engleski

POSITIVE RESPONSES TO RECENT CLIMATE CHANGES IN THE VEGETATION ACTIVITY OF THE COMMON BEECH (FAGUS SYLVATICA L.) ECOSYSTEMS IN CROATIA

The purpose of this study is to assess the recent trends in vegetation activity (1982-2013) of the beech ecosystems (bioclimatic types) in Croatia across a broad macro-climatic gradient (Mediterranean, Alpine and Continental) to the recent impacts of climate change. Accordingly, we used Normalized Difference Vegetation Index (NDVI) continuously gathered over the past 30 from NOAA’s Advanced Very High Resolution Radiometer (AVHRR) in the framework of the Global Inventory Monitoring and Modeling System (GIMMS) project. AVHRR GIMMS NDVI present global coverage 8 km resolution 15-day composite data set, carefully assembled from different AVHRR sensors that have been used for numerous local to global scale vegetation time series studies during recent years at continental and global scale. We assessed raster pixel-wise trends and vectors of mean vegetation NDVI for four major beech forest bioclimatic types: Subalpine beech forest, beech-fir forest, montane beech forest and sub-Mediterranean beech forest type. Also, the further objective of this research is to statistically infer the causes of the responses in NDVI using climatic predictors and indicators obtained from European Climate Assessment & Dataset (ECA&D) continuous daily gridded data for the respective period. We also analyze the main typological properties (climatic, orographic, edaphic) of assessed beech forest types. Our results indicate the significant positive trend in the vegetation activity of the beech forests together with increasing yearly NDVI variations due to the possible intensification of extreme events (dry and wet spells). This study also reveals preferential environmental conditions for the beech ecosystem types together with limiting conditions in the three margins of its distribution area: highest altitudinal zone, south-eastern continental Pannonian zone, and the Mediterranean. The results show that the common beech can adapt to a very wide range of environmental conditions: mean annual temperatures from 2.1oC to 13.5oC, annual precipitation from 739 mm to 3444 mm, and altitudinal range from 20.3 m up to 1576 m above sea level.

NDVI, AVHRR, NOAA, Beech forest

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