Evaluation of Abiotic Controls on Windthrow Disturbance Using a Generalized Additive Model: A Case Study of the Tatra National Park, Slovakia

ABSTRACTField and laboratory studies have indicated that rock fragments in the topsoil may have a large impact on soil properties, soil quality, hydraulic, hydrological and erosion processes. In most studies, the rock fragments investigated still remain visible at the soil surface and only properties of these visible rock fragments are used for predicting runoff and soil loss. However, there are indications that rock fragments completely incorporated in the topsoil could also significantly influence the percolation and water distribution in stony soils and therefore, also infiltration, runoff and soil loss rates. Therefore, in this study interrill laboratory experiments with simulated rainfall for 60 min were conducted to assess the influence of subsurface rock fragments incorporated in a disturbed silt loam soil at different depths below the soil surface (i.e. 0.001, 0.01, 0.05 and 0.10 m), on infiltration, surface runoff and interrill erosion processes for small and large rock fragment sizes (i.e. mean diameter 0.04 and 0.20 m, respectively). Although only small differences in infiltration rate and runoff volume are observed between the soil without rock fragments (control) and the one with subsurface rock fragments, considerable differences in total interrill soil loss are observed between the control treatment and both contrasting rock fragments sizes. This is explained by a rapid increase in soil moisture in the areas above the rock fragments and therefore a decrease in topsoil cohesion compared with the control soil profile. The observed differences in runoff volume and interrill soil loss between the control plots and those with subsurface rock fragments is largest after a cumulative rainfall (Pcum) of 11 mm and progressively decreases with increasing Pcum. The results highlight the impacts and complexity of subsurface rock fragments on the production of runoff volume and soil loss and requires their inclusion in process‐based runoff and erosion models. Copyright © 2011 John Wiley & Sons, Ltd.

<strong class="journal-contentHeaderColor">Abstract.</strong> Stony soils that have a considerable amount of rock fragments (RFs) are widespread around the world. However, experiments to determine the effective soil hydraulic properties (SHPs) of stony soils, i.e., the water retention curve (WRC) and hydraulic conductivity curve (HCC), are challenging. Installation of measurement devices and sensors in these soils is difficult, and the data are less reliable because of their high local heterogeneity. Therefore, effective properties of stony soils especially under unsaturated hydraulic conditions are still not well understood. An alternative approach to evaluate the SHPs of these systems with internal structural heterogeneity is numerical simulation. We used the Hydrus 2D/3D software to create virtual stony soils in 3D and simulate water flow for different volumetric fractions of RFs, <span class="inline-formula"><i>f</i></span>. Stony soils with different values of <span class="inline-formula"><i>f</i></span> from 11 % to 37 % were created by placing impermeable spheres as RFs in a sandy loam soil. Time series of local pressure heads at various depths, mean water contents, and fluxes across the upper boundary were generated in a virtual evaporation experiment. Additionally, a multistep unit-gradient simulation was applied to determine effective values of hydraulic conductivity near saturation up to <span class="inline-formula">pF=2</span>. The generated data were evaluated by inverse modeling, assuming a homogeneous system, and the effective hydraulic properties were identified. The effective properties were compared with predictions from available scaling models of SHPs for different values of <span class="inline-formula"><i>f</i></span>. Our results showed that scaling the WRC of the background soil based on only the value of <span class="inline-formula"><i>f</i></span> gives acceptable results in the case of impermeable RFs. However, the reduction in conductivity could not be simply scaled by the value of <span class="inline-formula"><i>f</i></span>. Predictions were highly improved by applying the Novák, Maxwell, and GEM models to scale the HCC. The Maxwell model matched the numerically identified HCC best.

Previous studies have revealed inconsistent correlations between fungal diversity and plant/soil properties from local to global scales. Here, we investigated the internal relationships between soil fungal diversity and plant/soil properties on the Loess Plateau following vegetation restoration, using Illumina sequencing of the internal transcribed spacer 2 (ITS2) region for fungal identification. We found significant effects of land use types (Af, Artificial forest; Ns, Natural shrub; Ag, Artificial grassland; Ng, Natural grassland; Sc, slope cropland) on soil fungal communities composition, and the dominant phyla were Ascomycota, Basidiomycota, and Zygomycota, which transitioned from Basidiomycota-dominant to Ascomycota-dominant community due to vegetation restoration. The Chao1 richness, Shannon’s diversity and ACE indices were significantly influenced by land use types with the order of Ns > Af > Ng > Ag > Sc, and the total number of OTUs varied widely. In contrast, Good’s coverage and Simpson’s diversity indicated no significant difference among land use types (p > 0.05). Correlation analysis showed that plant and soil properties were closely related to fungal diversity regardless of land use types. In addition, soil organic carbon (SOC) and Hplant (plant richness, Shannon-Wiener index) were strong driving factors that explained fungal diversity. As revealed by the structural equation model (SEM) and generalized additive models (GAMs), fungal diversity was directly and indirectly affected by soil and plant properties, respectively, providing evidence for strong links between soil fungal diversity and plant and soil properties on the Loess Plateau.

Rock fragments within topsoil have important effects on soil properties and plant growth. This study mainly aimed to investigate the relationships between rock fragments, soil carbon (C) and nitrogen (N) densities and vegetation biomass in an alpine steppe. Rock fragments, plant and soil samples were collected from four topographic positions (top, upper, lower, and bottom) on a hillslope. Volumetric rock fragment content within the 0–30 cm soil profile varied from 17.8 to 30.5%, the upper position value was significantly greater (P < 0.05) than those at other positions. The highest aboveground biomass was observed at the lower position (921 kg ha−1), while the highest belowground biomass within the 0–30 cm profile was found at the upper position (4460 kg ha−1). More fine earth and plant litter input accompanied by lower C and N losses induced by rainfall erosion resulted in higher soil organic C and total N densities (28.6 Mg C ha−1 and 2.87 Mg N ha−1) at the lower position. Rock fragments may promote root growth but limit aboveground biomass production, and can therefore change the biomass distribution pattern. Our findings provide more evidence for scientifically assessing alpine steppe productivity.

<strong class="journal-contentHeaderColor">Abstract.</strong> Society is set to experience significant land cover changes in order to achieve the temperature goals agreed upon under the Paris Agreement. Such changes carry both global implications, pertaining to the biogeochemical effects of land cover change and thus the global carbon budget, and regional/local implications, pertaining to the biogeophysical effects arising within the immediate area of land cover change. Biogeophysical effects of land cover change are of high relevance to national policy- and decision- makers and their accountance is essential towards effective deployment of land cover practices that optimises between global and regional impacts. To this end, ESM outputs that isolate the biogeophysical responses of climate to land cover changes are key in informing impact assessments and supporting scenario development exercises. Generating multiple such ESM outputs, in a manner that allows comprehensive exploration of all plausible land cover scenarios however, is computationally untenable. This study proposes a framework to agilely explore the local biogeophysical responses of climate under different land cover scenarios by means of a computationally inexpensive emulator. The emulator is novel in that it solely represents the land cover forced, biogeophysical responses of climate, and can be used as either a standalone device or supplementary to existing climate model emulators that represent greenhouse gas (GHG)- or Global Mean Temperature (GMT)- forced climate responses. We start off by modelling local minimum, mean and maximum surface temperature responses to tree cover changes by means of a month- and Earth System Model (ESM)- specific Generalised Additive Model (GAM) trained over the whole globe. 2-m air temperature responses are then diagnosed from the modelled minimum and maximum surface temperature responses using observationally derived relationships. Such a two-step procedure accounts for the different physical representations of surface temperature responses to tree cover changes under different ESMs, whilst respecting a definition of 2-m air temperature that is more consistent across ESMs and with observational datasets. In exploring new tree cover change scenarios, we employ a parametric bootstrap sampling method to generate multiple possible temperature responses, such that the uncertainty within the GAM's derived shape of the response is also quantified. The output of the final emulator is demonstrated for the SSP 1-2.6 and 3-7.0 scenarios. Relevant temperature responses are identified as those displaying a clear signal in relation to the surrounding uncertainty in shape of derived response, calculated as the "signal-to-noise" ratio between the sample set mean and sample set variability. The emulator framework developed in this study thus provides a first step towards bridging the information-gap surrounding biogeophysical implications of land cover changes, allowing for smarter land-use decision making.

Soil biological parameters (e.g., Collembola), soil types, soil chemical parameters (pH, humus substances), and plant communities were studied in different ecosystems and ecotones in alpine, subalpine, and spruce forest zones in the Tatra National Park, Slovak Republic. The preliminary, selected data, based on a long-term research program, showed a high sensitivity of some alpine ecotones and ecosystems to long-distance transported acid deposits. The changes in different ecosystem parameters since 1977 were more extensive in alpine grasslands on limestone than on granite. The greatest soil pH decrease was in the plant communities Festucetum versicoloris (-1.5 pH), Geranio-Alchemilletum crinitae (-1.32 pH), and Saxifragetum perdurantis (-1.25 pH), which are restricted to places with snow accumulation and water runoff gullies. In these ecosystems the greatest changes occurred in the leaching of humus substances. Some formerly less abundant and rare soil animals restricted to acid bedrock became dominant in some ecosystems on limestone as well as on granite; other formerly dominant species disappeared from the entire study area (e.g., Folsomia alpina). The aerial extent of some ecosystems changed substantially since 1977, and their surrounding ecotones moved into the space formerly occupied by one of the adjacent ecosystems. These changes are detectable by remote-sensing methods. In Central European mountains, strongly affected by global and regional industrial air pollution (e.g., Krusne Hory, Krkonose, Beskydy), spruce forests started to die back from higher to lower mountain elevations. The effects of air pollution on alpine and subalpine vegetation were not studied there. Strong alterations in alpine ecosystems and ecotones were detected by the author during long-term studies in the High Tatra Mountains, and I suggest that subalpine and mountain forest belts will be affected here in the near future as they were in the more polluted Central European mountains. The ecosystems and ecotones in higher alpine zones are likely to be affected earlier than the ecosystems at lower altitudes. Detection of ecosystem alteration in the alpine zone may be used for prediction of acidification processes and global change in ecosystems at lower altitudes. The consequences of global climate change are predictable by monitoring changes in the extent of some ecosystems located in discrete mountain geomorphological units (e.g., karstic sinkholes, water runoff gullies, wind shadows, ridges exposed to wind, etc.) and ecotones among them because of their dependence on duration of snow cover, water supply, wind and frost exposure, and other abiotic and biotic factors.

Soil bulk density (BD) is a key soil property in soil science. BD is measured at the scale of the soil horizon with conventional methods: core sampling and rubber balloon. Regardless of the method, BD measurement in the field is cumbersome and time consuming, especially in stony soils, and new, less invasive methods have emerged, but their measurement quality needs to be compared with conventional methods. The photogrammetric technique (SfM) consists of the reconstruction of a given scene in 3D from multi‐view photographs. The aim of the present work is to assess the SfM as a rapid, accurate method of measuring the volume of undisturbed soil for BD measurements, regardless of the soil depth and stone content. Ten soil horizons were investigated from various types of soils with different soil properties, especially texture (10 to 48% of clay) and stone content (0 to 73%). The bulk density of each horizon was measured with a reference method (core sampling), an excavation method (rubber balloon) and two recently developed sensor‐based methods: SfM and a lightweight flash LiDar. For the sensor‐based methods, an automated post‐processing method was developed to reduce the human operating time. The BDs measured from the SfM were significantly similar to those measured from core sampling. At this stage, the lightweight flash LiDar is not sufficient to measure the BD with high accuracy. Finally, we recommend the use of SfM to measure BD regarding its robustness in varying soil conditions, especially stony soils, and we discuss the potential of the method regarding the recent advances in its field use with smartphones.Highlights Soil bulk density (BD) is a key soil property in soil science The photogrammetric technique and flash Lidar were applied to measure BD in the field The photogrammetric technique and flash Lidar were compared to classical methods The flash lidar is not sufficient to measure the BD with high accuracy The photogrammetric technique is recommended especially in stony soils

Disturbance events may be human-induced or natural, both typically causing changes in ecosystem properties and functions (Wright and Coleman 2002). Many observations show an increasing frequency of risks related to natural hazards in most parts of Europe. Natural hazards (flood, drought, erosion, fire, storm damage, etc.), driven by weather extremes, are increasing as a consequence of climate change (Thurig et al. 2005, Anonymous 2007).

Microtopographic differences in soil properties and microbial community composition at the field scale

Environments affected by fire

Background Climate change (CC) is regarded as the main factor behind changes in alpine vascular plant assemblages (Gottfried et al. 2012, Pauli et al. 2012). In the alpine life zone, a shift in the floristic composition is often a consequence of upward species migration and local loss (Pauli et al. 2012). Moreover, local changes in abundance have led to species’ distribution ranges expanding or retracting (Staude et al. 2022), resulting in a shift towards more nutrient- and warm-demanding plant assemblages as well as drought-adapted vegetation types (Liberati et al. 2019, Gottfried et al. 2012). Here, we investigated the vascular plant assemblages and soil properties in a GLORIA (GLobal Observation and Research Initiative in Alpine environments) target region in the N-Apennines (Italy). The site was established in 2001 and has been monitored at seven year intervals. The study area is included in a LTER site and is part of the SENTINEL (The reSponsEs of italian mouNTaIN Ecosystems to cLimate change) project, initiated in 2023 with funding from the Italian Ministry of University and Scientific Research (MUR). The aims of this study consist of assessing temporal shifts in the ecology of plant assemblage requirements as well as to unravel possible environmental drivers such as warming temperature and soil inorganic N availability. Methods Across four summits in the study site (1722-1978 m a.s.l., https://www.lteritalia.it/wordpress/?page_id=264), we investigated directional changes of plant assemblages to assess eutrophication, thermophilization and xerophilization processes as well as to assess ecological requirements of “winner” (increasing in abundance) and “loser” (decreasing in abundance) plant species. Environmental conditions were indirectly assessed based on Pignatti’s ecologic indicators for the Italian flora (Pignatti 2005). Moreover, we assessed changes in species richness to assess the expected biodiversity loss. Soil properties were evaluated through 10 cm deep soil temperature trend since 2001 and by measuring inorganic N soil concentration in the summer of 2023. Results and discussion We found a net increase in species richness in the lowest summits at the treeline ecotone (+12) and lower alpine (+4) belts. The two highest summits, up to the alpine belt, had a net species loss (-2 each). Noteworthy losses were the low stature (sub)alpine perennial species Myosotis alpestris, Soldanella alpina and Aster alpinus, while the most successful colonizers were the graminoids Festuca paniculata and Poa pratensis, and the Fabaceae Anthyllis vulneraria and Trifolium repens. A shift towards more nutrient-demanding species was the most pronounced pattern we observed (Fig. 1), being more intense in the treeline ecotone and the lower alpine belt (Fig. 1). This finding is in line with a previous European study, highlighting signs of increased nutrient demands in 52 GLORIA summits up until 2015, although the trend not significant (Staude et al. 2022). We also detected low level of local thermophilization and adaption to drought, but both supported by a few obvious thermophilous and drought-adapted winners and losers. Changes in species abundance of winning (3-9% of the species) and losing (2-8% of the species) species supported significant shifts in the ecologic indicators, especially related to increased nutrient requirements (Fig. 2). Eutrophication appeared to lead to both the expansion of more acquisitive species such as Genista tinctoria, F. paniculata and Brachypodium genuense, and the retraction of species growing on more oligotrophic substrates like Agrostis rupestris and Viola calcarata subsp. cavillieri. In our study area, the soil N-NH4+ concentration at the end of the growing season was comparable to the values recorded in the alpine tundra at the LTER site Istituto Mosso (NW Italian Alps, 2525-2840 m asl) (Magnani et al. 2017), ranging between 3 - 8 mgkg-1. The N-NO3- concentration was high, especially at one site (Mommio), ranging between 0.5 - 2.7 mgkg-1. This high soil inorganic N content could be related not only to the increase in temperature but also to the high N wet deposition. At the LTER site Istituto Mosso, the N critical threshold was greatly exceeded, revealing that the area is exposed to excessive N input through atmospheric deposition (Balestrini et al. 2024). In the N-Apennines, an increased level of N deposition, affecting beech growth, has been already estimated for the period 1850-2014 (Gentilesca et al. 2018). Moreover, recent studies found the increase in plant nitrogen availability and use significantly controlled by increasing mean annual temperature (Hu et al. 2024, Salazar et al. 2020). The M. Cimone Meteorological Observatory, located in the study area, has recorded a large increase in the mean, minimum and maximum annual air temperature between 1951-2018 (Costanzini et al. 2024). The increase of in situ soil mean temperature (+0.46°C per decades) as well as increased in duration of the vegetative period in the Eastern slope of the GLORIA site ‘Pian Cavallaro’ (M. Cimone) reflects trends in air temperature during the last two decades. Thus, plant species’ productivity may also have been stimulated by the well-established trends of higher temperatures and longer growing seasons, promoting the growth of nitrophilous species compared to others. Conclusions This initial investigation has revealed a complex and multifaceted picture of the ongoing dynamics in alpine vascular plant assemblages, highlighting an alarming biodiversity loss. The stronger influence of eutrophication over thermophilization highlights multiple, complex responses to warming, likely acting beyond the simple increase of species demands for higher temperatures. The SENTINEL project will continue to investigate the relationships between vegetation, atmosphere, soil, and plant-insect multi-trophic interactions to disentangle CC impacts on plant species and ecosystem functioning.

Carpinus betulus (CB) is becoming increasingly important in the forests of Central Europe and is significantly increasing its proportion in various habitat types. We have analysed how the increase in CB affects soil properties. The study was conducted in the Białowieża Forest (BF). We monitored the changes in CB cover between 1962 and 2013 on 56 permanent plots and collected samples of the litter sub-horizons and the content of the underlying A horizons for laboratory analyses in 2014. During the study period, there was a significant increase in CB cover in the second tree layer by an average of 17.4 % (±1.8) and in the shrub layer by 3.8 % (±1.0), as well as an increase in species diversity from 41 % in the past to 59 % currently. The C/N ratio of the Oi sub-horizon was 32.0 (±0.9), and NH4+ compounds predominated over NO3-, with all nitrogen forms most closely associated with the C/N ratio. In the Oea sub-horizon, the C/N ratio was 23.4 (±0.4), and the sum of mineralised nitrogen reached 8%, with a clear predominance of NO3-. The characteristic most strongly associated with the increase in CB coverage was the NO3- content in the Oea sub-horizon. The MID analysis confirmed that the change in CB cover was not only significant, but also ecologically important. We suggest that there is a feedback loop in which the generally observed climate changes lead to trees occupying new habitats that supply the forest floor with high quality litter, which in turn affects the soil and promotes the persistence of changes in the species composition of the forest.

Effect of tillage on some soil properties, plant development and yield of spring wheat ( Triticum aestivum L.) in stony soil

Relationships were sought between infiltrability and the properties of hundreds of surface soils (pedoderms) sampled across Namibia and western South Africa. Infiltrability was determined using a laboratory method, calibrated against a rainfall simulator, which measures the passage of a suspension of soil in distilled water through a small column packed with the same soil. Other properties determined were EC, pH, water-soluble cations and anions, ammonium acetate-extractable cations, organic C, total N, a 7-fraction particle size distribution, water-dispersible silt and clay, and clay mineral composition. Our objective was to ascertain whether general principles pertaining to infiltrability can be deduced from an analysis of a wide diversity of soils. To achieve this we compared correlation analysis, generalised linear models (GLMs), and generalised additive models (GAMs) with a segmented quantile regression approach, in which parametric regression lines were fitted to the 0.9 and 0.1 quantile values of equal subpopulations based on the x variable. Quantile regression demarcated relational envelopes enclosing four-fifths of the data points. The envelopes revealed ranges for soil properties over which infiltrability is potentially maximal (spread over a wide range) or predictably minimal (confined to small values). The r2 value of the 0.9 quantile regression line was taken as an index of reliability in being able to predict limiting effects on infiltrability associated with a variety of soil properties. Prediction of infiltration was most certain from textural properties, especially the content of water-dispersible silt (r2 = 0.96, n = 581), water-dispersible clay (0.88, n = 581), very fine sand (0.86, n = 174), and medium sand (0.84, n = 174). Chemical properties such as EC, sodium status, organic C content, and clay mineralogy were less clearly related to infiltrability than was texture. The role of fine-particle dispersion in blocking pores was highlighted by the stronger prediction in all statistical analyses provided by the water-dispersible as opposed to total content of silt and clay. All the statistical analyses revealed a probable skeletal role of medium and fine sand fractions in shaping pores and a plasmic (mobile) role of finer fractions in blocking pores. A noteworthy discovery was an apparent switch in role from skeletal to plasmic at a particle diameter of about 0.1 mm (i.e. between fine and very fine sand).

Mining-induced ground fissures are the main type of geological disasters found on the Loess Plateau, China, and cause great impacts on the soil properties around ground fissures. However, little research has been conducted on the quantitative relationship between ground fissures and changes in soil properties. To address this, 40 ground fissures in the Yungang mining area, Datong City, Shanxi Province, China, were investigated, and changes in soil properties (soil organic matter, soil moisture, field capacity, bulk density, soil porosity, and grain compositions) were revealed by the difference in soil properties between the edge and contrast points around ground fissures. Redundancy analyses were used to illustrate the relationships between the value (Si_DV) and percentage (Si_DP) of the difference in soil properties between the edge and contrast points, as well as the ground fissures. The characteristics of ground fissures that had a significant correlation according to Pearson correlation analysis with Si_DP were selected and analyzed via multivariate linear fitting model, random forest model, and Back Propagation (BP) neural network model, respectively. Results show that soil organic matter, soil moisture content, bulk density, field capacity, and the content of clay at the edge points were significantly less than those at the contrast points; conversely, soil porosity at the edge points was significantly greater. The average percentage of the difference between the edge points and contrast points of ground fissures in these six properties was 15.27%, while soil moisture content showed the greatest change (20.65%). The Si_DP was significantly correlated with the width, slope, and vegetation coverage of ground fissures; however, the vegetation coverage was the determining factor. BP neural network model had the greatest performance in revealing the relationships between ground fissures and changes in soil properties. The model for soil organic matter had the highest accuracy (R2 = 0.89), and all others were above 0.5. This research provides insights into the quantitative relationship between ground fissures and their impacts on soil physical properties, which can be used in conjunction with remote sensing images to rapidly assess soil erosion risks caused by mining on a large scale, given that soil physical properties are closely related to topsoil stability.