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 D-k, and spherical contact distribution function HO 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.