Scaling up from the individual tree to the stand level in Scots pine. I. Needle distribution, overall crown and root geometry

We quantified and scaled up (from individual trees over average trees per diameter at breast height, DBH, class) various characteristics of canopy architecture such as leaf area index, needle aggregation, vertical and radial distribution of the foliage for a mature, even-aged Scots pine (Pinus sylvestris L.) stand in the Campine region, Brasschaat, Belgium. Both the vertical and radial needle distribution, scaled up to the stand level from destructive harvests of a limited number of trees, have been presented. Total leaf area index for the stand was 3.0 derived from the needle distribution in different canopy layers. The 'cloud' technique used to describe the position and aggregation of needles on branches, on branches in the crown and on crowns in the canopy has been described and applied. These clouds are well-defined spatial units, larger than clusters, on branches with between one and several clouds per branch. The regression equations used to relate needle properties, positions of clouds, needle distribution to stand-and tree-related parameters (such as diameter at breast height, frequency distribution) were developed, parameterised for the particular stand and applied for scaling up purposes. The fitted Rayleigh equation defined the midpoint of the canopy at a height of 19.6 m and the canopy depth as only being almost 5 m. The appropriate values for making conversions from needle mass to needle area were presented and discussed in relation to position in the crown. Overall crown and canopy geometry, as well as geometry and dimensions of the root system were also described and scaled up from individual trees to the stand level. The overall volume of the crown, of the root system and of the canopy were related to the volume of the clouds and the gaps in the canopy, and allowed us to quantify the 'space use efficiency' of the stand. ((C) Inra/Elsevier, Paris.).