Table 1 Results from 50,000 simulations of inventory of the complexly arranged population of individual trees (Fig. 1a) to estimate individual tree mean basal area, number of individuals in the population and population total basal area, together with their standard errors.
In all three cases, the average of the simulation estimates of the standard error of the tree mean basal area was close to that of the actual standard error of the 50,000 simulation estimates of the mean.
With an area sampling frame for both Methods 1 and 2 and when sampling from a list sampling frame, the mean of the simulation estimates of the individual tree mean basal area was the same (at least to the nearest 0.001 m2) as the true mean, supporting the contention that all three methods were unbiased estimators as expected for simple random samples.
Selection of nest trees by Black-backed Woodpeckers was influenced primarily by tree species (jack pine; Pinus banksiana) and also by the dbh of trees, while their selection of nesting stand habitat was influenced positively by the mean density of recent-solid snags and negatively by the mean basal area of live trees.
The DBH was expressed conventionally as the quadratic mean (QmDBH), which is the average stand diameter corresponding to tree arithmetic mean basal area (Curtis and Marshall 2000).
Canopy treatments consisted of four levels of timber harvest applied to loblolly pine stands: Control (uncut, mean basal area of 16.2 MedBA), MedBA (single-tree selection to a mean residual basal area of 9.0 m2/ha), LowBA (single-tree selection to a mean residual basal area of 6.4 m2/hand and Clearcut (complete canopy removal).
The mean basal area of dead standing pine trees in the forested part of the landscape was 1.7 m2∙hand and the estimated volume 12.7 m3∙ha−12.7
The number of trees available per plot ranged from 5 to 10 for the calculation of mean basal area with a total of 209 measured trees across the plots.
Fig. 4 Grouping of tree species based on maximum size (mean dbh of the 10%% biggest trees) and average growth rate (mean basal area growth, cm2/year) during the 25-year measurement interval 1972-1997.
Average tree diameters were smaller than in the past, but mean basal area and stocking remained similar over time because of the increase in density in current forests.
