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Use of Arthropod Rarity for Area Prioritisation : Insights from the Azorean Islands

Publication . Fattorini, Simone; Cardoso, Pedro; Rigal, François; Borges, Paulo A. V.

We investigated the conservation concern of Azorean forest fragments and the entire Terceira Island surface using arthropod species vulnerability as defined by the Kattan index, which is based on species rarity. Species rarity was evaluated according to geographical distribution (endemic vs. non endemic species), habitat specialization (distribution across biotopes) and population size (individuals collected in standardized samples). Geographical rarity was considered at ‘global’ scale (species endemic to the Azorean islands) and ‘regional’ scale (single island endemics). Measures of species vulnerability were combined into two indices of conservation concern for each forest fragment: (1) the Biodiversity Conservation Concern index, BCC, which reflects the average rarity score of the species present in a site, and (2) one proposed here and termed Biodiversity Conservation Weight, BCW, which reflects the sum of rarity scores of the same species assemblage. BCW was preferable to prioritise the areas with highest number of vulnerable species, whereas BCC helped the identification of areas with few, but highly threatened species due to a combination of different types of rarity. A novel approach is introduced in which BCC and BCW indices were also adapted to deal with probabilities of occurrence instead of presence/absence data. The new probabilistic indices, termed pBCC and pBCW, were applied to Terceira Island for which we modelled species distributions to reconstruct species occurrence with different degree of probability also in areas from which data were not available. The application of the probabilistic indices revealed that some island sectors occupied by secondary vegetation, and hence not included in the current set of protected areas, may in fact host some rare species. This result suggests that protecting marginal non-natural areas which are however reservoirs of vulnerable species may also be important, especially when areas with well preserved primary habitats are scarce.

2012-03Journal article

Open access

The seven impediments in invertebrate conservation and how to overcome them

Publication . Cardoso, Pedro; Erwin, Terry L.; Borges, Paulo A. V.; New, Tim R.

Despite their high diversity and importance for humankind, invertebrates are often neglected in biodiversity conservation policies. We identify seven impediments to their effective protection: (1) invertebrates and their ecological services are mostly unknown to the general public (the public dilemma); (2) policymakers and stakeholders are mostly unaware of invertebrate conservation problems (the political dilemma); (3) basic science on invertebrates is scarce and underfunded (the scientific dilemma); (4) most species are undescribed (the Linnean shortfall); (5) the distribution of described species is mostly unknown (the Wallacean shortfall); (6) the abundance of species and their changes in space and time are unknown (the Prestonian shortfall); (7) species ways of life and sensitivities to habitat change are largely unknown (the Hutchinsonian shortfall). Numerous recent developments in taxonomy, inventorying, monitoring, data compilation, statistical analysis and science communication facilitate overcoming these impediments in both policy and practice. We suggest as possible solutions for the public dilemma: better public information and marketing. For the political dilemma: red-listing, legal priority listing and inclusion in environmental impact assessment studies. For the scientific dilemma: parataxonomy, citizen science programs and biodiversity informatics. For the Linnean shortfall: biodiversity surrogacy, increased support for taxonomy and advances in taxonomic publications. For the Wallacean shortfall: funding of inventories, compilation of data in public repositories and species distribution modeling. For the Prestonian shortfall: standardized protocols for inventorying and monitoring, widespread use of analogous protocols and increased support for natural history collections. For the Hutchinsonian shortfall: identifying good indicator taxa and studying extinction rates by indirect evidence.

2011-08-12Journal article

Open access

Macroecological patterns of species distribution, composition and richness of the Azorean terrestrial biota

Publication . Borges, Paulo A. V.; Cardoso, Pedro; Cunha, Regina Tristão da; Gabriel, Rosalina; Gonçalves, Vitor; Hortal, Joaquín; Martins, António M. de Frias; Melo, Ireneia; Rodrigues, Pedro; Santos, Ana M.; Silva, Luís; Triantis, Kostas A.; Vieira, Paulo; Vieira, Virgílio

We investigate the macroecological patterns of the terrestrial biota of the Azorean archipelago, namely the species-range size distributions, the distance decay of similarity, and the island species–area relationship (ISAR). We use the most recent up-to-date checklists to describe the diversity at the island level for nine groups (Lichens, Fungi, Diatoms, Bryophytes, Vascular Plants, Nematodes, Molluscs, Arthropods, Vertebrates). The particularities of the Azorean biota result in some differences to the patterns commonly found in other oceanic archipelagos. Strikingly, bryophytes, molluscs and vertebrates show a bimodal species-range size distribution, and vascular plants a right unimodal distribution due the high numbers of widespread species. Such high compositional homogeneity between islands also results in non-significant or even negative decays of similarity with distance among islands for most groups. Dispersal ability, together with other particular characteristics of each taxon, also shapes these distributions, as well as the relationships between island species richness, and area and time. Strikingly, the degree of departure of the richness of the whole archipelago from the SAR of its constituent islands largely depends on the dispersal ability of each group. Comparative studies with other oceanic archipelagos of the globe are however needed to understand the biogeographical and evolutionary processes shaping the remarkably low diversity of the Azorean biota.

2011-01Journal article

Open access

Patterns of colonization and species distribution for Azorean arthropods: evolution, diversity, rarity and extinction

Publication . Borges, Paulo A. V.; Gaspar, Clara; Santos, Ana M. C.; Ribeiro, Sérvio P.; Cardoso, Pedro; Triantis, Kostas A.; Amorim, Isabel R.

Com base em estudos ecológicos e biogeográficos realizados nos Açores (um arquipélago remoto composto por nove ilhas vulcânicas) durante muitos anos de uma forma continuada, apresentamos um conjunto de questões. O grupo alvo são os artrópodes e o principal habitat é a Laurissilva, a floresta nativa dos Açores. A diversificação das espécies de artrópodes dos Açores é afectada pela idade das ilhas, área das ilhas e seu isolamento. No entanto, os estudos que decorreram durante os últimos dez anos mostram que os vários tipos de grupos taxonómicos e ecológicos são afectados de forma diferente por estes factores, tendo como consequência padrões de distribuição espacial únicos. A distribuição espacial dos artrópodes em cada ilha é causada for "efeitos de massa", muitas espécies possuindo dinâmicas "fonte-sumidouro". As espécies verdadeiramente raras à escala regional são aquelas que são especialistas de um particular habitat, muitas delas sendo espécies endémicas ameaçadas. Embora várias espécies endémicas persistam com populações sumidouro em habitats criados pelo Homem (e.g. florestas exóticas), mais de metade das espécies especialistas da floresta nativa já estão extintas ou poderão extinguir-se no futuro. De facto, aquelas espécies que evoluíram e apenas são encontradas nas florestas nativas foram afectadas de forma dramática como resultado da destruição alargada das florestas nativas dos Açores. Defendemos que a única forma de evitar a extinção de uma fauna única das florestas nativas dos Açores será através de medidas de restauro desta floresta.

2011Journal article

Open access

Integrating Landscape Disturbance and Indicator Species in Conservation Studies

Publication . Cardoso, Pedro; Rigal, François; Fattorini, Simone; Terzopoulou, Sofia; Borges, Paulo A. V.

Successful conservation plans are conditioned by our ability to detect anthropogenic change in space and time and various statistical analyses have been developed to handle this critical issue. The main objective of this paper is to illustrate a new approach for spatial analysis in conservation biology. Here, we propose a two-step protocol. First, we introduce a new disturbance metric which provides a continuous measure of disturbance for any focal communities on the basis of the surrounding landscape matrix. Second, we use this new gradient to estimate species and community disturbance thresholds by implementing a recently developed method called Threshold Indicator Taxa ANalysis (TITAN). TITAN detects changes in species distributions along environmental gradients using indicators species analysis and assesses synchrony among species change points as evidence for community thresholds. We demonstrate our method with soil arthropod assemblages along a disturbance gradient in Terceira Island (Azores, Portugal). We show that our new disturbance metric realistically reflects disturbance patterns, especially in buffer zones (ecotones) between land use categories. By estimating species disturbance thresholds with TITAN along the disturbance gradient in Terceira, we show that species significantly associated with low disturbance differ from those associated with high disturbance in their biogeographical origin (endemics, non-endemic natives and exotics) and taxonomy (order). Finally, we suggest that mapping the disturbance community thresholds may reveal areas of primary interest for conservation, since these may host indigenous species sensitive to high disturbance levels. This new framework may be useful when: (1) both local and regional processes are to be reflected on single disturbance measures; (2) these are better quantified in a continuous gradient; (3) mapping disturbance of large regions using fine scales is necessary; (4) indicator species for disturbance are searched for and; (5) community thresholds are useful to understand the global dynamics of habitats.

2013-05-01Journal article

Open access