Structural development in ageing temperate Scots pine stands

Abstract

Conversion management in ageing temperate Scots pine ( Pinus sylvestris L.) forests in West and Central Europe mainly focuses on changing species composition, without paying attention to quantitative stand structural features such as development of spatial point pattern, (relative) mingling and size differentiation. The consideration of such detailed stand structural features in management decision making may in some cases help to achieve one or more goals of sustainable forestry, such as the maintenance and enhancement of biodiversity. The main purpose of this paper is to quantify and interpret stand structure and its spontaneous development in unmanaged ageing Scots pine stands, based on the structural classes and the development pathways published by Kint et al. (2004a). Stand structure is quantified with the SIAFOR software, designed for the calculation of structural indices in completely stem-mapped monitoring plots. Spontaneous structural development at the stand level in ageing Scots pine stands is characterised, in the absence of major disturbances, by a tendency towards random spatial point pattern and random relative mingling, as well as increasing mingling and increasing tree size differentiation. Also clear development trends at the species level can be distinguished. As pine density in ageing Scots pine stands decreases, the spatial point pattern of pines tends to change from regular towards random. Birch regenerates in canopy gaps of pine. Regeneration of oak establishes prior to gap formation under a canopy of pine, and gradually grows up as more light becomes available in the gaps. Both birch and oak tend from clustered spatial point pattern and segregation towards random spatial point pattern and random mingling. Massive regeneration of pine on open areas after major disturbance is initially clustered. As a result of self-thinning, pine develops towards a regular spatial point pattern. Tree size differentiation of species may increase or decrease depending on the type and intensity of competition processes. The application of the results as a reference for forest management issues where stand structure is of relevance is discussed, with special attention to biodiversity.