Mean top height (MTH), mean top diameter, quadratic diameter, basal area per hectare, volume per hectare and survival/mortality were calculated.
The average height and diameter of the 100 largest-diameter stems per hectare were used to calculate mean top height and mean top diameter.
Mean top height and mean top diameter were calculated as the average height and quadratic mean diameter respectively of the 100 largest-DBH stems per hectare based on the height-DBH relationship established by Steward ([2011]).
Both TSV and V were significantly correlated to stand density, mean top height and stem diameter (Table 1).
The objective of this research was to develop models of Douglas-fir mean top height, basal area, volume, mean diameter (at breast height), green crown height and stand density from LiDAR and stand information.
Figure 2 Relationship between LiDAR height percentiles and (a) mean top height, (b) volume or (c) mean diameter.
This research demonstrates that strong relationships can be developed for mean top height, green crown height, volume, mean diameter and basal area from LiDAR and stand metrics.
Mean top height, green crown height, volume, mean diameter, basal area, and stand density, respectively, ranged, six-fold, 17-fold, 226-fold, six-fold, 73-fold and 12-fold across the plot series (Table 2).
Stem diameter was most strongly related to H95, which most likely acts as a surrogate for mean top height, reflecting the strong relationship between mean diameter and mean top height in the dataset (Table 3).
Values of RMSE for the final models of mean top height, green crown height, stem volume, mean diameter, basal area and stand density were, respectively, 1.02 m, 0.427 m, 20.2 m3 ha-1, 13.9 mm, 3.81 m2 and 355 stems ha-1.
Stand density and basal area were determined for each plot and mean top height, Hm (height of the 100 largest diameter trees per hectare) was derived from plot mean height, Hmean, and stand density, S, using the following function, H m = 1 / H mean 1 – 0.106 1 – exp – 0.228 S – 100 / 100 - 1 (1).
