Spatial patterning of tree distributions and density-dependent competition in a boreal forest of Alberta

Although competition has been considered as one of the most fundamental ecological processes regulating population dynamics, survival, growth and species coexistence, few studies have used spatial patterns of tree distribution for inferring the effect of competition on tree mortality and stand development of boreal forests. Here, I studied point patterns of trees and competition in a chronosequence consisting of four stands in northwest Alberta. Spatial point-pattern analyses found intraspecific competition to be an important mechanism influencing stand development throughout succession. However, these analyses revealed that interspecific competition was not important, suggesting that interspecific competition may not be strong enough to cause significant tree mortality. Logistic regression of mortality further supported the point-pattern results and identified the neighborhood density of large (DBH>25 cm), small (DBH<10 cm) and dead trees as significant factors in the mortality of both deciduous and coniferous trees. My research highlighted the effect of competition over succession in the boreal forest.