The shape and size of tree crown for Common beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) Karst.)

Oblika in velikost drevesne krošnje se v sestoju zelo razlikujeta od drevesa do drevesa, zato je ugotavljanje oblike in velikosti krošnje pogosto problematično. Najbolj natančne podatke dobimo pri sekcioniranju krošnje, ker pa je v sestoju pogosto težko dobiti dovolj podatkov, smo preizkusili, ali lahko oblike krošenj za bukev in smreko podamo z analitično funkcijo. Proučevali smo obliko in velikost krošnje v sestoju rastočih dreves, in sicer za bukev in smreko po razširjenih debelinskih razredih. Za ta namen smo fotografirali celotna drevesa z digitalno kamero. Primerjava je pokazala, da analitična funkcija dobro poda vrednosti za površino krošnje, medtem ko so privolumnih odstopanja večja. Enačbe na osnovi premera in dolžine krošnje so zelo odstopale od pravih vrednosti. Odvisnost med širino krošnje in prsnim premerom lahko dobro prikažemo z alometrijsko funkcijo.The shape and size of crowns within a stand vary considerably from tree to tree, hence determining the shape and size of a crown can often be problematic. The most accurate data can be obtained by sectioning the crown. It is however often difficult to get sufficient data in a stand, so we examined whether the crown shapes of spruce and beech trees could be calculated by an analytic function. We studied the shape and size of the crownin a stand of growing trees, specifically Common Beech and Norway Spruce,according to their diameter class. For this purpose we photographed whole trees in the field with a digital camera. The comparison showed that theanalytic function is accurate enough to determine the values of crown surface, but the volumes proved to be more discrepant. Formulas for cone and paraboloid describe crowns inaccurately, in most cases underestimating them. The relationship between crown width and DBH (tree diameter at breast height) can be described well by an allometric function