Relation of readily measurable tree dimensions in Populus tremuloides to above-ground biomass, leaf and caloric value

Abstract

Above- ground dry matter of 49 forest-grown aspen tree s was studied on a 0.02 ha plot in southwestern Alberta (altitude 4,700 ft). This plot was divided into four contiguous quadrats along a topographic gradient. All 49 trees within the plot were harvested and data of dry weights, tree dimensions, caloric contents and leaf area were obtained. Total dry matter of trees on the plot adds up to 77 metric tons/ha. This is equivalent to 3630 x 108 g cal/ha of energy with a leaf area index equal to 1.8. Tree and tree component weights are higher on the more productive downslope quadrat. This trend is also true for the relative proportion of trunk and branch dry weights . The overall low value of biomass obtained in the study area suggests a low productivity of the site. Allometric equations for estimating tree weights from tree dimensions were established for the whole plot and for individual quadrats. These equations are found to be highly correlated, especially when using dbh2 x ht to estimate total t r ee weight and trunk weight, and using diameter at base of crown to estimate dry weights of branches, foliage and total crown. Covariance analyses of these two readily measurable parameters (dbh 2 x ht and diameter at crown base) show that they are also suitable for estimation of tree weight parameters from different segments of a topographic gradient. Equations using dbh to estimate tree weights are not applicable to sites other than the sampling stand described here.