F. Raulier et al., INFLUENCE OF SOCIAL-STATUS ON CROWN GEOMETRY AND VOLUME INCREMENT IN REGULAR AND IRREGULAR BLACK SPRUCE STANDS, Canadian journal of forest research, 26(10), 1996, pp. 1742-1753
A model of bole volume increment based on crown dimensions and tree so
cial status is analyzed for its ability to predict bole volume increme
nt independently of stand structure. Data were collected in two boreal
black spruce (Picea mariana (Mill.) BSP) stands in Quebec. One stand
is even-aged and of seed origin, and the other stand is uneven-aged an
d of layer origin. A varying parameter approach is taken to show that
the crown profile of black spruce depends on competition. Formal expre
ssions for crown surface area and volume are developed from the crown
profile and are used to derive a potential growth function for bole vo
lume. Three social status indices are considered to characterize compe
tition experienced by a subject tree: a distance-dependent competition
index relating differences of height between the tree and its neighbo
rs to the distance separating them, and two distance-independent indic
es, one based on tree height relative to dominant stand height and one
based on height growth relative to potential height growth of a compe
tition-free tree. These indices are combined with the potential growth
function to successfully model bole volume increment. Both stands hav
e an equal weight in the unexplained residual variance. Furthermore, a
ll three social status indices perform equally well at predicting bole
volume increment. The use of a potential growth function with crown p
arameters is further discussed.