Comparative study of sapwood volume as an indicator of biological rotation age in six varieties of poplar

Abstract An exploratory analysis was conducted to compare the biological rotation age based on the commercial volume of the stem and the volume of sapwood using a growth and yield simulator developed for poplar varieties. The simulator is built upon the growth functions of stand state variables, with total volume and sapwood volume determined through tapering functions. The analysis revealed a significant reduction in the biological rotation age when calculations are based on the sapwood volume instead of the total commercial volume. This reduction varies depending on the degree of utilization of the stem, which is determined by the dimensions and quantity of potential products to be extracted. In the analysis of 210 stands, it was found that 41% of the stands reach the biological rotation age 1 or 2 years earlier if it is calculated based on the sapwood rather than based on the total volume. These findings suggest that determining the biological rotation age based on the sapwood may be a more appropriate approach than using total stem volume. This may be particularly relevant in poplar varieties that exhibit a distinct coloration between sapwood and heartwood, as these types of wood are destined for different uses and hold different market values. A reduction of 1 or 2 years in the biological rotation age can significantly impact income, especially for poplar varieties with relatively short biological rotation ages.