ZLV Online

Abstract

The aim of the study was to evaluate the impact of micro-site conditions on natural regeneration prosperity and quality of Scots pine (Pinus sylvestris L.) in shelterwood regeneration system. Data were collected in four localities across the Czech Republic in 26 forest stands. In each forest stand with pine natural regeneration a square 0.25 ha research plot was established. We evaluated pine regeneration density, dendrometric characteristics (height, diameter of root collar, increment in last five years, crown diameter), quality characteristics including angle of branching and silvicultural value of each individual. As independent explanatory variables we measured light conditions based on hemispheric image analysis, ground vegetation characteristics such as composition and coverage, thickness of surface humus horizons and competition expressed as distance to the nearest individuals of natural regeneration and to the nearest mature tree. Results showed high variability in natural regeneration density (for seedlings higher than 25 cm), its mean values amounted to 4,285 (Hradec) – 18,570 (Plasy) pc.ha-1 with 75% quantile of values 5,714 – 30,000 pc.ha-1. Number of regeneration individuals was significantly influenced by light conditions (the openness and diffuse PPFD (photosynthetic photon flux density) and by ground vegetation characteristics, especially the cover of mosses. The dendrometric and growth characteristics (height, diameter, increment, and crown diameter) were significantly influenced by intraspecific competition, but relative values of both the increment and crown diameter depended also on the diffuse PPFD. Relative height increment between 10% and 15% was reached at values higher than 2 MJ-m-2.day of diffuse PPFD corresponding to stand basal area below 25 m2.ha-1. The best quality individuals (with straight stem and regular crown) occurred mainly in the upper height class of the natural regeneration.