Effect of gap size on tree species diversity of natural regeneration – case study from Masaryk Training Forest Enterprise Křtiny

Abstract

Forest gaps remain the optimal forest management practice in modern forestry. Upon all the physical properties of forest gaps, the ‘gap size’ feature stands out as an essential property. The effect of gap size on tree species composition and diversity of natural regeneration in forest gaps of different sizes was investigated. Eight research forest gaps were selected from the Training Forest School Enterprise, also called Masaryk Forest in Křtiny, a temperate mixed forest in the Czech Republic. By given gap sizes, small (&lt; 700 m²) and large gaps (≥ 700 m²) were defined. Forty-one (41) regeneration microsites (RSs) of 1 m² circular area at 2 m intervals were demarcated within each forest gap. These RSs served as data collection points. From the total of eleven (11) species enumerated, large gaps obtained higher species composition (10) and diversity (Simpson = 0.5 1-D; Shannon = 1.0 H and Pielou’s evenness = 0.5 J indices) records, yet, small gaps presented favourable conditions for prolific natural regeneration significantly. Light-adapted species demonstrated no significant difference (P &gt; 0.05) between small and large gaps, however, intermediate and shade-tolerant species were significantly higher (P &lt; 0.05) in small gaps. There were progressive declines in height growth of natural regeneration from 0–20 cm to 21–50 cm and 51+ cm in small and large gaps at R²= 99% and 88%, respectively. <br /> The development of herbaceous vegetation in small and large gaps had positive and negative effects on the natural regeneration of Fagus sylvatica and Abies alba species, respectively.