University of Twente Student Theses


Modelling the potential distribution of three typical amphibians on Crete, and their response to climate and land use change

Buedi, Eric Bissila (2010) Modelling the potential distribution of three typical amphibians on Crete, and their response to climate and land use change.

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Abstract:niche modelling has become a very important component in the management of natural resources. It has been used as a tool to assess the impact of both land use and environmental change on the distribution of species. This study focused on two of the major problems causing amphibian decline; climate and land use change. Three amphibian species found on the Island of Crete were modelled using Maximum Entropy Modelling (MAXENT). The specific objectives of the study are: 1) to determine the geographic distribution of Pelophylax cretensis, Pseudepidelea viridis and Hyla arborea using climatic variables 2) to determine the influence of land cover on the predictive power of habitat suitability models for P. cretensis, P. viridis and H. arborea 3) to assess the potential of predicting the distribution of the three amphibian species in the future based on climate and land cover change scenarios. Four models were produced for each species in a “stepwise” combination of variables. This begins with the most basic of variables that include elevation and proximity to pond and ends with a model that includes climatic variables and land cover. The current species environment relationships were projected onto future climate and land use under three different scenarios of change. The current distribution models were evaluated with the Area under the Curve (AUC) and Cohen Kappa statistics. Analysis of Variance was used to establish significance between the means of the AUC and subsequently a pair wise comparison was used to determine which two means are different. The results indicate that the distribution of the three species could be modelled with test AUC that is significantly better than random for all three species. Pair wise comparison of the models suggests that P. cretensis can easily be modelled with relatively high accuracy using just elevation and proximity to water variables. Results also show that land cover does not significantly increase the accuracy of models for P. cretensis and H. arborea; however it increased the AUC for P. viridis. Visual observation of maps produced for all three species suggest that P. cretensis occurs on the lowlands mostly along the coast whilst P. viridis and H. arborea seem to be widely distributed on Crete. Future distribution of all three amphibians suggests there will be some gains and loss of suitable habitats. However, results did not show the clear shift in range as reported by other researchers. Keywords: Ecological niche modelling. MAXENT, AUC, climate change, land use change
Item Type:Essay (Master)
Faculty:ITC: Faculty of Geo-information Science and Earth Observation
Programme:Geoinformation Science and Earth Observation MSc (75014)
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