Spatial continuity of tree attributes, or tree similarity as a function of spatial separation, is a result of underlying spatially continuous variables such as competition and soil moisture. It provides a rarely examined measure of the degree of influence that trees exert on each other. Previous work in natural mixed hardwood forests showed spatial continuity of overstory tree basal area and of crown projection area equivalent to approximately four times the quadratic mean crown radius. This distance encompasses the direct and indirect (first and second order) neighbors and indicates possible propagation of competition beyond the direct neighbors. We examined whether artificially regenerated monospecific forest stands exhibit similar spatial dependence. We focused on sweetgum plantations planted at 1.5 m by 3 m spacing and examined the spatial continuity of tree basal areas.
Results/Conclusions
Our results indicated that spatial continuity was similar to that of natural stands extending to mostly the same relative distances. The results indicate that while natural tree mortality or tree removal may contribute to increased growth of the direct neighbors, it may have a negative impact on the growth of the second order neighbors. Moreover, in plantations the competitive effects may propagate even beyond the indirect neighbors.
