Variations In Elevation Research Articles

Unravelling spatial scale effects on elevational diversity gradients: insights from montane small mammals in Kenya

BackgroundMontane ecosystems play crucial roles as global biodiversity hotspots. However, climatic changes and anthropogenic pressure increasingly threaten the stability of montane community dynamics, such as diversity-elevation interactions, creating a challenge in understanding species biogeography and community ecology dynamics in these crucial conservation areas. We examined how varying sampling spatial grains influence small mammal diversity patterns within Kenya’s tallest montane ecosystems.MethodsEmploying a combination of multidimensional alpha diversity metrics and multisite beta diversity characteristics (species richness, phylogenetic and functional diversity and divergence, and multisite beta diversity) alongside spatial generalized additive multivariate regression analyses, we tested how spatial scaling influences elevational diversity gradient patterns and their associations with environmental and human activity variables.ResultsThe diversity-elevation associations were generally homogeneous across spatial grains; however, idiosyncratic patterns emerged across mountains. The total (taxonomic, phylogenetic, and functional) beta diversity, nestedness, and turnover resultant components monotonically increased or decreased with varying spatial grains. The associations between the diversity patterns and the environmental and human footprint variables increased with spatial grain size but also presented variations across mountains and indices. Species richness and phylogenetic and functional richness indices were more strongly influenced by spatial scale variations than were the divergence and community structure indices in both the diversity distribution patterns and their associations with the environmental and human variables.ConclusionsThe diversity-elevation and diversity-environment (including human activity pressure) relationships across spatial grains suggest that montane small mammal diversity patterns portray subtle but systematic sensitivity to sampling spatial grain variation and underscore the importance of geographical context in shaping these elevational diversity gradients. For improved effectiveness, conservation efforts should consider these spatial effects and the unique geographical background of individual montane ecosystems.

The Fungal Community Structure Regulates Elevational Variations in Soil Organic Carbon Fractions in a Wugong Mountain Meadow

Soil organic carbon (SOC) fractions are vital intrinsic indicators of SOC stability, and soil fungi are the key drivers of soil carbon cycling. However, variations in SOC fractions along an elevational gradient in mountain meadows and the role of the fungal community in regulating these variations are largely unknown, especially in subtropical areas. In this study, an elevation gradient experiment (with experimental sites at 1500, 1700, and 1900 m) was set up in a Miscanthus sinensis community in a meadow on Wugong Mountain, Southeast China, to clarify the effects of elevation on soil fungal community composition, microbial residue carbon, and SOC fractions. The results showed that the contribution of soil microbial residue carbon to SOC was only 16.1%, and the contribution of soil fungal residue carbon to SOC (15.3%) was far greater than that of bacterial residue carbon (0.3%). An increase in elevation changed the fungal community structure and diversity, especially in the topsoil (0–20 cm depth) compared with that in the subsoil (20–40 cm depth), but did not affect fungal residue carbon in the two soil layers. When separating SOC into the fractions mineral-associated organic carbon (MAOC) and particulate organic carbon (POC), we found that the contribution of MAOC (66.6%) to SOC was significantly higher than that of POC (20.6%). Although an increased elevation did not affect the SOC concentration, it significantly changed the SOC fractions in the topsoil and subsoil. The soil POC concentration and its contribution to SOC increased with an increasing elevation, whereas soil MAOC showed the opposite response. The elevational variations in SOC fractions and the POC/MAOC ratio were co-regulated by the fungal community structure and total nitrogen. Our results suggested that SOC stabilization in mountain meadows decreases with an increasing elevation and is driven by the fungal community structure, providing scientific guidance for SOC sequestration and stability in mountain meadows in subtropical areas.

30 years of terrestrial insect richness patterns across elevation: What have we learned? A global meta-analysis.

Understanding elevation variation in biodiversity is a classic question in ecology and has implications for understanding climate change impacts on mountain ecosystems. While insects are the largest group of animals, the global trend in insect species richness with elevation is unknown. To date, single studies and taxa-specific syntheses have provided no single picture, finding variable patterns of insect richness with elevation. A global synthesis across systems would provide a better understanding of how insect species richness changes with elevation and the possible environmental correlates of those patterns. We used published studies of terrestrial insect elevation gradients from 1990 to 2020 to ask: How do insect species richness change with elevation, and which environmental variables best explain this relationship statistically? With 1486 sites spanning 151 species richness-elevation gradients from 80 studies from four diverse insect taxonomic groups and five biomes, we found that overall proportional richness reached a low-elevation plateau and then decreased. We also show that mean annual temperature and seasonality best explain this trend. We suggest best practices and areas of interest for the future of insect richness-elevation studies, including underrepresented groups, geographic areas, and more standardized methods.

The gravity of Paleolithic hunting

Topographic relief potentially played an important role in Stone Age hunting from the Middle Paleolithic onwards. Natural physical features like arroyos and cliffs, among many others, likely served as traps to stop or hinder animal movement. Yet, the presence of elevation and slope variation on a landscape means that hunters also may have been able to use terrain to hunt from on high. Here, we explored via archaeological experiment how an elevated position would have interacted with projectile weaponry via the force of gravity to influence a missile’s functional efficacy. We assessed the velocity and kinetic impact energy of two Paleolithic projectile weapon systems, the thrown javelin and the atlatl (spearthrower) and dart, at ground level and then at three-, six-, and nine-meter launch heights. The experimental results of the javelin supported our predictions. Velocity and kinetic impact energy increased as launch height increased. Unexpectedly, however, atlatl-propelled darts did not conform to our predictions, not only failing to increase dart velocity or kinetic impact energy as launch height increased but also decreasing both variables’ values. These results suggest that Paleolithic hunting with an atlatl in certain contexts likely came with consequential, and previously undocumented, opportunity costs. Our results also have implications for several aspects of archaeological interpretation in Paleolithic and post-Paleolithic contexts.

A novel flood conditioning factor based on topography for flood susceptibility modeling

Flood is one of the most devastating natural hazards. Employing machine learning models to construct flood susceptibility maps has become a pivotal step for decision-makers in disaster prevention and management. Existing flood conditioning factors inadequately account for regional characteristics of flood in the depiction of topography, potentially leading to an overestimation of flood susceptibility in flat areas. Addressing this gap, this study proposes a novel flood conditioning factor, local convexity factor (LCF), to enhance the accuracy of flood susceptibility modeling. Initially, LCF is computed based on a standard normal Gaussian surface to highlight elevation variations in local terrain. Subsequently, LCF is applied to flood susceptibility modeling using seven machine learning models across four distinct basins. Comparative analysis is conducted between flood susceptibility maps with and without the application of LCF to evaluate its impact on flood susceptibility modeling. The results demonstrate that the proposed LCF can enhance the accuracy of flood susceptibility modeling to varying degrees, across the four basins investigated. The Fujiang basin exhibited the most substantial improvement, with its AUC improved from 0.861 to 0.886, Producer’s Agreement improved from 0.869 to 0.899, and Overall Agreement improved from 0.778 to 0.811. Comparation with hydrodynamic inundation maps shows that particularly in relatively flat terrain areas, flood susceptibility maps incorporating LCF offer more precise delineation between flood-prone and non-flood-prone zones. This research holds potential for widespread application in the prediction of flood susceptibility using machine learning models, providing a novel perspective for enhancing their accuracy

Untangling the influence of biotic and abiotic factors on the elevational variation of plant intrinsic water-use efficiency and nitrogen availability in an alpine-gorge region on the eastern Qinghai-Tibetan Plateau

Untangling the influence of biotic and abiotic factors on the elevational variation of plant intrinsic water-use efficiency and nitrogen availability in an alpine-gorge region on the eastern Qinghai-Tibetan Plateau

Road Surface Texture Evaluation and Relation to Low-Speed Skid Resistance for Different Types of Mixtures

Pavement skid resistance is significant for driving safety. British Pendulum Number (BPN) is commonly used as a low-speed skid resistance indicator, whereas sometimes it is impractical for data collection on roads in service. Since skid resistance is greatly affected by pavement surface texture, this research aims to evaluate pavement surface texture comprehensively and estimate the low-speed friction BPN from road surface texture on macro- and micro- scale. Asphalt Concrete (AC) and Stone Mastic Asphalt (SMA) were included. Road surface texture was evaluated from four aspects, texture depth, amplitude-related Root Means Square (RMS), elevation variances corresponding to different wavebands and texture spectral analysis. Texture depth indicators include Mean Texture Depth (MTD) and Mean Profile Depth (MPD). Elevation variances with three wavebands, from 5 mm to 50 mm, from 0.5 mm to 5 mm and from 0.024 mm to 0.5 mm respectively, were obtained. The results show that MPD is well correlated with MTD. Elevation variances with different wavebands demonstrates that the elevation variance of macro-texture with long wavelengths from 5 mm to 50 mm dominates the total variance. Spectral analysis shows that texture level is larger when the wavelength is beyond 4 mm, which is consistent with elevation variances. A linear regression between BPN and single texture index, as well as multiple linear regression analysis were conducted. The former regression result indicates that it is not feasible to estimate BPN using single index due to low correlation coefficient R2. The latter shows that the BPN can be estimated from texture levels corresponding to 64 mm and 2 mm, and the micro-texture. The R2 can be up to 0.684. This research will contribute to fast acquisition of BPN from pavement surface texture, thus improving skid resistance.

Evidence of Intraspecific Adaptive Variation in the American Pika (Ochotona princeps) on a Continental Scale Using a Target Enrichment and Mitochondrial Genome Skimming Approach.

Montane landscapes present an array of abiotic challenges that drive adaptive evolution amongst organisms. These adaptations can promote habitat specialisation, which may heighten the risk of extirpation from environmental change. For example, higher metabolic rates in an endothermic species may contribute to heightened cold tolerance, whilst simultaneously limiting heat tolerance. Here, using the climate-sensitive American pika (Ochotona princeps), we test for evidence of intraspecific adaptive variation amongst environmental gradients across the Intermountain West of North America. We leveraged results from previous studies on pika adaptation to generate a custom nuclear target enrichment design to sequence several hundred candidate genes related to cold, hypoxia and dietary detoxification. We also applied a 'genome skimming' approach to sequence mitochondrial DNA. Using genotype-environment association tests, we identified rare genomic variants associated with elevation and temperature variation amongst populations. Amongst mitochondrial genes, we identified intraspecific variation in selective signals and significant changes to the amino acid property equilibrium constant, which may relate to electron transport chain efficiency. These results illustrate a complex dynamic of adaptive variation amongst O. princeps where lineages and populations have adapted to unique regional conditions. Some of the clearest signals of selection were in a genetic lineage that includes pikas of the Great Basin region, which is also where recent localised extirpations have taken place and highlights the risk of losing adaptive alleles during environmental change.

Analysis of resting status reveals distinct elevational variation in metabolisms of lizards.

Animals spend a considerable proportion of their life span at rest. However, resting status has often been overlooked when investigating how species respond to environmental conditions. This may induce a large bias in understanding the local adaptation of species across environmental gradients and their vulnerability to potential environmental change. Here, we conducted an empirical study on montane agamid lizards, combined with mechanistic modeling, to compare elevational variations in body temperature and metabolisms (cumulative digestion and maintenance cost) between resting and active status. Our study on three populations of an agamid lizard along an elevational gradient revealed a trend of decreasing body temperature toward higher elevations, the main contributor of which was resting status of the lizards. Using population-specific reaction norms, we predicted greater elevational variation in hourly and cumulative digestion for resting lizards than for active lizards. Climate-change impacts, estimated as the change in cumulative digestion, also show greater elevational variation when resting status is factored into the analysis. Further, our global analysis of 98 agamid species revealed that in about half of their combined distributional range, the contribution of resting status in determining the elevational variation in cumulative digestion and maintenance cost of lizards was greater than the contribution made by a lizard's active status. Our study highlights the importance of considering resting status when investigating how species respond to environmental conditions, especially for those distributed over tropical and subtropical mountain areas.

Scale-dependence in elk habitat selection for a reintroduced population in Wisconsin, USA.

Habitat selection is a critical aspect of a species' ecology, requiring complex decision-making that is both hierarchical and scale-dependent, since factors that influence selection may be nested or unequal across scales. Elk (Cervus canadensis) ranged widely across diverse ecoregions in North America prior to European settlement and subsequent eastern extirpation. Most habitat selection studies have occurred within their contemporary western range, even after eastern reintroductions began. As habitat selection can vary by geographic location, available cover, season, and diel period, it is important to understand how a non-migratory, reintroduced population in northern Wisconsin, USA, is limited by the lack of variation in topography, elevation, and vegetation. We tested scale-dependent habitat selection on 79 adult elk from 2017 to 2020 using resource selection functions across temporal (i.e., seasonal) and spatial scales (i.e., landscape and home range). We found that selection varied both spatially and temporally, and elk selected areas with the greatest potential to influence fitness at larger scales, meaning elk selected areas closer to escape cover and further from "risky" features (e.g., annual wolf territory centers, county roads, and highways). We found stronger avoidance of annual wolf territory centers during spring, suggesting elk were selecting safer habitats during calving season. Elk selected habitats with less canopy cover across both spatial scales and all seasons, suggesting that elk selected areas with better access to forage as early seral stage stands have greater forage biomass than closed-canopy forests and direct solar radiation to provide warmth in the cooler seasons. This study provides insight into the complexity of hierarchical decision-making, such as how risky habitat features and land cover type influence habitat selection differently across seasons and spatial scales, influencing the decision-making of elk. Scale-dependent behavior is crucial to understand within specific geographic regions, as these decisions scale up to influence population dynamics.

Geo-spatial assessment of geomorphic characteristics of Swat Valley, Pakistan

Morphometric analysis is essential for understanding drainage networks and landform evolution, particularly in complex mountainous regions like the Swat Valley. Accurate characterization of these features aids in water resource management and mitigating climate-induced challenges. The study employed GIS and remote sensing technologies, utilizing SRTM-30m DEM data to perform a comprehensive morphometric and hypsometric analysis. Key morphometric parameters such as basin size, stream order, bifurcation ratio, drainage density, circularity ratio, and elongation ratio were calculated by using Whitebox tool. Additionally, three-dimensional parameters including basin relief, roughness number, ruggedness index, and slope were analyzed. Hypsometric analysis was conducted to examine area-elevation relationships, using empirical formulas and contour data. The basin was found to be irregularly shaped, with an elongation ratio of 6.97 and a circulatory ratio of 0.3091, indicating an elongated form. Flow accumulation data highlighted areas of rapid and moderate water flow. Hypsometric analysis showed that 14 sub-basins were in an erosional stage, 8 were mature, and the remainder were older and more resistant to erosion. The overall hypsometric integral (HI) of 0.406 reflects moderate elevation variation across the basin. The study provides critical insights into the geomorphometric controls of the Swat Valley's drainage system, contributing to improved water resource management strategies. Understanding morphometric and hypsometric characteristics is vital for adapting to climate-induced risks and safeguarding water resources in mountainous landscapes.

Timing of Laser Intervention on Facial Scars: A 3D Imaging and Scar Scale Analysis in a Retrospective Study.

Scars resulting from injuries or surgical procedures often present both physical and aesthetic challenges. Recent studies have indicated promising results in improving postoperative scar outcomes through the combined use of specific laser technologies. Nevertheless, there remains a crucial need for further exploration to ascertain the optimal timing for initiating such treatments. In this retrospective investigation, a cohort of 47 adult patients who did not require hospitalization was analyzed. These patients were divided into two distinct groups: Group A, which received intervention beginning 2 weeks after their respective operations, and Group B, which commenced intervention 4 weeks postoperation. Each group underwent a comprehensive treatment protocol consisting of five laser sessions. Initially, patients underwent three sessions of V-beam pulsed-dye laser (PDL) therapy followed by two sessions of ablative fractional CO2 laser (AFL) therapy. Evaluation of outcomes was conducted using advanced imaging techniques such as Antera 3D imaging, in conjunction with established scar assessment tools including the Vancouver Scar Scale (VSS) and the University of North Carolina "4P" Scar Scale (UNC4P). All patients successfully completed the full course of five treatment sessions, with no dropouts and no reported adverse events. Baseline cosmetic assessments of scars were equivalent across both groups. In Group A, the mean VSS scores decreased from 7.04 before treatment to 5.29 at 3 months posttreatment and further to 4.33 at 6 months posttreatment. Meanwhile, in Group B, scores decreased from 7.52 to 6.83 at 3 months and 6.17 at 6 months. There were no statistically significant differences in baseline VSS scores between the two groups (p = 0.34). At both the 3- and 6-month follow-up points, mean VSS scores were significantly lower in Group A compared to Group B (p < 0.05). Similar trends were observed in UNC4P scores. Statistically significant differences were noted across all time points (baseline, 3 months, and 6 months posttreatment) for both VSS and UNC4P scores (p < 0.05). Subset analysis revealed greater improvements in texture and depression volume at 3 months posttreatment, while improvements in depression area, depth, elevation variation, and area were more pronounced at the 6-month mark. Early intervention using the combined 595-nm pulse dye laser and CO2 ablative fractional laser (AFL) 2- and 4-weeks post-surgery proves to be an effective and safe method for improving scar outcomes, particularly for facial surgical scars when treatment starts 2 weeks after surgery. However, further research is needed to refine our understanding and address potential study limitations.

Efficiency Analysis of Open Polygon Method in Land Mapping in Mojoroto Kediri

In the building establishment process, the geotechnical characteristics of soil have a significant impact on the structural performance of buildings. Therefore, soil mapping becomes a critical step in understanding the properties of soil that can affect foundation and structural stability. The mapping method used is open polygon mapping, which allows flexibility in determining land boundaries. Measurements were taken at three survey points: roadside, middle of the field, and edge of the field. The mapping results reveal variations in soil characteristics that need to be considered in development planning to ensure solid and stable building foundations. The implementation of Geographic Information Systems (GIS) in this process facilitates deeper data analysis and better visualization of field conditions. The mapping results show significant variations in ground elevation at each survey point, emphasizing the importance of understanding the area's topography. Additionally, area measurements were conducted using open polygon data, providing fundamental information for area development planning. Contour maps generated through Surfer software provide clear visualization of ground elevations at each survey point, enhancing understanding of the area's topography. This research contributes significantly to understanding soil characteristics and topography in the rear area of Mojoroto. It is expected to serve as a guide for area development planning, ensuring the stability and safety of future building structures. Thus, soil mapping is a critical step in ensuring the safety and sustainability of future buildings and contributes to sustainable area development planning.

Soil bacteria and fungi on tropical mountainsides: Joint effects of weathering, climate, and chemical factors

Contemporary environmental factors such as temperature and pH are generally identified as primary influences on microbial diversity, while the role of geological processes remain understudied. Here, we investigated the diversity and community composition of bacteria and fungi along an elevational gradient from703 to 4514 m on Mt. Kilimanjaro, East Africa. We further examined the effects of contemporary environment and geological processes such as weathering on microbial communities and diversities. For community composition, bacteria and fungi showed clear differentiation along elevations and their community dissimilarities increased with elevational distance indicating elevational distance-decay relationships. Multiple variables such as weathering, climate and chemical factors were significantly associated with microbial communities and showed greater effects on bacterial than fungal communities. Specifically, soil pH mainly shaped bacterial communities, while mean annual temperature for fungi, followed by other variables such as weathering processes. For Shannon diversity, bacteria and fungi showed significant hump-shaped elevational patterns with the peak values at 1857 and 1436 m, respectively. Shannon diversity was mainly affected by soil weathering accounting for 8.9% of the total variance for bacteria, while jointly by weathering and climate accounted for 14.3% of fungi. For the community uniqueness, represented by local contribution to beta diversity (LCBD), there were U-shaped patterns for both taxonomic groups. LCBD was mainly explained by the joint effects of chemical and climate variables which accounted for 51.1% and 33.4% for bacteria and fungi, respectively. Our results highlight the effects of soil weathering processes on diversity and community composition for bacteria and fungi. Thus, the integration of weathering with contemporary environments could provide new insights into microbial elevational diversity patterns.

Plasticity cannot fully compensate evolutionary differences in heat tolerance across fish species.

Understanding how evolution and phenotypic plasticity contribute to variation in heat tolerance is crucial to predict responses to warming. Here we analyze 272 thermal death time curves of 53 fish species acclimated to different temperatures and quantify their relative contributions. Analyses show that evolution and plasticity account, respectively, for 80.5 % and 12.4 % of the variation in elevation across curves, whereas their slope remained invariant. Evolutionary and plastic adaptive responses differ in magnitude, with heat tolerance increasing 0.54 ºC between species and 0.32 ºC within species for every 1 ºC increase in environmental temperatures. After successfully predicting critical temperatures under ramping conditions to validate these estimates, we show that fish populations can only partly ameliorate the impact of warming waters via thermal acclimation and this deficit in plasticity could increase as the warming accelerates.

Functional and phylogenetic structure of mammals along elevational gradients in the Central and East Himalayas

BackgroundMountain ecosystems are critical hotspots of global biodiversity, yet the dynamics of community assembly along their elevational gradients are not well understood. This gap is primarily due to the complexity of environmental and biotic interactions that influence species distribution and community structure. Although extensive research has been conducted on certain taxa, such as small mammals and bats, comprehensive studies encompassing entire mammal assemblages are lacking. Our research aims to bridge this gap by examining the taxonomic, phylogenetic, and functional diversity, as well as the assemblage structures of mammal communities across elevational gradients in the Central and East Himalayas, exploring how diverse ecological and evolutionary processes impact community assembly.MethodsWe analyzed mammal elevational diversity patterns using species richness, functional diversity (FD), and phylogenetic diversity (PD). We compared the observed values of community structure, such as mean pairwise phylogenetic distance (MPD) and mean pairwise functional distance (MFD), with null-model corrected effect sizes to identify patterns and processes of community assembly. Using structural equation modeling and hierarchical partitioning, we investigated the relationships between climate, productivity, and various facets of diversity, describing the organization of each component across different elevations.ResultsTaxonomic, functional, and phylogenetic diversity generally decreased with elevation but showed varied patterns such as mid-elevation peaks, low-elevation plateaus, or monotonic declines across different regions. Richness-controlled functional diversity increased towards mid-low elevations and decreased at higher elevations in both regions, whereas richness-controlled phylogenetic diversity lacked consistent patterns. Phylogenetic structures tended to cluster from mid to high elevations, indicating closer relationships than those observed in random communities, likely due to significant environmental turnover near tree lines. Functional structure showed greater clustering at high elevations and increased over-dispersion at lower elevations, suggesting that species are more functionally similar than expected at higher elevations and more diverse at lower elevations. Our results revealed that environmental factors, evolutionary histories, and trait-driven ecological processes collectively shape species richness along these gradients.ConclusionsOur results showed incongruent community structures across phylogenetic and functional diversity. Generally, functional traits are closely linked to environmental conditions, reducing the chance of observing traits that are misaligned with their surroundings. Species with similar ecological roles or distinct evolutionary lineages often show convergent adaptations to highland environments. Additionally, our findings emphasize that community assembly varies with the biogeography and diversification history of individual mountain ranges, complicating the development of a generalized theory. Using multiple measures is important for accurate community structure assessments and effective conservation planning, as variable elevational patterns exist across different diversity dimensions.

An Interspecific Assessment of Bergmann's Rule in Tenebrionid Beetles (Coleoptera, Tenebrionidae) along an Elevation Gradient.

In endotherms, body size tends to increase with elevation and latitude (i.e., with decreasing temperatures) (Bergmann's rule). These patterns are explained in terms of heat balance since larger animals need to produce less heat relative to their size to maintain stable body temperatures. In ectotherms like most insects, where this mechanism cannot operate, a reverse pattern is frequently observed, as a higher surface area-to-volume ratio in colder climates may allow for more rapid heating and cooling. However, patterns of increasing body size with decreasing temperatures can also be observed in ectotherms if selection for more stable internal temperatures leads to smaller surface area-to-volume ratios. Data on tenebrionids from Latium (Central Italy) were used to model elevational variations in average values of body size (total length, mass and volume) and surface area-to-volume ratio. Analyses were performed by considering the whole fauna and two ecological groups separately: ground-dwelling species (geophilous) and arboreal (xylophilous) species. The surface area-to-volume ratios declined with increasing elevation in all cases, indicating that the need for heat conservation is more important than rapid heating and cooling. However, in xylophilous species (which typically live under bark), body size increased with increasing elevation, and in geophilous species, an opposite pattern was observed up to about 1000 m, followed by an increasing pattern. This suggests that a reduction in resource availability with elevation limits body size in geophilous species up to a certain elevation but not in xylophilopus species, which benefit from more climatically stable conditions and constant resources and need energy for overwintering.

Elevational variation in anatomical traits of the first-order roots and their adaptation mechanisms

Root anatomical traits play an important role in understanding the link between root physiological function and ecological process. To determine how plants change root anatomical traits to adapt to distinct environments, we measured four key root anatomical traits---stele diameter (SD), cortex thickness (CT), root diameter (RD), and the stele to root diameter ratio (SDRD)---of first-order roots of 82 species were collected from different vegetation zones along a 2000 m altitudinal gradient on the northern slope of Taibai Mountain. Compared with other altitudes, plants located in temperate birch and fir forests had thinner SD, CT, RD, and SDRD. We found that elevational variation in root anatomical traits could largely be explained by phylogenetic taxonomy (clade). In addition, changes in SD were driven by soil bulk density, whereas variations in CT and RD were influenced by soil available nitrogen. When phylogenetic factors were removed from our analysis, allometric relationships between RD and root anatomical traits (SD and CT) were observed across different altitudes. Our study reveals the influence of phylogeny and environment on the elevational variation in root anatomical traits and further supports the allometric relationship between root anatomical traits (SD and CT) and RD. These findings enhance our understanding of the evolutionary and adaptive mechanisms of root anatomical structures, providing a basis for predicting how root anatomical traits respond to global changes.

Elevational variations in climate warming impacts on West Himalayan fir growth

Elevational variations in climate warming impacts on West Himalayan fir growth

The Value of Piped Water and Sewers: Evidence from 19th Century Chicago

Abstract We estimate the impact of piped water and sewers on property values in late 19th century Chicago. The cost of sewer construction depends sensitively on imperceptible variation in elevation, and such variation delays water and sewer service to part of the city. This delay provides quasi-random variation for causal estimates. We extrapolate ate estimates from our natural experiment to the area treated with water and sewer service during 1874-1880 using a new estimator. Water and sewer access increases property values by a factor of about 2.8. This suggests that benefits are large relative to: the value of the value of averted mortality, many other infrastructure projects, and construction costs.