Regeneration imputation models for complex stands of southeastern British Columbia

Abstract

Two imputation techniques for predicting natural regeneration in complex stands prevalent in southeastern British Columbia (BC) were compared using data from the Interior Cedar-Hemlock moist warm subzone variant 2 (ICHmw2) in the vicinity of Nelson, BC. Imputation approaches offer advantages over other modeling approaches in that they provide estimates of many variables at one time (multivariate) and there are no assumptions regarding the probability distributions of the variables to be predicted. For the tabular imputation, the average regeneration per ha was calculated for each combination of five site groups, two residual density classes, five time-since-disturbance intervals, species, and height classes. For Most Similar Neighbour (MSN) imputation, data with both regeneration information, and overstory trees and site information (called reference plots) were used to impute regeneration of plots with only overstory trees and site information (called target plots), by selecting the most similar plot. Of the two approaches studied, the MSN approach gave better results than tabular imputation. The tabular imputation approach is simpler to implement, since tables of results can be published and made available for use. However, the MSN software has been made freely available, resulting in greater ease of access.