Preliminary assessment of effect of disturbance on natural regeneration in gaps of different sizes

Abstract

The study focused on natural regeneration of European beech (Fagus sylvatica), Norway spruce (Picea abies) and European larch (Larix decidua) within very small and four times bigger size gaps following a disturbance at a mixed temperate forest in the Czech Republic. In spring 2013, experimental gap design starts, when 1 m2 circular sampling plots along transects were delineated within four selected naturally occurring canopy openings with size below 20 m2. In December 2013, these initial canopy openings were artificially enlarged by felling to 226 m2 for small and 904 m2 for big gaps. Regeneration was monitored in the next two consecutive growing seasons after disturbance. Light conditions were measured before and after disturbance. Results indicated that four times larger gaps increased twice levels of light conditions, and that diffuse light starts to equilibrate to direct light there. Large gaps were favouring larch regeneration. Beech regeneration was predominant, independently on gap size as the study area belongs naturally to Beech Forest Vegetation Zone, however, the decline of spruce regeneration was presumably linked to drought. Gap size explained variation of larch regeneration in gaps. Contrarily, gap size could not be associated with the prolific regeneration of beech and abysmal regeneration performances of spruce in gaps.

Effects of Gap Size and Cardinal Directions on Natural Regeneration, Growth Dynamics of Trees outside the Gaps and Soil Properties in European Beech Forests of Southern Italy

“…In short, our result highlighted that in the small and medium gaps, the combination of moderate levels of diffuse light and relatively low levels of direct light created more favorable conditions in soil moisture and nutrients, particularly for nitrogen and potassium whose presence is important for beech natural regeneration (species shade tolerant), confirming previous observations of other authors [58,89,90]. As observed by Čater and Diaci and Hammond and Pokorný, [85,91], the small and medium gaps are generally beneficial for the regeneration of shade-tolerant species, whereas large gaps are more adapt for light-adapted ones, suggesting that the natural regeneration of species with different light-feeling can be steered with the size and distribution of gaps.…”

“…In fact, the European beech regeneration, expressed as the number of seedlings per m 2 , was significantly influenced by the gap size. On the other hand, recent studies resulted that the gap sizes may have an influence on establishment and growth of different tree species [24,84,85], confirming the strict dependence of natural tree regeneration with light and soil characteristics affected by light changes.…”

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

“…However, in large size gaps, the possibility of regular supply of ecologically required light factor for various suites of naturally regenerated tree species was the reason behind the full attainment of all considered height growth groupings among encountered tree species. The distribution pattern and dynamics of different height growths of natural regeneration of tree species in logging gaps of different sizes in this study attest that gap size is indeed a significant light resource regulator (Agyeman et al 1999;Hammond and Pokorný 2020c). Briefly, this result illustrates that light resource has significant influences on height growth of tree regeneration (Dobrovolný and Cháb 2013).…”

“…Logging usually creates gap openings with varying sizes within the canopy cover. These logging gaps provide heterogenous microclimatic conditions such as light, moisture, and temperature (Yamamoto 2000;Martins and Rodrigues 2005;Duah-Gyamfi et al 2014;Hammond and Pokorný 2020b;2020c), which are essential for a wide range of natural regeneration of tree species with different levels of shade tolerance mechanisms (Nagel et al 2010;Hammond and Pokorný 2020a). However, physical gap characteristics have a strong influence on the overall regeneration process (Martins and Rodrigues 2005;Sapkota and Oden 2009), particularly the gap size feature which is often used as a heterogeneity indicator of microclimatic conditions and resource sequestration within canopy openings (Agyeman et al 1999;McCarthy 2001).…”