Biodiversity Surrogates Research Articles

Assessing spatial patterns of phylogenetic diversity of Mexican mammals for biodiversity conservation

Phylogenetic diversity is a biodiversity measurement that describes the amount of evolutionary history contained by the taxonomic units in a region. It has proven to be an important metric for determining conservation priorities. Mammalian phylogenetic diversity patterns have been suggested as potential surrogates of biodiversity for establishing priority areas for conservation. This study aims to identify areas of high mammalian phylogenetic diversity in Mexico, a megadiverse country with high mammalian richness, and to assess how well protected areas encompass the phylogenetic diversity. IUCN distribution data for 479 Mexican mammals were used to estimate species richness. Data for the molecular markers cytB, 12S and COI, was gathered from GenBank and from laboratory extractions for reconstructing a maximum-likelihood phylogenetic tree. Spatial patterns in phylogenetic diversity were estimated by summing the branch lengths of the phylogenetic tree representing species presence across grid cells. The results were compared with the distribution of protected areas in Mexico in order to assess if phylogenetic diversity is effectively conserved. The southeastern part of Mexico was found to be the most diverse. The breadth of the phylogenetic tree was well represented within the protected areas. Beta-diversity analyses showed that the species composition between protected and unprotected areas is very similar. Protected areas group based on the phylogenetic composition of mammal species into three clusters corresponding to the Nearctic, Neotropical, and Mexican Transition Zone biogeographical regions, which suggests that protected areas could be managed based on these clusters.

Applying Biodiversity Metrics as Surrogates to a Habitat Conservation Plan

Unabated urbanization has led to environmental degradation and subsequent biodiversity loss across the globe. As an outcome of unmitigated land use, multi-jurisdictional agencies have developed land use plans that attempt to protect threatened or endangered species across selected areas by which some trade-offs between harm to species and additional conservation approaches are allowed among the partnering organizations. Typical conservation plans can be created to focus on single or multiple species, and although they may protect a species or groups of species, they may not account for biodiversity or its protection across the given area. We applied an approach that clustered deductive habitat models for terrestrial vertebrates into metrics that serve as surrogates for biodiversity and relate to ecosystem services. In order to evaluate this process, we collaborated with the partnering agencies who are creating a Multi-Species Habitat Conservation Plan in southern California and compared it to the entire Mojave Desert Ecoregion. We focused on total terrestrial vertebrate species richness and taxon groupings representing amphibians, birds, mammals, and reptiles, and two special status species using the Normalized Index of Biodiversity (NIB). The conservation planning area had a lower NIB and was less species rich than the Mojave Desert Ecoregion, but the Mojave River riparian corridor had a higher NIB and was more species-rich, and while taxon analysis varied across the geographies, this pattern generally held. Additionally, we analyzed desert tortoise (Gopherus agassizii) and desert kit fox (Vulpes macrotis arsipus) as umbrella species and determined that both species are associated with increased NIB and large numbers of species for the conservation area. Our process provided the ability to incorporate value-added surrogate information into a formal land use planning process and used a metric, NIB, which allowed comparison of the various planning areas and geographic units. Although this process has been applied to Apple Valley, CA, and other geographies within the U.S., the approach has practical application for other global biodiversity initiatives.

Plant spectral diversity as a surrogate for species, functional and phylogenetic diversity across a hyper‐diverse biogeographic region

AbstractAimWith plant biodiversity under global threat, there is an urgent need to monitor the spatial distribution of multiple axes of biodiversity. Remote sensing is a critical tool in this endeavour. One remote sensing approach for detecting biodiversity is based on the hypothesis that the spectral diversity of plant communities is a surrogate of multiple dimensions of biodiversity. We investigated the generality of this ‘surrogacy’ for spectral, species, functional and phylogenetic diversity across 1,267 plots in the Greater Cape Floristic Region (GCFR), a hyper‐diverse region comprising several biomes and two adjacent global biodiversity hotspots.LocationThe GCFR centred in south‐western and western South Africa.Time periodAll data were collected between 1978–2014.Major taxa studiedVascular plants within the GCFR.MethodsSpectral diversity was calculated using leaf reflectance spectra (450–950 nm) and was related to other dimensions of biodiversity via linear models. The accuracy of different spectral diversity metrics was compared using 10‐fold cross‐validation.ResultsWe found that a distance‐based spectral diversity metric was a robust predictor of species, functional and phylogenetic biodiversity. This result serves as a proof‐of‐concept that spectral diversity is a potential surrogate of biodiversity across a hyper‐diverse biogeographic region. While our results support the generality of spectral diversity as a biodiversity surrogate, we also find that relationships vary between different geographic subregions and biomes, suggesting that differences in broad‐scale community composition can affect these relationships.Main conclusionsSpectral diversity was shown to be a robust surrogate of multiple dimensions of biodiversity across biomes and a widely varying biogeographic region. We also extend these surrogacy relationships to ecological redundancy to demonstrate the potential for additional insights into community structure based on spectral reflectance.

The representation potential of raptors for globally important nature conservation areas

Stemming from a pervasive lack of knowledge on biodiversity, important areas for conservation are typically identified using a subset of well known species, commonly termed surrogate or indicator groups. Birds have been commonly used as biodiversity surrogates due to the good level of knowledge on their taxonomy, ecology and distribution. Raptors in particular have been often proposed as an effective surrogate for other biodiversity based on their dietary diversity, being at the top of the food chain, their preference for highly productive areas, their generally threatened status and high public appeal. However, so far the surrogacy effectiveness of raptors has been largely studied locally or using a narrow selection of surrogate and surrogated taxa.Here we use a spatial conservation planning tool to quantify the surrogacy performance of raptors, overall and by different raptor groups (hawks and eagles, falcons, vultures, owls) to represent important biodiversity areas (such as IUCN protected areas and key biodiversity areas), wilderness areas and the worlds ecoregions. We compared the above surrogacy performance with that of all other non-raptor avian species.We show that raptors perform marginally worse than all other avian species in representing important biodiversity areas and ecoregions. However, raptors representation for wilderness areas was similar or slightly better compared to that of using all non-raptor birds. We also report a large variation in the representation performance by the four raptor groups. Falcons had a particularly high potential in representing protected areas and wilderness areas, equaling or largely surpassing the representation potential provided by all raptors and all other non-raptor birds.Overall, the results suggest that raptors, and particularly falcons, can perform relatively well in representing some important areas for conservation, such as protected areas and wilderness areas, but are relatively poor surrogates for key biodiversity areas and ecoregions. These rather contrasting results call for caution on the use of raptors as global surrogates of wider biodiversity.

Leopards and mesopredators as indicators of mammalian species richness across diverse landscapes of South Africa

The rapid extinction of species over the past few decades has created a biodiversity crisis. Factors contributing to recent extirpations are linked to increased human population growth, habitat loss and fragmentation, and over-exploitation of wildlife. Only decisive, effective action to combat biodiversity loss can reverse these trends. The use of indicator species as surrogates for biodiversity provides a way to identify areas with high biodiversity so that conservation efforts can be accelerated and supported in those areas. Predators are considered important indicators of healthy, biodiverse ecosystems due to their high trophic level and their direct and indirect interaction with other species. Using camera trap data from 221 cameras set across five vegetation types and five land use zones in South Africa, we evaluated carnivores as potential surrogates for biodiversity. We used the leopard (Panthera pardus), and three meso-predators: caracal (Caracal caracal), honey badger (Mellivora capensis), and black-backed jackal (Canis mesomelas), as candidate indicator species. We used mammals captured at the camera traps as a measure of biodiversity referred to as mammalian species richness. The mammalian species richness was highest in the Orange River Nama Karoo vegetation type and in privately owned game reserves. We found that predator sightings were associated with significantly higher mammalian species richness which increased with increasing number of predator species. These findings suggest that the surrogate species concept can be applied to leopard and meso-predators.

Raptor breeding sites as a surrogate for conserving high avian taxonomic richness and functional diversity in urban ecosystems

Preserving biodiversity and ecosystem functions in rapidly increasing urban areas has become a focal issue of conservation science. With limited budgets and human resources, a potentially efficient conservation strategy is to prioritize important areas in urban ecosystems, based on raptor habitats. Here, northern goshawk (Accipiter gentilis) breeding sites in urban Kanagawa, Japan were used to explore the effectiveness of raptor habitats as conservation surrogates for biodiversity and ecosystem function. The presence of birds was recorded within 500 m of 37 goshawk breeding sites through point counts in the breeding season of 2019. Species richness and dendrogram-based functional diversity (FD) were then determined as measures of biodiversity and ecosystem function, respectively. As controls, 50 sites with landscape compositions similar to goshawk breeding sites were also evaluated. The analysis involved two generalized linear models using species richness and FD as response variables and the presence/absence of goshawk breeding sites as covariates. Goshawk breeding sites had a significant positive effect on species richness and FD, explaining most of their variance (species richness: 63.0%, FD: 56.9%). In conclusion, this study confirmed that goshawk breeding sites that maintain high urban biodiversity and ecosystem function can be used to prioritize and preserve important areas for conservation.

Congruence, but no cascade-Pelagic biodiversity across three trophic levels in Nordic lakes.

Covariation in species richness and community structure across taxonomical groups (cross‐taxon congruence) has practical consequences for the identification of biodiversity surrogates and proxies, as well as theoretical ramifications for understanding the mechanisms maintaining and sustaining biodiversity. We found there to exist a high cross‐taxon congruence between phytoplankton, zooplankton, and fish in 73 large Scandinavian lakes across a 750 km longitudinal transect. The fraction of the total diversity variation explained by local environment alone was small for all trophic levels while a substantial fraction could be explained by spatial gradient variables. Almost half of the explained variation could not be resolved between local and spatial factors, possibly due to confounding issues between longitude and landscape productivity. There is strong consensus that the longitudinal gradient found in the regional fish community results from postglacial dispersal limitations, while there is much less evidence for the species richness and community structure gradients at lower trophic levels being directly affected by dispersal limitation over the same time scale. We found strong support for bidirectional interactions between fish and zooplankton species richness, while corresponding interactions between phytoplankton and zooplankton richness were much weaker. Both the weakening of the linkage at lower trophic levels and the bidirectional nature of the interaction indicates that the underlying mechanism must be qualitatively different from a trophic cascade.

Promising yet variable performance of cross-taxon biodiversity surrogates: a test in two marine habitats at multiple times

Surrogates are a potential solution to the often-cited problem of there being insufficient information for biodiversity assessments or conservation planning. Cross-taxon surrogacy is the ability of a group of well-known taxa to represent variation in other poorly known taxa. To date, tests of the effectiveness of cross-taxon surrogacy in marine environments have yielded variable results and a significant qualification to the outcomes of tests that have demonstrated surrogacy is the near absence of tests for its persistence through time. This study tested for cross-taxon surrogacy and its persistence through time for three surrogates (crustaceans, molluscs, polychaetes). We used data on biodiversity variables and species assemblages of the surrogates and their targets that had been collected during multiple sampling events over 2.5 years in two habitats (seagrass, unvegetated sediment) in a large bay in south-eastern Australia. We tested surrogacy by fitting a series of linear models using generalized least squares for biodiversity variables and by Mantel tests of dissimilarity matrices of species assemblages. We also tested whether the type of data transformation affected Mantel tests. We found that each of the groups were effective surrogates for some but not all biodiversity variables (with molluscs or polychaetes being effective surrogates for species richness in both habitats), that none of the groups were effective surrogates for species assemblages, and that the outcomes of Mantel tests of dissimilarity matrices of surrogates and their targets were unaffected by the data transformation used. We conclude that while our results for surrogacy for biodiversity variables are promising the inconsistent results from other studies argues for caution about their application beyond the area and context in which they were assessed. The lack of evidence that we found for surrogates of species assemblages, and similar lack of evidence from other studies, suggests that assemblage-level surrogates are unlikely to be useful in biodiversity surveys.

Conserving focal insect groups in woodland remnants: The role of landscape context and habitat structure on cross-taxonomic congruence

• Wild bees and ground-dwelling beetles are sampled in remnant woodlands in Australian agriculture landscape. • Beetle diversity more strongly shaped by differing landscape contexts than bee diversity. • Species composition of both groups responds more strongly to the landscape than species richness. • Bee and beetle assemblages are poor surrogates for each other in modified landscapes. • Landscapes managed to conserve bees should not be assumed to benefit other insect groups. Determining the shared responses of different taxa to landscape modification is a key step for identifying which groups of species are good surrogates for other groups. Yet, surprisingly little is known about the spatial processes that drive cross-taxonomic congruence of diversity and how this knowledge can be used to improve the management of modified landscapes for biodiversity, especially insects. We investigated how assemblages of two ecologically important insect groups, wild bees and beetles, respond to different landscape contexts and habitat structure in an Australian agricultural landscape, and how this, in turn, influenced either group’s potential as a surrogate for the other. Bee and ground-active beetle assemblages were sampled in remnant woodland patches in two landscape contexts: woodland patches surrounded by pine plantation and woodland patches surrounded by open grazing land. Bee species richness, and the richness of functionally-defined bee groups did not differ between landscape contexts, in contrast to beetles. We found that landscape context exerted a stronger effect on species composition than species richness of both groups. Although some landscape and habitat variables were useful in predicting the diversity of both insect groups, few were shared. Our findings showed that bee and beetles are poor surrogates for each other in landscapes that are highly modified. Our study highlighted the need to consider: (1) taxon-specific responses to landscape context, (2) the influence of different metrics of cross-taxonomic surrogacy and, (3) dissimilar ecological attributes among insect taxa when selecting insects as biodiversity surrogates. It should not be assumed that agricultural landscapes managed to conserve specific insects (e.g. bees) will necessarily benefit other insects.

A new ecosystem-based land classification of Iran for conservation goals.

Land management and biodiversity protection are highly dependent on ecosystem classification. To identify the ecosystems, often ecologically homogenous areas are distinguished based on physical and biological features at various scales. These areas can also be considered as biodiversity surrogates for protection policies and planning. We classified the terrestrial areas of Iran into ecosystems using revised and updated layers of landform and climate as our two main criteria. Moreover, we applied a revised vegetation layer as the confirmatory criterion. At a scale of 1:1,000,000, we obtained a total of 119 homogenous ecological units, and based on the dominant vegetation types, we classified them into 21 terrestrial ecosystems at the national level. Of these ecosystems, 11 were dominated by vegetation, and the remaining 10 had sparse nondominant vegetation. Evaluation of the least and most frequent ecosystem patches and ranking of their size classes using landscape metrics provided an information basis for better land protection planning. We maintain that each ecosystem needs to be represented by a protected area and its size and distribution also helps us form a comprehensive and effective protection network in Iran. Graphical abstract.

The role of rarity as a surrogate of marine fish species representation

Because the distribution of most of the species is poorly known, conservationists use surrogates to help maximize the representation level of all species. Historically, species richness has been used to calculate the importance of priority areas for conservation, but several studies revealed sites with high species richness often fail to determine the smallest number of sites that will protect the highest number of species. Rarity, however, has played a prominent role in safeguarding planning units. While the performance of rarity has been previously assessed in terrestrial systems, we tested the hypothesis that rarity of a site can be used as a measure of the importance of a site to a conservation network in marine ecosystems. We used the presence data (at a 1-degree resolution) to calculate five rarity indices of fish diversity at a global extent and compared the results to those obtained by using species richness and site complementarity. Our objectives were to: (1) determine if rarity indices can be used as surrogates of fish biodiversity by representing the highest number of species in the smallest number of sites; and (2) determine if the effectiveness of these indices to represent fish biodiversity is impacted by the metric used to define rarity. Results indicate that rarity could be an effective surrogate for marine fishes, as most results showed a mean of 100% effectiveness. In the context of marine biodiversity conservation, results show that rarity indices could be considered affordable and feasible surrogates of species representation, with the most significant benefit to those areas of the world that are in most need to access alternative tools. Results also open a new area of collaboration between biogeography and marine conservation biology since planners can use biogeographical patterns of rarity to enhance the performance of the current protected area network.

Evaluation of five taxa as surrogates for conservation prioritization in the Transmexican Volcanic Belt, Mexico

Many biotic groups have been proposed as biodiversity surrogates; however, using different taxa could provide complementary information for choosing conservation priorities. There are two general ways to evaluate the performance of surrogates: (1) using cross-taxon congruency as an a priori test, before the application of some prioritization algorithm to select areas for conservation; and, (2) developing a system of priority areas as an a posteriori test. We have used both of these tests to evaluate five different taxa (Amphibia, Aves, Insecta, Mammalia and Magnoliopsida) as surrogates for each other; and likewise we evaluated three groupings of them (Invertebrates, Vertebrates and Plants). We also compared their performance in a priori and a posteriori tests based on their richness patterns and prioritization areas for conservation within the Transmexican Volcanic Belt. The prioritization was run in Zonation software. We evaluated whether the patterns are shared among taxa and groupings using two correlation analyses: Pearson and modified t test (to correct for spatial autocorrelation). Although we found some positive correlations between the richness patterns of taxa and groupings, the prioritized areas were uncorrelated. In general, the correlations were stronger for mammals and plants, and weaker for birds and insects. We found that patterns of richness and rarity (obtained through the prioritization) are not shared among taxa and groupings. Therefore, if conservation priorities are based on a single group and test, there is a high risk of leaving other groups unprotected.

Genomic analyses suggest strong population connectivity over large spatial scales of the commercially important baitworm, Australonuphis teres (Onuphidae)

Barriers to dispersal can disrupt gene flow between populations, resulting in genetically distinct populations. Although many marine animals have potential for long-distance dispersal via a planktonic stage, gene flow among populations separated by large geographic distances is not always evident. Polychaetes are ecologically important and have been used as biological surrogates for marine biodiversity. Some polychaete species are used as bait for recreational fisheries, with this demand supporting commercial fisheries for polychaetes to service the retail bait market. However, despite their ecological and economic importance, very little is known about the life history or population dynamics of polychaetes, and few studies have used genetic or genomic approaches to understand polychaete population connectivity. Here, we investigate the population structure of one commonly collected beachworm species used for bait on the eastern coast of Australia, namely, Australonuphis teres, by using genome-wide single-nucleotide polymorphism data. We sampled A. teres from hierarchical nested spatial scales along 900km of the coast in New South Wales. We identified six genetic groups, but there was no clear geographic pattern of distribution. Our results suggest that there is considerable gene flow among the sampled populations. These high-resolution genomic data support the findings of previous studies, and we infer that oceanographic processes promote genetic exchange among polychaete populations in south-eastern Australia.

Challenges of habitat mapping to inform marine protected area (MPA) designation and monitoring: An operational perspective

The UK has adopted a feature-based approach to MPA designation and monitoring to meet international and national obligations. Despite operational challenges, this approach is considered key to optimising conservation outcomes whilst making efficient use of limited resources. Drawing on lessons learnt from the UK's MPA Programme we discuss the practical issues which arise from: i) effective selection of conservation features identified as surrogates for biodiversity, ii) adequacy of feature representation across the MPA network and iii) implementation of quantifiable conservation objectives and ability to monitor progress in relation to them [4,5]. There is recognition that high-level feature surrogates adopted for MPA designation may not adequately represent the full range of biodiversity present across UK marine habitats, and several of these features are indiscernible using acoustic mapping techniques. This results in our inability to accurately map their distribution and extent. Additionally, monitoring progress in relation to conservation targets is hampered by a lack of reliable indicators to assess change in their ecological status. Recommendations for the optimisation of MPA designation and monitoring using a systematic, evidence based approach are provided. These include: 1) flexibility in feature classifications to allow additional features to be designated as required, 2) communication of limitations in the evidence base to enable informed use in adaptive management decisions, 3) use of innovative technologies to more accurately map habitat features and 4) development of wider UK and regional sea scale monitoring programmes which align with an ecosystem based approach to the ongoing assessment of marine biodiversity.

Complementary and protection value of a Biosphere Reserve buffer zone for increasing local representativeness of ground-living arthropods

Biosphere reserves (BRs) are areas of high biodiversity value that promote conservation and sustainable development. BRs consist of core, buffer, and transition zones. Buffer zones are where human and ecological activities overlap, and are key functional spaces that can have important complementarity value. We test this using ground-living arthropods in the highly biodiverse Kogelberg Biosphere Reserve in South Africa. We use generalized dissimilarity modelling to describe the compositional dissimilarity of assemblages as a function of environmental correlates between pairs of survey sites. Transformed spatial predictors were used as surrogates for biodiversity to assess complementarity. Important correlates of arthropod species turnover were related to mesoclimate, fire history, and geology. Buffer areas had important complementary value. Current habitat transformation across core and buffer zones does not change this, as results were the same when removing all transformed areas from the analyses. Important areas in buffer zones that increased local representativeness coincided with areas of increased intra-annual temperature variability. Orchards in transformed areas also influenced arthropod diversity in adjacent natural vegetation by <1km from orchard edges. This edge effect influenced both core and buffer sites due to the lack of a continuous buffer, indicating that the buffer zone is important for protecting the core. As fire management is an important correlate of arthropod turnover here, the complementary value of the buffer zone can have a strong temporal dimension. Given the important complementary value of the buffer zone, conservation management should not be restricted to core areas only, especially when maximising local representativeness.

Using ecological niche theory to avoid uninformative biodiversity surrogates

Surrogates and indicators of biodiversity are used to infer the state and dynamics of species populations and ecosystems, as well as to inform conservation and management actions. Despite their widespread use, few studies have examined how ecological theory can guide the selection or surrogates and indicators, and thus reduce the likelihood of failure or cost of validation. We argue that ecological niche theory and knowledge of the extent to which particular limiting factors (e.g. physiological tolerances, limits to growth rates, or competitive exclusion) affect species distributions, abundance and coexistence could inform the choice of potential surrogates. Focusing on the environmental characteristics that define species niches makes it possible to identify situations where surrogates are likely to be ineffective, such as when there is no mechanistic basis for a candidate surrogate to be related to a biodiversity target. We describe two case studies where different candidate surrogate variables are shown to have contrasting potential as indicators of sustainable farming. Variables not mechanistically linked to the driver of change or responsive over appropriate timeframes or spatial scales are suggested a priori to be uninformative. The niche concept provides a framework for exploring ecological relationships that can inform the selection or exclusion of potential biodiversity surrogates. We think that this new approach to integrating ecological theory and application could lead to improved effectiveness of biodiversity monitoring and conservation.

Applying the umbrella index across aquatic insect taxon sets for freshwater assessment

Abstract Biological surrogates in conservation biology are valuable for rapid biodiversity and environmental surveys, and as an early warning of potential threats. However, these surrogates need to be simple and inexpensive to apply. The umbrella index was applied here to quantify the selection of surrogate species for biodiversity assessments, but requires interrogation for application in areas rich in threatened endemic species. Aquatic larvae of Ephemeroptera, Plecoptera and Trichoptera (EPT), as well as the adult Odonata, are all highly responsive to changes in freshwater condition. Using the umbrella index, we evaluated the performance of the surrogate species approach for aquatic insect conservation in a region (Greater Cape Floristic Region) with an exceptional level of rare and endemic species, across multiple rivers with different disturbance levels. Due to a lack of species level information, EPT taxa were calculated using morphospecies within families, and Odonata were identified to species level. The umbrella index identified eight EPT species and seven Odonata species as potential surrogates. Both these groups co-occurred with high percentages of their own overall groups (EPT surrogates for overall EPT, and Odonata surrogates for overall Odonata), as well as for the other group (EPT surrogates for overall Odonata, and Odonata surrogates for overall EPT). The index was surprisingly flexible, and performed well in an area with so many species of conservation concern, as well as across spatial scales greater than a single river, with varying degrees of disturbance. Both EPT and Odonata showed promise as potential biodiversity surrogates, and for future conservation planning. Ideally, conservationists should aim to use taxa that are easy to identify to species level, with known sensitivities to human disturbance. However, when this is not a possibility, the umbrella index is still applicable and accurate for morphospecies (family level sensitivities).

Cross Taxon Congruence Between Lichens and Vascular Plants in a Riparian Ecosystem

Despite that congruence across taxa has been proved as an effective tool to provide insights into the processes structuring the spatial distribution of taxonomic groups and is useful for conservation purposes, only a few studies on cross-taxon congruence focused on freshwater ecosystems and on the relations among vascular plants and lichens. We hypothesized here that, since vascular plants could be good surrogates of lichens in these ecosystems, it would be possible to assess the overall biodiversity of riparian habitats using plant data only. In this frame, we explored the relationship between (a) species richness and (b) community composition of plants and lichens in a wetland area located in central Italy to (i) assess whether vascular plants are good surrogates of lichens and (ii) to test the congruence of patterns of species richness and composition among plants and lichens along an ecological gradient. The general performance of plant species richness per se, as a biodiversity surrogate of lichens, had poor results. Nonetheless, the congruence in compositional patterns between lichens and vascular plants varied across habitats and was influenced by the characteristics of the vegetation. In general, we discussed how the strength of the studied relationships could be influenced by characteristics of the data (presence/absence vs. abundance), by the spatial scale, and by the features of the habitats. Overall, our data confirm that the more diverse and structurally complex the vegetation is, the more diverse are the lichen communities it hosts.

The effectiveness of aquatic plants as surrogates for wider biodiversity in standing fresh waters

Abstract Freshwaters are among the most globally threatened habitats and their biodiversity is declining at an unparalleled rate. In an attempt to slow this decline, multiple approaches have been used to conserve, restore or enhance waterbodies. However, evaluating their effectiveness is time‐consuming and expensive. Identifying species or assemblages across a range of ecological conditions that can provide a surrogate for wider freshwater biodiversity is therefore of significant value for conservation management and planning. For lakes and ponds in three contrasting landscapes of Britain (lowland agricultural, eastern England; upland, north‐west England; urban, central Scotland) we examined the link between macrophyte species, macrophyte morpho‐group diversity (an indicator of structural diversity) and the richness of three widespread aquatic macroinvertebrate groups (molluscs, beetles, and odonates) using structural equation modelling. We hypothesised that increased macrophyte richness and, hence, increased vegetation structural complexity, would increase macroinvertebrate richness after accounting for local and landscape conditions. We found that macrophyte richness, via macrophyte morpho‐group diversity, was an effective surrogate for mollusc, beetle, and odonate richness in ponds after accounting for variation caused by physical variables, water chemistry, and surrounding land use. However, only mollusc richness could be predicted by macrophyte morpho‐group diversity in lakes, with no significant predicted effect on beetles or odonates. Our results indicate that macrophyte morpho‐group diversity can be viewed as a suitable surrogate of macroinvertebrate biodiversity across diverse landscapes, particularly in ponds and to a lesser extent in lakes. This has important implications for the restoration, conservation, and creation of standing water habitats and for assessing their effectiveness in addressing the decline of global freshwater biodiversity. Management actions prioritising the development of species‐rich and structurally diverse macrophyte assemblages will be likely to benefit wider freshwater biodiversity.

Evaluating the performance of rarity as a surrogate in site prioritization for biodiversity conservation

To solve the minimum-set coverage problem in conservation planning (representing the greatest number of species in the least number of sites), several metrics can be used to prioritize sites based on their conservation importance. Traditionally, species richness has been the most widely used approach, but previous studies suggest that it is one of the least effective. Alternative metrics such as complementarity algorithms have produced better results, for which they have been used in recent conservation studies. In this study, we assessed the performance of a new potential surrogate: rarity indices. Specifically, we tested rarity-weighted richness (RWR), index of summed rarity (ISR) and index of relative rarity (IRR), to determine if they are effective surrogates of biodiversity when solving the minimum-set coverage problem. We tested the rarity indices in 14 datasets spanning varying extents and grains, and found that rarity consistently outperformed species richness, even when accounting for the differences in rarity index performance. In some cases, rarity outperformed the complementarity solution, suggesting that it is a promising alternative surrogate that can be easily tested in situations where conservation action resources are limited. Rarity indices have been seldom assessed for their surrogacy effectiveness, and to the best of our knowledge, we are the first to test IRR and ISR in this context. Our results justify the need for future studies to elucidate the importance and applicability of rarity indices in conservation planning.