Anthropogenic modifications to water regimes are one of the main factors threatening the stability and existence of floodplain forests. This study presents an analysis of topsoil biogeochemistry within three floodplain forest stands with different levels of human alteration. Decreasing contents of soil organic carbon (OC) and microbial biomass were observed along the gradient from natural to plantation forest. High annual variations were observed in soil N contents and in microbial biomass, while comparable spatial variations were observed within the natural forest. High ground-water levels resulted in increased accumulation of available Na+ and SO42− in the natural forest soil, yet the concentrations of ions were at sub-saline levels. The increasing contents of available Mn, SO42− or Cl− had mostly positive effects on soil microbial activity across the sites, though the results indicate the existence of a certain ecological limit for soil microorganisms. Reintroduction of surface-water flooding should be considered in future forest and water management to promote the dilution of ions accumulated in soils and natural deposition of sediments rich in organic matter (OM) at the sites.
This study examines the soil environment of eight charcoal kiln platforms and the neighboring soil in Czech and Bohemian low-altitude forest stands. Both mixed and undisturbed soil samples were used to assess the hydrophysical soil properties, nutrient content, cation exchange capacity, enzyme activity, and soil active carbon content, while soil color, stoniness, root density, and horizon thickness were estimated in the field. Charcoal-rich horizons had high total organic carbon concentrations and total nitrogen content (about 150% and 40% higher than in the organomineral horizons of the control plot, respectively), with total carbon stocks being higher than those in neighboring forest soils. Fine root density was highest in the charcoal-rich horizons, encouraged by high soil porosity, aeration, and favorable chemical properties. Enzyme group activity differed between individual soil horizons and kiln and control plots, with depolymerization enzyme activity highest in charcoal-rich horizons and humification enzyme activity highest in mineral horizons. Phosphatase, chitinase, and phenoloxidase activity were highest in charcoal-rich horizons, while β-glucosidase activity remained similar across horizons. After long-term abandonment, kiln sites shift from inhospitable sites to localized hotspots for plant and microbial growth, having more favorable physical, enzymatic, and chemical soil properties than the surrounding areas. This study confirmed that kiln production platforms act as microhabitat hotspots, also providing information on a wide spectrum of soil properties linked with soil microorganisms and root growth.
Soil proteases are involved in organic matter transformation processes and, thus, influence ecosystem nutrient turnovers. Phytohormones, similarly to proteases, are synthesized and secreted into soil by fungi and microorganisms, and regulate plant rhizosphere activity. The aim of this study was to determine the effect of auxins, cytokinins, ethephon, and chlorocholine chloride on spruce forest floor protease activity. It was concluded that the presence of auxins stimulated native proteolytic activity, specifically synthetic auxin 2-naphthoxyacetic acid (16% increase at added quantity of 5 μg) and naturally occurring indole-3-acetic acid (18%, 5 μg). On the contrary, cytokinins, ethephon and chlorocholine chloride inhibited native soil protease activity, where ethephon (36% decrease at 50 μg) and chlorocholine chloride (34%, 100 μg) showed the highest inhibitory effects. It was concluded that negative phytohormonal effects on native proteolytic activity may slow down organic matter decomposition rates and hence complicate plant nutrition. The study enhances the understanding of rhizosphere exudate effects on soil microbial activity and soil nitrogen cycle.
Traditional forest management models could potentially be used to combat changes in environmental conditions by stimulating soil properties and supporting tree growth. In this study, we compare the effects of different oak (Quercus petraea /Matt./Liebl.) forest models [coppice, coppice-with-standard, stocked coppice (reference)] on seasonal variability in soil properties at upland igneous and sedimentary sites (280–418 m a.s.l.). Soils were sampled at 0–5 and 10–15 cm in 50 × 50 m model and reference plots in January, April, July and October between 2015 and 2019, and soil organic matter, soil respiration, enzyme activity, pH and water-holding capacity were determined. The effects of forest model and seasonality were then compared using time-series analysis, analysis of variance and discriminant analysis. Overall, the models differentiated subsurface soil horizons from the topsoil and their feedback varied between sites. While water-holding capacity increased at the igneous stands, acid phosphomonoesterase activity increased and nitrogen content decreased at the sedimentary site. While the most significant negative influence of the forest model on soil properties was observed at the sedimentary site, the greatest increase in soil organic matter and water holding capacity was registered at the igneous coppice-with-standards site. Consequently, using the appropriate forest management model on different subsoil types could be valuable for improving carbon sequestration and drought resistance.
Plant distribution is most closely associated with the abiotic environment. The abiotic environment affects plant species’ abundancy unevenly. The asymmetry is further deviated by human interventions. Contrarily, soil properties preserve environmental influences from the anthropogenic perturbations. The study examined the supra-regional similarities of soil effects on plant species’ abundance in temperate forests to determine: (i) spatial relationships between soil property and forest-plant diversity among geographical regions; (ii) whether the spatial dependencies among compared forest-diversity components are influenced by natural forest representation. The spatial dependence was assessed using geographically weighted regression (GWR) of soil properties and plant species abundance from forest stands among 91 biogeographical regions in the Czech Republic (Central Europe). Regional soil properties and plant species abundance were acquired from 7550 national forest inventory plots positioned in a 4 × 4 km grid. The effect of natural forests was assessed using linear regression between the sums of squared GWR residues and protected forest distribution in the regions. Total diversity of forest plants is significantly dependent on soil-group representation. The soil-group effect is more significant than that of bedrock bodies, most of all in biogeographical regions with protected forest representation >50%. Effects of soil chemical properties were not affected by protected forest distribution. Spatial dependency analysis separated biogeographical regions of optimal forest plant diversity from those where inadequate forest-ecosystem diversity should be increased alongside soil diversity.
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