Tracking tree history to understand better natural dynamics of old-growth forest stands

Abstract

The long-term study of old-growth forest stands helps to understand the small-scale natural forest dynamic processes driven by the population biology of trees. The sampled trees can be considered from the viewpoint of their life and death cycle from establishment through to growing and death to full degradation. We provide a methodological framework for tracking and interpreting tree history in interaction with resurvey sampling events. The history of living and dead trees is consecutive and closely related to each other due to mortality events. The evanescent rate of disintegrated and decomposed dead trees is also a substantial dynamic characteristic of stands like regeneration, maturation, and mortality rates. They all form the intrinsic stand dynamic profile based on the whole life-dead-decomposed cycle of trees. This framework fills a knowledge gap in the European forest dynamic studies, where most of the research approaches point the focus on forest structure and pattern of developmental stages, and separately on living population dynamic features and deadwood structure and decay processes. In our pilot study, we performed resurvey of 53 Permanent Sampling Plots of a long untouched forest at Várhegy Strict Forest Reserve, Hungary. We estimated annual rates of ingrowth regeneration, maturation, mortality (13.2, 1.5, and 10.0 tree/hectare/year respectively), and 2.4 tree/hectare/year evanescence of disintegrated and decomposed dead trees. Apparent trends that accumulation of dead trees increases considerably – especially in oak-hornbeam stands, while 67% of annual regeneration ingrowth density is produced by shrubs, and only 9% by upper canopy trees.