Does competition with wind‐pollinated species alter Echium plantagineum's attractiveness to a common pollinator Bombus terrestris?

1. In insect‐pollinated plants, pollinator attraction is influenced by flowers (e.g. number, size) and their associated rewards (e.g. pollen, nectar). These traits can depend on plant interactions. Indeed, below‐ground competition between plants can lead to a decrease in flower or reward production in insect‐pollinated species. 2. Wind‐pollinated plants, in particular, which are almost never studied in plant–pollinator networks, can alter insect‐pollinated plants' attractiveness through competition for nutrients. The response of pollinators to such changes has never been investigated. 3. A pot experiment was carried out in which an insect‐pollinated species, Echium plantagineum, was grown in binary mixture with three wind‐pollinated species selected to exert a panel of competitive interactions. Below‐ground competition was controlled using dividers limiting interspecific root competition. Floral traits of E. plantagineum (i.e. flower production, floral display size, flower size and nectar production) were measured. For each species mixture, the visits (i.e. first visit, number of visits, 10‐min sequences) of Bombus terrestris individuals released in a flight cage containing two pots were followed, one with and one without below‐ground competition. 4. Below‐ground competition significantly affected nectar's sucrose concentration but did not influence flower and nectar production. Likewise, pollinator visits were not influenced by below‐ground competition. Competitor identity significantly influenced flower and reward production of E. plantagineum, with a decrease in the presence of the most competitive wind‐pollinated species. A tendency for faster flower visitation events was also detected in the presence of the least competitive competitor. This study raises new questions regarding the influence of wind‐pollinated plants on plant–pollinator interactions.     

Does Neighborhood Floral Display Matter? Fruit Set in Carpenter Bee‐pollinated Heterophragma quadriloculare and Beetle‐pollinated Lasiosiphon eriocephalus

Fruit set is pollen‐limited in the self‐incompatible tree Heterophragma quadriloculare (Bignoniaceae), pollinated by long‐distance flying carpenter bees, and in the self‐compatible shrub Lasiosiphon eriocephalus (Thymdeaceae), pollinated by weak‐flying, sedentary beetles. We studied a single H. quadriloculare population over high and low flowering years and found no difference in bee visitation rates between these years. For H. quadriloculare, neighborhood floral display did not make a significant contribution to reproductive success. We investigated dense and sparse L. eriocephalus populations in the same year. In the low density L. eriocephalus population, individual floral displays were higher than in the dense population, yet reproductive success was low, indicating that plant isolation was a major factor influencing fruit set. This result was due to the extremely low number of beetles per plant and per flower in this population. In the dense L. eriocephalus population, although the displays of individual neighbors were smaller and plants were closer, neighborhood floral display did not contribute significantly to reproductive success, whereas the effect of individual floral display was ambiguous. Species with self‐incompatible rather than self‐compatible breeding systems are expected to experience neighborhood effects on reproductive success; however, at the spatial scale and floral display levels of plants in this study, only individual floral display affected fruit set in H. quadriloculare, whereas neither individual nor neighborhood display influenced fruit set in L. eriocephalus. Therefore, pollinator type, pollinator behavior, and plant and population isolation, rather than breeding system alone, will determine if neighborhood floral display affects fruit set.     

Does higher connectivity lead to higher genetic diversity? Effects of habitat fragmentation on genetic variation and population structure in a gypsophile

Habitat fragmentation is a major threat to the maintenance of genetic diversity in many plant populations. Genetic effects of population size have received far more attention than the effects of isolation—or connectivity—but both are key components of the fragmentation process. To analyze the consequences of fragment size and connectivity on the neutral genetic variation and population genetic structure of the dominant gypsophile Lepidium subulatum, we selected 20 fragments along two continuous gradients of size and degree of isolation in a fragmented gypsum landscape of Central Spain. We used eight polymorphic microsatellite markers, and analyzed a total of 344 individuals. Populations were characterized by high levels of genetic diversity and low inbreeding coefficients, which agrees with the mainly outcrossing system of L. subulatum and its high abundance in gypsum landscapes. Bayesian clustering methods, pairwise F _ST values and analysis of molecular variance revealed low among-population differentiation, with no significant isolation by distance. However, several genetic diversity indices such as allelic richness, number of effective alleles, expected heterozygosity and number of private alleles were negatively related to population isolation. The higher genetic diversity found on more connected fragments suggests higher rates of gene flow among more connected populations. Overall, our results highlight that fragmentation can have important effects on intra-population genetic processes even for locally abundant, dominant species. This, together with previously documented effects of connectivity on fitness of gypsophile species highlights the importance of including habitat connectivity in management and conservation strategies of this type of semiarid systems.     

Where do animals come from during post‐fire population recovery? Implications for ecological and genetic patterns in post‐fire landscapes

Identifying where animals come from during population recovery can help to understand the impacts of disturbance events and regimes on species distributions and genetic diversity. Alternative recovery processes for animal populations affected by fire include external recolonization, nucleated recovery from refuges, or in situ survival and population growth. We used simulations to develop hypotheses about ecological and genetic patterns corresponding to these alternative models. We tested these hypotheses in a study of the recovery of two small mammals, the Australian bush rat and the agile antechinus, after a large (> 50 000 ha), severe wildfire. The abundance of both species was severely reduced by fire and recovered to near or above pre‐fire levels within two generations, yet we rejected a hypothesis of recovery by external recolonization. While the agile antechinus showed genetic evidence for far greater dispersal capacity than the bush rat, neither species showed gradients in abundance or genetic diversity with distance from unburnt forest during population recovery. Population recovery was driven by local‐scale processes. However, the mechanisms differed between species, resulting from the spatial impacts of fire on habitat suitability. Agile antechinus populations recovered through population growth from in situ survivors. The bush rat followed a model of nucleated recovery, involving local recolonization from micro‐refuges in topographic drainage lines. Nucleated recovery by the bush rat was associated with changes in dispersal, and fine‐scale patterns of genetic admixture. We identified increased dispersal by females during recovery, contrasting with male‐biased dispersal in unburnt forest. Such flexibility in dispersal can potentially increase recovery rates compared to expectations based on dispersal behavior within undisturbed populations. Our study shows how the initial distribution of survivors, determined by fire effects on resource distribution, determines the subsequent scaling of population recovery patterns, and the sensitivity of population distribution and genetic diversity to changing disturbance regimes.     

Does sex matter? Gender-specificity and its influence on site-chronologies in the common dioecious shrub Juniperus communis

In recent years an increasing number of studies have shown shrubs to be reliable proxies of environmental conditions in regions where Trees − due to harsh climate conditions − are absent. Although many shrubs are monoecious, some are dioecious, which poses certain questions related to gender-specific growth as observed for trees in previous studies. Here, we address the questions whether dioecious shrubs, similar to trees, show growth differences between male and female plants, and − if so − whether this difference needs to be considered in terms of sample selection. We chose Juniperus communis. L., the most widely distributed woody plant, and a common and well-studied dioecious shrub species in the northern hemisphere, especially in the Boreal, Subarctic tundra and Alpine regions. Our samples were collected from four sites − three from the Ural Mountains and one site from Kirkenes in Norway. To see if there were differences in radial growth between sexes we performed four different analyses. First, we used multivariate explorative statistics to see if there were gender biased sub-populations and generally found no differences. Secondly, to compare growth over the lifetime of shrubs we computed cumulative annual increments of basal area which revealed no gender-specific growth patterns. Thirdly, to test if differences in radial growth between male and female shrubs affect the resulting site-chronology, we compared individual shrub chronologies with the site-chronology and found a significant differentiation between normalized correlations of gender-specific chronologies to the site-chronology. This significant difference was restricted to an overall comparison, but not evident at individual site-level. Lastly, we compared correlations of gender-specific chronologies and a mean site-chronology with monthly climate records to find only very few meaningful differences in their responses. In summary, we could not detect any clear gender-specific growth pattern in Juniperus communis but observed a trend towards more non-climatic signals in female junipers which may affect the resulting site-chronology.     

Does desertification diminish biodiversity? Enhancement of ant diversity by shrub invasion in south‐western USA

The conversion of desert grasslands to shrublands is a long‐standing concern in the south‐western United States, but the effects of this change on native animals defy generalization. Here, I consider evidence that shrub invasion and encroachment, particularly that of honey mesquite (Prosopis glandulosa), has led to increasing ecological dominance and diversity of ants in general, as well as increases in specific native taxa. The effects of shrub invasion on ants were measured at two scales: (1) between Chihuahuan Desert landscapes that vary slightly in temperature and strongly in the dominance of mesquite, and (2) across variation in mesquite density occurring within a generally mesquite‐dominated landscape. Ant richness and numerical dominance was measured at pitfall traps over 2 years and baits were used to assess ecological dominance across different temperatures. The mesquite‐dominated Jornada site harboured four times the number of ant foragers found at the relatively ‘pristine’ Sevilleta site, with several ecologically dominant taxa driving this pattern, especially Dorymyrmex bicolor. Species richness and ecological dominance were also greatest at the Jornada. Within the Jornada landscape, turnover in species composition was related to mesquite density, but local richness and abundance was unrelated to mesquite density. Coupled with the results of previous manipulative experiments and comparative studies, there is support for the notion that ant diversity is not negatively affected by shrub invasion but that several taxa prosper from it. The Jornada is uniquely saturated by dominant ant taxa, perhaps as a consequence of an overall high level of shrub availability that provides a reliable source of carbohydrate‐rich plant exudates. This raises important questions about the relationship between environmental degradation, ecosystem productivity, and animal diversity.     

Can a seed bank provide demographic and genetic rescue in a declining population of the endangered shrub <Emphasis Type="Italic">Acacia pinguifolia</Emphasis>?

Many threatened species suffer reduced genetic diversity as a result of small population size and isolation. However, species with a persistent seed bank may be buffered against genetic loss as seed banks are expected to accumulate the reproductive output of many seasons. For fire-dependent species in decline, prescribed ecological burning may be a means to stimulate germination and recover genetic diversity stored in the seed bank, providing a demographic and genetic rescue effect. Here we investigated the effectiveness of this strategy in a small, isolated and inbred population of the endangered shrub, Acacia pinguifolia. We surveyed genetic diversity and structure of remnant populations of A. pinguifolia and monitored regeneration before and after burning. Germination was stimulated by fire, but seedling numbers 18 months post-fire were low and barely above the number of adults killed by the fire. Genetic diversity was marginally higher in the post-fire seedling cohort than the pre-fire adults (H_E = 0.1 vs. 0.09, respectively). Outcrossing rates of open-pollinated seed from surrounding plants suggested moderately high levels of self-fertilisation (t _m  = 0.65) and analysis of fine-scale genetic structure implied pollen and seed dispersal over distances of several metres, suggesting that restricted gene flow and inbreeding may act to limit genetic diversity in the seed bank. We conclude that prescribed burning has not been immediately successful as a recovery strategy for this relictual population of A. pinguifolia, though future monitoring may detect additional recruits. Alternative conservation strategies, including performing inter-population crosses, may be required to restore genetic diversity and ameliorate extinction risks.     

Does phylogeny matter? Assessing the impact of phylogenetic information in ecological meta‐analysis

Meta-analysis is increasingly used in ecology and evolutionary biology. Yet, in these fields this technique has an important limitation: phylogenetic non-independence exists among taxa, violating the statistical assumptions underlying traditional meta-analytic models. Recently, meta-analytical techniques incorporating phylogenetic information have been developed to address this issue. However, no syntheses have evaluated how often including phylogenetic information changes meta-analytic results. To address this gap, we built phylogenies for and re-analysed 30 published meta-analyses, comparing results for traditional vs. phylogenetic approaches and assessing which characteristics of phylogenies best explained changes in meta-analytic results and relative model fit. Accounting for phylogeny significantly changed estimates of the overall pooled effect size in 47% of datasets for fixed-effects analyses and 7% of datasets for random-effects analyses. Accounting for phylogeny also changed whether those effect sizes were significantly different from zero in 23 and 40% of our datasets (for fixed- and random-effects models, respectively). Across datasets, decreases in pooled effect size magnitudes after incorporating phylogenetic information were associated with larger phylogenies and those with stronger phylogenetic signal. We conclude that incorporating phylogenetic information in ecological meta-analyses is important, and we provide practical recommendations for doing so.     

Nectary structure of Labiatae in relation to their nectar secretion and characteristics in a Mediterranean shrub community — Does flowering time matter?

We studied the interrelation between nectary structure (13 parameters), nectar characteristics (yield, chemical composition), and flower size of 11 Labiatae species in a Mediterranean shrub community near Athens, Greece. We also explored whether the above attributes are affected by the Mediterranean summer drought constraints. Our findings show that among all nectary parameters studied, nectary size and stomatal opening are the most important in (positively) shaping nectar secretion, nectary size being the most meaningful. Nectary structure is correlated to quantity of the nectar secreted, not its quality. Wide flowers bear wide nectaries with large stomatal openings, whereas deep flowers are not related to any nectary size. Corolla size (both length and width) and nectary stomatal opening decrease with flowering time. This applies also to nectary size, nectar volume and sugar content of the perennials (9 species). All above cases of time dependence show that there is a constraint effect of Mediterranean climate on floral and nectary structure, reflected also as a decrease in nectar secretion. Nectary structure in Labiatae is largely shaped by both phylogenetic and climate constraints. On the other hand, although nectar is largely influenced by nectary structure, it is to a large extent ecologically biased, implying that, in addition to phylogeny, there are many other ecological parameters interfering in its secretion such as time within the season, life history, and light requirements.     

How does farmer connectivity influence livestock genetic structure? A case‐study in a Vietnamese goat population

Assessing how genes flow across populations is a key component of conservation genetics. Gene flow in a natural population depends on ecological traits and the local environment, whereas for a livestock population, gene flow is driven by human activities. Spatial organization, relationships between farmers and their husbandry practices will define the farmer's network and so determine farmer connectivity. It is thus assumed that farmer connectivity will affect the genetic structure of their livestock. To test this hypothesis, goats reared by four different ethnic groups in a Vietnamese province were genotyped using 16 microsatellites. A Bayesian approach and spatial multivariate analysis (spatial principal component analysis, sPCA) were used to identify subpopulations and spatial organization. Ethnic group frequencies, husbandry practices and altitude were used to create cost maps that were implemented in a least-cost path approach. Genetic diversity in the Vietnamese goat population was low (0.508) compared to other local Asian breeds. Using a Bayesian approach, three clusters were identified. sPCA confirmed these three clusters and also that the genetic structure showed a significant spatial pattern. The least-cost path analysis showed that genetic differentiation was significantly correlated (0.131–0.207) to ethnic frequencies and husbandry practices. In brief, the spatial pattern observed in the goat population was the result of complex gene flow governed by the spatial distribution of ethnic groups, ethnicity and husbandry practices. In this study, we clearly linked the livestock genetic pattern to farmer connectivity and showed the importance of taking into account spatial information in genetic studies.     

Does artificial selection on diapause incidence cause correlational changes in other life‐history traits? Case study in a spider mite population

Theoretical studies suggest that the timing of entering hibernation by arthropods has large effects on long-term fitness, incurring strong selection pressure on diapause attributes every year. On the other hand, diapause attributes are often genetically correlated with other important life-history traits such as fecundity or development time. To understand the evolutionary process of life cycle formation, there is a need to investigate not only diapause attributes themselves but also their genetic association with other life-history traits. The Kanzawa spider mite, Tetranychus kanzawai Kishida (Acari: Tetranychidae), is a small herbivore that lives on the undersurface of host plant leaves. This mite has been investigated for the mode of inheritance of diapause attributes, but scarcely for genetic correlations with other life-history traits. Here, I investigated whether diapause proneness, measured as the proportion of diapausing females under short-day conditions, is genetically correlated with fecundity or development time under long-day conditions using artificial selection experiments. Diapause incidence responded to the selection for both increasing and decreasing directions, suggesting that high genetic variance in diapause proneness is maintained in the study population. However, the change in proportion of diapausing females during the selection period was not associated with responses in fecundity or development time. These results suggest that diapause proneness and other life-history traits have different genetic backgrounds, and thus diapause proneness may freely evolve without being constrained by changes in other life-history traits.     

Differential visibility of treponemal disease in pre‐Columbian stratified societies: Does rank matter?

Treponemal disease is known to be associated with the compromised community health of permanent village settlement. This association explains its high visibility in the village‐based, arguably chiefdom level, agriculturalist societies of late prehistoric (AD 1300–1600) North America. Within chiefdom‐level societies, health differences have often been demonstrated between mortuary‐defined “elite” and “nonelite” individuals. This theoretically should predict status‐based differences in treponemal disease visibility. The prediction is tested in a five‐site osteological sample (N = 650) from the Dallas phase (AD 1300–1550), a simple mortuary‐defined two‐tiered presumptive chiefdom level maize agriculturalist socioeconomic context from lower east Tennessee. The Dallas phase results affirm a general pre‐Colombian North American pattern of no sex differences and display comparable adult to subadult frequencies. The study also reveals that given a sufficient sample size, “elites” do indeed exhibit a significantly lower frequency of tertiary stage treponemal disease. This can be attributed to better baseline health, which has been previously demonstrated in this sample. It may also be affected by the mortuary inclusion of achieved status individuals whose good health may have facilitated sociopolitical advancement. Another pattern that emerged is an apparent young adult age bias in disease visibility. This suggests that tertiary treponemal disease morbidity may either directly or synergistically factor in early adult age at death. Future research will address the veracity of this association. Am J Phys Anthropol, 2011. © 2010 Wiley‐Liss, Inc.     

Do microbes have macroecology? Large‐scale patterns in the diversity and distribution of marine benthic ciliates

Aim The biogeography and global distribution of protists has long been disputed, with two primary, opposing views. To test these two sets of views in greater detail, we have compiled the available data for marine benthic ciliates and assessed the general patterns of their diversity and distribution compared with Metazoa. Location World‐wide. Methods A comprehensive database (1342 species, over 350 sources) was used to analyse the diversity, distribution, species occurrences and range size distribution of free‐living ciliates that inhabit marine sediments in 17 geographical regions. Results Twenty‐five per cent of the species have been found in a single region only, whereas 18% are widespread (they occur in more than half the regions covering both hemispheres). Only 5–7% of regional faunas are endemic, which is much lower than for macroorganisms. Regional diversity depends neither on total area nor on coastline length and does not show any obvious latitudinal trends, but correlates highly with the investigation effort expended in a region and (negatively) with the average salinity. A comparison of species composition reveals distinctions between the Arctic Area (the White, Barents and Kara seas), Laurasian Area (north Atlantic, north Pacific and European seas), Gondwanian Area (Southern Ocean) and the Antarctic. No clear geographical correlations are found for faunistic composition at the genus or family levels. There is the tendency to narrow the latitudinal ranges for species found at high latitudes (reversal of Rapoport's rule). Main conclusions Undersampling and data insufficiency are the key factors affecting the observed diversity and distribution of microorganisms. Nevertheless, marine benthic ciliates demonstrate certain patterns that generally agree with the ‘moderate endemicity’ model ( Foissner, 2004, 2008 ), but consistently contradict the regularities commonly observed for multicellular taxa. Thus, ciliates do have a biogeography, but their macroecological patterns may be different in some respects from that of macroorganisms.     

Post‐fire regeneration in alpine heathland: Does fire severity matter?

Fire severity is thought to be an important determinant of landscape patterns of post‐fire regeneration, yet there have been few studies of the effects of variation in fire severity at landscape scales on floristic diversity and composition, and none within alpine vegetation. Understanding how fire severity affects alpine vegetation is important because fire is relatively infrequent in alpine environments. Globally, alpine ecosystems are at risk from climate change, which, in addition to warming, is likely to increase the severity and frequency of fire in south‐eastern Australia. Here we examine the effects of variation in fire severity on plant diversity and vegetation composition, 5 years after the widespread fires of 2003. We used floristic data from two wide‐spread vegetation types on the Bogong High Plains: open heathland and closed heathland. Three alternative models were tested relating variation in plant community attributes (e.g. diversity, ground cover of dominant species, amount of bare ground) to variation in fire severity. The models were (i) ‘linear’, attributes vary linearly with fire severity; (ii) ‘intermediate disturbance’, attributes are highest at intermediate fire severity and lowest at both low‐ and high‐severity; and (iii) ‘null’, attributes are unaffected by fire severity. In both heathlands, there were few differences in floristic diversity, cover of dominant species and community composition, across the strong fire severity gradient. The null model was most supported in the vast majority of cases, with only limited support for either the linear and intermediate disturbance models. Our data indicate that in both heathlands, vegetation attributes in burnt vegetation were converging towards that of the unburnt state. We conclude that fire severity had little impact on post‐fire regeneration, and that both closed and open alpine heathlands are resilient to variation in fire severity during landscape scale fires.     

Does Locomotor Ability Influence Flight Initiation Distance in Yellow‐Bellied Marmots?

Flight initiation distance (FID) is the distance between a potential threat and the point at which a potential prey flees. Animals may modify their FID to compensate for increased risk generated by external/extrinsic factors such as habitat type, visibility, group size, time of year, predator‐approach velocity, and distance to burrow, as well as internal/intrinsic factors such as physical condition, body temperature, crypsis, and morphological antipredator defenses. The intrinsic speed at which an animal can escape a predator is a factor that should influence FID. We studied the relationship between an individual's intrinsic escape speed and FID in yellow‐bellied marmots (Marmota flaviventris) to determine whether marmots compensated for slower escape speeds by fleeing at greater distances. We found no evidence of risk compensation. Rather, we found that slower marmots tolerated closer approaches. This behavioral syndrome may be explained by a coevolution of FID and escape speed in determining an individual's antipredator behavior, an idea upon which we expand.     

Does governance play a role in the distribution of invasive alien species?

Invasive alien species (IAS) constitute a major threat to global biological diversity. In order to control their spread, a detailed understanding of the factors influencing their distribution is essential. Although international trade is regarded as a major force structuring spatial patterns of IAS, the role of other social factors remains unclear. Despite studies highlighting the importance of strong governance in slowing drivers of biodiversity loss such as logging, deforestation, and agricultural intensification, no study has yet analyzed its contribution to the issue of IAS. Using estimates of governance quality and comprehensive spatiotemporal IAS data, we performed multiple linear regressions to investigate the effect of governance quality upon the distribution of species listed under “100 of the worst” IAS in 38 Eurasian countries as defined by DASIE. Our model suggested that for countries with higher GDP, stronger governance was associated with a greater number of the worst IAS; in contrast, for the lowest GDP countries under analysis, stronger governance was associated with fewer of these IAS. We elucidate how the quality of governance within a country has implications for trade, tourism, transport, legislation, and economic development, all of which influence the spread of IAS. While our findings support the common assumption that strengthening governance benefits conservation interventions in countries of smaller economy, we find that this effect is not universal. Stronger governance alone cannot adequately address the problem of IAS, and targeted action is required in relatively high‐GDP countries in order to stem the influx of IAS associated with high volumes of trade.     

Does titanium in ionic form display a tissue-specific distribution?

Most studies have focused on the biodistribution of titanium(IV) oxide as nanoparticles or crystals in organism. But several reports suggested that titanium is released from implant in ionic form. Therefore, gaining insight into toxicokinetics of Ti ions will give valuable information, which may be useful when assessing the health risks of long-term exposure to titanium alloy implants in patients. A micro synchrotron radiation-induced X-ray fluorescence (µ-SRXRF) was utilized to investigate the titanium distribution in the liver, spleen and kidneys of rats following single intravenous or 30-days oral administration of metal (6 mg Ti/b.w.) in ionic form. Titanium was mainly retained in kidneys after both intravenous and oral dosing, and also its compartmentalization in this organ was observed. Titanium in the liver was non-uniformly distributed—metal accumulated in single aggregates, and some of them were also enriched in calcium. Correlation analysis showed that metal did not displace essential elements, and in liver titanium strongly correlated with calcium. Two-dimensional maps of Ti distribution show that the location of the element is characteristic for the route of administration and time of exposure. We demonstrated that µ-SRXRF can provide information on the distribution of titanium in internal structures of whole organs, which helps in enhancing our understanding of the mechanism of ionic titanium accumulation in the body. This is significant due to the popularity of titanium implants and the potential release of metal ions from them to the organism.     

Enough space in a warmer world? Microhabitat diversity and small‐scale distribution of alpine plants on mountain summits

Aim

Global warming is predicted to shift distributions of mountain species upwards, driven by a release from climatic restrictions at their upper distribution limit and increased biotic pressure at their lower distribution limit. In alpine ecosystems, which are characterized by large microclimatic diversity and sparse vegetation cover, the relative importance of abiotic and biotic drivers for species distribution is poorly understood. To disentangle abiotic and biotic mechanisms affecting distributions of alpine species, we investigated how alpine plant species with differing elevational ranges and frequency trends over the past century differ in their microhabitat distribution, and how they respond to neighbouring vegetation.

Location

A total of 11 summits (2635—3410 m a.s.l.) in SE‐Switzerland.

Methods

We quantified the microscale abundance of 12 species in relation to biogeographic (frequency trend, i.e., change in occurrences over the past century, and elevational range on summits) and local microhabitat characteristics (temperature, substrate type). We assessed species size traits in relation to neighbouring vegetation characteristics to investigate possible neighbour interactions.

Results

Species with increasing frequency on summits over the past century were most abundant on scree and warmer slopes. Species with negative or stable frequency trends on summits were more abundant on organic soil and colder slopes. The preferred microhabitats of the latter were rarest overall, decreased with increasing elevation, and had the most competitive neighbours. Size of one high‐alpine specialist, Ranunculus glacialis was negatively related to cover of neighbouring vegetation, whereas other species showed no response to neighbours.

Main conclusions

Long‐term frequency trends of species correlate with their microhabitat association. Species with most negative frequency trends show preferences for the rarest microhabitat conditions, where they likely experience higher competitive pressure in a warming climate. This finding emphasizes the importance of characterizing microhabitat associations and microclimatic diversity to assess present and future distributions of alpine plant species.