Patterns of biodiverse,understudied groups do not mirror those of the surrogate groups that set conservation priorities: a case study from the Mid-Atlantic Coastal Plain of eastern North America

We conducted biodiversity inventories of lichens, woody plants, and sedges at 32 sites on the Mid-Atlantic Coastal Plain of eastern North America between November 2012 and June 2015. Each site comprised a single, uniform habitat, consisting of either Coastal Plain Floodplain forest, Coastal Plain Flatwood swamp, Coastal Plain Oak-Pine forest, Maritime forest, Mixed Mesic Hardwood forest, or Tidal forest. We compared alpha diversity and community assemblages of each organismal group across the sites, and compared selected minimal reserve sets in order to visualize biodiversity patterns and assess whether specific components of vascular plants (sedges and woody plants) serve as an effective surrogate for lichens. Woody plants provide a direct substrate for lichen growth, but there is no significant correlation between the alpha diversity of these groups. For conserving maximal species richness among the studied groups, lichens outperform the sedges and woody plants as the best surrogate group for building minimum reserve sets, even though vascular plants are more commonly used as a surrogate. Likewise, sedge alpha diversity does not correlate with lichens, or with woody plants. Although no group is an effective indicator for high alpha diversity sites of other organisms, a significant correlation between the community assemblages of lichens and woody plants suggests that protecting varied types of plant communities might serve as a workable surrogate for protecting lichens. The lack of congruence between species richness patterns across organismal groups suggests that the mechanisms that shape patterns of diversity are not identical, and that identifying and incorporating specific biodiversity indicators for understudied groups in conservation policy is necessary to ensure their protection.     

Vascular plants as surrogates of butterfly and grasshopper diversity on two Swiss subalpine summer pastures

Summer pastures in the Swiss Alps are currently affected by land-use changes that cause a decrease in biodiversity. Although these habitats make up one-third of the whole Swiss agricultural area, direct payments dedicated to support their management are very low. Current political instruments do not support efforts to conserve the biodiversity in these areas, but a vegetation-based approach such as the one implemented in the permanently utilized agricultural areas is under discussion. However, available studies evaluating the surrogate value of vascular plants for other (particularly animal) taxa have yielded inconsistent results, and very few have been conducted in habitats at high elevations. We investigated the extent to which vascular plants are adequate surrogates for butterfly and grasshopper diversity, examining the congruence of species richness and community similarity in two heterogeneous subalpine pastures in the Swiss Alps. Results at the species richness level (Spearman’s rank correlation) varied widely according to the study site and taxa assessed. In contrast, at the community similarity level (Procrustean randomization tests with Bray–Curtis similarity), congruencies between vascular plant and invertebrate taxa were generally highly significant. We therefore recommend the use of community similarity as a basis for estimating biodiversity patterns. Our results suggest that conservation measures aimed primarily at enhancing the floristic diversity of subalpine grasslands are also likely to benefit butterfly and grasshopper diversity, at least at the local scale.     

The surrogacy potential of white-tailed sea eagle nesting habitat on islands of the Baltic Sea

In order to tackle the current biodiversity crisis, a plethora of tempting shortcuts, such as the surrogate species approach, have recently been used to pinpoint important areas for protection. At the same time, species-specific conservation programmes are implemented in order to ameliorate the status of target threatened species. In the cases where species-specific programmes are evaluated and found to provide no apparent benefit to the target species, it is important to evaluate whether such conservation efforts may benefit other taxa sharing the same landscape with the target species. Here we assess the surrogacy potential of white-tailed sea eagle (WTSE) nesting habitat as indicator of biodiversity richness (using vascular plants and fungi as surrogated taxa) on islands of the Archipelago Sea in South-western Finland. We compared species richness on islands with and without a WTSE nest. We found weak evidence that islands with a WTSE nest support higher richness of vascular plants than islands without a nest. Conversely, we found no evidence that WTSE nests could be valid surrogates for fungi species inhabiting old-growth forests. Within the spatio-temporal and ecological limits of the present study, we suggest that the nesting habitat of WTSE may hold some surrogate potential for taxa, such as vascular plants, that may indicate high habitat diversity. This finding however remains to be confirmed. At the same time, it appears evident that the WTSE nesting habitat has poor surrogate potential with regards to old-growth forests. Overall, our findings line up with a growing body of other studies calling for caution and careful evaluation of the surrogacy efficiency of single species.     

Indicator groups and congruence of assemblage similarity, species richness and environmental relationships in littoral macroinvertebrates

The rapid decrease of biodiversity and limited resources for surveying it have forced researchers to devise short-cuts for biodiversity surveys and conservation planning. These short-cuts include environmental surrogates, higher taxon surrogates, indicator species and indicator groups. We considered indicator groups as surrogates for wholesale biodiversity and cross-taxon congruence in biodiversity patterns in littoral macroinvertebrates of boreal lakes. Despite the fact that we considered indicator groups amongst a wide variety of taxa, such as two-winged flies, mayflies, caddisflies, beetles, bugs and molluscs, none of the proposed groups possessed all of the qualities of a good indicator taxon for biodiversity surveys and conservation planning. We found generally weak, yet typically significant, relationships between the proposed indicator groups and remaining taxa in both species richness and assemblage similarity. Low congruence was paralleled by somewhat differing relationships of the taxonomic groups to various environmental features of lakes. Furthermore, the relationships of most indicator groups to the environmental features of lakes were not particularly strong. The present findings are unfortunate, because indicator groups did not perform well in predicting the wholesale biodiversity of littoral macroinvertebrates. Thus, there appears to be no short-cut for considering all groups of macroinvertebrates in biodiversity surveys, conservation planning and characterisation of environmental relationships of lake littoral assemblages.     

Bryophyte conservation on a North Atlantic hotspot: threatened bryophytes in Madeira and Selvagens Archipelagos (Portugal)

On oceanic islands, the evolution of plants and animals with particular characteristics is favoured due to their isolation, populations normally comprising a large number of unique, endemic species. The Madeira and Selvagens archipelagos are considered biodiversity hotspots, containing an especially rich bryoflora. Due to its characteristically small size, this taxonomic group does not get much attention in conservation programmes. However, these plants are an important component of terrestrial ecosystems, representing a major part of biodiversity and playing a vital role in the ecosystem's functioning. As such, the development of the first Red List for Madeira and Selvagens Archipelagos has the potential to guide conservation efforts focused on taxa and habitats where threatened species and endemics are better represented. By applying the International Union for Conservation of Nature and Natural Resources (IUCN) criteria, recently revised to apply to small islands, it was possible to obtain the percentage of threatened taxa present in the archipelagos (23.6%), and for each habitat type. It was verified that high mountain habitats and the Laurel forest represent areas that host higher percentages of threatened taxa (29.5% and 22.2%). An important result of the present Red List is the identification of hotspots for bryophyte diversity, supporting the definition of reserves/microreserves. The information obtained can also be linked up with the Red Lists of other taxonomic groups to work towards the definition of a more holistic conservation strategy.     

Searching for biodiversity indicators in running waters: do bryophytes, macroinvertebrates, and fish show congruent diversity patterns?

The degree to which different taxonomic groups show congruence in diversity patterns has attracted increased attention, yet such studies on stream biota are lacking. We examined environmental correlates of and congruence in the species richness patterns of bryophytes, macroinvertebrates, and fish in 101 boreal streams in Finland. Congruence in species richness among the taxonomic groups was generally low, mainly because of their differing responses to major environmental gradients. Bryophytes and macroinvertebrates showed the strongest degree of congruence, but even this relationship had a relatively weak predictive power. Bryophyte diversity showed the strongest relationship with water colour, followed by habitat stability, and stream size. Macroinvertebrate diversity increased with stream size, and further variation was accounted for by water colour and acidity. Fish species richness showed a weak and complex relationship with geographical location, stream size, and in-stream habitat characteristics. The regression models explained 23, 45, and 26% of the variation in species richness of bryophytes, macroinvertebrates, and fish, respectively. Our results suggest that indicator taxa may be of limited value in stream biodiversity inventories. Habitat-based approaches are suggested as an alternative surrogate measure in the conservation evaluation of lotic biodiversity.     

Assessing conservation status and trends for the world��s butterflies: the Sampled Red List Index approach

Red List Indices provide a method for assessing global trends in species?? conservation status, and for monitoring progress towards achieving conservation targets (for example, commitments under the Convention on Biological Diversity). Red List Indices are based on categorization of taxa in terms of their threat status using information on, for example, current and projected abundances, distributions, and threats. Global assessments have now been undertaken for a suite of well-known vertebrate taxa. However, highly diverse invertebrate taxa are currently very poorly represented in such assessments, and there is a danger that their threats and their utility as biodiversity indicators will be overlooked. Unlike most invertebrates, butterflies are relatively well-known globally. We describe ongoing efforts to incorporate butterflies into the Red List Index process. Because of high species richness (approximately 15,000 Papilionoidea globally) a comprehensive assessment is not feasible. Instead, we apply a ??Sampled Red List Index?? approach which draws on a subset of 1,500 focal taxa. We illustrate the process and the challenges (particularly taxonomic issues and issues of data deficiency) using a variety of case studies. The information provided should be relevant to other researchers seeking to apply the Red List Index approach to invertebrates and other diverse but poorly studied taxa.     

Surrogate species versus landscape metric: does presence of a raptor species explains diversity of multiple taxa more than patch area?

Prioritizing conservation areas is a central theme in conservation biology. The use of surrogate species and landscape metrics to identify areas with high conservation value is common. However, few studies have examined the relative efficacy of these two surrogates. In this study, we compared the efficacy of the presence/absence (PA) of a top predator (Eastern Marsh Harrier, Circus spilonotus) and wetland patch area on species richness, total abundance, and community composition of birds, plants, and small mammals, but species richness and community composition only for plants, in a fragmented wetland landscape. Although harrier PA was an effective indicator of the distribution of birds, it had no significant efficacy on the distributions of plants and small mammals. Patch area was more effective indicator of the distributions of plants and small mammals. These results suggest that surrogate species can be more effective indicators than landscape surrogates when there are ecological linkages between surrogate species and the focal taxa (e.g., similarity of habitat requirements between surrogate species and focal taxa or hetero-specific attraction). On the other hand, landscape surrogates would be useful when ecological knowledge about the relationships is limited.     

Hot spots, indicator taxa, complementarity and optimal networks of taiga

If hot spots for different taxa coincide, priority-setting surveys in a region could be carried out more cheaply by focusing on indicator taxa. Several previous studies show that hot spots of different taxa rarely coincide. However, in tropical areas indicator taxa may be used in selecting complementary networks to represent biodiversity as a whole. We studied beetles (Coleoptera), Heteroptera, polypores or bracket fungi (Polyporaceae) and vascular plants of old growth boreal taiga forests. Optimal networks for Heteroptera maximized the high overall species richness of beetles and vascular plants, but these networks were least favourable options for polypores. Polypores are an important group indicating the conservation value of old growth taiga forests. Random selection provided a better option. Thus, certain groups may function as good indicators for maximizing the overall species richness of some taxonomic groups, but all taxa should be examined separately.     

《中国生物多样性红色名录》的制定 及其对生物多样性保护的意义

早在20世纪80年代, 我国就引入IUCN红色名录原理, 对我国生物物种的濒危状况开展评估工作。但是随着经济发展和气候变化, 一些物种的数量和分布区发生了变化, 加之在以往的评估中存在一些不足, 亟需对我国生物物种的濒危状况开展一次全面的评估。2008年, 环境保护部联合中国科学院启动了《中国生物多样性红色名录》的编制工作, 《中国生物多样性红色名录——高等植物卷》和《中国生物多样性红色名录——脊椎动物卷》分别于2013年9月和2015年5月正式对外发布。本文回顾了《中国生物多样性红色名录》的编制背景、过程和取得的成果。《中国生物多样性红色名录》完成了对我国34,450种高等植物和除海洋鱼类外的4,357种脊椎动物受威胁状况的评估, 是迄今为止对象最广、信息最全、参与专家人数最多的一次评估。在评估中取得了一系列成果: 统计了中国已知高等植物和脊椎动物物种数, 确定了物种丰富度在世界上的排名; 完善了国际上所使用的IUCN红色名录评估等级标准体系; 评估分析了我国已知高等植物和脊椎动物的受威胁程度及分布差异; 评估分析了高等植物和脊椎动物濒危灭绝的原因, 其中人类活动导致的生境丧失和退化是首要因素。这些成果将对我国生物多样性保护和管理工作产生积极的影响。     

One taxon does not fit all: Herb-layer diversity and stand structural complexity are weak predictors of biodiversity in Fagus sylvatica forests

Since adequate information on the distribution of biodiversity is hardly achievable, biodiversity indicators are necessary to support the management of ecosystems. These surrogates assume that either some habitat features, or the biodiversity patterns observed in a well-known taxon, can be used as a proxy of the diversity of one or more target taxa. Nevertheless, at least for certain taxa, the validity of this assumption has not yet been sufficiently demonstrated.We investigated the effectiveness of both a habitat- and a taxa-based surrogate in six European beech forests in the Apennines. Particularly, we tested: (1) whether the stand structural complexity and the herb-layer species richness were good predictors of the fine-scale patterns of species richness of five groups of forest-dwelling organisms (beetles, saproxylic and epigeous fungi, birds and epiphytic lichens); and (2) the cross-taxon congruence in species complementarity and composition between herb-layer plants and the target taxa.We used Generalized Linear Mixed Models (GLMMs), accumulation curves and Procrustes analysis to evaluate the effectiveness of these surrogates when species richness, complementarity and composition were considered, respectively.Our results provided a limited support to the hypothesis that the herb-layer plants and the stand structural complexity were good surrogates of the target taxa. Although the richness of the herb-layer plants received a stronger support from the data than structural complexity as a predictor for the general patterns of species richness, the overall magnitude of this effect was weak and distinct taxa responded differently. For instance, for increasing levels of herb-layer richness, the richness of lichens showed a marked increase, while the richness of saproxylic fungi decreased. We also found significantly similar complementarity patterns between the herb-layer plants and beetles, as well as a significant congruence in species composition between herb-layer plants and saproxylic fungi. Finally, when different stand structural attributes were considered singularly, only the total amount of deadwood received support from the data as a predictor of the overall species richness.At the fine scale of this study, herb-layer plants and stand structural complexity did not prove to be effective surrogates of multi-taxon biodiversity in well-preserved southern European beech forests. Rather than on weak surrogates, these results suggest that sound conservation decisions should be supported by the information provided by comprehensive multi-taxonomic assessments of forest biodiversity.     

Cross-taxon congruence in tree,bird and bat species distributions at a moderate spatial scale across four tropical forest types in the Philippines

Indicator species groups are often used as surrogates for overall biodiversity in conservation planning because inventories of multiple taxa are rare, especially in the tropics where most biodiversity is found. At coarse spatial scales most studies show congruence in the distribution of species richness and of endemic and threatened species of different species groups. At finer spatial scale levels however, cross-taxon congruence patterns are much more ambiguous. In this study we investigated cross-taxon patterns in the distribution of species richness of trees, birds and bats across four tropical forest types in a ca. 100 × 35 km area in the Northern Sierra Madre region of Luzon Island, Philippines. A non-parametric species richness estimator (Chao1) was used to compensate for differential sample sizes, sample strategies and completeness of species richness assessments. We found positive but weak congruence in the distribution of all and endemic tree and bird and tree and bat species richness across the four forest types; strong positive congruence in the distribution of all and endemic bat and bird species richness and low or negative congruence in the distribution of globally threatened species between trees, birds and bats. We also found weak cross-taxon congruence in the complementarity of pairs of forest types in species richness between trees and birds and birds and bats but strong congruence in complementarity of forest pairs between trees and bats. This study provides further evidence that congruence in the distribution of different species groups is often ambiguous at fine to moderate spatial scales. Low or ambiguous cross-taxon congruence complicates the use of indicator species and species groups as a surrogate for biodiversity in general for local systematic conservation planning.     

Application of the IUCN Red Listing system to setting species targets for conservation planning purposes

Biodiversity targets, or estimates of the quantities of biodiversity features that should be conserved in a region, are fundamental to systematic conservation planning. We propose that targets for species should be based on the quantitative thresholds developed for the Vulnerable category of the IUCN Red List system, thereby avoiding future listings of species in an IUCN Red List threat category or an increase in the extinction risk, or ultimate extinction, of species already listed as threatened. Examples of this approach are presented for case studies from South Africa, including threatened taxa listed under the IUCN Red List criteria of A to D, a species listed as Near Threatened, a species of conservation concern due to its rarity, and one species in need of recovery. The method gives rise to multiple representation targets, an improvement on the often used single representation targets that are inadequate for long term maintenance of biodiversity or the arbitrary multiple representation and percentage targets that are sometimes adopted. Through the implementation of the resulting conservation plan, these targets will ensure that the conservation status of threatened species do not worsen over time by qualifying for higher categories of threat and may actually improve their conservation status by eliminating the threat of habitat loss and stabilizing population declines. The positive attributes ascribed to the IUCN Red List system, and therefore to the species targets arising from this approach, are important when justifying decisions that limit land uses known to be detrimental to biodiversity.     

Co-variation and indicators of species diversity: Can richness of forest-dwelling species be predicted in northern boreal forests?

Design and establishment of ecologically good networks of conservation areas often requires quick assessments of their biodiversity. Reliable indicators would be useful when doing such assessments. In order to explore the potential indicators for species richness in boreal forests, we studied (1) the co-variation of species richness and composition of species assemblages among beetles, polypores, birds and vascular plants, (2) the relationships between species richness and four boreal forest site types, (3) the relationship between species richness and forest physical structure and (4) the suitability of potential indicator groups within the four taxa to predict the species richness generally. The data show that there are probably not a single taxonomic or forest structural characteristic to be used as a general biodiversity indicator or surrogate for all the species. The correlations in species richness among the four taxa studied were low. However, group-specific indicators were obvious: forest site type was a good surrogate for vascular plant richness, and quantity and quality of dead wood predicted the species richness of polypores. The results support the view that different indicators shall be used for different forest types and taxonomic groups. These indicators should facilitate relatively rapid methods to assess biodiversity patterns at the forest stand level.     

A proposal of framework to obtain an integrated biodiversity indicator for agricultural ponds incorporating the simultaneous effects of multiple pressures

One of the promising approaches to monitoring biodiversity is assessing the status of pressures driving the biodiversity state. To achieve this, we need to identify the principal pressures that cause simultaneous biodiversity loss across taxonomic groups and clarify how multiple pressures act synergistically or at least simultaneously to decrease biodiversity in the focal ecosystem. Here, we used a series of 64 ponds as a case study and we developed a framework for an integrated biodiversity indicator that took into consideration the estimated relative importance of multiple pressures. The indicator is defined as a function of the pressure(s) and is parameterized to explain a number of individual indicators of biodiversity, such as richness, abundance, and functional diversity of focal taxa. We selected aquatic macrophytes, Odonata, and benthic macroinvertebrates as the focal taxa. In addition, we focused on three types of pressure: eutrophication (represented by total phosphorus, total nitrogen, suspended solids, chlorophyll a, and density of cyanobacteria of pond water), habitat destruction (land-use type around the pond and pond bank protection), and invasive alien species (abundance of bluegill, largemouth bass, red swamp crayfish, and American bullfrog). We then evaluated the relationships among direct pressures and the individual biodiversity indicators and used a hierarchical Bayesian approach to calculate the integrated biodiversity indicator. Using this framework, we demonstrated that eutrophication had greater effects on the state of biodiversity of the agricultural ponds than did habitat destruction or the presence of invasive alien species. We also showed that the integrated indicator could well explain the behaviors of several individual biodiversity indicators, including total richness, endangered species richness, and functional diversity of focal taxa. These results demonstrate the advantages of the framework in providing a more practical method for assessing biodiversity, and quantifying the relative importance of the major threats to biodiversity to prioritize strategies in conservation planning and policy making.     

Global habitat suitability models of terrestrial mammals

Detailed large-scale information on mammal distribution has often been lacking, hindering conservation efforts. We used the information from the 2009 IUCN Red List of Threatened Species as a baseline for developing habitat suitability models for 5027 out of 5330 known terrestrial mammal species, based on their habitat relationships. We focused on the following environmental variables: land cover, elevation and hydrological features. Models were developed at 300 m resolution and limited to within species' known geographical ranges. A subset of the models was validated using points of known species occurrence. We conducted a global, fine-scale analysis of patterns of species richness. The richness of mammal species estimated by the overlap of their suitable habitat is on average one-third less than that estimated by the overlap of their geographical ranges. The highest absolute difference is found in tropical and subtropical regions in South America, Africa and Southeast Asia that are not covered by dense forest. The proportion of suitable habitat within mammal geographical ranges correlates with the IUCN Red List category to which they have been assigned, decreasing monotonically from Least Concern to Endangered. These results demonstrate the importance of fine-resolution distribution data for the development of global conservation strategies for mammals.     

Assessing the diversity pattern of cryophilous plant species in high elevation habitats

This study aimed to better document the diversity and distribution patterns of vascular cryophilous species across major habitat types in a high-elevation Mediterranean system in central Italy. The research addressed the following questions: (a) whether different habitats support similar levels of biodiversity in terms of total vascular plants richness and cryophilous species richness, and (b) how each habitat contributes to the total cryophilous species diversity. A random stratified sampling approach based on a habitat map was applied to construct rarefaction curves for overall cryophilous species richness and habitat type-specific cryophilous richness. Rarefaction curves were also constructed for all-species and exclusive species. To determine whether the targeted species represented a constant proportion of all species, the ratio between the rarefaction curves of the cryophilous species and all species was also calculated. The results highlight the importance of the different habitat types in overall and cryophilous species conservation because these different habitat types had progressively higher richness values. At the regional scale, steep slopes had the highest species diversity, the greatest exclusive species richness and a steep rarefaction curve. The diversity pattern of cryophilous taxa was not related to the general pattern of total species richness, with these species being more common in three habitat types with extreme environmental conditions: ridges, cliffs, and screes. For the establishment of successful biodiversity conservation programs, it is imperative to include species-poor habitats containing a high proportion of cryophilous species, which are considered to be threatened by climate warming.     

Primates as Predictors of Mammal Community Diversity in the Forest Ecosystems of Madagascar

The geographic distribution of species is the typical metric for identifying priority areas for conservation. Since most biodiversity remains poorly studied, a subset of charismatic species, such as primates, often stand as surrogates for total biodiversity. A central question is therefore, how effectively do primates predict the pooled species richness of other mammalian taxa? We used lemurs as indicator species to predict total non-primate mammal community richness in the forest ecosystems of Madagascar. We combine environmental and species occurrence data to ascertain the extent to which primate diversity can predict (1) non-primate mammal α-diversity (species richness), (2) non-primate complementarity, and (3) non-primate β-diversity (species turnover). Our results indicate that primates are effective predictors of non-primate mammal community diversity in the forest ecosystems of Madagascar after controlling for habitat. When individual orders of mammals are considered, lemurs effectively predict the species richness of carnivorans and rodents (but not afrosoricids), complementarity of rodents (but not carnivorans or afrosoricids), and all individual components of β-diversity. We conclude that lemurs effectively predict total non-primate community richness. However, surrogate species alone cannot achieve complete representation of biodiversity.     

Indicators of Diptera diversity in wet grassland habitats are influenced by environmental variability,scale of observation,and habitat type

In low intensity agri-ecosystems such as wet grassland habitats, the inclusion of invertebrates in conservation assessments and monitoring is usually limited to charismatic groups such as bees or butterflies. However, wet grasslands support a wide range of inveterate groups, some of which may exhibit limited movement not generally represented by more mobile groups such as those typically examined. The use of surrogate species which exemplify broader invertebrate diversity has been suggested as a possible means of including these overlooked invertebrates (such as Diptera) in conservation planning within these habitats. Based on collections made by Malaise trap, we utilized two families of Diptera (Sciomyzidae and Syrphidae) as indicators of a wider range of dipteran diversity (nine Diptera families identified to parataxonomic unit level [PUs]) in wet grassland habitats. We examined the role of environmental variability, spatial scale, and habitat type on patterns of cross-taxon congruence for all three assemblages. Both environmental correlation and community congruence were significantly stronger among assemblages when examined at low spatial scales, highlighting the need to examine dipteran groups at scales untypical of current agri-environmental assessments; namely field and farm level. Furthermore, when wet grasslands were differentiated into two habitat categories (sedge and rush dominated grasslands), the significance of the community congruence increased markedly. This correlation was particularly strong between Sciomyzidae and PUs which demonstrated similar differentiation based on habitat type, implying that assemblages which exhibit comparable ecological partitioning are more likely to be useful surrogates of one another. Correlations between richness, abundance and Shannon’s diversity were highly variable among groups, suggesting compositional analysis as the most appropriate examination of dipteran diversity for surrogacy studies. The results indicate that cross-assemblage congruence of Diptera is influenced by similarity of response to environmental variability, scale of observation, and examination of assemblages differentiated into appropriate habitat categories. The results illustrate the need to investigate invertebrate biodiversity surrogates at scales appropriate to the indicator groups and examine congruence among assemblages within specific habitat categories. Such an approach has the potential to maximise gamma diversity in areas where wet grasslands are under threat of intensification or abandonment.     

Human population, grasshopper and plant species richness in European countries

Surprisingly, several studies over large scales have reported a positive spatial correlation of people and biodiversity. This pattern has important implications for conservation and has been documented for well studied taxa such as plants, amphibians, reptiles, birds and mammals. However, it is unknown whether the pattern applies also to invertebrates other than butterflies and more work is needed to establish whether the species–people relationship is explained by both variables correlating with other environmental factors. We studied whether grasshopper species richness (Orthoptera, suborder Caelifera) is related to human population size in European countries. As expected, the number of Caelifera species increases significantly with increasing human population size. But this is not the case when controlling for country area, latitude and number of plant species. Variations in Caelifera species richness are primarily associated with variations in plant species richness. Caelifera species richness also increases with decreasing mean annual precipitation, Gross Domestic Product per capita (used as an indicator for economic development) and net fertility rate of the human population. Our analysis confirms the hypothesis that the broad-scale human population–biodiversity correlations can be explained by concurrent variations in factors other than human population size such as plant species richness, environmental productivity, or habitat heterogeneity. Nonetheless, more populated countries in Europe still have more Caelifera species than less populated countries and this poses a particular challenge for conservation.