately 5% of the sampled farms. Habitat scarcity is not the only constraint on native bees in agricultural landscapes, with increasing concern over disease and chemicals. However, we observed that restored areas on marginal lands of conventional farms can support abundant and species‐rich populations of native bees.  相似文献   

10.
Private lands provide critical habitat for threatened and endangered species, but only recently have farm-based conservation programs focused on at-risk, invertebrate species. The USDA Conservation Reserve Program State Acres for Wildlife Enhancement (CRP-SAFE) is one of the first federal programs to do so with a Wisconsin-based initiative for the US federally endangered Karner blue butterfly (KBB). This study is the first to evaluate how well the KBB-SAFE provides suitable habitat for the Karner and other butterflies. It also provides a critical foundation for better understanding the potential of new USDA programs that create pollinator habitat including for declining species such as the Monarch butterfly. Here we compare data (2009–2014) on assemblages of grassland communities, blooming floral resource availability, and abundance and richness of butterflies, between KBB-SAFE and native prairie sites. We found that KBB-SAFE and native sites had distinctly different forb species assemblages, with SAFE sites having fewer native blooming species available during the first flight of the KBB yet similar availability during second flight. Butterfly abundance was ultimately greater on native sites compared to SAFE sites, but richness was comparable between sites. We conclude that KBB-SAFE can provide habitat for many grassland species, and serve as surrogate KBB habitat. We provide straightforward management recommendations designed to better meet the needs of the Karner blue and other sensitive butterfly species and we provide further evidence that increased abundance and richness of native forbs and grasses on land formerly used for agriculture can provide habitat for butterflies adapted to early successional habitats.  相似文献   

11.
Tropical forest loss and fragmentation can change bee community dynamics and potentially interrupt plant–pollinator relationships. While bee community responses to forest fragmentation have been investigated in a number of tropical regions, no studies have focused on this topic in Australia. In this study, we examine taxonomic and functional diversity of bees visiting flowers of three tree species across small and large rainforest fragments in Australian tropical landscapes. We found lower taxonomic diversity of bees visiting flowers of trees in small rainforest fragments compared with large forest fragments and show that bee species in small fragments were subsets of species in larger fragments. Bees visiting trees in small fragments also had higher mean body sizes than those in larger fragments, suggesting that small‐sized bees may be less likely to persist in small fragments. Lastly, we found reductions in the abundance of eusocial stingless bees visiting flowers in small fragments compared to large fragments. These results suggest that pollinator visits to native trees living in small tropical forest remnants may be reduced, which may in turn impact on a range of processes, potentially including forest regeneration and diversity maintenance in small forest remnants in Australian tropical countryside landscapes.  相似文献   

12.
Ecological restoration is increasingly used to reverse degradation of rare ecosystems and maintain biological diversity. Pollinator communities are critical to maintenance of plant diversity and, in light of recent pollinator loss, we tested whether removal of invasive glossy buckthorn (Frangula alnus L.) from portions of a prairie fen wetland altered plant and pollinator communities. We compared herbaceous plant, bee, and butterfly abundance, diversity, and species composition in buckthorn invaded, buckthorn removal, and uninvaded reference plots. Following restoration, we found striking differences in plant and pollinator abundance and species composition between restored, unrestored, and reference plots. Within 2 years of F. alnus removal, plant species diversity and composition in restored plots were significantly different than invaded plots, but also remained significantly lower than reference plots. In contrast, in the first growing season following restoration, bee and butterfly abundance, diversity, and composition were similar in restored and reference plots and distinct from invaded plots. Our findings indicate that a diverse community of mobile generalist pollinators rapidly re‐colonizes restored areas of prairie fen, while the plant community may take longer to fully recover. This work implies that, in areas with intact pollinator metapopulations, restoration efforts will likely prevent further loss of mobile generalist pollinators and maintain pollination services. On the other hand, targeted restoration efforts will likely be required to restore populations of rare plants and specialist pollinators for which local and regional species pools may be lacking.  相似文献   

13.
The forb communities of kopjes (rock outcrops) in the Simba, Maasai and Loliondo areas of the Serengeti National Park were examined to determine differences in species composition from surrounding grassland communities, and among sites within kopje and grassland communities. Species diversity measures and multivariate ordination techniques were used to examine the community similarity and species turnover between sites. All measures of forb species diversity were higher on the kopje sites with the exception of one grassland site, and the community composition significantly differed between these two habitat types, with more species and families exclusive to the kopje habitat. Species turnover was very high in grassland habitats, with two of the three areas (Simba and Loliondo) exhibiting a complete change in species composition. Kopjes, on the other hand, had remarkably similar forb communities, suggesting that the populations of the species present on these rock outcrops form patch structures. The distinct flora and higher diversity of kopje forbs raise interesting questions regarding distribution, dispersal and patch dynamics.  相似文献   

14.
Nontarget species such as pollinators may be of great importance to the restoration process and the long‐term functioning of restored habitats, but little is known about how such groups respond to habitat restoration. I surveyed bee communities at five equal‐aged restored sites, paired with five reference sites (riparian remnants) along the Sacramento River, California, United States. Flower availability and bee visitation patterns were also measured to examine the restoration of pollination function. Restoration of structural vegetation allowed diverse and abundant native bee communities to establish at the restoration sites; however, the composition of these important pollinator communities was distinct from that in the remnant riparian sites. Differences did not arise primarily from differences in the composition of the flowering‐plant community; rather there must be other physical characteristics of the restored sites or differences in nesting site availability that led to the different pollinator communities. Because sites were spatially paired, the differences are unlikely to be driven by landscape context. Bee life‐history and other biological traits may partially explain the differences between bee communities at restored and remnant sites. Patterns of visitation to native plant species suggest that pollination function is restored along with pollinator abundance and richness; however, function may be less robust in restored habitats. An examination of interaction networks between bees and plant species found at both restored and remnant riparian sites showed less redundancy of pollinators visiting some plants at restored habitats.  相似文献   

15.
1. Parasites can affect the communities of their hosts; and hosts, in turn, shape communities of parasites and other symbionts. This makes host–symbiont relationships a key but often overlooked aspect of community ecology. 2. Mites associated with bees have a range of lifestyles; however, little is known about mites associated with wild bees or about factors influencing the make‐up of bee‐associated mite communities. This study investigated how mite communities associated with bumble bees (Bombus spp.) are shaped by the Bombus community and geographic proximity. 3. Bees were collected from 15 sites in Ontario, Canada, and examined for mites. Mite abundance and species richness increased with local bee abundance. Several bee species also differed in mite abundance, species richness, prevalence, and diversity. Locally uncommon species tended to have more mites than other bees. Queen bees had the most mites, and males had more mites than workers. 4. Spatial proximity was not a predictor of mite community composition, despite a strong effect of proximity on bee community similarity. 5. On the 11 Bombus spp. examined, 33 mite species were found. Whereas nearly half of these mite species are obligate associates of bumble bees, none was restricted to particular Bombus species. 6. The best predictor of mite community composition was bee identity. Although many parasite communities show strong geographic patterns, the communities of primarily commensalistic bee‐mites in this study did not. These findings have implications for bumble bee conservation, given that pollen‐feeding commensals might become harmful at high densities or act as disease vectors.  相似文献   

16.
Power EF  Kelly DL  Stout JC 《PloS one》2012,7(5):e38073
Parallel declines in insect-pollinated plants and their pollinators have been reported as a result of agricultural intensification. Intensive arable plant communities have previously been shown to contain higher proportions of self-pollinated plants compared to natural or semi-natural plant communities. Though intensive grasslands are widespread, it is not known whether they show similar patterns to arable systems nor whether local and/or landscape factors are influential. We investigated plant community composition in 10 pairs of organic and conventional dairy farms across Ireland in relation to the local and landscape context. Relationships between plant groups and local factors (farming system, position in field and soil parameters) and landscape factors (e.g. landscape complexity) were investigated. The percentage cover of unimproved grassland was used as an inverse predictor of landscape complexity, as it was negatively correlated with habitat-type diversity. Intensive grasslands (organic and conventional) contained more insect-pollinated forbs than non-insect pollinated forbs. Organic field centres contained more insect-pollinated forbs than conventional field centres. Insect-pollinated forb richness in field edges (but not field centres) increased with increasing landscape complexity (% unimproved grassland) within 1, 3, 4 and 5km radii around sites, whereas non-insect pollinated forb richness was unrelated to landscape complexity. Pollination systems within intensive grassland communities may be different from those in arable systems. Our results indicate that organic management increases plant richness in field centres, but that landscape complexity exerts strong influences in both organic and conventional field edges. Insect-pollinated forb richness, unlike that for non-insect pollinated forbs, showed positive relationships to landscape complexity reflecting what has been documented for bees and other pollinators. The insect-pollinated forbs, their pollinators and landscape context are clearly linked. This needs to be taken into account when managing and conserving insect-pollinated plant and pollinator communities.  相似文献   

17.
In recent years restoration project efforts in arid grasslands of the Pacific Northwest have increased; however, little is known about the bee communities in these areas or how restoration affects them. Native bees provide an essential ecosystem service through pollination of crops and native plants and understanding their response to restoration is a high priority. To address this issue, we conducted a three‐year study in an arid bunchgrass prairie with three objectives: (1) describe the bee community of this unique grassland type and its temporal variability; (2) investigate environmental variables influencing the community; and (3) examine effects of restoration on the community. We identified 62 bee species and found strong seasonal and inter‐annual variation in bee abundance, richness, diversity, and species composition. Unexpectedly, these temporal trends did not correspond with patterns in floral resources; however, several variables were associated with variation in bee abundance, richness, and diversity among sites. Sites with high levels of litter cover had more bees, while sites with taller vegetation or more blooming flowers had greater species richness but lower diversity. We found no detectable effect of restoration on bee abundance, richness, diversity, or composition. Species composition at native sites differed from those in actively and passively restored sites, which did not differ from each other. Restored sites also had fewer flowers and differing floral composition relative to native sites. These results suggest that if grassland restoration is to benefit bees, efforts should focus on both expanding floral resources and enhancing variables that influence nesting habitat.  相似文献   

18.
Neotropical rainforests sustain some of the most diverse terrestrial communities on Earth. Euglossine (or orchid) bees are a diverse lineage of insect pollinators distributed throughout the American tropics, where they provide pollination services to a staggering diversity of flowering plant taxa. Elucidating the seasonal patterns of phylogenetic assembly and functional trait diversity of bee communities can shed new light into the mechanisms that govern the assembly of bee pollinator communities and the potential effects of declining bee populations. Male euglossine bees collect, store, and accumulate odoriferous compounds (perfumes) to subsequently use during courtship display. Thus, synthetic chemical baits can be used to attract and monitor euglossine bee populations. We conducted monthly censuses of orchid bees in three sites in the Magdalena valley of Colombia – a region where Central and South American biotas converge – to investigate the structure, diversity, and assembly of euglossine bee communities through time in relation to seasonal climatic cycles. In particular, we tested the hypothesis that phylogenetic community structure and functional trait diversity changed in response to seasonal rainfall fluctuations. All communities exhibited strong to moderate phylogenetic clustering throughout the year, with few pronounced bursts of phylogenetic overdispersion that coincided with the transition from wet‐to‐dry seasons. Despite the heterogeneous distribution of functional traits (e.g., body size, body mass, and proboscis length) and the observed seasonal fluctuations in phylogenetic diversity, we found that functional trait diversity, evenness, and divergence remained constant during all seasons in all communities. However, similar to the pattern observed with phylogenetic diversity, functional trait richness fluctuated markedly with rainfall in all sites. These results emphasize the importance of considering seasonal fluctuations in community assembly and provide a glimpse to the potential effects that climatic alterations may have on both pollinator communities and the ecosystem services they provide.  相似文献   

19.
20.
Conserving and maintaining a diverse assemblage of wild bees is essential for a healthy and functioning ecosystem, as species are uniquely evolved to deliver specific plant–pollination requirements. Understanding the biology and ecology of bees in poorly studied regions is the first step towards conservation. Detailed surveys in New Hampshire reveal a broad diversity of 118 species of wild bees in different guilds and habitats including 17 bee species representing new state records. Network analyses reveal a complex community structure and relatively poorly connected plant–pollinator associations, thus species may be susceptible to disturbance. Phenological analyses document that at least one representative of five native bee families was present throughout the foraging season and both abundance and diversity were highest in June and July. This study provides important baseline information on bee abundance, diversity, phenology, and host plant associations necessary for future conservation efforts.  相似文献   

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