Forest canopy analysis in the Alpine environment: comparison among assessment methods

Abstract

Forest canopy is an important ecological feature of forest stands and can be expressed as Leaf Area Index (LAI) or canopy cover percentage. LAI is the ratio between leaf area and ground area (m2 m-2) and it can be measured using an angle of 180°. Instead, the canopy cover is the percentage of forest area occupied by the vertical projection of tree crowns; consequently, LAI expresses the canopy closure rather than the canopy cover. This paper focuses on the estimation of LAI and canopy cover percentage in 54 sampling points randomly distributed over the main forest types of Trentino (beech forests, Scots pine forests, Norway spruce forests and European larch forests). The main purpose was the analysis of relationship between LAI and canopy cover percentage, the latter measured with two different techniques: visual estimation and estimation using the spherical densiometer. In the last part of the paper, LAI data collected in the four main forest types of Trentino are compared with values reported in the literature for the same forest types.