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

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

Integrated terrestrial-freshwater planning doubles conservation of tropical aquatic species

Conservation initiatives overwhelmingly focus on terrestrial biodiversity, and little is known about the freshwater cobenefits of terrestrial conservation actions. We sampled more than 1500 terrestrial and freshwater species in the Amazon and simulated conservation for species from both realms. Prioritizations based on terrestrial species yielded on average just 22% of the freshwater benefits achieved through freshwater-focused conservation. However, by using integrated cross-realm planning, freshwater benefits could be increased by up to 600% for a 1% reduction in terrestrial benefits. Where freshwater biodiversity data are unavailable but aquatic connectivity is accounted for, freshwater benefits could still be doubled for negligible losses of terrestrial coverage. Conservation actions are urgently needed to improve the status of freshwater species globally. Our results suggest that such gains can be achieved without compromising terrestrial conservation goals

Anuran responses to pressures from high-amplitude drought–flood–drought sequences under climate change

We measured changes in the occurrence, abundances and evidence of breeding of frogs to a sequence of severe drought–extreme wet–drought in south-eastern Australia, which is projected to characterize the regional climate in the coming decades.We collected data on anuran abundances, species richness and breeding by using aural surveys and visual searches in 80 waterbodies in 10 landscapes. We surveyed six times during the austral winter-springs of 2006 and 2007 (9–10 years into the 13-year ‘Big Dry’ drought), six times in the corresponding seasonsof 2011 and 2012 (the ‘BigWet’) and another six times in 2014 and 2015, which had lapsed into another intense dry period (‘post-BigWet’). The relatively small gains in species occupancy rates and evidence of breeding achieved during the Big Wet following the Big Dry were eroded and reversed in the years after the Big Wet period, with several biotic measures falling substantially below the values for the Big Dry. The global prognosis is for long-term drying and warming, notwithstanding much geographic variation in the degree and temporal patterns of drying. Longer droughts with short periods of wet/benign conditions are projected for many parts of the world. For water-dependent fauna such as most amphibians, our results signal widespread declines in lowland regions experiencing such patterns. If droughts exceed lifespans of frogs, then resistanceto drought will be so low that populations will plunge to levels from which the short periods of more benign conditions will be insufficient to enable substantial recovery