Stem Profile Patterns ofPinus nigraandPinus sylvestrisGrowing in Mixed Stands

Abstract

AbstractTaper equations provide one of the most successful approaches of calculating tree volume to specified top diameters from standing tree measurements. This study assessed the stem profile patterns of Black pine (Pinus nigra Arnold.) and Scots pine (Pinus sylvestris L.) trees growing in mixed stands in northwestern Türkiye using a segmented polynomial taper equation. Models were fitted with the continuous second-order autoregressive structure to correct for the autocorrelation. The models fit the data well, describing more than 99%, 98%, and 97% of variation in diameter, merchantable volume, and total stem volume, respectively. However, the prediction errors were slightly larger for black pine than for Scots pine. Results also revealed that the model coefficients for these species were significantly different. Models developed in this study should provide more accurate upper stem diameter and volume estimates when the objective is to estimate such attributes for black pine and Scots pine growing in the mixed stands.Study Implications: Estimates of total and merchantable tree volume in a stand are essential for forest management and planning. Taper models are one of the most accurate approaches to estimating upper stem diameters and volume to any merchantability limit. There has been an increasing interest in managing mixed-species stands but limited work has been done on taper equations for trees growing in mixed stands. This study assessed the stem profile patterns of black pine and Scots pine trees growing in mixed-species stands in northwestern Türkiye. As has been reported for pure stands, species-specific taper equations were more accurate upper stem diameter and volume estimations in mixed-species stands. The developed taper models should play an important role in planning and inventorying mixed Black pine and Scots pine stands in Türkiye.