Concept of forest development phases: identification and classification issues

The decision making in forestry and choosing the appropriate silvicultural practices are based on the knowledge about forest development. Usually, forest development is described as a cycle or sequence of phases similar to the development cycles of organisms. The information about the development cycle of unmanaged forest ecosystems is applied and adapted to managed stands to refine the managerial approaches and decision making. Besides, natural forests are more stable and resist pests and diseases better. Thus knowing the mechanisms that lie behind this self-sustainability could help in forest stand management. Assigning a patch of a stand a specific development phase makes it possible to arrive at conclusions about its productivity and making decisions about necessary silvicultural operations. Yet there is no single opinion among the scientists about how many phases the forest’s life cycle has, not to mention that different classifications offer different and sometimes even contradictional criteria to define the current forest development phase for a given subplot. The confusion in terminology for stand structures and stand development phases is also an issue to be considered. Several, the most popular approaches to assigning forest development phases are compared. A short overview of the algorithms used to define the forest development phases is given. There is a lack of a complex approach in the offered algorithms of assigning a subplot to a certain development phase. In particular, soil properties, as well as belowground biomass, are entirely ignored. It is necessary to develop a more comprehensive and detailed approach to defining forest development phases and arranging the diagnostic criteria in a clear and easy-to-use system that could be applied for decision making forestry. Only several studies are currently focused on soil properties and belowground biomass in temperate deciduous forests under different development phases. Although there is still little information on this issue, the data is insufficient and controversial. Our study offers several possible directions to make the forest development phases classifications more elaborate by considering the soil and belowground parameters. They include but are not limited to, quantity, density, humidity, and acidity of forest floor, soil respiration, and content of water-extractable organic matter in the soil.