Influence of vertical foliage structure on the distribution of stem cross-sectional area increment in western hemlock and balsam fir.

摘要: A set of western hemlock ( Tsuga heterophylla Raf. [Sarg.]) and balsam fir (Abies balsamea [L.] Mill.) from Washington, USA Newfoundland, Canada, respectively, were destructively sampled to examine relationships between vertical foliage structure distribution stem cross-sectional area increment. series growth models describing the relationship amount above a given height increment at that was derived pipe model theory. These with increasing generality so two commonly held assumptions could be explicitly tested: (1) linear increase in area; (2) constant below base live crown. Overall, performed very well, accounting for over 80% observed variation both species. The results show that, while increases current foliage, is not proportional (i.e., linear). Furthermore, rate crown found smaller trees decrease larger trees. suggest per unit may change as grow.