Effect of cultivating croplands and grazing in arid grassland habitats on the conservation of melitaeine butterflies in a mountainous area in Northern China

In the study area (Yanjiaping Village, Hebei Province, China), grazing extensity varies at different locations, small and discontinuous croplands are imbedded in some arid grassland, which are habitats for the melitaeine butterflies, Euphydryas aurinia and Melitaea phoebe. These two species of butterfilies coexist in this area, in which grazing and cultivation are the main disturbances. Grazing and cultivation have a reciprocal effect on E. aurinia, rather than M. phoebe. We observed that E. aurinia preferred to occupy patches with moderate grazing and imbedded with small and discontinuous croplands, where E. aurinia also has high population density. The percentage of E. aurinia larval groups in the ribbings was significantly higher than that of M. phoebe, whereas larvae of both species tended to increase in recent years. Our data also showed that the population density and the patch occupancy rate of both E. aurinia and M. phoebe were the highest under moderate grazing. It indicates that cultivation of small and discontinuous croplands within the patch has a significant effect on the population density of both species of melitaeine butterflies. Thus, to artificially create or maintain semi-natural habitats, complemented by moderate grazing, might be an ecological strategy to conserve melitaeine butterflies effectively. Considering the distinct impacts of cultivation and grazing on the population distribution and dynamics of the two different species, human disturbance in the mountainous area might be strategically involved in proposing conservation plans for the target species in the future.     

两种共存网蛱蝶幼期的生命表研究

在河北省赤城县大海坨国家自然保护区内,从2002年到2004年应用生命表方法研究了在同一网络斑块中共存的金堇蛱蝶Euphydryas aurinia和大网蛱蝶Melitaea phoebe两个世代的幼期各阶段的死亡情况,目的是了解影响种群动态的重要因子,为它们的长期保育提供信息。结果表明,金堇蛱蝶幼期总累积死亡率都较小,两个世代分别为59%和72%; 而大网蛱蝶总累积死亡率较高,两个世代分别为89%和80%。影响大网蛱蝶死亡的最重要因子是放牧,两个世代与放牧相关的k值分别为0.559和0.167;尤其是在越冬后大网蛱蝶幼虫组聚集取食阶段,导致两个世代分别有50%和25%的幼虫组死亡。寄生蜂在大网蛱蝶小种群下也分别使两个世代4%和9%的5～6龄期幼虫以及13%和24%的蛹死亡。金堇蛱蝶死亡主要发生在越冬期,与越冬死亡相关的k值两个世代分别为0.073和0.199, 而寄主植物的质量影响越冬期幼虫组死亡; 寄生蜂则对金堇蛱蝶种群的调控作用极小,只有在2003～2004世代有4.0% 的越冬后幼虫被寄生和7%的蛹被寄生。影响两种蛱蝶种群动态的关键因子不同,采取的保护措施应有所不同。在春季减少源斑块内的放牧,对于以源-汇集合种群形式存在的大网蛱蝶种群恢复和增长十分必要; 而对以经典集合种群形式存在的金堇蛱蝶, 通过适当植被管理提高繁殖区域内寄主植物质量,可以提高越冬期幼虫组存活率,有利于其长期持续生存。     

Contrasting movement patterns in two species of chequerspot butterflies, Euphydryas aurinia and Melitaea phoebe, in the same patch network

Abstract.  1. Mark–release–recapture studies were conducted on two species of chequerspot butterfly, Euphydryas aurinia and Melitaea phoebe , in the same habitat patch network in Yanjiaping, a small basin in the Taihang Mountains, north-west of Beijing, China, in 2000.
2. Euphydryas aurinia tended to stay in the habitat patches and to move to neighbouring patches, whereas M. phoebe moved widely among patches in the entire network.
3. The parameters of the virtual migration model showed higher daily emigration propensity in M. phoebe and in E. aurinia males than in E. aurinia females, and significantly greater average daily movement distance in M. phoebe than in E. aurinia .
4. The results are consistent with the previous findings showing genetic structuring among local populations of E. aurinia but not among local populations of M. phoebe .
5. Based on the genetic and ecological results, it was concluded that E. aurinia has a classic metapopulation in the study area, whereas M. phoebe appears to have a source–sink metapopulation.
6. In 2000, when there was an overall increase in the abundance of the two species, the limited mobility of E. aurinia resulted in an increase in the average local population size, whereas the increase in the number of local populations in M. phoebe was due to its high mobility .     

两种共存网蛱蝶的卵块特征及其雌性成虫对产卵地的选择

对同一网络斑块中金堇蛱蝶(Euphydryas aurinia)和大网蛱蝶(Meiltaea phoebe)雌性成虫的产卵地进行了调查,以确定影响它们斑块质量的因素.结果表明,2种网蛱蝶雌性成虫均选择体积大的寄主植物、周围植被高度低、开放的区域产卵,它们的卵块主要分布在温暖向阳的坡面.金堇蛱蝶的卵块距离农田边缘为3.55±0.33 m (n=246),且集中分布在＜3 m区域内;大网蛱蝶卵块距离农田边缘为7.34±1.53 m (n=25),但在＜3 m区域内的数量少.研究表明,由于这2种网蛱蝶雌性成虫对产卵地要求的特异性,评价它们斑块质量以及对其制定保护管理措施时均应有所不同.     

栖息地质量对两种网蛱蝶集合种群结构和分布的影响

在河北省赤城县研究了栖息地质量对大网蛱蝶Melitaea phoebe和金堇蛱蝶Euphydryas aurinia两种网蛱蝶集合种群结构和分布的影响。这两种网蛱蝶在约10 km_²的区域内共存,成虫期的蜜源植物几乎相同,大网蛱蝶的发生峰期比金堇蛱蝶晚约一个月,两者只有不到一周左右的时间重叠。大网蛱蝶和金堇蛱蝶幼虫的寄主植物分别是: 祁州漏芦（菊科）和华北蓝盆花（川续断科）。蜜源植物的丰度与两种网蛱蝶的局域种群大小呈正相关;祁州漏芦的密度对大网蛱蝶的局域种群大小影响很大,金堇蛱蝶的局域种群大小则与其寄主植物华北蓝盆花的高度正相关;斑块内平均植被高度与两种网蛱蝶的局域种群大小均呈正相关,植物多样性、植物均匀性和植被盖度均与金堇蛱蝶的局域种群大小负相关,与大网蛱蝶的关系不大。同时分析了其他因子如斑块的坡向、坡度等的影响。主要结论是：1）幼虫寄主植物的不同和成蝶飞行峰期的分离允许两种网蛱蝶在这样一个小的斑块区域内共存;2）蜜源是重要的限制因子,并且受气候随机性的影响很大,蜜源的波动可以很好地解释网蛱蝶集合种群在年度间的动态变化;3）大网蛱蝶和金堇蛱蝶的飞行、食物搜寻能力的不同以及各自寄主植物的生物学特性、空间分布的不同决定了它们具有不同的集合种群结构： 金堇蛱蝶是经典的集合种群,大网蛱蝶是源-汇集合种群;4）斑块质量和昆虫行为共同决定了两种网蛱蝶的集合种群结构和分布。     

Relative contributions of local and regional factors to species richness and total density of butterflies and moths in semi-natural grasslands

Metapopulation theory predicts that species richness and total population density of habitat specialists increase with increasing area and regional connectivity of the habitat. To test these predictions, we examined the relative contributions of habitat patch area, connectivity of the regional habitat network and local habitat quality to species richness and total density of butterflies and day-active moths inhabiting semi-natural grasslands. We studied butterflies and moths in 48 replicate landscapes situated in southwest Finland, including a focal patch and the surrounding network of other semi-natural grasslands within a radius of 1.5 km from the focal patch. By applying the method of hierarchical partitioning, which can distinguish between independent and joint contributions of individual explanatory variables, we observed that variables of the local habitat quality (e.g. mean vegetation height and nectar plant abundance) generally showed the highest independent effect on species richness and total density of butterflies and moths. Habitat area did not show a significant independent contribution to species richness and total density of butterflies and moths. The effect of habitat connectivity was observed only for total density of the declining butterflies and moths. These observations indicate that the local habitat quality is of foremost importance in explaining variation in species richness and total density of butterflies and moths. In addition, declining butterflies and moths have larger populations in well-connected networks of semi-natural grasslands. Our results suggest that, while it is crucial to maintain high-quality habitats by management, with limited resources it would be appropriate to concentrate grassland management and restoration to areas with well-connected grassland networks in which the declining species currently have their strongest populations. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Dynamic populations in a dynamic landscape: the metapopulation structure of the marsh fritillary butterfly

The marsh fritillary butterfly Euphydryas aurinia is an endangered species in most of northern Europe. We describe the metapopulation structure of E. aurinia in Finland, where the species has declined drastically in the past decades. We found two types of habitat patches suitable for the species: semi-permanent meadows and transient clearcuts in the forest. Patch area was the most significant variable predicting the occurrence of E. aurinia in a habitat patch. The species tended to be found in young rather than old clearcuts, apparently because the vegetation became too high in the latter. We used the incidence function model to simulate the metapopulation dynamics of E. aurinia in its dynamic landscape and discovered that the continued presence of the semi-permanent meadows is essential for the survival of the species in the study area in southeast Finland.     

Drivers of local densities of endangered Lycaena helle butterflies in a fragmented landscape

Due to their specialised habitat requirements, butterflies are particularly vulnerable to habitat loss and fragmentation. Understanding the drivers of local abundances of species is essential for their effective conservation in fragmented landscapes. We investigated factors affecting population densities of an endangered European butterfly, the Violet Copper (Lycaena helle), occurring in a small metapopulation near the city of Kraków, southern Poland. The environmental parameters tested as predictors of the local densities of the species included both the variables associated with spatial structure of habitats such as patch sizes, their isolation and fragmentation as well as those potentially reflecting habitat quality. Patch area and vegetation height turned out to be the only factors significantly influencing L. helle densities, both having a positive effect. The positive impact of patch area is a bit surprising, since its relationship with population densities is typically negative in butterflies. In our study system it is likely to derive from source-sink dynamics as the smaller habitat patches are apparently too small to sustain viable local populations. In turn, the positive influence of vegetation height implies that the ongoing succession does not deteriorate the quality of the recently abandoned meadows yet, whereas higher turf may provide better sheltering places. The loss of almost half of L. helle habitat patches in the study area in recent years is alarming. However, its inclusion into the Natura 2000 system should help to conserve the species as long as this act is followed by proper management of its habitats.     

Changing demography and dispersal behaviour: ecological adaptations in an alpine butterfly

High mountain ecosystems are extreme habitats for all organisms and therefore demand specific adaptations. In this context, we studied the ecology of the butterfly Euphydryas aurinia debilis in the High Tauern (Austria) and compared the obtained data against the ecology of the species in lower elevation habitats. We performed mark-release-recapture studies over the entire flight periods (end of June to end of July) in 2007 and 2008 to analyse the fundamental ecological parameters of a population. The demography of males and females was similar in both years, and no indication of typical protandry was detected. We observed a generally low dispersal of the individuals in both years, but males dispersed significantly more than females in 2008; this finding of low vagility was supported by allozyme analyses. Furthermore, butterflies survived periods of several days of continuously closed snow cover without any indication of increased mortality rates. In these three traits, this alpine population of E. aurinia apparently has ecological and physiological adaptations to the extreme requirements of high-altitude habitats and strongly deviates from the lower elevation populations.     

A multivariate analysis of fine-scale species density in the plant communities of a saltwater lagoon – the importance of disturbance intensity

Several factors might influence an organism's tendency or willingness to leave a given patch. One such factor is conspecific density, which may affect the per capita emigration rate. Some previous field studies on butterflies have reported positively density-dependent dispersal (emigration increases with population density) whereas the opposite, negatively density-dependent dispersal, has been found in other species. We investigated the effect of conspecific density on both the tendency to cross a patch boundary and within-patch mobility in Melitaea cinxia , by experimentally manipulating density in large outdoor cages divided into two habitat patches, separated by a barrier of unsuitable habitat. In contrast to previous results for M. cinxia , we found that the butterflies moved away from a patch at higher rates in high conspecific density (positively density-dependent emigration). The within-patch mobility, measured as the distance travelled per time unit, was however unaffected by butterfly density. A possible explanation for the seeming discrepancy with previous results could be that we used higher butterfly densities. For species with fluctuating population dynamics, such as M. cinxia , dispersal activity both at low and at high local density will be important for population phenomena such as fluctuations in distributional range over good and bad years.     

不同尺度下荒漠草原建群种短花针茅的空间分布对载畜率的响应

为探讨不同尺度下短花针茅种群密度空间分布对载畜率的响应特点及差异,本研究以内蒙古四子王旗短花针茅荒漠草原建群物种短花针茅为对象,分析了不同尺度(1 m×1 m小尺度和5 m×10 m中尺度)下对照、轻度放牧、中度放牧和重度放牧4种处理短花针茅种群的空间异质性。结果表明: 与小尺度相比,中尺度的对照与轻度放牧下短花针茅种群密度显著降低。在2种尺度下,与对照相比,放牧使得短花针茅种群密度显著增加。通过半方差函数进行模型拟合, 小尺度下,对照、轻度放牧、中度放牧及重度放牧样地短花针茅种群分布分别符合线性、指数、指数和指数模型,中尺度下分别为高斯、指数、高斯和指数模型。不同尺度和放牧强度下短花针茅种群空间结构发生改变,小尺度下,对照样地短花针茅分布格局较简单、空间结构较好;而重度放牧样地短花针茅分布格局较复杂、空间结构较差;中尺度下,重度放牧样地短花针茅分布格局较简单、空间结构较好,而中度放牧样地短花针茅分布格局较复杂、空间结构较差。中、小尺度下,中度和重度放牧使得短花针茅种群空间异质性降低且分布更为均匀;此外,对照、中度和重度放牧下中、小尺度短花针茅种群空间分布趋势基本一致,而轻度放牧则有所不同。     

放牧强度对荒漠草原建群种短花针茅空间异质性的影响

为探讨不同放牧强度下短花针茅种群密度空间分布的变化特点及差异,本研究以内蒙古四子王旗短花针茅荒漠草原建群物种短花针茅为对象,分析了对照、轻度放牧、中度放牧和重度放牧4块样地短花针茅种群小尺度空间分布异质性.结果表明: 短花针茅种群密度分别为重度放牧(27.81株·m^-2)>中度放牧(22.17株·m^-2)>对照(11.31株·m^-2)>轻度放牧(10.76株·m^-2),中度与重度放牧显著增加了短花针茅种群密度;通过半方差函数进行模型拟合,对照、轻度放牧、中度放牧及重度放牧样地短花针茅种群分布分别符合指数模型、球状模型、指数模型和球状模型;通过对短花针茅种群的空间分布格局分析,各样地结构比分别为对照(99.7%)>重度放牧(94.7%)>轻度放牧(92.7%)>中度放牧(87.9%),表明4块草地空间自相关性程度均较高,主要受结构性因素影响,中度放牧草地短花针茅种群结构比最小,受随机性因素影响相对较大;通过分形维数分析,4块草地空间结构良好,空间分布简单,并随着放牧强度增大,空间分布更简单且均质化;结合2D及3D图看,轻度放牧及重度放牧均造成短花针茅种群空间分布从梯度分布变成斑块分布,并使空间异质性降低.     

Metapopulation structure and movements in five species of checkerspot butterflies

We studied the patterns and rates of migration among habitat patches for five species of checkerspot butterflies (Lepidoptera: Melitaeini) in Finland: Euphydryas aurinia, E. maturna, Melitaea cinxia, M. diamina and M. athalia. We applied the virtual migration (VM) model to mark-release-recapture data collected from multiple populations. The model includes parameters describing migration and survival rates and how they depend on the areas and connectivities of habitat patches. The number of individuals captured varied from 73 to 1,123, depending on species and sex, and the daily recapture probabilities varied between 0.09-0.52. The VM model fitted the data quite well. The results show that the five species are broadly similar in their movement rates and patterns, though, e.g. E. maturna tends to move shorter distances than the other species. There is no indication of any phylogenetic component in the parameter values. The parameter values estimated for each species suggest that a large percentage (80-90%) of migration events were successful in the landscapes that were studied. The area of the habitat patch had a substantial effect on emigration and immigration rates, such that butterflies were more likely to leave small than large patches and large patches were more likely than small patches to receive immigrants.     

Effects of local and landscape factors on the abundance of an endangered multivoltine butterfly at riverbanks

Plebejus argyrognomon is one of the grassland‐dwelling butterflies undergoing rapid decline in recent decades. Grassland habitats for butterflies are generally threatened by fragmentation and invasive species, hence are among the most vulnerable ecosystems. We studied the seasonal abundance of P. argyrognomon at habitat patches along the banks of the Kinugawa River in eastern Japan, to identify environmental factors suitable for population persistence of this species, including habitat patch connectivity. Results showed that the patch's host plant cover had a positive effect on abundance in all three seasons, while the shading of the host plants by surrounding non‐host plants and nearby forested area showed negative effects. Additionally, habitat patch connectivity and nectar richness could be considered as positive factors in autumn and summer, respectively. Analysis of habitat connectivity also showed that the Kinugawa River did not appear to act as a dispersal barrier for P. argyrognomon. Our findings emphasize the importance of understanding environmental factors that may vary among seasons, and such understanding could contribute to habitat management of multivoltine butterflies in fragmented landscapes.     

Spatial ecology of host–parasitoid interactions: a threatened butterfly and its specialised parasitoid

Habitat conservation for threatened temperate insect species is often guided by one of two paradigms: a metapopulation approach focusing on patch area, isolation and number; or a habitat approach focusing on maintaining high quality habitat for the focal species. Recent research has identified the additive and interacting importance of both approaches for maintaining populations of threatened butterflies. For specialised host-parasitoid interactions, understanding the consequences of habitat characteristics for the interacting species is important, because (1) specialised parasitoids are particularly vulnerable to the consequences of fragmentation, and (2) altered interaction frequencies resulting from changes to habitat management or the spatial configuration of habitat are likely to have consequences for host dynamics. The spatial ecology of Cotesia bignellii, a specialist parasitoid of the threatened butterfly Euphydryas aurinia, was investigated at two spatial scales: within habitat patches (at the scale of individual aggregations of larvae, or ‘webs’) and among habitat patches (the scale of local populations). Parasitism rates were investigated in relation to larval web size, vegetation sward height and host density. Within patches, the probability of a larval webs being parasitized increased significantly with increasing number of larvae in the web, and parasitism rates increased significantly with increasing web isolation. The proportion of webs parasitized was significantly and negatively correlated with cluster density. Among habitat patches the proportion of parasitized webs decreased as cluster density increased. Clusters with a high proportion of larval webs parasitized tended to have lower parasitism rates per larval web. These results support the call for relatively large and continuous habitat patches to maintain stable parasitoid and host populations. Conservation efforts directed towards maintenance of high host plant density could allow E. aurinia to reduce parasitism risk, while providing C. bignellii with sufficient larval webs to allow population persistence.     

Butterfly diversity and historical land cover change along an altitudinal gradient

Land cover and climate change are both major threats for biodiversity. In mountain ecosystems species have to adapt to fragmented habitats and harsh environmental conditions but so far, altitudinal effects in combination with land cover change have been rarely studied. The objective of this study was to determine the effects of altitude and historical land cover change on butterfly diversity. We studied species richness patterns of butterflies occuring in wetlands and other open habitats along an altitudinal gradient in a low mountain region (340–750 m a.s.l., Bavaria, Germany) with drastic loss of open habitats within the last 40–60 years. We recorded in 27 sites a total of 4,523 individuals of 49 butterfly species and five species of burnet moths. Species richness peaked at mid elevation and increased with patch size. Land cover change was most pronounced at high altitudes, but neither current open habitats, nor the historical loss of open habitats affected the species richness of butterflies. Neither open land specialized butterflies nor generalist and forest species were significantly affected by the loss of open habitats. However, increasing forest area in high altitudes reduces possible refuge open habitats for butterflies at their thermal distribution limits. This could lead to extinction of such butterfly species when temperatures further rise due to global warming.     

Do asynchronies in extinction debt affect the structure of trophic networks? A case study of antagonistic butterfly larvae–plant networks

Habitat loss and fragmentation affect species richness in fragmented habitats and can lead to immediate or time‐delayed species extinctions. Asynchronies in extinction and extinction debt between interacting species may have severe effects on ecological networks. However, these effects remain largely unknown. We evaluated the effects of habitat patch and landscape changes on antagonistic butterfly larvae–plant trophic networks in Mediterranean grasslands in which previous studies had shown the existence of extinction debt in plants but not in butterflies. We sampled current species richness of habitat‐specialist and generalist butterflies and vascular plants in 26 grasslands. We assessed the direct effects of historical and current patch and landscape characteristics on species richness and on butterfly larvae–plant trophic network metrics and robustness. Although positive species‐ and interactions–area relationships were found in all networks, structure and robustness was only affected by patch and landscape changes in networks involving the subset of butterfly specialists. Larger patches had more species (butterflies and host plants) and interactions but also more compartments, which decreased network connectance but increased network stability. Moreover, most likely due to the rescue effect, patch connectivity increased host‐plant species (but not butterfly) richness and total links, and network robustness in specialist networks. On the other hand, patch area loss decreased robustness in specialist butterfly larvae–plant networks and made them more prone to collapse against host plant extinctions. Finally, in all butterfly larvae–plant networks we also detected a past patch and landscape effect on network asymmetry, which indicates that there were different extinction rates and extinction debts for butterflies and host plants. We conclude that asynchronies in extinction and extinction debt in butterfly–plant networks provoked by patch and landscape changes caused changes in species richness and network links in all networks, as well as changes in network structure and robustness in specialist networks.     

Allometric density responses in butterflies: the response to small and large patches by small and large species

Species are differentially affected by habitat fragmentation as a consequence of differences in mobility, area requirements, use of the matrix, and responses to edges. A quantitative understanding of these differences is essential not only for conservation biology but also for basic ecological theory. Here, we examine density responses by butterflies to patch size and use a quantitative theory on the scaling of population density with patch size to interpret results. Theory suggests that the density distribution of mobile species along a patch size gradient should depend on the scaling of net migration rates, whereas the density distribution of less mobile species should depend more on local growth. Using data from 11 localities in three European countries, we calculated the slope in the relationship between patch size and population density. These slopes were evaluated in relation to butterfly traits and matrix composition. As estimates of butterfly mobility we used both wing span and expert mobility rankings. The slope of the density–area relationship changed as predicted with wing span and the association of species to grasslands. Large and highly mobile species had a negative slope, similarly for grassland specialists and generalist species, and the slope matched quantitative predictions based on the scaling of net migration rates. Small and less mobile grassland specialists had a slope that was less negative than the slope of large and mobile grassland specialists, whereas the slope did not change with size for generalist species. These analyses suggest that the variability in response among butterfly species to patch size could be explained by accounting for body size/mobility and habitat associations among species. A caveat is that edge effects are not explicitly included in the model analysis, and future research should aim to combine area and edge effects in a common theoretical framework.     

Assessing the status of the marsh fritillary butterfly (Eurodryas aurinia): an example from Glamorgan, UK

We surveyed populations of Eurodryas aurinia (a butterfly listed as Threatened in Europe) in Glamorgan (South Wales, UK). The survey may provide a model for similar work, which is urgently needed throughout the species' European range. For each colony, we established population size, vegetation types, and current management regimes. Populations were assessed using larval surveys, a method which has several advantages over conventional adult surveys. With approximately 35 local populations, Glamorgan is among the most important areas for E. aurinia in the UK, and is of importance in a European context. However, 15 local populations were under immediate threat from unfavourable management or industrial developments, and only seven populations were on Sites of Special Scientific Interest. Colonies showed a clustered pattern, and varied greatly in size: 50% supported 20 or fewer larval webs. Many of the small populations may be temporary offshoots of larger, more permanent populations nearby. The largest local populations occupied Molinia caerulea - Cirsium dissectum fen meadow habitats (National Vegetation Community M24), which were unmanaged, grazed by cattle, horses or ponies, or subject to periodic burning. Detailed local surveys such as this one, which assess the relative sizes of populations and the impact of current management practices, may be the best way to plan future conservation measures for E. aurinia.     

Effects of patch size and density on flower visitation and seed set of wild plants: a pan-European approach

1.  Habitat fragmentation can affect pollinator and plant population structure in terms of species composition, abundance, area covered and density of flowering plants. This, in turn, may affect pollinator visitation frequency, pollen deposition, seed set and plant fitness.
2.  A reduction in the quantity of flower visits can be coupled with a reduction in the quality of pollination service and hence the plants' overall reproductive success and long-term survival. Understanding the relationship between plant population size and/or isolation and pollination limitation is of fundamental importance for plant conservation.
3.  We examined flower visitation and seed set of 10 different plant species from five European countries to investigate the general effects of plant populations size and density, both within (patch level) and between populations (population level), on seed set and pollination limitation.
4.  We found evidence that the effects of area and density of flowering plant assemblages were generally more pronounced at the patch level than at the population level. We also found that patch and population level together influenced flower visitation and seed set, and the latter increased with increasing patch area and density, but this effect was only apparent in small populations.
5.   Synthesis. By using an extensive pan-European data set on flower visitation and seed set we have identified a general pattern in the interplay between the attractiveness of flowering plant patches for pollinators and density dependence of flower visitation, and also a strong plant species-specific response to habitat fragmentation effects. This can guide efforts to conserve plant–pollinator interactions, ecosystem functioning and plant fitness in fragmented habitats.