Effects of gap size and associated changes in light and soil moisture on the understorey vegetation of a Hungarian beech forest

Abstract

In European beech forests windstorms often create canopy gaps and change the level of incident light, soil moisture and nutrient availability on the forest floor. Understanding the interrelations between gap size and environmental change, and the effects these have on regeneration processes is a prerequisite for developing techniques of nature-based forestry. The aims of this study were to investigate the effects of gap size on the resulting spatial distributions of key abiotic environmental variables (light and soil moisture) in gaps, and to study how light and soil moisture affect the abundance and distribution of herb layer species. To do this we used eight artificially created gaps -three large (diameter: 35 -40 m) and five small (diameter: 10 -15 m) -in a mesotrophic submontane beech forest. Data on species' importance and substrate types were collected in systematically distributed 1 mÂ1 m quadrats before gap creation and on four occasions during the next two growing seasons. Hemispherical photographs were taken and analysed to estimate relative light intensity. Soil moisture was measured by frequency domain and capacitance probes. It was found that gap size had a profound effect on the environmental variables measured. While relative light intensity values in small gaps did not reach those in large gaps, soil moisture levels did reach similar maximum values in gap centres regardless of gap size. Richness, composition and total cover of herbaceous vegetation were different in small versus large gaps. Much of this difference was attributed to the presence of specific relative light intensities and also to the increased amount of available soil moisture in gaps. Species were differently affected by the combined effects of light and soil moisture, as well as by differences in available substrates. All this resulted in species-specific distribution patterns within gaps.

Effect of thinning-induced gap size on soil CO2 efflux in a reforested spruce forest in the eastern Tibetan Plateau

“…Similar results have been reported for other spruce forests (Nilsen and Strand, 2008;Vranova et al, 2009) and other forest ecosystems (Brumme, 1995;Sullivan et al, 2008;Tang et al, 2005b). Reductions in R s rate by forest thinning are linked to thinninginduced changes in microclimate (Galhidy et al, 2006;Gray et al, 2002), substrate availability (Selig et al, 2008;Zu et al, 2009), soil microbes (Arunachalam and Arunachalam, 2000;Zhang and Zak, 1998), and fine roots (Peng and Thomas, 2006;Tang et al, 2005b).…”

“…In the terrestrial ecosystem, R s rate is profoundly influenced by both biotic 2010). Thinning may affect R s rate by influencing root biomass (Brumme, 1995;Peng and Thomas, 2006;Tang et al, 2005b), soil microclimate (Galhidy et al, 2006;Gray et al, 2002;Pang et al, 2013), belowground C allocation (Selig et al, 2008;Tian et al, 2010;Zu et al, 2009), and microbial community structure (Arunachalam and Arunachalam, 2000;Zhang and Zak, 1998;Zu et al, 2009). Thinning may cause the immediate decrease in R s rate due to the decrease in respiration from tree roots (Tang et al, 2005b).…”

Light Conditions, Soil Moisture, and Vegetation Cover in Artificial Forest Gaps in Western Hungary

“…Manninger (2008) states that there are differences in absolute value of soil moisture in the gaps and in the surrounding closed forest, but the directions and values of change are similar. Gálhidy et al (2006) claim there are no significant soil moisture differences in a small or large gap, but the values in a large gap are more diverse. Moreover, soil moisture was higher in gaps than it was under a closed stand.…”

“…Csépányi (2008) shows several examples for oak regeneration and proposes how to choose the required gap size, shape, and bearing. Gálhidy et al (2005Gálhidy et al ( , 2006 makes intensive studies in beech stands. Török (2006) fully assays the methods of exposure-orientated regeneration in beech forests; however, such a detailed work does not exist for oaks yet.…”

Introduction of suitable species for planting in gaps of different size (case study: Loveh forest, Golestan, Iran)

“…The gap size depends on the number of harvested or fallen trees and alters ecological conditions of created microclimate (Denslow, Hartshorn 1994;lowman, rinker 2004;ritter et al 2005;Galhidy et al 2006). tree species have different ecological demands and their response differs due to the gap size (naaf, Wulf 2007).…”