Spatial continuity in tree diameter distribution

Abstract: Investigation for spatial continuity in tree diameter distribution is attempted. Parametric and non-parametric approaches are employed to see whether tree diameter distribution acts as regionalized variable or not. Tree diameter at breast height (dbh) with size five ems or greater is recorded in circular plot along with the relative geo­ referenced co-ordinates of the plot center at compartment level. For the parametric approach, truncated two parameter Weibull distribution is found best fit for plot data and that an overlook of truncated data may result in wrong inference. From the truncated Weibull distribution, the maximum likelihood scale and shape parameter estimates of each plot data is obtained. Consequently, both parameter estimates, as attributes of tree dbh distribution, are subjected to spatial variation study usmg omnidirectional semivariogram and associated models at compartment level. Computation of cumulative distribution function of dbh at selected cutoff ( cdf) in the plots is followed by investigation for spatial continuity in the non-parametric case. The spatial continuity study of the number of stems per hectare greater or equal to the selected cutoff is also considered. The variograms and cross validation study of the Weibull parameter estimates, cdf and number of stems as attributes of tree dbh distribution seem to be very indicative to suggest that tree diameter distribution exhibits spatial continuity in the same fashion to regionalized variable.