Abstract

CABRELLI, D.; REBOTTARO, S.  and  EFFRON, D.. Characterization of forest canopy and light microenviroment in stands with management different, using hemispherical photography. Quebracho (Santiago del Estero) [online]. 2006, n.13, pp.17-25. ISSN 0328-0543.

The canopy structure and light microenvironment in Pinus elliottii Engelm. plantations were characterized using hemispherical photography technique. The experimental work was carried out in two stands: one plantation without thinning (W) and other thinned from below (T). The parameters used to characterize the forest canopy were the Leaf Index Area (IAF) and Canopy Openness (CO). The microenvironmental parameters were Indirect Site Factor (ISF), Direct Site Factor (DSF), Global Site Factor (GSF) and mean duration of sunflecks (MDS). The results showed that the thinning produced changes in the canopy and microenvironment. The LAI varied from 1.45 (T) to 3.0 m² m^-2 (W). The income of solar radiation in stand without thinning was 15 %, while that in thinned stand was 30 %. Frequency distribution of the sunfleck duration showed that in closed canopy there are many small gaps and few big gaps. On the other hand, the thinning produced same proportion of small and large gaps. The W stand presented higher values of correlation between LAI and radiation income. In both stands, the indirect radiation was better index for characterizing the light environment. Our results showed that MDS could be recommended in order to describe pine stands with different canopy, but not be useful in order to show differences between microsites inside same population.

Keywords : Pinus elliottii; Canopy openness; Leaf area index; Solar radiation income; Sunflecks.