Published in Scientific Papers. Series A. Agronomy, Vol. LXI, Issue 1
Written by Tiberiu Paul BANU, Manfred SCHӦLCH, Constantin BANU, Gheorghe Florian BORLEA
Percentage Canopy Cover (PCC) has an important role in forest inventories and, as an ecological indicator, can also determine light conditions, habitats or microclimates. Canopy gaps, which are the result of natural causes or anthropogenic activities, have an important influence on the incoming light that controls how regeneration and the understory biota evolve. Unmanned aerial vehicle (UAV) remote-sensing has become an efficient, increasingly used alternative method, with the advantage of spatially-explicit mapping of the smallest canopy gaps. Following endeavors for 'near-natural' silviculture vertical analyses of tree crowns could provide substantial information for a consecutive management. In this paper, UAV-based measurements of canopy cover, tree crowns and canopy gaps are made in a pure-beech pristine forest and a managed old mixed beech with oak stand. Very high resolution images (3-4 cm/pixel) were acquired and assembled into orthomosaics. The canopy gaps and the upper tree crowns were delineated and the PCC, area (A), perimeter (P) and position of each tree crown were determined. For canopy gaps, calculations of: area (A), perimeter (P), perimeter/area (P/A), circularity (C) and gap shape complexity index (GSCI) were made. The results represent the mentioned structural determinations and the spatial distribution of trees and gaps in both study plots, results which are further compared and discussed.
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