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 (< 700 m<sup>2</sup>) and large gaps (≥ 700 m<sup>2</sup>) were defined. Forty-one (41) regeneration microsites (RSs) of 1 m<sup>2</sup> 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 > 0.05) between small and large gaps, however, intermediate and shade-tolerant species were significantly higher (P < 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 R<sup>2 </sup>= 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.

Natural regeneration in logging gaps of different sizes in Subri River Forest Reserve (Ghana)

“…Even though we anticipated a higher number of individuals within large size gaps due to the presence of a fairly higher level of microclimatic light condition: an essential resource for plant growth, rather our results support previous findings that large size gaps (> 600 m 2 ) only promote tree species regeneration during the early growth stage (i.e., germination and establishment) (Lu et al 2015) and are seemingly not suitable for overall seedling growth and regeneration abundance of different tree species due to weak light competition among species (Sapkota and Oden 2009). Subsequently, an undesirable effect of large size gaps on seedling growth had been reported in the Czech Republic (Hammond et al 2020) and Indonesia (Tuomela et al 1996). This finding corroborates an earlier study of Agyeman et al (2010), who recorded poor regeneration of different suites of tree species under the light condition above 70% irradiance within large gaps.…”

“…Natural regeneration in gaps is often considered an associated positive effect of logging disturbance. Many papers have expressed it in lowland evergreen rainforest, Amazonia forests (Darrigo et al 2016;De Carvalho et al 2017), tropical moist semi-deciduous forests (Hawthorne 1995;Duah-Gyamfi et al 2014;Hammond et al 2021), dry Sal forests (Sapkota and Oden 2009), tropical dry semi-deciduous forest (Appiah 2013), temperate Asia secondary forest (Lu 2015), temperate mixed European forests (Nagel et al 2010;Hammond et al 2020), etc. Logging usually creates gap openings with varying sizes within the canopy cover.…”

“…Variation of gap size is directly linked with the intensity of logging disturbance (De Carvalho et al 2017), alongside tree size, crown dimensions, and single or multiple tree falls (McCarthy 2001;Muscolo et al 2014;Hammond and Pokorný 2020b). Previous studies suggest gap size as the most crucial determining factor in tree species composition in gap regeneration management (Nagel et al 2010;Hammond et al 2020) because large gaps determine the maintenance of pioneer/shade-intolerant tree species whilst small gaps are a beneficial stimulator for shade-tolerant tree species regeneration (Martins and Rodrigues 2005;Lu et al 2015). Gaps largely promote diversity of naturally regenerated tree species through the provision of yielding microsites for the coexistence of tree species with different light requirements.…”

Impact of Canopy Gap Ecology on the Diversity and Dynamics of Natural Regeneration in a Tropical Moist Semi-Deciduous Forest, Ghana

“…Thus, our finding is consistent with Schnitzer and Carson [5] that gaps play a similar role in maintaining tree species diversity in many tropical forests. By contrast, disprove gap size as a significant variable on naturally regenerated tree species composition and diversity according to Hammond et al [3]. Generally, this observation solidly corroborates a view that gap-based silviculture plays a vital role in forests by promoting ecological species assemblage mechanisms that enable species coexistence which significantly relates to the positive impacts of species diversity on forest ecosystem's stability and functions [3].…”

“…Differences among tree species in establishment, germination, development, survival, growth, and canopy recruitment within gap sites explain the crucial role of canopy gaps in shaping forest composition [1,2]. This very important role of canopy gaps had been well documented in numerous gap regeneration studies conducted in temperate [3] and tropical [4] forest ecosystems. Studies primarily focus on the effects of canopy gaps on species diversity [4,5], leaving only a few researching into the ecological positive effects of canopy gaps on natural regeneration dynamics [6].…”