Anlagda våtmarkers betydelse för klockgrodan – analys av landmiljön med hjälp av GIS
Sammanfattning: The fire-bellied toad (Bombina bombina) is an amphibian that since its national classification as an endangered species in 2005 (NT- Near Threatened) has increased in population size and distribution. Today the population in Sweden is considered viable since 2010 (LC- Least Concern) and it is possible that constructed wetlands in Scania have had positive effects on the fire-bellied toad. The importance of constructed wetlands for the populations of fire-bellied toads has however not been evaluated. Moreover it is important to identify the aquatic and terrestrial factors that result in colonization to fire-bellied toads in constructed wetlands.
The study was based on data from 2008-2009 in 14 constructed wetlands/ponds in the area of Baldringe, Scania. The aim was to study the underlying causes for establishment of the fire bellied toad. The method used was GIS (Geographical Information System)-based analysis in which different terrestrial parameters were compared and quantified. More data from various aquatic parameters were also used in order to further expand the analysis. The results from the GIS analysis were summarized using PCA (Principal Component Analysis) and then a t-test compared the characteristics between wetlands that were or were not colonized by fire-bellied toads.
These results showed that the terrestrial environment surrounding the constructed wetlands did not appear to have any influence on the establishment of a population of fire-bellied toad. The parameters of greatest importance were age of the wetland/pond, coverage of submersed vegetation, pH, distance to roads and conductivity. It was more likely to find fire- bellied toads in older wetlands/ponds, if there was a dense coverage of submersed vegetation, had a pH of at least 8,84 and longer distance to roads in general. At the same time conductivity should be lower than 55 mS/m. This study suggest that some constructed wetlands indeed could have positive effects on the fire-bellied toads and that GIS can be a good tool for analyzing these type of questions.
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