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Forest cover outside protected areas plays an important role in the conservation of the Vulnerable guiña Leopardus guigna
- Nicolás Gálvez, Felipe Hernández, Jerry Laker, Horacio Gilabert, Robert Petitpas, Cristián Bonacic, Alessandro Gimona, Alison Hester, David W. Macdonald
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Habitat loss and fragmentation are affecting populations of forest dwelling mammalian carnivores worldwide. In southern Chile, a biodiversity hotspot, anthropogenic activities have resulted in high loss of native forest cover. The guiña, or kodkod cat, Leopardus guigna is a small forest-dwelling felid with a narrow range in the temperate forest of southern Chile. The few existing studies of the species have suggested that it is almost exclusively restricted to large tracts of native forest. This paper reports a study in the temperate forest within a fragmented Andean piedmont landscape which demonstrates that smaller forest fragments in the farmland matrix are playing a key role in the persistence of the guiña. We estimated occupancy in both continuous native forest and remnant forest fragments and, with single-species/single-season models, evaluated the extent to which forest cover, habitat type and proximity to protected areas have a modulating effect on occupancy. A continuous survey during 2008–2009, in three seasons of 90–100 days each, accumulated 6,200 camera trap days and returned 47 photographs of guiña. Total detection in fragments was higher than in continuous forests, with detection confirmed in almost 70% of studied fragments. We found that probability of a site being occupied significantly increased with forest cover (adult/secondary forest, scrubland) and probability was low (< 0.2) in sites with < 50% of surrounding forest cover. Our study highlights the importance of remnant forest fragments in the mosaic of extensive agriculture for the spatial dynamics of a guiña population and hence for the future conservation of the species.
8 - Sinks, sustainability, and conservation incentives
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- By Alessandro Gimona, The James Hutton Institute, Aberdeen, J. Gary Polhill, The James Hutton Institute, Aberdeen, Ben Davies, University of Aberdeen
- Edited by Jianguo Liu, Michigan State University, Vanessa Hull, Michigan State University, Anita T. Morzillo, Oregon State University, John A. Wiens
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- Sources, Sinks and Sustainability
- Published online:
- 05 July 2011
- Print publication:
- 30 June 2011, pp 155-178
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Summary
Sustainability of agro-ecosystems can be achieved if farming systems are both ecologically sound and economically viable. Therefore, it is critically important for conservation scientists to see wide-scale biodiversity policy as only one aspect of a complex socio-ecological system, in which independent land managers, subject to financial constraints, make choices subject to a range of objectives, most of which are only tangentially influenced by considerations of nature conservation. Conservation incentives are a policy instrument to reconcile conservation and land managers’ objectives. Two broad approaches – payment for specific conservation actions (payment-for-activities), and payment for specific environmental outcomes (payment-for-results) – warrant particular attention. We investigate how undetected sinks might influence species persistence and richness in different policy and socio-economic contexts. To this end, we used a spatially explicit agent-based model of land use decision making, coupled with a spatially explicit metacommunity model. Our results show that, except when land managers are satisfied by low financial returns, the assumptions made by policy makers regarding habitat suitability of target species can have serious consequences on species’ persistence when sinks are present but not detected. Sinks are more influential for species associated with habitat that does not tend to become rare, due to the profitability associated with land use conversion under free-market conditions. For other habitat types, habitat turnover due to market-driven land use change is more important for conservation.
A conditional simulation of acoustic survey data: advantages and potential pitfalls
- Alessandro Gimona, Paul G. Fernandes
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- Journal:
- Aquatic Living Resources / Volume 16 / Issue 3 / July 2003
- Published online by Cambridge University Press:
- 15 July 2003, pp. 123-129
- Print publication:
- July 2003
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Standard geostatistical techniques provide effective methods for estimating the global abundance and precision of a variable of interest, for mapping its spatial distribution and for describing its spatial structure. In the case of acoustic survey data, however, obtaining a measure of precision of the global abundance estimate is confounded by the combination of variances from the interpolation of both the acoustic data and the concomitant fish length data. Even if the global estimation variance could be calculated, the distribution of the estimation error is not known and so confidence intervals cannot be determined. Furthermore, kriged distribution maps, in minimising the estimation variance, tend to smooth out local details of the attribute’s spatial variation: small values can be overestimated and larger ones underestimated, such that the kriged map is smoother than reality. This can lead to serious shortcomings when trying to detect patterns of extreme attribute values, such as the high densities encountered in some fish schools. Stochastic geostatistical simulations, conditional on sampled locations, provide a solution to many of these problems. They can deliver a measure of uncertainty for local (density) estimates, a confidence interval estimation for the global mean density, and finally, reproduce global statistics, such as the sample histogram and variogram. In so doing, they also provide maps of the attribute, which are spatially realistic because the variogram is reproduced; these are generated as a number of equiprobable realisations. In the present paper, we apply these techniques to acoustic data from an acoustic survey of North Sea herring. Sequential gaussian simulations are used to generate realisations for fish length and values of the nautical area scattering coefficient. These are then combined to produce realisations of herring density. The combined set of multiple realisations is then used to provide confidence intervals for the global abundance estimate: 95% of the herring abundance estimates are between 5677 and 6271 millions of individuals. Although the method presented in this paper contributes to the assessment of total uncertainty for acoustic surveys, the approach may have suffered from bias due to the use of off-the-shelf data transformation algorithms on fisheries acoustic data, which are often very positively skewed. We discuss this limitation and propose corrections for future work.