Towards biodiversity hotspots effective for conserving mammals with small geographic ranges

The main goal of using global biodiversity hotspots for conservation purposes is to protect taxa with small geographic ranges because these are highly vulnerable to extinction. However, the extent to what different hotspots types are effective for meeting this goal remains controversial because hotspots have been previously defined as either the richest or most threatened and richest sites in terms of total, endemic or threatened species. In this regard, the use of species richness to set conservation priorities is widely discussed because strategies focused on this diversity measure tend to miss many of the taxa with small geographic ranges. Here we use data on global terrestrial mammal distributions to show that, hotspots of total species, endemism and threat defined in terms of species richness are effective in including 27%, 29% and 11% respectively, of the taxa with small geographic ranges. Whilst, the same hotspot types defined in terms of a simple diversity index, which is a function of species richness and range-size rarity, include 68%, 44% and 90% respectively, of these taxa. In addition, we demonstrate that index hotspot types are highly efficient because they conserve 79% of mammal species (21% more species than richness hotspot types), with 59% of species shared by three hotspot types (31% more than richness hotspot types). These results suggest that selection of different diversity measures to define hotspots may strongly affect the achievement of conservation goals.     

Tropical dry forests in New Caledonia

Tropical dry forest is the most endangered major vegetation type in the New Caledonia biodiversity hotspot. Vegetation surveys following a transect method used by Gentry were undertaken in two tropical dry forest sites, Ouen-Toro and Pindai, in order to compare species richness, floristic composition, and structure. Pindai contained significantly higher species richness than Ouen-Toro, although there was little difference in forest structure. Tropical dry forest sites in New Caledonia were compared to seven other biodiversity hotspots with tropical dry forest where Gentry's transect method was employed. New Caledonia and other tropical dry forests on islands contain significantly lower species richness than mainland tropical dry forests in biodiversity hotspots. However, New Caledonia contained the highest number of threatened species based on IUCN global conservation categories. Tropical dry forest in New Caledonia appears to be the world's most endangered tropical dry forest based on the extent of forest, number of reserves, and threatened species. Management of tropical dry forests on private and community lands is absolutely imperative to the long-term persistence of this ecosystem.     

An assessment of the efficiency of protection status through determinations of biodiversity hotspots based on endemic bird species,Taiwan

Evaluations of species richness patterns have been performed at diverse scales, and biodiversity hotspots, especially endemism hotspots, have received much attention in conservation biology. We estimated the distributions of endemic bird species based on a 12-yr avian inventory project in Taiwan, identified biodiversity hotspots of endemism on a regional scale based on predictions from the ensemble forecasting framework and frequency histogram approach, and assessed the efficiency of protected areas. The results indicated that the predicted endemism hotspots were mostly located in mid- and high-elevation areas along the Central Mountain Range of Taiwan. An observed endemism hotspot was defined as one in which at least five of Taiwan's 17 endemic bird species were present. This criterion was used because the 5% of the sampled grid squares that were the richest in endemic bird species all had 5 endemic bird species or more. Seventy to seventy-one percent of the observed biodiversity hotspots matched the predicted biodiversity hotspots. This outcome was obtained whether the richness biodiversity in a grid square was based on summed predicted probability or summed predicted richness. The majority of the protected areas for these Taiwanese endemic bird species were national parks, protecting 24.1% of the predicted hotspot areas, whereas nature reserves and wildlife refuges protected less than 7%. Most of the predicted endemism hotspots were not adequately protected. We conclude that the ensemble forecasting framework and the frequency histogram approach are useful for selecting critical habitats and biodiversity hotspots for endemic species and for appraising the efficiency of the protection status provided by governments.     

Patterns of species richness hotspots and estimates of their protection are sensitive to spatial resolution

Aim

Species richness is a measure of biodiversity often used in spatial conservation assessments and mapped by summing species distribution maps. Commission errors inherent those maps influence richness patterns and conservation assessments. We sought to further the understanding of the sensitivity of hotspot delineation methods and conservation assessments to commission errors, and choice of threshold for hotspot delineation.

Location

United States.

Methods

We created range maps and 30‐m and 1‐km resolution habitat maps for terrestrial vertebrates in the United States and generated species richness maps with each dataset. With the richness maps and the GAP Protected Areas Dataset, we created species richness hotspot maps and calculated the proportion of hotspots within protected areas; calculating protection under a range of thresholds for defining hotspots. Our method allowed us to identify the influence of commission errors by comparing hotspot maps.

Results

Commission errors from coarse spatial grain data and lack of porosity in the range data inflated richness estimates and altered their spatial patterns. Coincidence of hotspots from different data types was low. The 30‐m hotspots were spatially dispersed, and some were very long distances from the hotspots mapped with coarser data. Estimates of protection were low for each of the taxa. The relationship between estimates of hotspot protection and threshold choice was nonlinear and inconsistent among data types (habitat and range) and grain size (30‐m and 1‐km).

Main conclusions

Coarse mapping methods and grain sizes can introduce commission errors into species distribution data that could result in misidentifications of the regions where hotspots occur and affect estimates of hotspot protection. Hotspot conservation assessments are also sensitive to choice of threshold for hotspot delineation. There is value in developing species distribution maps with high resolution and low rates of commission error for conservation assessments.     

Are there habitats that contribute best to plant species diversity in coastal dunes?

The following paper describes patterns of diversity across major habitat types in a relatively well preserved coastal dune system in central Italy. The research addresses the following questions: (a) whether different habitats defined on the base of a land cover map support similar levels of biodiversity in terms of vascular flora richness and number of rare and endangered species, and (b) how each habitat contributes to the total species diversity of the coastal environment. A random stratified sampling approach based on a detailed land cover map was applied to construct rarefaction curves for each habitat type and to estimate total species richness. In addition, the number of exclusive, rare and endangered species was calculated for each habitat type. Results highlight the importance of the coastal dune zonation (embryo-dune, main dune, transition and stabilized dune) in species conservation because they harbour progressively higher species richness. However, differences among these habitats were not significant, so no particular species rich “hotspots” could be evidenced. On the contrary, rarefaction curves show that the upper beach (strand) habitat sustains significantly smaller number of species, but surprisingly, it shows the highest rarity values and highest proportion of endangered species. Therefore, for the establishment of successful biodiversity conservation programs in these coastal environments, it is imperative not only to conserve biologically rich hotspots but also to include species poor habitats containing endangered or unique elements. Thus, the complete coastal vegetation mosaic including all coastal habitats is important to adequately characterize the plant species diversity of coastal dune ecosystems.     

Modeling Spatial Trends in Estimated Species Richness using Breeding Bird Survey Data: A Valuable Tool in Biodiversity Assessment

We used data from the French breeding bird survey to estimate local bird species richness within sampled sites, using capture–recapture models. We investigated the possible effects of habitat structure and composition (landscape fragmentation, habitat cover and diversity) on estimated species richness at a local scale, and used the identified trends to help with modeling species richness at a large spatial scale. We performed geostatistical analyses based on spatial autocorrelation – cokriging models – to interpolate estimated species richness over the entire country, providing an opportunity to predict species-rich areas. We further compared species richness obtained with this method to species and rarity richness obtained using a national atlas of breeding birds. Estimated species richness was higher in species richness hotspots identified by the atlas. Combining informations on rare species from Atlas and species richness estimates from sound sampling based schemes should help with identifying species-rich areas for various taxa and locating biodiversity hotspots to be protected as high conservation value areas, especially in temperate zones where diversity hotspots are likely to match centers of high species richness because of very few centers of true endemicity.     

Species richness and complementarity of beetle faunas in a mediterranean-type biodiversity hotspot

Regions of mediterranean-type climate represent most extra-tropical biodiversity hotspots, being both highly diverse and highly endangered. Though renowned for their plant richness, these regions’ insects constitute the bulk of their alpha diversities. Data on insect distribution and rarity are generally lacking for such regions, and are often considered unattainable. Intensive field inventories combined with statistical extrapolation methods can provide a sufficient understanding of alpha, beta, and gamma diversity components for application to conservation planning. These are essential to assessing the adequacy of a regional reserve network for the conservation of insect diversity. Here the beetle faunas of three protected areas spanning three major ecoregions in the California Floristic Province were inventoried and analyzed for species richness, complementarity, and uniqueness. These surveys produced collectively nearly 1,200 species from all three sites, estimated to be about 80% of their total faunas. Diversity was highly partitioned among sites, no one site containing more than 60% of the species. Dissimilarity was moderate to high for all comparisons, and all sites contained >40% unique species. Comparison of these results with those based on species of co-occurring plants reveal incongruent species richness but congruent similarities among sites. These results provide quantitative support to the perception that mediterranean insect faunas show high spatial variability. Along with online specimen level data on distribution, rarity, and seasonality, these results will help speed the incorporation of insect data into serious conservation planning.     

Integrating the Rabinowitz rarity framework with a National Plant Inventory in South Korea

Increasingly large presence‐only survey datasets are becoming available for use in conservation assessments. Potentially, these records could be used to determine spatial patterns of plant species rarity and endemism. We test the integration of a large South Korean species record database with Rabinowitz rarity classes. Rabinowitz proposed seven classes of species rarity using three variables: geographic range, habitat specificity, and local population size. We estimated the range size and local abundance of 2,215 plant species from species occurrence records and habitat specificity as the number of landcover types each species’ records were found in. We classified each species into a rarity class or as common, compared species composition by class to national lists, and mapped the spatial pattern of species richness for each rarity class. Species were classed to narrow or wide geographic ranges using 315 km, the average from a range size index of all species (D_max), based on maximum distance between observations. There were four classes each within the narrow and wide range groups, sorted using cutoffs of local abundance and habitat specificity. Nationally listed endangered species only appeared in the narrow‐range classes, while nationally listed endemic species appeared in almost all classes. Species richness in most rarity classes was high in northeastern South Korea especially for species with narrow ranges. Policy implications. Large presence‐only surveys may be able to estimate some classes of rarity better than others, but modification to include estimates of local abundance and habitat types, could greatly increase their utility. Application of the Rabinowitz rarity framework to such surveys can extend their utility beyond species distribution models and can identify areas that need further surveys and for conservation priority. Future studies should be aware of the subjectivity of the rarity classification and that regional scale implementations of the framework may differ.     

Conservation of Freshwater Biodiversity: a Comparison of Different Area Selection Methods

The biodiversity of freshwater systems is endangered, especially in Mediterranean semiarid areas such as the south east of the Iberian Peninsula, whose rich and endemic biota is threatened by the development of surrounding land-crop irrigation. For this reason, the prioritization of areas for biodiversity conservation is an urgent target. In this study we used data records of water beetles from a province of the southeast of Spain for assessing priority areas for freshwater biodiversity conservation. We compare the performance of various area-selection methods, ranging from scoring procedures to complementarity-based algorithms, which are based on different criteria such as richness, rarity and vulnerability. The complementarity approaches were more efficient than methods using scoring or richness and rarity hotspots for representing conservation targets in a given number of areas and for identifying the minimum set of areas containing all species at least once. Within these, the richness-based algorithm was more efficient than rarity-based algorithm. Crucial target habitats for aquatic biodiversity conservation in the area studied are streams at medium altitude, hypersaline streams, and endorreic and karstic complexes.     

Global diversity of land planarians (Platyhelminthes, Tricladida, Terricola): a new indicator-taxon in biodiversity and conservation studies

Biodiversity conservation requires prioritization of areas for in situ conservation. In that perspective, the present study documents the global diversity of a component of the soil macrofauna, the land planarians, and concerns an exploratory analysis of their possible role as indicators of biodiversity. Diversity is described by three quantitative methods: (1) hotspots of species richness, selecting areas richest in species, (2) hotspots of range-size rarity, identifying areas richest in narrowly endemic species, and (3) complementarity, prioritizing areas according to their greatest combined species richness. The biodiversity measures of species richness and range-size rarity show a great correspondence in the identification of hotspots of diversity; both measures identify the following seven areas as the most biodiverse for land planarians: Sao Paulo, Florianopolis, western Java, Tasmania, Sri Lanka, North Island/New Zealand, and Sydney. It is discussed to what extent the results for the land planarians correspond with those obtained in other studies that assessed biodiversity hotspots for taxa on a global scale. It is noteworthy that land planarians identify a few global hotspots of diversity that generally do not feature, or only have low rankings, in other studies: New Zealand, southeastern Australia, and Tasmania.     

Assessing bee species richness in two Mediterranean communities: importance of habitat type and sampling techniques

The decline of bees has raised concerns regarding their conservation and the maintenance of ecosystem services they provide to bee-pollinated wild flowers and crops. Although the Mediterranean region is a hotspot for bee species richness, their status remains poorly studied. There is an urgent need for cost-effective, reliable, and unbiased sampling methods that give good bee species richness estimates. This study aims: (a) to assess bee species richness in two common Mediterranean habitat types: semi-natural scrub (phrygana) and managed olive groves; (b) to compare species richness in those systems to that of other biogeographic regions, and (c) to assess whether six different sampling methods (pan traps, variable and standardized transect walks, observation plots and trap nests), previously tested in other European biogeographic regions, are suitable in Mediterranean communities. Eight study sites, four per habitat type, were selected on the island of Lesvos, Greece. The species richness observed was high compared to other habitat types worldwide for which comparable data exist. Pan traps collected the highest proportion of the total bee species richness across all methods at the scale of a study site. Variable and standardized transect walks detected the highest total richness over all eight study sites. Trap nests and observation plots detected only a limited fraction of the bee species richness. To assess the total bee species richness in bee diversity hotspots, such as the studied habitats, we suggest a combination of transect walks conducted by trained bee collectors and pan trap sampling.     

Geographic patterns in the distribution of Palearctic songbirds

A database was created of digitized equal area distribution maps of 3,036 phylogenetic species of Palearctic songbirds. Biogeographic patterns are reported for two data sets: (1) including all passeriform bird species reported as breeding within the boundaries of our study map, (2) passeriform species restricted in their distribution to our study region, thus excluding the partly extra-limital taxa. With respect to the data set excluding partly extra-limital taxa, the average range size is 238 grid cells (grid cell area: 4,062 km²). Analysis of the geographic distribution of species richness for the full data set showed several hotspot regions, mostly located in mountainous areas. The index of range-size rarity identified similar hotspot regions as that for species richness, albeit that the range-size rarity de-emphasized the central Siberian hotspot. Range-size rarity hotspots that are not evident on the measure of species richness concern a great number of islands. Much more prominent on the index of range-size rarity are the Atlas Mountains of northern Africa, the Jabal al Akhdar region in NE Libya, and the eastern border of the Mediterranean. Restricting the analysis of geographic variation to the 25% of the species with smallest ranges resulted in a greatly simplified pattern of hotspots. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Contribution of rare and common species to richness patterns at local scales

Several studies have recently reported that common species are more important for species richness patterns than rare species. However, most such studies have been based on broad‐scale atlas data. We studied the contribution of different species occupancy, i.e. number of plots occupied, to species richness patterns emerging from species data in 50 by 50 m plots within six 140–200 ha forests in Norway. The study included vascular plants, lichens, bryophytes, and polypore fungi. We addressed the following questions: 1) are common species more correlated with species richness than rare species? 2) How do occupancy classes combine at various levels of species richness? 3) Which occupancy class is best in identifying the overall most species‐rich sites (hotspots) by sampling? The results showed that rare species were better correlated with species richness than common species when the information content was accounted for, that high species richness was associated with a higher proportion of less frequent species, and that the best occupancy class for local hotspot identification was species present in 10–30% of the plots within a forest. We argue that the observed correlations between overall richness and sub‐assembly richness are primarily structured by the combination of the distributions of species richness and species occupancy. Although these distributions result from general ecological processes, they may also be strongly affected by idiosyncratic elements of the individual datasets caused by the specific environmental composition of a study area. Hence, different datasets collected in different areas may lead to different results regarding the relative importance of common versus rare species, and such effects should be expected on both broad and fine spatial scales. Despite these effects, we suggest that infrequent species will tend to be more strongly correlated to species richness at local scales than at broader scales as a result of more right‐skewed species‐occupancy distributions.     

Geographic discrepancies between global and local rarity richness patterns and the implications for conservation

The emerging interest in the biological and conservation significance of locally rare species prompts a number of questions about their correspondence with other categories of biodiversity, especially global rarity. Here we present an analysis of the correspondence between the distributions of globally and locally rare plants. Using biological hotspots of rarity as our framework, we evaluate the extent to which conservation of globally rare plants will act as a surrogate for conservation of locally rare taxa. Subsequently, we aim to identify gaps between rarity hotspots and protected land to guide conservation planning. We compiled distribution data for globally and locally rare plants from botanically diverse Napa County, California into a geographic information system. We then generated richness maps highlighting hotspots of global and local rarity. Following this, we overlaid the distribution of these hotspots with the distribution of protected lands to identify conservation gaps. Based on occupancy of 1 km² grid cells, we found that over half of Napa County is occupied by at least one globally or locally rare plant. Hotspots of global and local rarity occurred in a substantially smaller portion of the county. Of these hotspots, less than 5% were classified as multi-scale hotspots, i.e. they were hotspots of global and local rarity. Although, several hotspots corresponded with the 483 km² of protected lands in Napa County, some of the richest areas did not. Thus, our results show that there are important conservation gaps in Napa County. Furthermore, if only hotspots of global rarity are preserved, only a subset of locally rare plants will be protected. Therefore, conservation of global, local, and multi-scale hotspots needs serious consideration if the goals are to protect a larger variety of biological attributes, prevent extinction, and limit extirpation in Napa County.     

Continental scale patterns of biodiversity: can higher taxa accurately predict African plant distributions?

The distribution maps of a total of 3563 species, which represent 8.9% of the known African angiosperm flora, were entered into cells representing a one-degree latitude–longitude grid of Sub-Saharan Africa. The computer programme WORLDMAP was used to explore continental scale patterns of biodiversity. The maps were used to assess the use of higher taxa as a surrogate measure for predicting patterns of species richness. Genera were found to predict species richness distributions most closely, with higher taxa (families, orders, subclasses) exhibiting progressively worse correlations. However in two areas, the Cape Region of South Africa and coastal Cameroon, there was a higher species to genus ratio than in other areas of Africa. In the Cape Region this meant that generic richness failed to predict species richness. Hotspots, defined as the 5% of grid cells with the highest scores for richness and range-size rarity, were identified for species and higher taxa. Whilst a high percentage of species richness hotspots were predicted by higher taxa, there were important exceptions like the Cape Region. Species range-size rarity hotspots were not well predicted by higher taxa. Hotspots of higher taxa (families and orders) do not therefore accurately predict the location of species hotspots. Higher taxa appear to provide a powerful and accurate tool that can be used to predict large scale patterns of species biodiversity in Sub-Saharan Africa. However care must be taken when using taxa higher than genera, especially if selecting areas of highest conservation priority. The special case of the Cape Region indicates the danger of extending predictive generalizations as the ecological mechanisms that promote and retain species may not be the same in all places. © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 138 , 225–235.     

Assessing stream dwelling caddisfly assemblages (Insecta: Trichoptera) collected by light traps in Hungary

In the present study the conservation status of light trap-collected stream dwelling caddisfly assemblages was evaluated on the basis of original data and also from the literature representing different regions in Hungary. Altogether the catches of eight complete seasons were compared. Species richness, diversity and endangerment indices as well as a newly introduced rarity index (RI) expressing the average rarity of the collected species in Hungary were calculated to evaluate the conservation status of the streams in the Bakony, Börzsöny and Bükk Mountains and in the Zala Hills. The results highlight the importance of streams in maintaining endangered species of caddisfly in Hungary and bring to attention the fact that species richness or diversity are not necessarily the best indicators of conservation status of caddisfly assemblages. Indicators, for instance RI, which take into consideration the general rarity of the species seem to reflect more sharply conservation status and thus are more appropriate for the assessment of caddisfly assemblages.     

Topographic Heterogeneity Plays a Crucial Role for Grasshopper Diversity in a Southern African Megabiodiversity Hotspot

Topographic heterogeneity as a determinant of insect diversity pattern has been little studied. Responses of grasshopper assemblages to three hill sizes were assessed in the arid Succulent Karoo, South Africa. This area is one of the world’s 25 hotspots for conservation priorities. Small hills overall were more speciose than medium or large hills. There were also significantly higher densities of small-sized grasshoppers on small hills than on medium or large ones. The slopes of the three hill sizes did not differ significantly either in their species richness or abundance, and there was no significant difference in species richness between summits only of the three hill sizes. Patterns of grasshopper species dominance were markedly variable among sites, but with clear differences between small and larger hills, associated with vegetation characteristics. Vegetation cover and grass cover was less on the small hills. Grasshopper taxonomic groups varied among the three hill sizes, with small hills being taxonomically more diverse, supporting species from four families and nine subfamilies, while medium and large hills only supported Acrididae. It is concluded that topography has a remarkably strong effect on various aspects of grasshopper spatial heterogeneity and that small hills in particular are a major factor to consider in spatial conservation planning.     

Geographic distribution,conservation effectiveness,and gaps for national key protected wild plants in China

National key protected wild plants (NKPWPs) are species with important conservation value based on genetics, ecology, culture, and/or scientific research, which are also confronted with serious threats. However, their geographical distribution patterns and conservation status remain unclear. In this study, we compiled 1032 species of NKPWPs. We measured the diversity to identify hotspots of NKPWPs based on species richness, weighted range size rarity and a complementarity-based analysis. Comparing the distribution and hotspots of NKPWPs with the coverage of Chinese nature reserves (NRs), we assessed conservation effectiveness and identified conservation gaps. The results identified 13 diversity hotspots; only 9.5% of them were covered by NRs with >30% of the grid cell area, and even 19.5% were not covered at all by NRs. Overall, 44.7% of NKPWPs were effectively protected by national NRs. Despite this success, 571 species in Yunnan, Guizhou, Sichuan, Chongqing, Guangxi, Guangdong, southern Hainan, Taiwan, and northern Xinjiang remain unprotected by NRs. The protected proportion of plants with first-level protection was lower than that of plants with second-level protection. The low overall proportion of protected hotspots indicates that the conservation outlook for NKPWPs is not optimistic. This study identifies priority conservation areas and conservation gaps and provides a scientific reference for the conservation of wild plants in China.     

Will hotspots conserve extra primate and carnivore evolutionary history?

Setting aside biodiversity hotspots would be especially compelling if they contained not just enormous numbers of species but also excessive evolutionary history. A recent study seemed to provide evidence for this incentive for hotspot conservation. Sechrest et al . (2002 ) reported that hotspots contain more endemic phylogenetic diversity (PD) than expected based on the numbers of primate and carnivore species they contain. We extend their analysis and revise some of their claims. For primates and threatened carnivores, we show that the original analysis was driven by a single hotspot (Madagascar) that contains an ancient endemic clade. The remaining hotspots harbour less rather than significantly more endemic PD than expected. Thus, while one hotspot contains an enormous excess of evolutionary history, the remaining hotspots do not. Our analysis reveals that the overriding influence of a single hotspot can create the misleading impression that hotspots generally contain excessive evolutionary history. Justification for the hotspot initiative should be based on robust evidence. We join others in endorsing an increased role for detailed phylogenetic analysis in conservation planning.