Estimation of newly grown needle area in Norway spruce based on simple biometrical tree parameters

Estimation of newly grown needle area, as the most active part of assimilation apparatus, is important for better understanding of biochemical processes of trees. This paper investigates the relationship between the projected area of newly grown needles and other biometric tree parameters (tree height H-TREE diameter at breast height DBH, projected crown area and crown length) of Norway spruce trees. The total projected area of newly grown needles of seven sampled trees was estimated using a detailed inventory of the number and length of shoots. The relationship between this value and other readily measurable biometric tree characteristics was tested to find the best model for estimating total area of newly grown needles. The model using H-TREE*DBH with a coefficient of determination of 0.96 had the best performance. The DBH and H-TREE inventory of all trees in the studied plot was used to estimate the total projected area of newly grown needles of the entire forest stand (4506.7 m(2) per hectare). We also investigated specific leaf area (SLA) of newly grown needles in vertical profile of tree crown. SLA increased constantly from the tree top (28.7 cm(2).g(2)) to the crown base (80.3 cm(2).g(2) ).