High Elevation Research Articles

Germination ecology of Phytolacca americana L. in its invasive range

AbstractInvasive species are a worldwide problem, and the germination process is useful to understand the characteristics that allow alien species to be invasive and their projected response to global climate change. Phytolacca americana is one of the most invasive plants in Italy, and we tested, for different populations (from different altitudes) how light, temperature, and cold stratification affect seed germination. According to our analyses, P. americana produces an exceptionally high number of seeds that may potentially survive in soil for extended periods. Seeds subjected to cold stratification and exposed to warmer temperatures, both in light and darkness, exhibited faster germination, with a higher germination rate and a shorter T50. Seeds collected at the highest elevation (337 m a.s.l.) have germinated in all tested thermal conditions, albeit with a lower germination percentage and a longer T50 compared with seeds collected at lower elevations (5 and 50 m a.s.l.) and tested under warm and moderate temperatures. In general, P. americana seems to adapt to moderate‐warm temperatures (at low elevations) and moderate‐cool temperatures (at highest elevations) and appears to increase germination with seeds exposed to cold stratification. These results, in a scenario of climate change, show that the invasiveness of P. americana may increase in the future.

Leaf-cutting ants’ distribution in an elevation gradient in central Argentina

ABSTRACT Leaf-cutting ants are among the most prominent herbivores in neotropical forests and savannas, and Argentina represents the southern limit of their distribution. Despite their importance, few systematic studies analyze the presence and distribution of leaf-cutting ants in Argentina. Our aim was to describe, through an intensive field sampling, the leaf-cutting ant species present in the central Argentine mountains and analyze their distribution along the elevation gradient. We collected ants from 69 nests in 56 out of the 250 plots visited along the study elevation gradient (400–2700 m above sea level) in seven different habitats, from forests to rocky areas. We found six species. The most frequent were Acromyrmex lobicornis and Acromyrmex crassispinus, while Acromyrmex heyeri, Amoimyrmex silvestrii, Amoimyrmex striatus, and Amoimyrmex bruchi were far less frequent. The species distributed at the highest elevation was A. lobicornis (1223 to 2163 m a.s.l.), showing significant differences with the other species. We found leaf-cutting ants in all habitats, with a higher presence in grazing lawns, shrublands, and exotic forests. Our results indicate that leaf-cutting ants are present in most of the mountain range, as the area above their upper limit of distribution represents less than 5% of the total mountain area.

Exploring spatial variations in geomorphic features of a young intracontinental orogenic belt: A case study of the High Atlas range

Morphotectonic parameters are sensitive to crustal and/or mantle dynamics, especially in young convergent margins and contractional orogenic systems. In northwest Africa, the High Atlas orogen is a natural example where tectonics interact with mantle dynamics to shape the orogen's topography.The High Atlas Mountains are an intracontinental segment of the peri-Mediterranean belt in northwest Africa, formed during the Late Cretaceous-Cenozoic period as part of the Alpine orogeny. An important aspect in the evolutionary history of the High Atlas belt is the presence of uplifted asthenosphere beneath the range, overlaying the Late Cretaceous-Cenozoic crustal shortening. This study aims to investigate the geomorphic and topographic features that reflect the influence of tectonics and mantle dynamics in the High Atlas orogen. A morphotectonic approach is employed, utilizing analysis of geomorphic indices such as relief, slope, channel steepness index, and stream length gradient. Additionally, eleven 30 km wide and 150 to 230 km long swath profiles are constructed to illustrate the variations in topography and geomorphology along the range.The geomorphic indices display a similar pattern of evolution across the High Atlas, with higher values of these indices associated with the primary faults that control the structure of the range. By combining the geomorphic indices and swath profiles, it is evident that the eastern part of the orogen exhibits geomorphic asymmetry, with the northern border experiencing greater neotectonic activity and surface uplift. The central part of the range displays more geomorphic symmetry, while the western part is asymmetrical, characterized by higher elevations and elevated values of geomorphic indices along the southern border. This variation in geomorphology is attributed to the oblique intersection of the High Atlas orogen and a region of thinned lithosphere, which facilitated increased neotectonic activity and surface uplift in the northern part of the Eastern High Atlas and the southern part of the Western High Atlas. In the westernmost portion of the range, the role of structural inheritance is critical in the neotectonic activity. At a local scale, the role of lithology in the drainage reorganization is evident especially in basement exposures such as Mougueur inlier, Skoura inlier and Ouzellarh salient.This study underscores the robustness of tectonic geomorphology as a tool to understand the complex interplay between crustal processes and mantle dynamics, together with surface processes, in young orogenic belts like the High Atlas.

Abundance and diversity of the culturable nectar mycobiome in Rhododendron catawbiense varies with elevation

Abstract The nectar microbiome can influence pollinator choice and plant fitness. Previous research has shown that changes in environmental conditions at large spatial scales can influence nectar microbiome composition. However, little is known about how changes in climate with increasing elevation affect nectar microbiome abundance and composition. Here we describe the culturable nectar mycobiome of Rhododendron catawbiense (Ericaceae) by quantifying colony abundance, identity, and richness of fungal genera. We further evaluate how the culturable nectar mycobiome (CNMB) abundance, diversity, and composition (i.e., the fungal species within the nectar microbiome) varies at two different elevations. Nectar samples were collected from R. catawbiense individuals at a high and low elevation and were cultured on yeast agar with 0.01% chloramphenicol media. Fungal colonies were categorized morphologically, quantified, and then identified using DNA barcoding. In total, 2,822 fungal colonies were recorded belonging to six genera across both elevations. Elevation did not influence CNMB diversity (Simpson’s diversity index) or genera richness per flower, however only three genera were found at the high elevation while six were found at the low elevation. Elevation had a significant effect on colony abundance with a 95% increase in the number of colonies in nectar samples at low compared to the high elevation. Variation in abundance and overall genera composition of fungal colonies across elevations may have the potential to affect nectar quantity and quality and ultimately pollination success. This study adds to our understanding of the drivers of CNMB composition across spatial scales its potential implications for plant-pollinator interactions.

Components of dissolved organic carbon in relation to environmental factors in lakes along an altitudinal gradient in central China.

Dissolved organic carbon (DOC) is an important organic substance that affects biogeochemical processes and underwater light conditions in aquatic ecosystems. To explore altitudinal variations in DOC components and water quality, 66 surface water samples were collected along an altitudinal gradient (10-1857m) in three regions of central China, including a montane region (Enshi Prefecture) and two floodplain regions (Dongting Lake Basin and Wuhan City). DOC components were measured using a three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectroscopy, in conjunction with fluorescence regional integration (FRI) and fluorescence indices. Generally, lakes at high elevations (Enshi Prefecture) had higher DOC concentrations (a mean value of 6.43mgL-1) than floodplain lakes in Dongting Basin (4.51mgL-1) and Wuhan City (3.89mgL-1). Fluorescence index (FI, a range of 1.37-1.92) and biological index (BIX, a range of 0.47-0.74) indicated that DOC mainly originated from allochthonous sources in the three regions. Enshi Prefecture had relatively lower FI and BIX values, suggestive of a larger contribution of allochthonous carbon in this montane region in comparison with the floodplain regions. Humic-like substances were more abundant than other four fluorescent components, including tyrosine-like, tryptophan-like, fulvic acid-like, microbial-like substances. Spearman rank correlation analyses showed that tryptophane-like substances were positively correlated with K+, Mg2+, and Na+, while humic-like substances were negatively correlated with these cations. Taken together, the results can improve our understanding on altitudinal variations in DOC components and potential driving forces.

Vehicle modeling and state estimation for autonomous driving in terrain

The automobile industry usually ignores the height of the path and uses planar vehicle models to implement automatic vehicle control. In addition, existing literature mostly concerns level terrain or homogeneous road surfaces for estimating vehicle dynamics. However, ground vehicles utilized in forestry, such as forwarders, operate on uneven terrain. The vehicle models built on level terrain assumptions are inadequate to capture the rolling or pitching dynamics of such machines as rollover of such vehicles is a potential risk. Therefore, knowledge about the height profile of the path is crucial for automating such off-road operations and avoiding rollover. We propose the use of a six-degrees-of-freedom (6-DOF) dynamic vehicle model to solve the autonomous forwarder problem. An adaptive linear tire model is used in the 6-DOF model assuming the vehicle operates in a primary handling regime. The force models are modified to include the three-dimensional (3D) map information. The calibration procedures, identifying actuator dynamics, and quantifying sensor delays are also represented.The proposed vehicle modeling contributed to realizing the continuous-discrete extended Kalman filter (CDEKF), which takes into account the 3D path during filtering and fixed-lag smoothing. Polaris (an all-terrain electric car) is used as a case study to experimentally validate the vehicle modeling and performance of the state estimator. Three types of grounds are selected — an asphalt track, a concrete track with a high elevation gradient, and a gravel track inside a forest. Stable state estimates are obtained using CDEKF and sparse 3D maps of terrains despite discontinuities in satellite navigation data inside the forest. The height estimation results are obtained with sufficient accuracy when compared to ground truth obtained by aerial 3D mapping. Finally, the proposed model’s applicability for predictive control is demonstrated by utilizing the state estimates to predict future states considering (3D) terrain.

Spruce suffers most from drought at low elevations in the Carpathians, though shows high resilience

More frequent and severe droughts have affected forest ecosystems throughout Europe in recent decades. In Central Europe, large-scale dieback of Norway spruce has, for example, been observed, whereas Norway spruce decline was so far less widespread in Eastern Europe. To assess the potential future impacts of drought on Norway spruce in the southeastern part of its natural distribution, studies on drought resilience are urgently needed. Here, we use a tree-ring network consisting of more than 3000 trees from 158 managed Norway spruce stands of different ages distributed along elevational gradients in the Eastern Carpathians to assess growth responses to drought. Specifically, we analyzed differences in resilience components (e.g., resistance, recovery, resilience, recovery period) with elevation and tree age, and used the ‘line of full resilience’ concept to comprehensively assess drought resilience. Our results show that Norway spruce at low elevations (<800 m) is characterized by the lowest resistance to drought, though has a high recovery, while at high elevations (>1400 m), a higher resistance is associated with a low recovery. In general, older trees were found to need more time to recover. Resilience decreases with a higher water deficit, suggesting that Norway spruce is at risk in the Carpathians with ongoing climate change, urging the need for adaptative forest management.

Experimental investigation and fluid-structure interaction modelling of the casting of self-compacting concrete for CRTS III slab track in the curved segments

Ensuring the casting quality of self-compacting concrete (SCC) is crucial for the operational safety and durability of China railway track system (CRTS) III slab track. However, the mechanisms of key factors influencing flow behaviors of SCC and structural responses remain insufficiently understood, nor is the relationship between flow behaviors and structural responses during casting. In this study, fluid-structure interaction (FSI) models of SCC casting were developed and verified by full-scale physical tests, comprising slump flow, L-box flow and casting of SCC in an actual track at the field of Laixi-Rongcheng high-speed railway. Through in-depth analysis on the casting process of SCC in curved segments with a super elevation of 80 mm, the relationship between flow behaviors and structural responses was established. Furthermore, the influence mechanisms of key factors on flow behaviors and structural responses were investigated systematically. Results show that during gravity-fed SCC casting, its flow velocity diminishes, thus increasing the static pressure and the forces exerted on the slab by SCC. These vertical and lateral forces increase to 147.16 and 7.83 kN through three stages of development, acceleration and stabilization, resulting in commensurate structural responses. At the end of casting process, the central region of the slab exhibits maximum vertical deformation of 0.95 mm and tensile stress of 1.07 MPa. The tension rods at the side with lower elevation bear greater vertical and lateral forces than the ones at the side with higher elevation. The rise of funnel height from 1.05 to 1.35 m accelerates the casting process but increases the forces exerted by SCC by up to 26 % and augments the associated response of entire structures, whereas the funnel diameter shows little effect. Increasing yield stress of SCC from 9.3 to 49.3 Pa produces a more uniform flow morphology and thus higher static pressure and force by SCC in the middle region of the slab, impacting the structural responses by up to 15 %. The growth of plastic viscosity from 59 to 99 Pa⋅s significantly affects the volume rate and casting time by up to 66 % but has little effect on the flow morphology, fluid pressure and structural responses. In order to ensure high quality casting of SCC, five clamping beams are suggested with two beams positioned at either side of the slab and the other three evenly placed along the middle region of the slab.

The effects of working with a passive arm-support exoskeleton on objective and self-reported measures during field tasks – a randomised cross-over study

Musculoskeletal disorders (MSDs) are prevalent under poor working situations. Where it is not possible to remove the root cause of MSDs, passive exoskeletons could be a solution. In this randomised cross-over field study we investigated the effect of a passive arm-support exoskeleton. Ten participants, recruited from a Dutch gas company, were measured with and without exoskeleton assessing muscle activity, heart rate (HR), arm elevation, and reported about their experiences. Participants spent more time in high arm elevation levels with the exoskeleton than without. Muscle activity was lower in the trapezius (Beta: −1.8 [−3.1; −0.4]) and deltoid (Beta: −1.4 [−2.3; −0.6]) muscles, but not the biceps muscle, during the measurements with exoskeleton than without, suggesting effectiveness of the exoskeleton. HR and discomfort did not statistically significantly differ between the two conditions. Participants would recommend an exoskeleton to their colleagues, but mainly for repetitive work. Their opinions about the usefulness during work varied.

Quantifying spatially explicit uncertainty in empirically downscaled climate data

AbstractEcological simulations including forest and vegetation growth models require climate inputs that match the resolution and extent of the process being modelled. Climate inputs are often derived at resolutions coarser than the scale of many ecosystem processes. Machine learning models can be trained to spatially downscale climate data to fine (30 m) resolution using topographic variables such as elevation, aspect and other site‐specific factors. Statistically downscaled climate models will have spatially varying uncertainty that is not usually incorporated into downscaling techniques for error propagation into later models, are often applied on smaller areas, are not fine enough resolutions for many modelling techniques, or are not always scalable to large spatial extents. There remains opportunity to leverage machine learning advancements to downscale climate to very fine (30 m) resolutions with associated spatially explicit uncertainty to represent microclimatic variation in ecological models. In this study, we used quantile machine learning to produce 30 m downscaled temperature and precipitation data and associated model prediction uncertainty for the state of California. Temperature models were accurate at downscaling 4 km climate data to 30 m, performing better than the 4 km data at high and low slope positions and at high elevations, especially where there were fewer weather observations. Precipitation model predictions did not show global improvement over the 4 km scale, but were more accurate at high elevations, slopes with higher solar radiation and in valleys. For all climate variables, the added detail of spatial explicit uncertainty via 90% prediction intervals provides critical insight into the utility of empirically downscaled climate. The resulting 30 m spatially contiguous outputs can be used as ecological model inputs with uncertainty propagation, to illuminate climate trends over time as a function of fine‐scale spatial factors, and to highlight areas of spatially explicit uncertainty.

Distentanging the late-Holocene human–environment interactions in the Altai Mountains within the Arid Central Asia

Understanding the impacts of human activities on landscapes necessitates a comprehensive analysis of historical changes in climate, vegetation, fire and land utilization. The human-environment interactions were investigated through the analysis of new charcoal data from Kelashazi Peat in the Altai Mountains, compared with the detailed paleoenvironmental records and historical human activities (e.g., agriculture and pastoralism) at other three distinct sites. The findings suggest that the late-Holocene (prior to ∼2000 years ago) fire activities were mainly influenced by temperature at higher elevations and were primarily driven by vegetation cover at lower elevations. Over the past two millennia, human activities have increasingly impacted fire dynamics. Elevated fire frequencies during the Medieval Warm Period at higher elevations were linked to warmer climates and intensified pastoral activities. Lower fire incidences at lower elevations may be attributed to population outflows during the Medieval Warm Period, while heightened fire occurrences at lower elevations might result from increasing agricultural activities during the Little Ice Age. This study underscores the intricate interplay between natural climate-vegetation-fire dynamics and anthropogenic burning trends in the late Holocene across different elevations of the Altai Mountains within the Arid Central Asia.

How cushion plant communities structure nival soil biodiversity: A metabarcoding study in the French Alps

In the challenging environmental conditions of high elevation ecosystems, cushion plants create micro-climatic and fertile shelters which host a vast diversity of organisms. Yet, the taxonomic diversity of these hosts remains poorly described, and to what extent cushion plants structure these communities remains unclear. We sampled soils beneath six different species of cushion plants, along with bare-ground controls, across two different elevation gradients in the French Alps. We used environmental DNA metabarcoding to investigate the effect of different species of cushion plants on the α and β diversity of fungi, bacteria, eukaryotes, and for the first time in these ecosystems, unicellular eukaryotes and soil worms. Cushion plants hosted a surprisingly large diversity of organisms, from bacteria to mites and collembolans, forming rich and complex ecosystems. α-diversity between cushion plant and bare soil samples differed only for fungi, with communities partly structured by the cushion plant species’ identity. The effect of cushion plant species on composition and β-diversity of eukaryotic and fungal communities surpassed the environmental effect, while it equaled the site effect for bacterial communities. These results highlight the key role of biotic interactions in shaping the composition of high elevation communities, and clarify the role of cushion plants as engineer and foundation species in these harsh environments. By sheltering highly diverse communities at such high elevation, cushion plants may play a prominent role in the ecological assembly of these diverse, yet poorly known, ecosystems.

Spatial patterns of Geological Culture Villages (Towns) and their influential factors in China

Geological Culture Villages Towns (GCV(T)s) serve as rich repositories of geological resources, embodying significant historical and cultural values that mirror the dynamic interplay between Earth's evolution and human societies. Despite their importance, the theoretical underpinnings of GCV(T)s have not been thoroughly explored and elucidated. This study explores the relationship between geological culture and societal development, revealing the linkage between geological culture and societal advancement with the aim of promoting a harmonious coexistence between humanity and the environment. Focusing on 96 GCV(T)s in China, this study employs spatial analytical techniques such as the nearest-neighbor index, kernel density analysis, geographic connectivity, and geographic detector to scrutinize the spatial distribution patterns and identify key influencing factors. The findings reveal that (1) GCV(T)s exhibit uneven distribution, with concentrations in the Yangtze River Delta region, Beijing-Tianjin-Hebei region, and Shanxi-Gansu and Ningxia Provinces. (2) These sites tend to be situated in areas characterized by active geological formations, abundant geological relics, higher elevations, gentle topography, and ample rainfall. (3) The establishment and evolution of GCV(T)s are shaped by a complex interplay of geological heritage, natural factors, and human interventions. While the selection and spatial arrangement of these sites are predominantly influenced by geological and natural factors, the innovative development of their geological cultural heritage is driven by humanistic considerations. Overall, the distribution and evolution of GCV(T)s stem from multifaceted interactions among diverse factors. Recognizing this intricate web of influences is crucial for safeguarding geocultural diversity and formulating conservation strategies for geoheritage protection. The development of GCV(T)s transcends mere geoheritage preservation, it embodies a pivotal stride toward safeguarding the varied and multi-dimensional global geoheritage.

Assessment of climatic influences on net primary productivity along elevation gradients in temperate ecoregions

Elevation gradients significantly influence net primary productivity (NPP), but the relationship between elevation, climate variables, and vegetation productivity remains underexplored, particularly in diverse ecological zones. This study quantifies the impact of elevation and climatic variables on NPP in northern Pakistan, hypothesizing that elevation modulates NPP through its influence on temperature and precipitation patterns. Using remote sensing data (MODIS ERA5) and advanced ecological models like the Eddy Covariance-Light Use Efficiency (EC-LUE) model and the Thornthwaite Memorial Model (TMM), we analyzed Gross Primary Productivity (GPP) dynamics across various vegetation types and elevations from 2001 to 2023. Our findings show a mean annual NPP of 323.46 g C m-2 a-1, with an annual increase of 5.73 g C m-2 a-1. Significant elevation-dependent variations were observed, especially in mid-elevation zones (401 to 1600 meters), where NPP increased at a rate of 0.174 g C m-2 a-1 per meter (R² = 0.808, p < 0.01). In contrast, higher elevations (2800-5200 meters) exhibited a decline in NPP, decreasing by -0.171 g C m-2 a-1 per meter (R² = 0.905, p < 0.001). Temperature and precipitation were key drivers, with precipitation positively correlating with NPP across all vegetation types, particularly in Evergreen Needleleaf and Broadleaf Trees. The EC-LUE model's GPP estimates closely matched MODIS data (R² = 0.82), demonstrating the model's reliability. These findings highlight the critical role of elevation and climatic factors in vegetation productivity and underscore the need for targeted ecological management and conservation strategies. The insights from this research are vital for global climate adaptation policies and sustainable development goals, contributing to ecological resilience and carbon sequestration efforts worldwide.

The surface deformation of permafrost and active layer thickness in the upper reaches of the Black River basin, revealed by InSAR observations and independent component analysis

The Heihe River Basin, located in the northeastern part of the Qinghai-Tibetan Plateau, is part of the perennial permafrost belt of the Qilian Mountains. Recent observations indicate ongoing permafrost degradation in this region. This study utilizes data from 255 observations provided by Sentinel-1 satellites, MODIS Land Surface Temperature, SMAP-L4 soil moisture data, GNSS measurements, and in situ measurement. We introduced Variational Bayesian independent Component Analysis (VB-ICA) in multi-temporal Interferometric Synthetic Aperture Radar (MT-InSAR) processing to investigate the spatial-temporal characteristics of surface deformation and permafrost active layer thickness (ALT) variations. The analysis demonstrates strong agreement with borehole data and offers improvements over traditional methodologies. The maximum value of ALT in the basin is found to be 5.7 m. VB-ICA effectively delineates seasonal deformations related to the freeze-thaw cycles, with a peak seasonal deformation amplitude of 60 mm. Moreover, the seasonal permafrost's lower boundary reaches an elevation of 3700 m, revealing that permafrost is experiencing widespread degradation and associated soil erosion in the high elevation region of The Heihe River Basin. The paper also explores the efficacy of reference point selection and baseline network establishment for employing the InSAR method in monitoring freeze-thaw deformations. The study underscores the InSAR method's adaptability and its importance for interpreting permafrost deformation and related parameters.

Land-atmosphere coupling amplified the record-breaking heatwave at altitudes above 5000 meters on the Tibetan Plateau in July 2022

In July 2022, regions with elevations exceeding 5 000 m on the inner Tibetan Plateau (TP) witnessed a record-breaking heatwave. But how the atmospheric circulation and soil moisture play roles in the occurrence and maintenance of the heatwave in such high elevation climate sensitive region remains unknown. Here, by using the flow analogue method, we find that negative soil moisture anomalies explain more than half of the extreme high temperature during the heatwave, while atmospheric circulation explains less than half. The high soil moisture-temperature coupling metric and the increased correlation between latent heat flux and soil moisture during heatwave revealed strong land-atmosphere feedback in the Qiangtang Plateau which has amplified the heatwave. Analyses of numerical experiments confirm that the presence of interaction between soil moisture and the atmosphere has increased the intensity of hot extreme event under the same atmospheric circulation conditions. Under the warming background, land-atmosphere coupling leads to a faster increase in extreme high temperatures compared to the global mean warming rate, and it is twice as fast as the increase in extreme high temperatures without coupling. We highlight the increased probability of extreme high temperature over the TP in the future due to soil moisture feedback and the results are hoped to inform policymakers in making decisions for climate adaptation activities.

Organic farming is more related to topography than to soil characteristics in extensively and intensively managed grasslands in Switzerland

Organic farming and other agri-environmental schemes (AES) are important policy tools to support environmental-friendly agriculture. Often, AES require a direct reduction of actual management intensity to sustain biodiversity and non-marketable ecosystem services. In addition to lower management intensity, differences in topography and soils between AES and non-AES land can occur, driven by the targeted placement of AES in the landscape. Many of the latter effects of an AES are, however, widely unknown and frequently ignored, limiting a comprehensive understanding of how organic farming and other AES deliver environmental outcomes. We analysed pedological, topographical and other spatial characteristics of parcels under two grassland AES, i.e., organic farming (vs. conventional) and extensive management (vs. intensive). Thus, this study assessed whether organic farming is related to differences in topography and soil conditions in both extensively and intensively managed grasslands in the study region in the north of Switzerland. Therefore, we combined a regional-scale spatial analysis of permanent grassland parcels and a soil survey. Both AES were tested not only in interaction with each other but also within the two main harvest types, i.e., meadows (mainly mown) and pastures (mainly grazed), resulting in eight distinct grassland types that were studied. Results show both AES to be linked to differences in soil nutrients as well as topographical and other spatial characteristics. We found interactions of the two AES with the harvest type, i.e., meadow versus pasture. This was particularly pronounced for extensively managed conventional meadows, which were frequent at low elevation and on land potentially suitable for arable farming. Extensively managed pastures and all organic grasslands exhibited reduced production conditions (i.e., higher elevation, steeper slope, lower soil phosphorus concentrations). Yet, differences between organic and conventional grasslands were by tendency more pronounced in intensively than extensively managed grasslands. Our results show that farmers preferentially adopted both AES on land not ideal for intensive production, with the exception of many extensively managed meadows in low elevations. Our study therefore demonstrated that an assessment of the ecological outcomes of an AES must not only account for direct effects via management restrictions but also for indirect effects via spatial targeting by farmers. More research is still needed to assess and compare direct and indirect effects of AES to support evidence-based policymaking and improve spatial targeting of different land-use types.

3D study of dyke-induced asymmetric graben: The 1971 Mt. Etna (Italy) case by structural data and numerical modelling

In this work, we have integrated field data and numerical models to characterise a unique dyke-induced graben system, exposed both in section and plan view, with an unexpected asymmetric fault geometry. This volcanotectonic feature is related to the 1971 eruption of Mt. Etna (southern Italy) and is located near the northern wall of the Valle del Bove, a huge depression carved into the eastern flank of the edifice. A new structural map and quantitative data were obtained from the analysis of aerial stereophotos collected before the onset of the 1971 eruption and after, high-resolution drone-derived models and field surveys carried out in the summer of 2022. In plan view, the graben is 2-km-long and its width ranges 27–143 m from the bottom to the upper part of the section view, with about 82 m of difference in elevation from top to bottom. Graben faults clearly show an asymmetric setting in terms of attitude, with one fault that dips 70° to the south, and the other one that dips 50° to the north. Vertical offset values are greater at higher elevations. We also ran a set of numerical models, aimed at investigating the distribution and orientation of stresses around the inferred dyke tip and in the host rock. The comparison between field data and numerical models suggests a key role of the inclined topography, as shown in section view, in determining the orientation of dyke-induced σ1 and σ3 in the host rock. This, in turn, controls the geometry of the graben faults, resulting in the observed asymmetric setting. Additionally, dyke-induced stress concentrations and vertical offset values support the hypothesis of a downward propagation of the graben faults, from the surface down to the dyke tip.

Variations of soil metal content, soil enzyme activity and soil bacterial community in Rhododendron delavayi natural shrub forest at different elevations

BackgroundRhododendron delavayi is a natural shrub that is distributed at different elevations in the karst region of Bijie, China, and that has an important role in preventing land degradation in this region. In this study, we determined the soil mineral element contents and soil enzyme activities. The composition of the soil bacterial community of R. delavayi at three elevations (1448 m, 1643 m, and 1821 m) was analyzed by high-throughput sequencing, and the interrelationships among the soil bacterial communities, mineral elements, and enzyme activities were determined.ResultsThe Shannon index of the soil bacterial community increased and then decreased with increasing elevation and was highest at 1643 m. Elevations increased the number of total nodes and edges of the soil bacterial community network, and more positive correlations at 1821 m suggested stronger intraspecific cooperation. Acidobacteria, Actinobacteria and Proteobacteria were the dominant phyla at all three elevations. The Mantel test and correlation analysis showed that Fe and soil urease significantly affected bacterial communities at 1448 m; interestingly, Chloroflexi was positively related to soil urease at 1448 m, and Actinobacteria was positively correlated with Ni and Zn at 1821 m. Fe and soil urease significantly influenced the bacterial communities at lower elevations, and high elevation (1821 m) enhanced the positive interactions of the soil bacteria, which might be a strategy for R. delavayi to adapt to high elevation environments.ConclusionElevation significantly influenced the composition of soil bacterial communities by affecting the content of soil mineral elements and soil enzyme activity.

Strategies for falcata (Falcataria falcata (L.) Greuter and R.Rankin) farmers to mitigate gall rust severity across elevations

The extent of gall rust severity in Falcata plantations across various elevations and locations in the country is insufficiently documented, posing challenges for developing an integrated disease management strategy. This study aimed to assess the conditions favorable for gall rust severity in Falcata plantations at different elevations in Mindanao. Our survey revealed that gall rust severity is significantly higher at elevations exceeding 400 m above sea level (asl), with potential yield losses estimated between 23% and 52% of the total log volume per hectare. Factors contributing to increased severity, regardless of elevation, include low stand density (&lt;1000 trees/ha), extended distances from natural vegetation (&gt;1000 m), low understorey species diversity, and low average temperatures (&lt;24°C). These factors interact significantly with elevation, as higher severity was observed in plantations with greater understorey vegetation diversity and elevated temperatures (&gt;24°C), particularly at elevations over 600 m (asl). Based on our findings, it is recommended to avoid planting Falcata in areas with elevations exceeding 400 m (asl). However, if planting at higher elevations is unavoidable, adequate tree spacing (3 m x 3 m or 3 m x 4 m) should be maintained to achieve a moderate stand density (1000-1500 trees/ha). This practice can help regulate air circulation within the plantation, mitigate pathogen spread, and control understory vegetation growth and temperature impacts. Additionally, establishing and maintaining native vegetation or forest within 1000 m around Falcata plantations is advisable to create a protective buffer zone, thereby reducing gall rust severity.