Annotated Bibliography

Carlos Davidson, H. Bradley Shaffer, and Mark R. Jennings. 2001. Declines of the California Red-legged frog: Climate, UV-B, habitat, and pesticides hypotheses. Ecological Applications 11(2): 464-479
This paper compares historic population distributions of California red-legged frogs (Rana aurora draytonii) with current population distributions to evaluate four hypothesized causes of amphibian population declines. The hypotheses tested were climate change, UV-B increases, habitat degradation, and pesticide drift. The authors used ArcView to determine latitude, elevation and land use types for all sites (extant and extinct populations) and to generate polygons of pesticide drift around sites. The authors then compared the patterns of extinct populations to the patterns predicted by each hypothesis. The authors found no support for the climate change hypothesis, but the other three hypotheses were supported by observed changes in distribution. The UV-B hypothesis was supported along an elevational gradient but not along a latitudinal gradient, with fewer extant populations at higher elevations. Comparisons of predicted trends for the habitat degradation hypothesis suggest that urbanization affects California red-legged frog populations more than agriculture, although this may be an artifact of recent losses in agricultural land. Predictions from the pesticide drift hypothesis most closely matched the observed population distribution, with fewer frog populations in areas downwind from agricultural areas.
Pierre Joly, Claire Morand, and Aurélie Cohas. 2003. Habitat fragmentation and amphibian conservation: building a tool for assessing landscape matrix connectivity. Comptes Rendus Biologies 326: S132-S139.
This paper uses habitat resistance indices to model connectivity in a floodplain habitat used by the common toad (Bufo bufo). Resistance indices were created according to physiological needs (e.g. desiccation prevention, energetic costs crossing terrain, etc). ArcView was used to define migration zones of suitable habitat in the floodplain. The authors also included risk of mortality from road traffic in their analysis. The methods devised by the authors in this paper can be used to create buffer habitats in agriculturally impacted areas that allow for seasonal movements of terrestrial animals.
Katarina Löfvenhaft, Siv Runborg and Per Sjögren-Gulve. 2004. Biotope patterns and amphibian distribution as assessment tools in urban landscape planning. Landscape and Urban Planning 68: 403-427.
This paper examines the relationship between land use change and amphibian populations in Sweden. The authors define a biotope as an area "characterized by certain conditions and populated by a characteristic biota". Aerial photographs of Stockholm from 1945/50 and 1998 were used to identify biotopes and the change in biotopes over time. The authors found that the temporal distribution of amphibians is negatively related to fragmentation of critical habitat (driven by heavily-trafficked roads). The authors seek to identify landscape-ecological zones (biotopes) within urban areas that should be maintained during urban planning. The study also suggests that a time-lag of several decades exists between land use change and observed impact on amphibian populations. The results of this paper highlight the importance of using long-term data in urban planning decisions.
D. M. Mensing, S. M. Galatowitsch and J. R. Tester. 1998. Anthropogenic effects on the biodiversity of riparian wetlands of a northern temperate landscape. Journal of Environmental Mangagement 53: 349-377.
This paper examines the effects of both direct modification to wetland/stream habitat and the modification of upland land use on riparian biodiversity at 5 spatial scales. The authors use 15 research sites and quantified land use based on historical data, state and county survey data, aerial photographs, and field surveys. The authors also conducted biological surveys of vegetation, aquatic macro-invertebrates, amphibians, fish and birds. Biodiversity of each faunal group was quantified using abundance, species richness and the Shannon diversity index. ArcInfo was used to assess the spatial relationship between land use types and biodiversity. Each faunal group appears to respond to some type of anthropogenic disturbance, with wet medow plants, aquatic macroinvertebrates, amphibians, and fish responding at multiple spatial scales. The percentage of cultivated land was the best predictor of biodiversity. Amphibian abundance was related to land use at 500 m and 1000m scales, with lower abundance in the presence of range and urban land. Amphibian diversity is also affected at the site scale by local disturbances (changes to stream structure, grazing, nutrient loading) and environmental factors such as pH of surface waters.
Robin D. Moore, Richard A. Griffiths and Alvaro Román. 2004. Distribution of the Mallorcan midwife toad (Alytes muletensis) in relation to landscape topography and introduced predators. Biological Conservation 116: 327-332.
The Mallorcan midwife toad (Alytes muletensis) is endemic to the island of Mallorca and was once widespread. However, following the introduction of the viperine snake (Natrix maura) and the green frog (Rana perezi), the distribution of the toads on Mallorca was reduced to a few small populations in steep-sided gorges. Many researches have posited that these introduced predators are unsuccessful in these gorges, thereby allowing populations of the midwife toad to persist. The authors use ArcView to examine the spatial relationship between altitude, slope, aspect and toad populations and the relationship of these factors to populations of introduced species in Mallorca. Toad populations were positively associated with steep slopes, while introduced predator populations were negatively correlated with elevation. In addition, the number of pools per site within a population was strongly associated with reproductive success for the population. In individual pools, elevation was positively correlated with reproductive success. Interestingly, the populations of the two introduced predators were almost perfectly correlated, suggesting that the presence of the green frog is necessary for the persistence of the viperine snake. The authors suggest that these results can be used in planning reintroduction sites for the midwife toad.
 
Nicholas Ray, Anthony Lehmann and Pierre Joly. 2002. Modeling spatial distribution of amphibian populations: a GIS approach based on habitat matrix permeability. Biodiversity and Conservation 11: 2143-2165.
Matrix permeability can have large impacts on population dynamics in altered landscapes, particularly in animals with seasonal movements. The biphasic life history of amphibians requires movement between natal ponds and the adult habitat, usually forest or scrublands. Alterations to habitats around wetlands can decrease the probability of juvenile recruitment to adult habitat be increasing the resistance in intervening habitats. These authors use ArcView spatial analyst to create a model of spatial distribution of two amphibian species (common toad, Bufo bufo; and alpine newt, Triturus alpestris) based on both distance between larval and adult habitats and the permeability of the matrix between the two habitats. The cost distance function was used to compute migration zones for the entire dataset. The results of these models provide predictions of species occurrence and persistence within the existing land use framework. In addition, these methods and results can be used to model the effects of proposed changes on the two amphibian species in these models.
 
H. L. Rustigian, M. V. Santelmann and N. H. Schumaker. 2003. Assessing the potential impacts of alternative landscape designs on amphibian population dynamics. Landscape Ecology 18: 65-81.
This paper predicts the consequences of three potential land use policies on four species of amphibians in Iowa. The authors estimated the effects of three scenarios on the landscape using GIS. The three scenarios, production, water quality, and biodiversity would have very different impacts on the landscape and therefore correspondingly different impacts on amphibian populations. The authors used current (1994) GIS coverages as a comparative reference for their models. Of the three scenarios, the least likely biodiversity scenario was the only policy to allow significant retention of critical habitat and breeding populations of the most sensitive species (Ambystoma tigrinum and Pseudacris triserata).
 
Nathan H. Schumaker, Ted Ernst, Denis White, Joan Baker and Patti Haggerty. 2004. Projecting wildlife responses to alternative future landscapes in Oregon's Willamette Basin. Ecological Applications 14(2): 381-400.
This paper uses GIS to predict changes in wildlife populations caused by landscape change. The authors compare two assessment methods based on either descriptive statistics applied to an entire faunal group or a more complex individual-based model of a subset of the faunal group. The simpler assessment used both GIS imagery and species-habitat relationships of non-fish vertebrate species. They used change in the amount of habitat available to these species as an indication of change in biodiversity. The more complex assessment used spatially explicit population models that connected species' habitat requirements to survival, reproduction and movement rates for 17 of the 279 wildlife species in the simpler assessment. Both assessments compared effects of historic landscape change and alternative future landscape change scenarios on wildlife populations. Not surprisingly, the historic landscape provided more habitat with less fragmentation than any of the alternative future scenarios. Each assessment showed more diversity under historic landscape conditions compared to future scenarios. Even the "Conservation 2050" scenario, which had larger populations than current (1990) populations, had smaller populations compared to the historic landscape conditions. However, the "Conservation 2050" scenario predicts recovery of some habitats and species and is preferable to the two other plans with regards to biodiversity.
 
Raymond D. Semlitsch and J. Russell Bodie. 1998. Are small, isolated wetlands expendable? Conservation Biology 12(5): 1129-1133.
This paper examines the assumption that wetland area, rather than number of pools within a wetland is an acceptable measure of wetland suitability for amphibian species. Although small pools are much more common in wetlands, recent policy changes reduce the protection for small isolated pools. GIS was used to examine the size class and spatial distribution of wetlands in the Savannah River Site, South Carolina. The distribution of size classes was highly skewed towards smaller pools, with 46% of total pools being 1.2 ha or less. These small pools are vitally important to amphibian species, with smaller pools housing amazing diversity. The authors suggest that larger pools tend to be less diverse because they tend to be permanent and therefore usually contain large predatory fish. Small isolated wetlands are also important in metapopulation dynamics. Loss of small wetlands tends to decrease diversity overall and increases the distance between populations.
 
J. Teixeira and J. W. Arntzen. 2002. Potential impact of climate warming on the distribution of the Golden-striped salamander, Chioglossa lusitanica, on the Iberian Peninsula. Biodiversity and Conservation 11: 2167-2176.
The Golden-striped salamander is endemic to the Iberian Peninsula and is listed on the IUCN Red List. It is the only extant member of its genus. Its distribution can be easily predicted based on a few habitat variables, including precipitation, slope and mean July temperature. Because temperature has a large impact on this species, predicted increases in global mean temperatures may impact the distribution of this salamander. The authors used presence/absence data for this salamander from a country-wide survey for this species and HasCM2 Global Change Models in a GIS package to predict changes in the distribution of C. lusitanica. Simulations indicated a reduction in the distribution of these salamanders, mediated through a reduction in potential habitat. Reductions of up to 34.5% were predicted for the year 2080.
 
James E. Woodford and Michael W. Meyer. 2003. Impact of lakeshore development on green frog abundance. Biological Conservation 110: 277-284.
Recent construction along lakeshores in Wisconsin has reduced the quality and abundance of lakeshore habitat. This study uses GIS to compare the abundance of green frogs along developed and undeveloped regions of 24 lakes in Wisconsin. The authors used habitat surveys in conjunction with aerial orthophotography to measure lakeshore quality and house and cottage density. They classified the shoreline of each lake as one of eight cover types and compared adult abundance to lakeshore quality. Adult abundance was significantly greater in undeveloped lakes. A significant negative relationship was found between number of houses per 100 m of shoreline and the % shoreline classified as suitable green frog habitat.