Deciduous forest communities in the Black Sea coastal Strandzha region: temporal and spatial characteristics of leaf area index and density

The seasonal variation and vertical distribution of leaf area index are important characteristics of forest stands and their structure, not in the least for modelling and assessing biogeochemical and biogeophysical processes. In this paper results are presented from 2 years' measurements with the Li-Cor LAI-2000 Plant Canopy Analyser in the south-eastern part of the Bulgarian Black Sea coast, where Quercus frainetto stands are well represented but so far little studied. Mixed Fagus orientalis and Quercus polycarpa stands were also studied. The Q. frainetto effective LAI-2000 leaf area index values (one-sided) ranged from 1.43 to 3.21 with maximum values in June. Several Q. frainetto and F. orientalis + Q. polycarpa stands in the coastal zone were studied extensively and are shown to follow the seasonal variation at an intensive-measurements site, with an increase in leaf area index by 39.6% and 45.5% in June, respectively, related to the April values. The vertical profile of the canopy in the intensive-measurements site is presented and destructive measurements are compared with the LAI-2000 data. Data show that most of the leaves are located close to the middle of tree height (at around 40% of it). The analysis suggests that the intensive-measurements site is a good representative of the region, and that LAI-2000 measurements can provide sufficiently good information for further mapping of its forest leaf-area characteristics.