Effectiveness of Biodiversity Surrogates for Conservation Planning: Different Measures of Effectiveness Generate a Kaleidoscope of Variation

Abstract

Conservation planners represent many aspects of biodiversity by using surrogates with spatial distributions readily observed or quantified, but tests of their effectiveness have produced varied and conflicting results. We identified four factors likely to have a strong influence on the apparent effectiveness of surrogates: (1) the choice of surrogate; (2) differences among study regions, which might be large and unquantified (3) the test method, that is, how effectiveness is quantified, and (4) the test features that the surrogates are intended to represent. Analysis of an unusually rich dataset enabled us, for the first time, to disentangle these factors and to compare their individual and interacting influences. Using two data-rich regions, we estimated effectiveness using five alternative methods: two forms of incidental representation, two forms of species accumulation index and irreplaceability correlation, to assess the performance of ‘forest ecosystems’ and ‘environmental units’ as surrogates for six groups of threatened species—the test features—mammals, birds, reptiles, frogs, plants and all of these combined. Four methods tested the effectiveness of the surrogates by selecting areas for conservation of the surrogates then estimating how effective those areas were at representing test features. One method measured the spatial match between conservation priorities for surrogates and test features. For methods that selected conservation areas, we measured effectiveness using two analytical approaches: (1) when representation targets for the surrogates were achieved (incidental representation), or (2) progressively as areas were selected (species accumulation index). We estimated the spatial correlation of conservation priorities using an index known as summed irreplaceability. In general, the effectiveness of surrogates for our taxa (mostly threatened species) was low, although environmental units tended to be more effective than forest ecosystems. The surrogates were most effective for plants and mammals and least effective for frogs and reptiles. The five testing methods differed in their rankings of effectiveness of the two surrogates in relation to different groups of test features. There were differences between study areas in terms of the effectiveness of surrogates for different test feature groups. Overall, the effectiveness of the surrogates was sensitive to all four factors. This indicates the need for caution in generalizing surrogacy tests.

Spatial Conservation Prioritization in Data-Poor Areas of the World

“…If known benefits are low but uncertainty is favorably biased, there is scope for positive surprises -this could be the case of poorly surveyed areas. Dozens of very different conservation strategies have been proposed in scientific literature, including such as "increase connectivity", "translocate species", "practice adaptive management", "study responses of species to climate change", and so on (Heller & Zavaleta 2009) Surrogacy is a major theme in conservation biology (Cabeza et al 2008;Grantham et al 2010). It is essentially about the investigation of the co-occurrence of biodiversity features, aiming to use distributions of easily observable features as surrogates for those features for which distribution information is not available and cannot be modeled.…”

Distinction between effective pattern-based and selection-based biodiversity surrogates is essential: caveats for managers

“…In these types of applications, these surrogates are used as statistical 'predictors' or 'indicators' of other biodiversity features (for which data are limited). Such surrogates have recently been described as 'pattern-based surrogates' (Grantham et al 2010).…”

“…It would then be compared to a reference scenario targeting the inclusion of all recorded species into the system. There are different methods to assess the effectiveness of selection-based surrogates, all based on a comparison between the ability of the design method to include the feature(s) of interest in the system when using the surrogate and when using the specified reference (see Grantham et al 2010 for a description of the main methods). Typically, if the habitat-based reserve system includes a similar number of species within a similar number of protected units in the set of reserves, compared to the speciesbased reserve system, the habitat can be considered an efficient surrogate of total biodiversity from a conservation planning standpoint.…”

“…In most cases, these prioritization methods are selection or optimization algorithms ). Such surrogates are known as 'selection-based surrogates' (Grantham et al 2010).…”

Cross-taxon congruence in the rarity of subtidal rocky marine assemblages: No taxonomic shortcut for conservation monitoring

“…Biodiversity 61 surrogates fall in two main categories (Grantham et al, 2010): environmental surrogates, which 62 use a combination of physical and biological data to estimate or predict biodiversity, and 63 taxonomic surrogates, predominantly based on the use of one or several taxonomic groups to 64 estimate biodiversity. We focus here on the second category, i.e.…”