engleski

To what extent spatial precision of chorological data affects our perception of the preffered environmental conditions of invasive species – a case study of Ailanthus altissima in Croatia

Flora Croatica Database contains chorological data (with assigned geographical coordinates) that differ in their spatial accuracy which is indicated with 11 levels, ranging from the least accurate that corresponds to whole Croatia or a region (e.g. Dalmatia) to the most accurate level corresponding to coordinates obtained by GPS devices. We were interested to see to what extent environmental variables assigned to those locations by means of spatial overlap differ between data sets of different spatial accuracy. For that purpose, we have selected invasive plant Tree of Heaven for which there is sufficient data with different levels of spatial accuracy, namely: IDPrec11 (GPS coordinates) ; IDPrec7 (100-200 metres accuracy – coordinates taken from the topographic map on scale M1:100.000) ; IDPrec6 (1 km2 accuracy) ; IDPrec5 (5 km2 accuracy). Environmental data on topography (elevation, slope, sine and cosine of aspect), distance from roads and water bodies and selection of climatic variables from BioClim (Bio1 ; Bio7 ; Bio10 ; Bio11 ; Bio12 ; Bio17 ; Bio18) were used. Descriptive statistics were calculated, and ANOVA with Tukey’s post-hoc test was employed to test whether there are significant differences amongst data sets of various spatial precision. ANOVA has detected significant differences between datasets, while Tukey’s post-hoc test found most differences among climatic variables. Less consistency (i.e. more statistically significant differences) was observed for annual climatic variables (Annual Mean Temperature ; Temperature Annual Range ; Annual Precipitation) compared to quarterly ones. Among topographic variables elevation was least consistent, although it is a result of disparity of one particular data set (i.e. IDPrec6) that was significantly different from the other three datasets. There were no significant differences observed for distance from roads and water bodies, which could be attributed to overall distribution of the Tree of Heaven in Croatia, which is mainly present alongside roads, and is not affected by the low soil moisture. Based on obtained preliminary analyses, it seems that this kind of analyses should be performed on a larger number of invasive plants belonging to several ecologically distinct groups in order to identify some general trends.

uncertainty ; spatial analyses ; GIS

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