From young to adult trees: How spatial patterns of plants with different life strategies change during age development in an old-growth Korean pine-broadleaved forest

We used point pattern analysis (pair-correlation function, K2 function, distance to kth neighbor Dk, and spherical contact distribution function Hs) to describe the process of plant pattern formation for five dominant tree species with different life strategies in a mixed-forest stand with Korean pine (Pinus koraiensis Sieb. et. Zucc.) in the southern part of the Sikhote-Alin mountain range (southeastern Russia). We subdivided each species pattern using an ontogenetic classification of individuals: immature, virginal, and generative. We also analyzed stump pattern structure, which marks canopy gap formation locations in recent decades. We also studied the shade tolerance changes of pre-generative plants during their development. As a result, we found similarities between the processes of pattern transformation for the different species. Namely, they transform from pronounced aggregated distributions of plants at several spatial scales (immature plants) to a random pattern (middle-aged and old generative plants). This transformation of pattern structure occurs because the immature plants accumulate under a canopy and require significantly improved light conditions that can only be found in gaps to transition into the virginal and young-generative stage. In turn, the process of gap formation is stochastic, and the stand is characterized by a low-intensity disturbance regime. Thus, the pre-generative plant patterns are filtered by randomly formed gaps, and thus only individual randomly distributed plants reach the middle-aged and old generative ontogenetic states.