engleski

Analysis of canopy closure in the Omphalodo-Fagetum forests in Croatia using hemisphere photography

Hemisphere (or fish-eye) photography has been used in forestry research for almost 50 years now. Today with development of personal computer's hardware and software its applications becomes more easily to apply and spread to various environmental monitoring, modelling and research. To adopt the methodology, during extensive field survey in dinaric part of the silver fir – beech forest areal, hemisphere photography of forest canopy were taken at 151 plots. Photographs were taken during the 2002 growing season using the Sigma 8mm fish-eye lens mounted on Nikon F601 camera body and tripod with levelling head. Photographs were scanned, classified based on the quality of their contrast and analysed with Gap Light Analyzer software. Percentage of canopy openness and LAI (leaf area index) were calculated. At this stage, the results were analysed with descriptive statistics and linear regression. For portion of sampled area satellite ETM+ image was available which enable 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 number of present plant species for best-contrasted photographs. Obtained results will point at the methodological steps that have to be improved and direct the future investigations to take most from the hemisphere photography data.

hemisphere photography; canopy; Omphalodo-Fagetum; LAI index; NDVI

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