Spatially explicit determination of individual tree target diameters in beech

TY - JOUR

T1 - Spatially explicit determination of individual tree target diameters in beech

AU - Meilby, Henrik

AU - Nord-Larsen, Thomas

PY - 2012/4/15

Y1 - 2012/4/15

N2 - In its basic definition, the individual tree target diameter is the hypothetical end diameter to which trees should be grown in order to maximize the expectation value of the forest stand. Most studies on target diameter harvesting have focused on the estimation of simple, static target diameters common to all trees or groups of trees. However, dynamic interaction between trees and differences in growth potential and quality affect the rate of return of individual tree growth, and thereby the target diameter of the tree. Based on a 4.9. ha experimental beech (Fagus sylvatica L.) stand in southern Sweden, we estimated individual tree target diameters by maximizing the expectation value of the stand while taking the spatial position and interaction of the trees into consideration. At moderate levels of required rate of return (2-3%) the average target diameter was 59-66. cm with a standard deviation of 13-19. cm. Results indicated that the target diameter depends strongly on stem quality, distance to neighboring trees (competition), and the quality of neighboring trees. When analyzing the effect of including neighborhoods of different size in the assessment of target diameters, the marginal change of the total expectation value remained significant, even when 10-12 trees had already been included, but converged fast for larger neighborhoods. Expectation values obtained using simplified management approaches were 10-20% lower than that of the spatially optimal solution. It is thus evident that the inclusion of the spatial position and quality of individual trees improves profitability of forest management considerably.

AB - In its basic definition, the individual tree target diameter is the hypothetical end diameter to which trees should be grown in order to maximize the expectation value of the forest stand. Most studies on target diameter harvesting have focused on the estimation of simple, static target diameters common to all trees or groups of trees. However, dynamic interaction between trees and differences in growth potential and quality affect the rate of return of individual tree growth, and thereby the target diameter of the tree. Based on a 4.9. ha experimental beech (Fagus sylvatica L.) stand in southern Sweden, we estimated individual tree target diameters by maximizing the expectation value of the stand while taking the spatial position and interaction of the trees into consideration. At moderate levels of required rate of return (2-3%) the average target diameter was 59-66. cm with a standard deviation of 13-19. cm. Results indicated that the target diameter depends strongly on stem quality, distance to neighboring trees (competition), and the quality of neighboring trees. When analyzing the effect of including neighborhoods of different size in the assessment of target diameters, the marginal change of the total expectation value remained significant, even when 10-12 trees had already been included, but converged fast for larger neighborhoods. Expectation values obtained using simplified management approaches were 10-20% lower than that of the spatially optimal solution. It is thus evident that the inclusion of the spatial position and quality of individual trees improves profitability of forest management considerably.

U2 - 10.1016/j.foreco.2011.08.037

DO - 10.1016/j.foreco.2011.08.037

M3 - Journal article

SN - 0378-1127

VL - 270

SP - 291

EP - 301

JO - Forest Ecology and Management

JF - Forest Ecology and Management

ER -