An Individual-Tree Measure of Growing Stock and Stand Density

Abstract

Implicit in the concepts of growing stock and stand density is that they are functionally related to the number and size of the trees in a stand. If they are additive, they should be a function of the size and number of trees within a stand. To test this idea, data from a slash pine (Pinus elliotii) spacing and thinning study were fit to the nonlinear regression model i_v/i_h =β₀ D₀^β1 + ϵ where i_v=periodic annual increment of stem volume, i_h=periodic annual increment of stem height, D₀= initial stem diameter at breast height, and β₀ and β₁are parameters to be estimated. Previous research indicates that ∑i_v/i_h is proportional to Dq^xN, the general mathematical form of Reineke’s stand density index. Since Dq^xN can be closely approximated by ∑D₀^x , the relationship should also extend to single trees. The value of β₀D₀^β1 will indicate the value of a single tree to total growing stock or stand density. Results show that the power function fits the data well with little bias due to initial spacing and age. For these data the value of a single slash pine tree in terms of i_v/i_h is 8.5 x 10^-4D₀^1.8. This result may be useful in furthering our understanding of how tree structure affects growth and also in determining the appropriate mix of stem diameters in uneven-aged stand structure.

Parent Publication

• Proceedings of the 22nd Biennial Southern Silvicultural Research Conference

Citation

Dean, Thomas J. 2024. An Individual-Tree Measure of Growing Stock and Stand Density. In: Bragg, Don C.; Oswald, Brian P.; Koerth, Nancy E., eds. Proceedings of the 22nd biennial southern silvicultural research conference. Gen. Tech. Rep. SRS-274. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station: 20–25. https://doi.org/10.2737/SRS-GTR-274-Pap4.