ANALYSIS OF CANOPY CLOSURE IN THE DINARIC SILVER FIR – BEECH FORESTS (OMPHALODO-FAGETUM) IN CROATIA USING HEMISPHERICAL PHOTOGRAPHY
Keywords:
Omphalodo-Fagetum, hemisphere photography, canopy, CART, LAI, NDVI, CroatiaAbstract
Hemispherical (or fisheye) photography has wide applicability in various forms of environmental monitoring, modelling and research. Since understory light conditions are a very important determinant of vegetation pattern, during extensive field survey in the Dinaric part of the silver fir – beech forest area of distribution, hemispherical photographs of forest canopy were taken at 151 plots. The photographs were scanned, classified based on the quality of their contrast and analysed with Gap Light Analyzer software. The percentages of canopy openness and LAI (leaf area index) were calculated. The results were analysed with descriptive statistics, linear regression and CART analyses. For the portion of the sampled area a satellite ETM+ image was available which enables comparison of canopy features with NDVI (Normalized Difference Vegetative Index). Statistically significant negative correlation was detected between canopy openness and NDVI for best-contrasted photographs, while LAI was positively correlated with NDVI for all analysed photographs, and negatively correlated with the number of present plant species for best-contrasted photographs. According to CART analyses LAI was an important predictor variable for estimating the number of present plant species. The results obtained point to the methodological steps that have to be improved, and also direct the future investigations in order to take most from the hemispherical photographs data.Downloads
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