Evaluating Short-Term Impacts of Forest Management and Microsite Conditions on Understory Vegetation in Temperate Fir-Beech Forests: Floristic, Ecological, and Trait-Based Perspective

Abstract

Forest understory vegetation is largely influenced by disturbances and given local abiotic conditions. Our research focuses on the early response of understory vegetation to various forest management intensities in Dinaric fir-beech forests in Slovenia: (i) control, (ii) 50% cut of stand growing stock, and (iii) 100% cut of stand growing stock. Apart from identifying overstory removal effects, we were interested in fine-scale variation of understory vegetation and environmental determinants of its species composition. Vegetation was sampled within 27 karst sinkholes, which represent a dominant landform in studied forests. Within each sinkhole, five sampling plots, varying in slope aspect (centre, north, east, south, west), were established (135 in total), where pre-treatment (in 2012) and post-treatment (in 2014) floristic surveys were conducted. The sampled understory species were characterized in terms of Ellenberg's indicator values (EIVs) and plant functional traits (plant height, seed mass, specific leaf area, leaf dry matter content). Diversity metrics (species richness, total cover, Shannon index) increased in plots where the silvicultural measures were applied. Tree species richness also increased in 100% cutting. A redundancy analysis revealed that species composition was related to environmental variables, which are directly influenced by management interventions (overstory canopy cover, microclimate-maximum daily temperature, soil properties-thickness of organic soil layer) as well as by topographic factors (slope inclination and surface rockiness). EIVs for light were significantly affected by treatment intensity, whereas soil-related EIVs (moisture, reaction, nutrients) depended more on the within-sinkhole position. Canopy gaps, compared with uncut control plots, hosted a higher number of colonizing species with a higher plant height and smaller seeds, while leaf traits did not show a clear response. We found a negative correlation between pre-treatment species (functional) richness and post-treatment shifts in floristic (functional) composition. Plots with higher richness exhibited smaller changes compared with species-poor communities. Incorporating different perspectives, the results of this study offer valuable insights into patterns of understory vegetation response to forest management in fir-beech forests.

Effect of tree canopy on species composition, diversity and biomass of herbaceous vegetation and soil characteristics in semi-arid forests of the Aravalli hills

“…al., 2018). Similar to the present study, canopy gaps hosted a higher number of colonizing species with greater plant height in temperate r-beech forests (Kermavnar et. al., 2019).…”

Water Regulation Ecosystem Services Following Gap Formation in Fir-Beech Forests in the Dinaric Karst

“…The Brook90 model estimated that 71-72% of annual precipitation (1271 to 1281 mm) drained from the forest to the subsurface. In the experimental gap, almost all precipitation falls directly on the ground vegetation cover or soil, which havea smaller interception surface than the multilayered mixed foliage of fir-beech forests [31]. Accordingly, drainage accounted for up to 81% of annual precipitation (1452 mm) in the large experimental gap, indicating a long-lasting reduction in water retention capacity even 12 years after formation.…”

“…The rest of the stem volume consists of sycamore maple. A long tradition of sustainable forest management, systematic silvicultural planning, and more recently the development of close-to-nature management [29], with the idea of mimicking natural disturbance regimes and forest dynamics as closely as possible [31], have led to the relatively preserved vegetation composition of these forests [36]. They are traditionally managed with an irregular shelterwood system sensu Mathews [30], in which small canopy gaps are gradually increased and successful natural regeneration of European beech, sycamore maple, and silver fir in mixed forests is encouraged to ensure continuous forest cover and minimize soil degradation [47].…”

“…To minimize the negative effects of forest management on ecological processes in karst aquifers, there is a long tradition of sustainable forest management, systematic silvicultural planning, and more recently the development of close-to-nature management [29] in Dinaric Karst forests. The creation of canopy gaps by removing only a small group of trees or the traditional irregular shelterwood system sensu Matthews [30] has been applied in the region to mimic as closely as possible the natural disturbance regimes and structural characteristics of old-growth forests [31], with unevenly aged and horizontally and vertically structured forest [29,32,33], as opposed to conventional clearcutting, which involves harvesting large areas of forest [34,35]. However, due to socio-economic changes in recent decades, a shift towards larger canopy gaps has been promoted as more convenient for forest management and to promote valuable tree species (e.g., sycamore maple) in the Dinaric Karst [31,36].…”

“…The creation of canopy gaps by removing only a small group of trees or the traditional irregular shelterwood system sensu Matthews [30] has been applied in the region to mimic as closely as possible the natural disturbance regimes and structural characteristics of old-growth forests [31], with unevenly aged and horizontally and vertically structured forest [29,32,33], as opposed to conventional clearcutting, which involves harvesting large areas of forest [34,35]. However, due to socio-economic changes in recent decades, a shift towards larger canopy gaps has been promoted as more convenient for forest management and to promote valuable tree species (e.g., sycamore maple) in the Dinaric Karst [31,36]. Nevertheless, large canopy gaps with diameters greater than the height of the surrounding forest can significantly alter the water regulating the capacity of vegetation [37].…”