Application of a numerical algorithm to the selection of reserves in semi-arid New South Wales

An iterative analysis was used to identify the number and area of pastoral properties needed to contain the full range of natural environments (land systems) in part of western New South Wales. A minimum of 32 properties (3·1% of total number) and 7980 km² (5·7% of total area) was required to represent every land system at least once. Full representation required a greater overall number and area when the analysis began with properties already acquired for conservation. Excluding land systems atypical of the study area did not greatly reduce the number and area of properties required. Complete representation of land systems in each geographical subdivision in which they occur required a much greater overall number and area of properties than when the analysis was run for the study area as a whole. The algorithm used in this study produced very similar results to other iterative analyses applied to reserve selection in Australia.     

Assessing critical habitat: Evaluating the relative contribution of habitats to population persistence

A principal challenge of species conservation is to identify the specific habitats that are essential for long-term persistence or recovery of imperiled species. However, many commonly used approaches to identify important habitats do not provide direct insight into the contribution of those habitats to population persistence. To assess how habitats contribute to overall population viability and characterize their relative importance, a spatially-explicit population viability model was used to integrate a species occurrence model with habitat quality and demographic information to simulate the population dynamics of the Ord’s kangaroo rat (Dipodomys ordii) in Alberta, Canada. Long-term productivity (births-deaths) in each patch was simulated and iterative patch removal experiments were conducted to generate estimates of the relative contribution of habitat types to overall population viability. Our results indicated that natural dune habitats are crucial for population viability, while disturbed/human-created habitats make a minor contribution to population persistence. The results also suggest that the habitats currently available to Ord’s kangaroo rats in Alberta are unlikely to support long-term persistence. Our approach was useful for identifying habitats that did not contribute to population viability. A large proportion of habitat (39%) represented sinks and their removal increased estimated population viability. The integration of population dynamics with habitat quality and occurrence data can be invaluable when assessing critical habitat, particularly in regions with variable habitat quality. Approaches that do not incorporate population dynamics may undermine conservation efforts by under- or over-estimating the value of habitats, erroneously protecting sink habitats, or failing to prioritize key source habitats.     

A comparison of constructed and natural habitat for frog conservation in an Australian agricultural landscape

Constructed ponds are an important consideration in the conservation of wetland biota in agricultural landscapes. Twenty-two natural ponds and 22 adjacent constructed ponds (farm dams) were surveyed on the Southern Tablelands of New South Wales to compare patterns of use by frogs and develop frog conservation recommendations. Farm dams supported similar numbers of frog species to natural ponds, although differences in frog assemblage were observed between the pond types. Limnodynastes tasmaniensis and Uperolia laevigata were significantly more likely to occur at farm dams while L. peronii was more likely to occur at natural ponds. Results suggest waterbodies with high levels of emergent vegetation cover that lack fish are likely to support a high number of frog species, regardless of origin (i.e. natural or constructed). However, it is important for landholders to conserve natural waterbodies as these environments appear likely to support frog species that do not use farm dams.     

Ecological analyses of carabid communities— potential use in biological classification for nature conservation

Because insects have an important role in ecosystems, they should be included in any classification regarding the conservation of natural resources. On a basis of pitfalltrap captures, a scheme for utilising such information about carabid communities in a classification of habitats is proposed. Habitats can, to some extent, be classified according to characteristic species or species groups, but analyses of degrees of similarity and calculations of species diversity values are also necessary to provide a more exact documentation of the conservation value of different habitats. The information obtained has made a valuable contribution to existing habitat classification systems.     

Uncertainty in coarse conservation assessments hinders the efficient achievement of conservation goals

Conservation planning is sensitive to a number of scale-related issues, such as the spatial extent of the planning area, or the size of units of planning. An extensive literature has reported a decline in efficiency of conservation outputs when planning at small spatial scales or when using large planning units. However, other key issues remain, such as the grain size used to represent the spatial distribution of conservation features. Here, we evaluate the effect of grain size of species distribution data versus size of planning units on a set of performance measures describing efficiency (ratio of area where species are represented/total area needed), rate of commission errors (species erroneously expected to occur), representativeness (proportion of species achieving the target) and a novel measure of overall conservation uncertainty (integrating commission errors and uncertainty in the actual locations where species occur). We compared priority areas for the conservation of freshwater fish in the Daly River basin (northern Australia). Our study demonstrates that the effect of grain size of species distribution data was more important than planning unit size on conservation planning performance, with an increase in commission errors up to 80% and conservation uncertainty over 90% when coarse data were used. This was more pronounced for rare than common species, where the mismatch between coarse representations of biodiversity patterns and the smaller areas of actual occupancy of species was more evident. Special attention should be paid to the high risk of misallocation of limited budgets when planning in heterogeneous or disturbed environments, where biodiversity is patchily distributed, or when planning for conservation of rare species.     

An indicator species approach for result-orientated subsidies of ecological services in grasslands - A study in Northwestern Germany

Agri-environmental subsidies for grasslands of high conservation interest are usually associated with fairly strict management rules, but have not always been successful in terms of the preservation of species. A new approach now links the subsidies paid to the ecological value of a grassland site: the farmers are paid for keeping up a high plant species richness, and they can control the species richness of their sites by using vascular plants as indicator species. The method was tested in different grassland communities in six regions of Lower Saxony in Northwestern Germany, mainly addressing the question whether the number of selected indicator species was correlated with the total species richness of vascular plants and with the number of endangered species.Field work was carried out in 2004. Total species richness of vascular plants was recorded in all grassland sites, and the number of indicators was counted along two transects, usually being the diagonals of a rectangular site. Each transect was divided into three segments in which all indicators growing within 1 m distance from the transect line were recorded. In total 43 indicators were selected, mostly representing species that are fairly easy to recognise.The number of indicators was significantly positively correlated with the total number of species in all regions, also when correcting for autocorrelation (except in one region). When using grassland area as a co-variable, the same results were obtained, supporting the low significance of grassland size for the predictive ability of the method. In all regions but one, the mean number of indicators per segment was also significantly positively related to the number of red-listed and near-threatened species in the grasslands. Grassland size and transect length were found to be of minor importance for the application of the method.In conclusion, the study shows that the indicator approach is suitable for identifying those grassland sites that have a high plant species richness and a high number of endangered species. It may thus form the basis for result-orientated subsidies in grasslands.     

Priority areas for the conservation of coastal marine vertebrates in Chile

In the past decade, there has been growing concern about the rapid degradation of marine ecosystems due to anthropogenic causes. Consequently, identifying priority areas for the conservation of marine biodiversity has become a crucial conservation issue. Taking into account the influence of human population density, we performed complementarity analyses to identify priority areas for the conservation of all coastal marine vertebrate species in Chile (265 species), and evaluated congruence among the different target groups. The distribution ranges of all species were digitized in a geographic information system and analyses were performed on latitudinal bands of 0.5°. Our results show that 12 latitudinal bands (∼16% of all latitudinal bands) are necessary to conserve at least one population of each species. Ten of these bands are irreplaceable, whereas two are flexible. Many of the irreplaceable sites lie within areas that have high human population density. In order to conserve all threatened and endemic species, six and three latitudinal bands are needed, respectively. Four latitudinal bands are needed to represent all species of fish, reptiles, and mammals, whereas nine bands are needed to protect all bird species. Taking flexible sites into account, reserve networks that meet the minimum representation goal for each taxonomic group, and for threatened and endemic species, represent subsets of the 12 latitudinal band network selected for all species. Spatial congruence among reserve networks selected for each target group was relatively low and only significantly higher than random in 9 out of 21 pairwise comparisons. However, with the exception of reptiles, conservation areas selected for different surrogate groups represented other groups relatively well, compared to randomly selected sites.     

Captive breeding genetics and reintroduction success

Since threatened species are generally incapable of surviving in their current, altered natural environments, many conservation programs require to preserve them through ex situ conservation techniques prior to their reintroduction into the wild. Captive breeding provides species with a benign and stable environment but has the side effect to induce significant evolutionary changes in ways that compromise fitness in natural environments. I developed a model integrating both demographic and genetic processes to simulate a captive-wild population system. The model was used to examine the effect of the relaxation of selection in captivity on the viability of the reintroduced population, in interaction with the reintroduction method and various species characteristics. Results indicate that the duration of the reintroduction project (i.e., time from the foundation of the captive population to the last release event) is the most important determinant of reintroduction success. Success is generally maximized for intermediate project duration allowing to release a sufficient number of individuals, while maintaining the number of generations of relaxed selection to an acceptable level. In cases where a long residence time in captivity cannot be avoided, the use of distinct, genetically independent captive breeding units allows more efficient purging of the genetic load in the reintroduced population, and substantially improves its viability. Overall, the study allows to identify situations in which the genetic cost associated with selection relaxation may overwhelm the demographic benefits of programs.     

Isolation and edge effects among woodland key habitats in Sweden: Is forest policy promoting fragmentation?

Fragmentation of natural forests is a major threat to forest biodiversity. In areas with a long history of forestry, the remaining patches of old forests constitute only a minor part of the landscape. In such situations small stands may be valuable and important for conservation. However, as they may suffer from strong edge effects and isolation, their value may be lower than anticipated. In Sweden a national inventory of woodland key habitats (WKHs) has identified about 1% of the forest landscape as sites where red-listed species occur or may occur. Most are small (national median 1.4 ha) and isolated stands within an intensively managed landscape. The present analyses calculate WKH core area based on a range of depths of edge influence, and isolation based on both distance to nearest WKH and a weighted isolation measure that includes all neighboring WKHs and protected forest. These analyses are done on the WKHs in Norrbotten County in northern Sweden and include almost 5000 stands. The actual core area in the WKHs is about 30% given a 50 m edge influence. The degree of isolation is species dependent but the results indicate that only species with high dispersal abilities may effectively utilize the network of WKHs. For species with effective dispersal distances of less than 2 km the network is probably insufficient. The results emphasize the need to create buffer zones, to increase reserve areas and to manage the matrix so that species dispersal is promoted. This likely includes a necessity to aggregate biodiversity efforts on the landscape scale.     

Endemism and evolutionary history in conflict over Madagascar’s freshwater conservation priorities

Regional-scale biodiversity indicators provide important criteria for the selection of protected areas in conservation, but their application is often hindered by a lack of taxonomic knowledge. Moreover, different indicators include different types of information, sometimes leading to divergent conservation priorities. Madagascar tops the world list of biodiversity hotspots and much conservation effort has been directed toward its threatened plants and vertebrates. In contrast, its highly diverse freshwater invertebrate fauna has received comparatively little conservation attention. We conducted an inventory of Malagasy adephagan water beetles (Coleoptera, Dytiscidae, Noteridae, Gyrinidae, Haliplidae) using a combined morphological and molecular approach. In total, 2043 beetles from 153 sites were sequenced for cytochrome oxidase subunit I (cox1), and species delimitation was carried out using the coalescent-based GMYC model. Phylogenetic relationships of the resulting entities were established using cox1 combined with partial 16S rRNA and 28S rRNA sequences. Ten national parks were assessed for their species richness, phylogenetic diversity (PD) and endemism. We were particularly interested in the contribution of endemic species to PD. Congruence between molecular and taxonomic identifications was high (91%), with 69% of sampled species endemic to Madagascar. Interestingly, we found that PD at a site was negatively correlated to the proportion of endemic species, most likely because endemics are the result of recent radiations with relatively little branch-length contribution to the measure of PD. This suggests that ranking sites for conservation priority based solely on PD potentially disfavor endemic species by underrating areas where the evolutionary process is most active.     

Does size matter? The relationship between pond area and biodiversity

Larger areas support more species. To test the application of this biogeographic principle to ponds, we consider the relationship between size and diversity for 80 ponds in Switzerland, using richness (number of species) and conservation value (score for all species present, according to their degree of rarity) of aquatic plants, molluscs (Gastropoda, Sphaeriidae), Coleoptera, Odonata (adults) and Amphibia. Pond size was found to be important only for Odonata and explained 31% of the variability of their species richness. Pond size showed only a feeble relationship with the species richness of all other groups, particularly the Coleoptera and Amphibia. The weakness of this relationship was also indicated by the low z-values obtained (< 0.13). The SLOSS analyses showed that a set of ponds of small size has more species and has a higher conservation value than a single large pond of the same total area. But we also show that large ponds harbour species missing in the smaller ponds. Finally, we conclude that in a global conservation policy (protection, restoration, management), all size ranges of ponds should be promoted.     

Status and distribution of stipitate hydnoid fungi in Scottish coniferous forests

Stipitate hydnoid fungi (specifically members of the genera Bankera, Hydnellum, Phellodon, Sarcodon) have become the focus of increasing conservation concern, particularly following the detection of widespread declines in abundance. To assess their status in Scotland, 103 field surveys were undertaken, including searches of 50 of the 77 native pinewood sites, traversing a total of 902 km. Hydnoid fungi were encountered on 30 of the searches (29%), primarily in eastern regions of Scotland. A maximum of 8 species was recorded on a single search, 11 species being encountered in total. Of 22 plantation sites surveyed, 11 were found to contain populations of hydnoid fungi. Four species were relatively widespread, both in native woodlands and plantations: Bankera fuligineoalba, Hydnellum peckii, Phellodon tomentosum, and Sarcodon imbricatus. All species tended to be associated with particular microsites, especially riverbanks, tracksides or areas of exposed mineral soil; median values for percentage bare ground cover surrounding each sporome were generally above 50%. Median values for diameter at breast height (dbh) of associated trees were in the range 20-50 cm for all species. Data from the field surveys were pooled with previous records to assess the number of hydnoid species recorded for each native pine woodland. When examined by regression, a positive relationship was recorded between the number of species and woodland area (r²=0.69, P<0.001, n=50). To assess the occurrence of declines, the number of 10 km gridsquares for each species was compared using records made pre- and post-1970. These data provided evidence for declines in only four of the 17 species considered. However, 12 species are threatened with extinction according to the IUCN Red List criteria, owing to their restricted patterns of distribution. The implications of these results for the conservation of hydnoid fungi in Scotland are discussed.     

Habitat requirements of the endangered pygmy bluetongue lizard, Tiliqua adelaidensis

The pygmy bluetongue lizard, Tiliqua adelaidensis, occupies spider burrows as home sites. It is an endangered species, known from only 19 small natural grassland sites in the mid-north of South Australia, all on privately owned land. Habitat requirements of the pygmy bluetongue lizard were investigated at four sites. Both within and between sites, lizards were more likely to be found in areas with a greater number of deep spider burrows. Areas where lizards were not found tended to lack these burrows. Strong site similarities were found for a range of habitat parameters examined. Within these grasslands there was no specific vegetation community associated with areas occupied by pygmy bluetongue lizards. However there was a distinct vegetation community associated with an absence of lizards. Generally there was no difference in the abundance and diversity of ground dwelling invertebrates between areas with and without lizards. As the only protected area of natural grassland within the known distribution, Mokota Conservation Park was assessed as a potential reintroduction site. It was found to be unsuitable due to a low number of deep spider burrows and a vegetation community similar to that found in uninhabited areas of known lizard inhabited sites. Unless other conservation areas can be established, preservation of this lizard will rely on habitat management by private land holders. Community goodwill and informed advice to the land holders will be essential in this process.     

Public understanding of protected area designation

Protected areas have a central role to play in educating people about biodiversity and nature conservation. However, there is little evidence regarding how effective public education efforts related to protected areas have been. We used on-site questionnaires at Sites of Special Scientific Interest to determine whether visitors to sites were aware of their protected status. Less than one-third of visitors knew the site they were visiting was a SSSI. However, there was substantial variation in understanding across sites (8-43%). When we compared this variation to five possible predictor variables, only membership of conservation organisations was retained in all models in the 95% confidence set, with members of these groups being better informed about protected area designations. However, the predictive power of all models was low. These results represent a challenge for those aiming to reengage people with conservation and the countryside, and to educate them about its value and contribution.     

Do epiphytic orchids behave as metapopulations? Evidence from colonization, extinction rates and asynchronous population dynamics

Previous in situ studies of orchid population dynamics with conservation relevance have focused on one or a few populations in a limited area. Many species of orchids occur as hyperdispersed populations in ephemeral habitats (epiphytic, twig epiphytes, short lived or vulnerable host). In this contribution, we show that orchid populations that are patchily distributed and that exist in disturbance-prone environments may act somewhat like a metapopulation with high turnover and low correlation in population dynamics. We tested for evidence of metapopulation dynamics in the riparian orchid Lepanthes rupestris by sampling over 1000 sites (250 initially occupied, 750 initially unoccupied) in biannual surveys for 5 years. Extinction and colonization of groups of orchids on a single substrate or patch (either trees or boulders) was common and more or less consistent across different time periods, and asynchronous subpopulation dynamics were evident among the populations. From this we predict non-zero equilibrium values for site occupancy () of L. rupestris. Nevertheless, this study species differed from a typical Levins’ metapopulation system in that small populations were more likely to go extinct than large populations, and that colonization of previously occupied sites was more common than colonization of initially unoccupied sites suggesting that site quality may influence population persistence and colonization. A major difficulty applying the metapopulation approach to orchid conservation is identifying empty sites suitable for colonization. In spite of this limitation, our study highlights the necessity of following multiple orchid subpopulations (e.g., an entire orchid “metapopulation” in the broad sense) may provide a more accurate basis for predicting persistence in epiphytic orchids.     

Incorporating connectivity into conservation planning: A multi-criteria case study from central Mexico

The interdigitation of the Nearartic and Neotropical biogeographic zones in the Transvolcanic Belt (TVB) of central Mexico provides the region with high faunal richness and endemicity. Biodiversity conservation in the TVB must accommodate the region’s human population of more than 40 million. The current study presents conservation plans for the TVB intended to protect 99 non-volant mammal species while minimizing the impact on the human population. A rarity-complementarity algorithm was used to select a conservation area network (CAN) from sites with untransformed vegetation to represent 10% of each species’ habitat. In addition, a new method was developed for augmenting the connectivity of CANs using graph theory. External sites were assigned quality scores based on the frequency with which they were selected at different targets of representation for species. Graph algorithms identified the highest-quality sites needed to link all conservation areas in an economical manner. These connectivity areas can facilitate migration or egress of biota in the event of local environmental stress. The network initialized with existing protected areas occupied 9.13% of the TVB, whereas the network built from scratch occupied 6.02%. In both cases, an additional area of only about 1.5% of the region was required to link all conservation areas in the network. Finally, a multiple criterion synchronization technique was used to select those connected networks which minimized both total area and human population impact.     

Prioritisation of conservation areas in the Western Ghats, India

Areas of high conservation value were identified in the Western Ghats using a systematic conservation planning approach. Surrogates were chosen and assessed for effectiveness on the basis of spatial congruence using Pearson’s correlations and Mantel’s tests. The surrogates were, threatened and endemic plant and vertebrate species, unfragmented forest areas, dry forests, sub-regionally rare vegetation types, and a remotely sensed surrogate for unique evergreen ecosystems. At the scale of this analysis, amphibian richness was most highly correlated with overall threatened and endemic species richness, whereas mammals, especially wide-ranging species, were better at capturing overall animal and habitat diversity. There was a significant relationship between a remote sensing based habitat surrogate and endemic tree diversity and composition. None of the taxa or habitats served as a complete surrogate for the others. Sites were prioritised on the basis of their irreplaceability value using all five surrogates. Two alternative reserve networks are presented, one with minimal representation of surrogates, and the second with 3 occurrences of each species and 25% of each habitat type. These networks cover 8% and 29% of the region respectively. Seventy percent of the completely irreplaceable sites are outside the current protected area network. While the existing protected area network meets the minimal representation target for 88% of the species chosen in this study and all of the habitat surrogates, it is not representative with regard to amphibians, endemic tree species and small mammals. Much of the prioritised unprotected area is under reserve forests and can thus be incorporated into a wider network of conservation areas.     

On species richness and nature reserve design: An empirical study of UK woodland avifauna

The numbers and turnover of breeding bird species are compared for sets of 5, 3,2 and 1 similar UK woodland sites, each set having the same total area. Five small (8 ha) sites support the largest total number of species, though it is argued on theoretical grounds that this result may be scale-dependent. Species turnover is lowest for the set of five small sites and hence their overall species composition will be more predictable in time. An attempt is made to predict the expected number of species remaining in sites that act as refuges in the absence of an external species pool; the data indicate that one large refuge may come to retain more species than several smaller refuges as extinctions occur, provided that the refuges are effectively isolated from one another. The implications for avifaunal conservation are discussed, with emphasis on the need for an empirical approach to evaluating nature reserve design options.     

Spatial variation in anthropic and natural factors regulating the breeding success of the cinereous vulture (Aegypius monachus) in the SW Iberian Peninsula

The management of the cinereous vulture (Aegypius monachus) populations, the largest bird of the Western Palæarctic and considered an umbrella species, requires the understanding of the factors limiting the breeding success. As part of a management program, we studied such factors in seven breeding colonies in Extremadura (SW Iberian Peninsula). Using a Geographic Information System and multivariate models, we analyzed the relationship of breeding success with anthropic and natural factors at the nest site and in the foraging area of the adults. We incorporated into the models density-dependent effects between pairs and the spatial autocorrelation of the environmental variables. The differences in breeding success resulted from spatial variations in natural and anthropic conditions, with present human disturbance to nests and future alteration of climate having an expected negative effect at all the sites. Management measures must set calendar restrictions for the immediate environment of the nests, mainly with respect to forestry and hunting activities. A second key element is the protection of the habitats at the nest sites and in their surrounding area, with the aim of there being both wooded areas available for the location of the nest and open environments for the availability of food. The Special Protection Areas showed a partial effectiveness of conservation measures for the species, and the need for future improvement. Lastly, in a scenario of global warming, management policies with respect to nesting habitats will have to be extended to higher altitude zones, actions that should be guided by the study of the selection of potential nesting habitat.     

Threats to dragonflies on land islands can be as great as those on oceanic islands

We ask whether oceanic islands and equivalent-sized continental blocks, which we call here ‘land islands’, are similar or not in their species richness, number of range-restricted species, and in number of threatened species. We used sites in southern Africa and islands in the Western Indian Ocean. We chose dragonflies as they are taxonomically tractable, well surveyed, and provide a range of characteristics from narrow-range endemics to widely-spread and vagile opportunists. We then selected as many oceanic islands as possible where there were sufficient data to make comparisons with land islands of a similar area in African savanna, grassland and mountains rich in endemic species. Generalized Linear Mixed Models were used to analyse the overall, range-restricted and threatened species richness for all islands (both oceanic and land) and then for the two types of island separately. Species richness increased with island size, with oceanic and land island size relationships being similar. Land islands overall had significantly more range-restricted species. Species on land islands were as threatened as those on oceanic islands. However, the land islands of the Western Cape were under a higher level of threat than oceanic islands of comparative size. The large islands of Madagascar and Sri Lanka were outliers with very high levels of threat. Translated into conservation, the results illustrate that over-generalizations about island faunas being more threatened than continental ones are not necessarily valid. While not wishing to draw attention away from the urgent conservation action needed on many tropical islands, we argue that comparisons of oceanic versus land islands detract from the more urgent task of local conservation action based on the special needs of any particular area, whether land or oceanic. It is more meaningful to establish how threats operate and how to mitigate them on small populations rather than focusing purely on any particular island type per se.