North-facing Slopes Research Articles

Topography is more important than forest type as a determinant for functional trait composition of Collembola community

The relative importance of topography and vegetation in shaping local soil invertebrate communities is poorly understood. We investigated changes in the species and trait compositions of Collembola communities associated with different topography and forest types. Our study sites encompassed various topographies with different slope aspects and forest types; specifically, natural deciduous broad-leaved forests and deciduous coniferous plantations in Japan. The body length and edaphic adaptation score, which are representative of a certain life-form, were used as Collembola traits. Across a topographic gradient from south to north-facing slopes, the total biomass of Collembola was higher in dry plots than in humid plots, and the forest types did not affect either abundance, biomass, or species diversity. Variation partitioning analysis revealed that topography played an important role in determining species composition and functional traits, whereas forest types and spatial distance had minor roles. The responses of community weighted mean traits (CWMs) to environmental change were more pronounced than those of species composition. The CWM and functional diversity of body length were higher in the dry plots than in the humid plots. These changes in traits might be explained by food supply or habitat structure increasing large individuals via topography, rather than by physical stress filtering out intolerant small individuals. These results suggest that slope topography is an important determinant of the Collembola community structure in cool-temperate forest ecosystems.

Differences in C, N,δ13C, andδ15N among plant functional types after a wildfire in a black spruce forest, interior Alaska

We measured differences in %C, %N, δ13C, and δ15N of plant functional types (PFTs) between burned and unburned ground surfaces soon after a wildfire on a north-facing slope in interior Alaska. The C and N were measured for 16 species and Sphagnum litter. δ13C differed among the PFTs and was low for trees and shrubs, suggesting that woody stems slowed C dynamics or showed low water use efficiency. δ15N concentrations suggested that the herbaceous plants depended less on the mycorrhizal associations that became weak on the burned surfaces. The shrub leaves showed the lowest δ15N of PFTs and showed higher δ15N on the burned surface, showing that N transfer from the soils to the leaves in the shrubs was slowed by the wildfire. Mosses showed the highest C/N ratio. Sphagnum litter decomposed faster on the burned surface, and %N and δ15N in the litter increased from the second to third year on both burned and unburned surfaces, while %C changed little. In conclusion, the responses to the wildfire differed among the PFTs as characterized by their C and N dynamics.

Assessment of suspended sediment dynamics in a small ungauged badland catchment in the Northern Apennines (Italy) using an in-situ laser diffraction method

The volumes and dynamics of suspended sediments drained from a watershed are often unknown, especially in small creeks and tributaries where continuous discharge measurements are seldom available. The objective of this study was to assess in a qualitative and quantitative way the sediment dynamics of a small ungauged watershed in the Northern Apennines, Italy. We analysed and correlated the sediment volume concentration and grain-size distribution of the suspended sediments with the precipitation pattern. The study area is a small ungauged watershed (0.15 km2) that is dominated by intensive soil erosion processes and related landforms. The basin is oriented East-West with the south-facing slopes characterized by badland erosion processes. The north-facing slopes are cultivated and dominated by rill-interrill erosion phenomena. An morphometrical characterization of the basin was performed using a high-resolution DTM with a 1 × 1 m resolution. Subsequently, the physical characteristics of the topsoil were investigated based on grain size laboratory analysis. A detailed NDVI analysis of the vegetation was performed using Sentinel-2A images. Finally, we assessed the suspended sediments at the outlet of the basin using a laser diffraction technique. The Suspended Sediment Volume Concentration (SSC) and the Sauter Mean Diameter (SMD) of the eroded sediments, provide insights into the morphogenetic processes and the sediment transport dynamics of the basin. The measurements were conducted in autumn 2018 after an intense precipitation period and in spring 2019 after a dry phase. The results show a direct relationship between precipitation and SSC with a delay of about 2 h after the most intense precipitation events. Moreover, we reveal that the SMD values are inversely related to the precipitation due to turbidity effects. The SSC and SMD measurements allow for a detailed assessment of the dynamics between precipitation and suspended sediment load even though discharge volumes were not measured directly.

Determination of the representative elementary area (REA) of biocrusts: A case study from the Hilly Loess Plateau region, China

Biological soil crusts (biocrusts) are mixed communities of cyanobacteria, lichens and mosses in different ratios, contributing to important ecological functions in arid and semiarid regions worldwide. Biocrusts are spatially variable, and the variability in biocrust composition and coverage is scale-dependent. The following question can then be asked: What is the appropriate spatial scale for observing ecological functions? Without clarifying this issue, we cannot fully understand the ecological functions of biocrusts. The key to answering this question is to determine a threshold area, or representative elementary area (REA). Accordingly, we analyzed red–green–blue (RGB) images of 90 biocrust plots (2.0 m × 2.0 m) from nine revegetated grasslands in the Hilly Loess Plateau region of China. The variability in biocrust composition and coverage across the plot sizes was studied by gradually expanding the plot size from 0.01 m2 to 4.00 m2. The results showed that as the plot sizes increased from 0.01 m2 to 4.00 m2, the number of biocrust types logarithmically increased. Biocrust patches of a particular type (such as moss, cyanobacteria or lichen) were often characteristic of a plot size of 0.01 m2, whereas plot sizes larger than 0.25 m2 supported mixed biocrusts of multiple patch types. The variability in coverage of mixed biocrusts logarithmically decreased with increasing plot sizes. The coverage of mixed biocrusts maintained an approximately constant value after a certain critical plot size was reached (1.00 m2 in this study). Our data indicated that REAs of mixed biocrusts exist at the slope scale. The REAs of mixed biocrusts were 0.5–1.0 m2, 1.5–2.5 m2 and 3.0–3.8 m2, with alpha (α) values of 0.1, 0.05 and 0.01, respectively. The size of the REAs on the north-facing slope was larger than that on the south-facing slope, and the patch density of biocrusts had an important influence on the REAs. The results of this study could provide a method for determining the REAs of mixed biocrusts and guide surveys and experimental layouts.

Fast and persistent responses of alpine permafrost microbial communities to in situ warming

Global warming in mid-latitude alpine regions results in permafrost thawing, together with greater availability of carbon and nutrients in soils and frequent freeze–thaw cycles. Yet it is unclear how these multifactorial changes will shape the 1 m-deep permafrost microbiome in the future, and how this will in turn modulate microbially-mediated feedbacks between mountain soils and climate (e.g. soil CO2 emissions). To unravel the responses of the alpine permafrost microbiome to in situ warming, we established a three-year experiment in a permafrost monitoring summit in the Alps. Specifically, we simulated conditions of warming by transplanting permafrost soils from a depth of 160 cm either to the active-layer topsoils in the north-facing slope or in the warmer south-facing slope, near the summit. qPCR-based and amplicon sequencing analyses indicated an augmented microbial abundance in the transplanted permafrost, driven by the increase in copiotrophic prokaryotic taxa (e.g. Noviherbaspirillum and Massilia) and metabolically versatile psychrotrophs (e.g. Tundrisphaera and Granulicella); which acclimatized to the changing environment and potentially benefited from substrates released upon thawing. Metabolically restricted Patescibacteria lineages vastly decreased with warming, as reflected in the loss of α-diversity in the transplanted soils. Ascomycetous sapro-pathotrophs (e.g. Tetracladium) and a few lichenized fungi (e.g. Aspicilia) expanded in the transplanted permafrost, particularly in soils transplanted to the warmer south-facing slope, replacing basidiomycetous yeasts (e.g. Glaciozyma). The transplantation-induced loosening of microbial association networks in the permafrost could potentially indicate lesser cooperative interactions between neighboring microorganisms. Broader substrate-use microbial activities measured in the transplanted permafrost could relate to altered soil C dynamics. The three-year simulated warming did not, however, enhance heterotrophic respiration, which was limited by the carbon-depleted permafrost conditions. Collectively, our quantitative findings suggest the vulnerability of the alpine permafrost microbiome to warming, which might improve predictions on microbially-modulated transformations of mountain soil ecosystems under the future climate.

Novel brominated flame retardants (NBFRs) in soil and moss in Mt. Shergyla, southeast Tibetan Plateau: Occurrence, distribution and influencing factors

Research on the environmental fate and behavior of novel brominated flame retardants (NBFRs) remains limited, especially in the remote alpine regions. In this study, the concentrations and distributions of NBFRs were investigated in soils and mosses collected from two slopes of Shergyla in the southeast of the Tibetan Plateau (TP), to unravel the environmental behaviors of NBFRs in this background area. The total NBFR concentrations (∑7NBFRs) ranged from 34.2 to 879 pg/g dw in soil and from 72.8 to 2505 pg/g dw in moss. ∑7NBFRs in soil samples collected in 2019 were significantly higher than those in 2012 (p < 0.05). Decabromodiphenyl ethane (DBDPE) was the predominant NBFR, accounting for 90% of ∑7NBFRs on average. The ratio of the concentrations in moss and soil showed significantly positive correlations with LogKOA except for DBDPE (p < 0.05), indicating that the role of mosses as accumulators compared to soils are more pronounced for more volatile NBFRs. In addition, the concentrations of NBFRs generally decreased with increasing altitude on the south-facing slope, whereas on the north-facing slope some NBFRs exhibited different trends, suggesting concurrent local and long-range transport sources. Normalization based on total organic carbon/lipid concentrations strengthened the correlation with altitude, implying that the altitude gradient of the mountain slope and forest cover could jointly affect the distribution of NBFRs in the TP. Furthermore, principal components analysis (PCA) with multiple linear regression analysis (MLRA) showed that the average contribution of the mountain cold trapping effect (MCTE) accounted for the major (77%) contribution and forest filter effect (FFE) has only a modest contribution to the deposition of NBFRs in soil.

Slope aspect and altitude effect on selected soil organic matter characteristics in Beskid Mountains forest soils

Abstract In the era of dynamic climate change, it is important to have knowledge on the interactions between climatic factors and processes occurring in the soil environment. The present study aimed to determine how slope aspect and altitude above sea level influence carbon and nitrogen accumulation and dehydrogenases activity of forest soils. The study was conducted in the Beskid Żywiecki in the south-facing part of Poland. Soils of the same texture, with similar vegetation species composition, in different altitude variants (600, 800, 1000 and 1200 m above sea level) and different north-facing and south-facing slope aspect were selected for the study. For each height and slope aspect variant, samples were collected from the surface horizons of soils for further analyses. The basic chemical properties and dehydrogenases activity of the soil samples were determined. Carbon and nitrogen stocks in the surface horizons of the soils were calculated. The analyses confirmed the influence of location conditions on the carbon and nitrogen stocks in mountain forest soils. The stock of carbon and nitrogen increased with the height up to 1000 m a.s.l. In the soils at the highest altitude, the reserve of carbon and nitrogen decreased regardless of the slope aspect variant. There were no statistically significant differences in carbon and nitrogen stocks between slope aspect variant. The highest dehydrogenases activity was associated with the organic horizons of the soils at the lowest altitude in height gradient. In our study, higher dehydrogenases activity was observed in the north-facing slope soils, and this finding can be explained by more stable thermal conditions.

The tempo of greening in the European Alps: Spatial variations on a common theme.

The long-term increase in satellite-based proxies of vegetation cover is a well-documented response of seasonally snow-covered ecosystems to climate warming. However, observed greening trends are far from uniform, and substantial uncertainty remains concerning the underlying causes of this spatial variability. Here, we processed surface reflectance of the moderate resolution imaging spectroradiometer (MODIS) to investigate trends and drivers of changes in the annual peak values of the Normalized Difference Vegetation Index (NDVI). Our study focuses on above-treeline ecosystems in the European Alps. NDVI changes in these ecosystems are highly sensitive to land cover and biomass changes and are marginally affected by anthropogenic disturbances. We observed widespread greening for the 2000-2020 period, a pattern that is consistent with the overall increase in summer temperature. At the local scale, the spatial variability of greening was mainly due to the preferential response of north-facing slopes between 1900 and 2400m. Using high-resolution imagery, we noticed that the presence of screes and outcrops locally magnified this response. At the regional scale, we identified hotspots of greening where vegetation cover is sparser than expected given the elevation and exposure. Most of these hotspots experienced delayed snow melt and green-up dates in recent years. We conclude that the ongoing greening in the Alps primarily reflects the high responsiveness of sparsely vegetated ecosystems that are able to benefit the most from temperature and water-related habitat amelioration above treeline.

Changes in Root-Shoot Allometric Relations in Alpine Norway Spruce Trees After Strip Cutting.

Silvicultural interventions such as strip cuttings can change the resource availability of the edge trees. This may alter tree allometry, as light regime, water, and nutrient availability can change at the forest edge. Increased root growth may optimize resource uptake and/or enhance tree anchorage to withstand the altered wind regime. However, little is known about the patterns of the root–shoot allometric responses to strip cuttings. In three alpine stands differing in climate, site productivity, and stand characteristics, we selected 71 Norway spruce trees and took increment cores from stems, root collars, and main roots. This enabled us to study changes in the long-term root-stem allometry for 46 years and short-term allometric responses to intervention. The effects of cutting were compared between edge trees and trees from the stand interior in 10 years before and after the intervention. The long-term allocation to roots increased with stem diameter, with the strongest effects on the regularly managed stand with the tallest and largest trees. These results support the allometric biomass partitioning theory, which postulates resource allocation patterns between different plant organs to depend on plant size. Strip cutting on north-facing slopes boosted edge-tree growth in all plant compartments and enhanced allocation to roots. This change in allometry started 2 years after cutting but disappeared 7–8 years later. In the post-cutting period, the highest root–shoot increase was observed in the small trees independent of the site. This indicates the change in growing conditions to have the strongest effects in formerly suppressed trees. Thus, the effect of such acclimation on the wind firmness of subdominant spruce trees is a question with high importance for optimizing cutting layouts in lowering post-cutting vulnerability to disturbance. The results from this case study contribute to a better understanding of the structural acclimation of spruce trees from high-elevation forests to new forest edges. However, for a more mechanistic understanding of environmental drivers, further analyses of tree-ring stable isotopes are recommended.

The Effect of Aspect and Elevation on Critical Zone Architecture in the Reynolds Creek Critical Zone Observatory: A Seismic Refraction Study

In the northern hemisphere within snow-dominated mountainous watersheds north-facing slopes are commonly more deeply weathered than south-facing slopes. This has been attributed to a more persistent snowpack on the north facing aspects. A persistent snowpack releases its water into the subsurface in a single large pulse, which propagates the water deeper into the subsurface than the series of small pulses characteristic of the intermittent snowpack on south-facing slopes. Johnston Draw is an east-draining catchment in the Reynolds Creek Critical Zone Observatory, Idaho that spans a 300 m elevation gradient. The north-facing slope hosts a persistent snowpack that increases in volume up drainage, while the south-facing slope has intermittent snowpack throughout the drainage. We hypothesize that the largest difference in weathering depth between the two aspects will occur where the difference in snow accumulation between the aspects is also greatest. To test this hypothesis, we conducted four seismic refraction tomography surveys within Johnston Draw from inlet to outlet and perpendicular to drainage direction. From these measurements, we calculate the weathering zone thickness from the P-wave velocity profiles. We conclude that the maximum difference in weathering between aspects occurs ¾ of the way up the drainage from the outlet, where the difference in snow accumulation is highest. Above and below this point, the subsurface is more equally weathered and the snow accumulations are more similar. We also observed that the thickness of the weathering zone increased with decreasing elevation and interpret this to be related to the observed increase soil moisture at lower elevations. Our observations support the hypothesis that deeper snow accumulation leads to deeper weathering when all other variables are held equal. One caveat is the possibility that the denser vegetation contributes to deeper weathering on north-facing slopes via soil retention or higher rates of biological weathering.

Microclimatic Gradient as a Source of Variations in Cultivable soil Microfungal Communities at the Negev Desert, Israel

We studied the effect of microclimatic gradient on the spatial (8 habitats) and seasonal (autumn, winter, and summer) variations of culturable soil microfungal communities at the north-facing slope (NFS) and the south-facing slope (SFS) of Nahal Boker, the Central Negev Desert, Israel. Using the soil dilution plate method, a total of 122 species from 56 genera was isolated. The communities' composition was subjected to pronounced interslope variations in each season. While xerotolerant melanin-containing species (mainly with the protective multicellular spore morphology) predominated in the soil of NFS, peaking up in the summer, thermotolerant and thermophilic Aspergillus spp. were especially abundant at the SFS. Aspergilli also dominated the thermotolerant communities isolated at 37 °C from both slopes. The more severe microclimatic regime at the SFS resulted in the least pronounced spatial and seasonal intraslope variability of the community composition as compared to the more benign and heterogeneous NFS. The quantitative parameter—the density of microfungal isolates, exhibited significant and positive relationship with organic matter and moisture content. In seasonal dynamics, the severe summer conditions significantly reduced the differences in isolate density at the NFS, which were markedly expressed in the autumn and winter between habitats receiving additional water by runoff and the adjacent habitats that did not benefit from runoff water.

Modeling spatially distributed snow instability at a regional scale using Alpine3D

AbstractAssessing the avalanche danger level requires snow stratigraphy and instability data. As such data are usually sparse, we investigated whether distributed snow cover modeling can be used to provide information on spatial instability patterns relevant for regional avalanche forecasting. Using Alpine3D, we performed spatially distributed simulations to evaluate snow instability for the winter season 2016–17 in the region of Davos, Switzerland. Meteorological data from automatic weather stations were interpolated to 100 m horizontal resolution and precipitation was scaled with snow depth measurements from airborne laser scanning. Modeled snow instability metrics assessed for two different weak layers suggested that the weak layer closer to the snow surface was more variable. Initially, it was less stable than the weak layer closer to the ground, yet it stabilized faster as the winter progressed. In spring, the simulated snowpack on south-facing slopes stabilized faster than on north-facing slopes, in line with the regional avalanche forecast. In the winter months January to March 2017, simulated instability metrics did not suggest that the snowpack on south-facing slopes was more stable, as reported in the regional avalanche forecast. Although a validation with field data is lacking, these model results still show the potential and challenges of distributed modeling for supporting operational avalanche forecasting.

Shading and Masking of PV Collectors on Horizontal and Sloped Planes Facing South and North—A Comparative Study

With the increase in PV system installations, the available free land and rooftops for these systems may become scarcer, and therefore sloped fields facing the north may be utilized for that purpose. In deployments of PV collectors in multiple rows, either on horizontal or sloped planes, the second and subsequent rows are subject to two effects: shading and masking. Both effects reduce the electric energy generated by the PV systems. Multiple rows of collectors are deployed on horizontal planes and on sloped planes facing south, and literature on the topic has been published. No literature deals analytically with deployments of PV fields on north-facing slopes in the northern hemisphere, to the best of our knowledge. The present study develops explicit analytical expressions for the shadow height and length cast on a collector row by a row in front in multiple-row PV systems installed on slopes facing north. In addition, analytical expressions are developed for row spacing and sky view factors, altogether leading consequently to the determination of shading and masking losses. Having the developed expressions, a comparison was made between PV deployments on north-facing sloped planes to PV deployments on horizontal and south-facing slopes regarding shading and masking losses. The main finding is that the percentage of masking losses (diffuse radiation) may exceed the percentage of shading losses (beam radiation) in PV fields. At the local site 32∘ N, collector inclination angle β=25∘ and sloped-plane ε=10∘, for example, the percentage of masking losses for a horizontal plane is 6.90%; for a sloped plane facing south, the losses are 5.39%, and for a sloped plane facing north, the losses are 6.86%. In comparison to the masking losses, the percentage of shading losses for the horizontal plane is 0.83%; for the sloped plane facing south, the losses are 0.42%, and for the sloped plane facing north, the losses are 1.37%.

Diversity of birds recorded at different altitudes in central Nepal Himalayas

Factors determining the spatial distribution of bird species along altitudinal gradients have been important in their ecological and biogeographical research. Here, have used the data on bird species recorded in Manang, central Nepal Himalayas and attempt to determine the drivers of bird species diversity. We also carried out indicator species analysis to observe if any bird species are associated with different altitudinal ranges and land use gradients. We recorded 1331 individuals belonging to 82 species of both resident and itinerant birds. In our study, altitude was the major factor determining species richness and abundance. Position of study localities is main factor determining bird community composition. Diversity of bird species were mainly found in habitats that were far human settlements, having high annual mean temperature and more roughness. Species diversity was high during July-August compared to September-October and in north-facing slopes, and also in shrub and tree covered areas than grassland and places with mostly snow and grassland. Indicator species analysis showed only 21 species were significantly associated with altitudinal gradients, mostly below 3000 m a.s.l. and only eight bird species were associated with two land use gradients (grassland and snow-glacier). In conclusion, position of sampled localities, altitude, aspect, land use types and different climatic factors were important determinants of bird diversity along altitudinal gradients in Manang. To protect bird diversity in Manang, we need to protect habitats that are located mainly in low altitudes for most of the bird species. However, high altitude habitats with snow and glaciers are also important for few bird species. Thus, a large area with heterogenous habitats is important for bird species management and conservation.

Local Landscape Position Impacts Demographic Rates in a Widespread North American Steppe Bunchgrass

Photo 1. Widely spaced bluebunch wheatgrass (Pseudoroegneria spicata) surrounded by smaller annual grasses on a south-facing slope at Wallula Gap Biological Station, WA, USA. Photo credit: Timothy Parker. Photo 2. Densely distributed bluebunch wheatgrass (Pseudoroegneria spicata) and other perennial bunchgrasses on a north-facing slope at Wallula Gap Biological Station, Washington, USA. Photo credit: Timothy Parker. Photo 3. A comparison between a north-facing slope (left) and a hotter, drier south-facing slope (right) at Wallula Gap Biological Station, Washington, USA. Note the widely spaced green clumps of bluebunch wheatgrass (Pseudoroegneria spicata) on the south-facing slope in the foreground and the much denser concentration of green perennial grasses, many of which are bluebunch wheatgrass, on the north-facing slopes. Photo credit: Timothy Parker. These photographs illustrate the article “Local landscape position impacts demographic rates in a widespread North American steppe bunchgrass” by Shriver et al. published in Ecosphere. https://doi.org/10.1002/ecs2.3351

Signatures of an abiotic decomposition pathway in temperate forest leaf litter

Photodegradation helps explain why leaf litter mass loss rates are comparable between mesic environments and drylands, despite water availability limiting decomposer activity in drylands. With photodegradation, light energy directly mineralizes photoreactive organic molecules such as lignin, which contrasts with biotically-driven decomposition where lignin persists in decomposing leaf litter relative to other compounds. Photodegradation of leaf litter has largely been studied in dryland systems, but whether it occurs in mesic, deciduous forest systems is uncertain. As such, we examined potential photodegradation in maple and oak litter in the Southern Appalachian Mountains (USA) during the non-growing season, when newly fallen leaves are exposed to maximum solar radiation without deciduous canopies. The proportion of oxidized lignin in the leaf litter relative to other carbon compounds decreased with maximum solar radiation during the non-growing season. With a closed canopy, however, the proportion of total lignin relative to other compounds in the leaves increased. This pattern was particularly strong for the syringyl- S6 and guaiacyl-G6 lignin monomers. The relative proportion of S6 and G6 in the litters was reduced by 10–65% in the first 5 months. The largest reductions in lignin occurred on south-facing mountain slopes where solar radiation was highest (relative to north-facing slopes) in the Northern Hemisphere. Overall, however, the changes in lignin did not alter cumulative litter mass lost. Our results suggest that photodegradation promotes the transformation and relative loss of lignin in the early stages of litter decomposition in mesic deciduous forests.

Factors controlling the asymmetry of soil moisture and vegetation dynamics in a hilly Mediterranean catchment

The interaction between hydrology, terrain, and vegetation, is an essential element in understanding complex landscapes, and in forecasting their evolution under climate change. In Mediterranean Europe, few studies have been performed on the interrelation between them. In this study, soil moisture, vegetation, and water table dynamics were measured on opposing hillslopes of a semi-arid, Mediterranean catchment in southern Spain, to quantify the aspect influence on ecohydrological dynamics of an oak-woodland savanna or “dehesa”.Observations of a network of 32 soil moisture sensors on two opposing hillslopes, a north-facing slope (NFS), and a south-facing one (SFS), detected a similar moisture dynamics, although the influence of the vegetation induces a lagged response where the NFS dries out earlier compared to the SFS. Analysis of successive soil water profiles after storm events suggests that the water moves downwards as an unsaturated preferential flow along the walls of the fractured granite material, with residence times between 16.3 and 36.7 days. Our results show that there is a direct coupling between the hillslope hydrology, the depth of the weathered bedrock, much higher on the NFS, and the vegetation dynamics. Vegetation is much denser on NFS, as LIDAR-derived biomass estimates were 29% higher than on the SFS. The evolution of the normalized difference vegetation index (NDVI), obtained from the Sentinel-2 time series, also shows completely opposing trends with a minimum value at the end of winter for the NFS, whereas the SFS reaches minimum values in summer. A significant correlation between NDVI and soil moisture was found for the SFS (Pearson’s R of 0.81). However, this correlation is very poor on the NFS, but a good correlation with water table was found (R = 0.46). This shows how the deep weathering on the NFS allows for an additional water source, contained in the rock moisture and saturated zone, that represents an important source for the vegetation, whereas on the SFS only soil moisture supports the vegetation. These vegetation differences in turn directly impact surface soil moisture, leading to the observed, relatively similar trends on both hillslopes.

Effects of forest disturbance on seasonal soil temperature changes in the Tatra Mountains in southern Poland

Abstract The purpose of the study was to examine the effects of forest disturbance on seasonal changes in soil temperature in the Tatra Mountains (Poland). In the years 2015–2020 soil temperatures were measured at a depth of 20 cm on north- and south-facing mountain slopes in a catchment where forest was disturbed by hurricane-force winds in 2013 and in a control neighboring woodland catchment. The effect of forest disturbance was manifested first and foremost in an increase in the soil temperature during the summer months – average by 1.8 to 2.4 °C on a south-facing mountain slope – and by about 1 °C on a north-facing slope. The buffer effect of forest on soil temperature can be observed via lower coefficients of correlation between soil temperature and air temperature in a woodland catchment versus a disturbed catchment in the summer. In the winter, the effect of forest disturbance on soil temperature was less pronounced than in the summer. Small differences in soil temperature in the winter between the woodland catchment and the disturbed catchment were associated with the presence of snow cover and its capacity to yield thermal insulation. Good insulation of the soil from the atmosphere generated by snow cover yielded a very weak relationship between soil temperature and air temperature in the winter. In springtime the soil temperature increased the fastest on a south-facing slope in the disturbed catchment while in the autumn season, soil temperatures declined most rapidly on a slope facing north in the disturbed catchment.

Spatial variations in the growth rate of Hylocomium splendens and the thickness of the organic layer on a north-facing slope in Interior Alaska

High-resolution data on spatial variations in the productivity of bryophytes and the mass of the organic layer are important components in geochemical models for northern forests. We investigated spatial variations in growth rates of the feather moss Hylocomium splendens and the thickness of the organic layer in relation to environmental factors on a north-facing slope in Interior Alaska. The forest floor on the 600 m × 600 m slope was classified into four types, i.e., Classes I–IV, characterized mainly by the dominance of leaf litter, H. splendens, Pleurozium schreberi, and Sphagnum spp., respectively. Spatial autocorrelation analyses showed clustering patterns for some tree and forest floor variables, which were associated with the distribution of the four classes on the slope. Mean growth (length) rates of H. splendens were high in Class II, while growth rates by weight were high in Class I due to a high weight-to-length ratio of shoots. The thickness of the organic layer in bryophyte patches ranged from 6.0 to 40.7 cm and was also controlled by slope orientation. The presence of large trees, particularly Betula neoalaskana, mediated the relationship between topography and forest floor characteristics.

Weak effect of plant canopy but strong impact of depth on variation of cultivable microfungal communities through soil profiles in semiarid Spain

We studied the effect of plant canopy on the distribution of microfungi through 0−30-cm soil profiles under canopies of three plant species and in their adjacent interspace at sun-exposed plain and north-facing slope in the Tabernas Desert, Spain. Using the soil dilution plate method, 142 species from 68 genera were isolated. Melanin-containing fungi dominated in the topsoil layers because of high temperatures and dryness. By contrast, light-colored fungi generating a high amount of small thin-walled conidia substantially increased their abundance in the deeper soil layers – thermotolerant Aspergillus spp. in the 1−5-cm layers and mesophilic Penicillium spp. in the 10−20-cm layers. The significant increase in density of microfungal isolates at 1−10 cm-depth could be associated with the deposition of conidia of aspergilli and penicillii caused by shallow water infiltration in the fine-grained soil and their survival at these depths due to more appropriate edaphic conditions (mainly higher water availability and root concentration). Generally, the effect of plant canopy on microfungal communities was only weakly expressed in higher variations of isolate densities and species richness through the profiles, and in reduced abundance of melanized species with protective multicellular spore morphology in the topsoil layers; at the same time, soil depth strongly influenced all community characteristics. The study highlights the remarkable role of edaphic factors (temperature, water regime, and soil texture) in the distribution of microfungi through soil depth in semi-arid areas.