A novel approach based on information theory to rank conservation strategies: an application to amphibian metapopulations

Abstract

Habitat fragmentation, reduction and degradation as well as the quality of habitat connecting environments are critical for species persistence. Spatially explicit metapopulation models considering environmental effects are natural candidates for modelling population viability. However, metapopulations share the inherent uncertainties of the population concept with vague field population definitions. The recognition of the fuzzy nature of populations leads to operational definitions for management purposes. To deal with scarce information and uncertainties in predictions of intervention effects, Adaptive Management is useful. Accordingly, the synthesis of monitoring information is performed with models whose features are continuously adapted to the level of available information. To derive useful indices for conservation strategy evaluation, we propose a novel approach based on the Kullback-Leibler information measure. This is used to evaluate strategies aimed at the conservation of amphibians in an alpine Rhine valley region (Canton of the Grisons, Switzerland) and it is applied to outputs from an incidence function model for Bufo bufo and Rana temporaria. For these species, establishing four additional breeding sites along the Rhine river is a better strategy than placing two additional sites in intensively cultivated land. Artificial ponds in residential areas contribute to species conservation, and transfer of individuals to new sites has advantages over reliance on spontaneous colonization. Bufo bufo and R. temporaria reacted similarly to conservation measures, possibly due to their quite similar ecologies.

Steps towards better amphibian conservation

“…First, the metapopulation model cannot be used if species are uncommon (Gilioli et al 2008). This is unfortunate because uncommon species are often of conservation concern.…”

“…Unfortunately, the dialogue between scientists and conservationists is often insufficient and conservation practitioners rarely base their decisions on scientific evidence (Sutherland et al 2004, Pullin and Knight 2005, Field et al 2007. Therefore, the contribution by Gilioli et al (2008) where conservation practitioners and scientists join forces to solve a real-world conservation problem is highly welcome. The metapopulation model and information-theoretic approach presented by Gilioli et al (2008) is an interesting addition to the methods that can be used to assess alternative management options and the importance of individual patches for metapopulation persistence (e.g.…”

“…Therefore, the contribution by Gilioli et al (2008) where conservation practitioners and scientists join forces to solve a real-world conservation problem is highly welcome. The metapopulation model and information-theoretic approach presented by Gilioli et al (2008) is an interesting addition to the methods that can be used to assess alternative management options and the importance of individual patches for metapopulation persistence (e.g. Etienne, Vos & Jansen, 2003, Rustigian, Santelmann & Schumaker, 2003, Pyke 2005, Runge, Runge & Nichols, 2006.…”

“…Third, Schmidt & Pellet (2005) and Pellet et al (2007) showed that patch area was unrelated to patch occupancy or local extinction probabilities in two anuran species. Gilioli et al (2008) argue that patch area can be corrected for spatial variation in habitat quality. This should be done to assess the robustness of the model output.…”

“…To maximize the gain from a model-based assessment of management strategies, a further step that is not described by Gilioli et al (2008) is necessary. If modelling is indeed to be embedded in an adaptive management framework, then it is mandatory to monitor the state of the metapopulation after management actions were carried out.…”