Elevation Sites Research Articles

Quantifying Concentrations and Emissions of Hexachlorobutadiene - A New Atmospheric Persistent Organic Pollutant in northern China

Hexachlorobutadiene (HCBD) was listed as a new persistent organic pollutant for global regulation under Stockholm Convention in 2015, and there has been scarce information on its atmospheric concentrations, distributions, and emission sources. HCBD air samples were collected and analyzed to characterize concentrations and distributions at high elevation and urban sites as well as emission source locations in Northern China. We found ambient concentrations of HCBD in Northern China averaged at 34 ± 16 and 36 ± 28 pptv at urban sites in Jinan and Tai'an, respectively, and 31 ± 21 pptv at a high-elevation site Mount Tai. HCBD concentrations at the high elevation and urban sites were found to be affected by long-range transport under the influence of the East Asian monsoon climate. Over potential sources areas, we found concentrations of 76 ± 33 pptv in a mixed factory park, 59 ± 21 pptv in a rubber plant and 74 ± 8 pptv in a municipal solid waste (MSW) landfill area, which were all several times higher than in urban sites. The large concentration gradient across the various environments revealed strong emission sources of HCBD, especially over MSW landfill and Cl-compound production and application areas. An emission rate of 9.2 × 104 kg/yr and an oxidation rate of 32.9 kg/yr for HCBD were estimated for the mixed factory park. OH and Cl are much more active in reaction with HCBD than other oxidants in the atmosphere. Dry deposition and oxidation removed about 5.3% and 0.04%, respectively, of the emitted, suggesting that ∼95% of the emitted HCBD remaining in the atmosphere and could be transported for redistribution. Our findings revealed significant emission sources of HCBD in northern China, which was in turn affected by major sources in East-central China. The regional influence of HCBD pollution warrants serious concerns and points to the need to develop mitigation strategies.

Evaluation of volume changes following lateral window maxillary sinus floor elevation using Minics software.

BackgroundSignificant volume changes at the site of lateral window maxillary sinus floor elevation have been reported 6 months postoperatively, with stabilization thereafter. However, at present, there is no consensus regarding the gold standard to assess the shape and volume of the bone graft site after implantation. This study aimed to analyze volume changes in the lateral window maxillary sinus floor elevation region using Minics software.MethodsWe analyzed 40 patients who underwent lateral window maxillary sinus floor elevation surgery at the Stomatology Department of Binhaiwan Central Hospital, Dongguan, China between 2017 and 2020. Twenty patients underwent lateral window maxillary sinus floor elevation with simultaneous implantation, while 20 patients underwent lateral window maxillary sinus floor elevation with delayed implantation 6 months later. Minics software was used for three-dimensional analysis of the elevation site on the day after surgery (T1) and 6 months after surgery (T2) in both groups.ResultsThe elevation site volume was reduced 6 months after lateral window maxillary sinus floor elevation. The differences in the length, width, height from the tip, and volume of the implant between T1 and T2 were statistically significant.ConclusionsThe length, width, height, and volume of the lateral window maxillary sinus floor elevation region were reduced using Minics software, suggesting that the volume of the elevation site should be enlarged as much as possible during the operation to prevent volume shrinkage.

Reproductive phenology of the spider Micrommata ligurina (C.L. Koch, 1845) (Araneae; Sparassidae) across an elevational gradient in Northeast Algeria

Abstract Decreased ambient temperature and shorter reproductive seasons are the two main obstacles that ectotherms face at higher elevations. Studies have shown that some life history traits such as phenological windows of activity, duration, and fitness components vary as elevation increases. However, studies on the elevational gradient at the southern range limit of species are lacking. In this study, we aim at assessing some aspects of the life history of a spider species, the sprassid Micrommata ligurina (C.L. Koch, 1845), across an elevational gradient from 30 to 1030 m in Northeast Algeria. There was strong evidence of an elevational shift in the phenology of reproduction with a delay rate of 2.2 days per 100 m of elevation, and the three quantiles of the phenology (10, 50, and 90%) shifted with the same magnitude across elevation. In all sites from low to high elevation, the species showed a decrease in number of individuals. The mean number of eggs was 200 ± 35 eggs, and the mean number of hatching eggs was 110.9 ± 23.5 eggs. The clutch size at high elevation sites was higher than that of low-elevation sites, but in contrast, the hatching success was higher at lower elevation sites. Overall, the species exhibited clear elevational clines in life history traits and abundance, suggesting a high potential of plasticity. This work constitutes the first study carried out on spider species ecology in the region.

Exploring the thermal limits of malaria transmission in the western Himalaya.

Environmental temperature is a key driver of malaria transmission dynamics. Using detailed temperature records from four sites: low elevation (1800), mid elevation (2200 m), and high elevation (2600–3200 m) in the western Himalaya, we model how temperature regulates parasite development rate (the inverse of the extrinsic incubation period, EIP) in the wild. Using a Briére parametrization of the EIP, combined with Bayesian parameter inference, we study the thermal limits of transmission for avian (Plasmodium relictum) and human Plasmodium parasites (P. vivax and P. falciparum) as well as for two malaria‐like avian parasites, Haemoproteus and Leucocytozoon. We demonstrate that temperature conditions can substantially alter the incubation period of parasites at high elevation sites (2600–3200 m) leading to restricted parasite development or long transmission windows. The thermal limits (optimal temperature) for Plasmodium parasites were 15.62–34.92°C (30.04°C) for P. falciparum, 13.51–34.08°C (29.02°C) for P. vivax, 12.56–34.46°C (29.16°C) for P. relictum and for two malaria‐like parasites, 12.01–29.48°C (25.16°C) for Haemoproteus spp. and 11.92–29.95°C (25.51°C) for Leucocytozoon spp. We then compare estimates of EIP based on measures of mean temperature versus hourly temperatures to show that EIP days vary in cold versus warm environments. We found that human Plasmodium parasites experience a limited transmission window at 2600 m. In contrast, for avian Plasmodium transmission was not possible between September and March at 2600 m. In addition, temperature conditions suitable for both Haemoproteus and Leucocytozoon transmission were obtained from June to August and in April, at 2600 m. Finally, we use temperature projections from a suite of climate models to predict that by 2040, high elevation sites (~2600 m) will have a temperature range conducive for malaria transmission, albeit with a limited transmission window. Our study highlights the importance of accounting for fine‐scale thermal effects in the expansion of the range of the malaria parasite with global climate change.

Elevational Pattern and Control Factors of Soil Microbial Carbon Use Efficiency in the Daiyun Mountain

Microbial carbon use efficiency (CUE) refers to the C transformation to microbial biomass from C uptake. The study of soil microbial CUE is very important for understanding the soil C cycle. Here, CUE, Cgrowth, and Crespiration were measured using the 18O-H2O-DNA labeling method at six elevational sites (980-1765 m) in Daiyun Mountain, a subtropical montane forest, to understand the variation characteristics and influencing mechanisms. The results showed that:CUE varied from 0.1 to 0.4 and increased linearly with elevation; CUE was positively correlated with Cgrowth, Crespiration, and qgrowth but negatively correlated with qCO2, indicating that CUE increased with elevation by increasing microbial growth and inhibiting respiration; and temperature was the first controlling factor for the elevation variation in microbial CUE in the subtropical forest ecosystem.

Brown Bear Food-Probability Models in West-European Russia: On the Way to the Real Resource Selection Function

Most habitat suitability models and resource selection functions (RSFs) use indirect variables and habitat surrogates. However, it is known that in order to adequately reflect the habitat requirements of a species, it is necessary to use proximal resource variables. Direct predictors should be used to construct a real RSF that reflects the real influence of main resources on species habitat use. In this work, we model the spatial distribution of the main food resources of brown bear Ursus arctos L. within the natural and human-modified landscapes of the Central Forest State Nature Reserve (CFNR) for further RSF construction. Food-probability models were built for Apiaceae spp. (Angelica sylvestris L., Aegopodium podagraria L., Chaerophyllum aromaticum L.), Populus tremula L., Vaccinium myrtillus L., V. microcarpum (Turcz. ex Rupr.) Schmalh., V. oxycoccos L., Corylus avellana L., Sorbus aucuparia L., Malus domestica Borkh., anthills, xylobiont insects, social wasps and Alces alces L. using the MaxEnt algorithm. For model evaluation, we used spatial block cross-validation and held apart fully independent data. The true skill statistic (TSS) estimates ranged from 0.34 to 0.95. Distribution of Apiaceae forbs was associated with areas having rich phytomass and moist conditions on southeastern slopes. Populus tremula preferred areas with phytomass abundance on elevated sites. Vaccinium myrtillus was confined to wet boreal spruce forests. V. microcarpum and V. oxycoccos were associated with raised bogs in depressions of the terrain. Corylus avellana and Sorbus aucuparia preferred mixed forests on elevated sites. Distribution of Malus domestica was associated with meadows with dry soils in places of abandoned cultural landscapes. Anthills were common on the dry soils of meadows, and the periphery of forest areas with high illumination and low percent cover of tree canopy. Moose preferred riverine flood meadows rich in herbaceous vegetation and sparse mixed forests in spring and early summer. The territory of the human-modified CFNR buffer zone was shown to contain a higher variety of food resources than the strictly protected CFNR core area.

Keeping it cool to take the heat: tropical lizards have greater thermal tolerance in less disturbed habitats.

Global climate change has profound effects on species, especially those in habitats already altered by humans. Tropical ectotherms are predicted to be at highrisk from global temperature increases, particularly those adapted to cooler temperatures at higher altitudes. We investigated how one such species, the water anole (Anolis aquaticus), is affected by temperature stress similar to that of a warming climate across a gradient of human-altered habitats at high elevation sites. We conducted a field survey on thermal traits and measured lizard critical thermal maxima across the sites. From the field survey, we found that (1) lizards from the least disturbed site and (2) operative temperature models of lizards placed in the least disturbed site had lower temperatures than those fromsites with histories of human disturbance. Individuals from the least disturbed site also demonstrated greater tolerance to high temperatures than those from the more disturbed sites, in both their critical thermal maxima and the time spent at high temperatures prior to reaching critical thermal maxima. Our results demonstrate within-species variability in responses to high temperatures, depending on habitat type, and provide insight into how tropical reptiles may fare in a warming world.

Evaluation of unmanned aerial vehicles for surveys of lek‐mating grouse

AbstractUnmanned aerial vehicles (UAVs), or drones, are being utilized by wildlife biologists to monitor populations of birds and mammals. However, the reaction of wildlife to drones varies by species, so a preliminary evaluation must be conducted to determine if the target species can be detected via drone footage and to determine how the target species will react to drone presence. Lek‐mating prairie‐chickens (Tympanuchus spp.) seem amenable to drone‐based surveys because they are relatively large and display in groups on elevated sites with sparse vegetation. The goal of our study was to determine what flight characteristics maximize prairie‐chicken detection on drone video footage, to document the birds' reactions to the drones, and to compare how the noise produced by the drones compares to ambient sounds. We tested 3 sizes of rotary‐winged drones, flown at 3 heights, with 3 different camera angles by flying over known prairie‐chicken leks. We determined that >65% of prairie‐chickens present were detected using video footage at a height of 100 m with a 10° camera angle. Drones of different sizes had similar detectability. However, observers in blinds adjacent to leks routinely detected more birds than were detected on drone footage (detection on drone footage was 39.7 ± 9.6% of birds present). Prairie‐chickens flushed in 96% of trials when a drone was flown over display locations. Time to return to the lek following drone disturbance was similar to prairie‐chickens' reactions to natural predators. Prairie‐chickens flushed when drone sound levels were comparable to ambient noise. Developing guidelines for the ethical use of drones in wildlife research will require quantifying the amount of taxa‐specific disturbance caused by drones. Our study begins to close this knowledge gap by documenting disturbance to upland, lek‐mating grouse of conservation concern, and suggests that the focal species' reaction to aerial predators may provide clues as to how that species may react to drones.

Enhanced Deposition of Atmospheric Soluble Iron by Intrusions of Marine Air Masses to East Antarctica

AbstractBio‐essential iron can relieve nutrient limitation and stimulate marine productivity in the Southern Ocean. The fractional iron solubility of aerosol iron is an important variable determining iron availability for biological uptake. However, estimates of dissolved iron (dFe; iron < 0.2 μm) and the factors driving the variability of fractional iron solubility in pristine air masses are largely unquantified. To constrain inputs of fractional iron solubility to remote East Antarctic waters, dFe, total dissolvable iron (TDFe), trace elements and refractory black carbon were analyzed in a 9‐year‐old snow pit (2005–2014) from a new ice core site at Aurora Basin North (ABN) in Wilkes Land, East Antarctica. Extremely low annual dFe deposition fluxes were estimated (0.2 × 10−6 g m−2 y−1), while annual TDFe deposition fluxes (70 × 10−6 g m−2 y−1) were comparable to other Antarctic sites. TDFe is dominantly sourced from mineral dust. Unlike coastal Antarctic sites where the variability of fractional iron solubility in modern snow is explained by a mixture of dust and biomass burning sources, dFe deposition and fractional iron solubility at ABN (ranging between 0.1% and 6%) is enhanced in episodic high precipitation events from synoptic warm air masses. Enhanced fractional iron solubility reaching the high elevation site at ABN is suggested through the mechanism of cloud processing of background mineral dust that modifies the dust chemistry and increases iron dissolution during long‐range transport. This study highlights a complex interplay of sources and processes that drive fractional iron solubility in pristine air masses.

Linkage between microbial functional genes and net N mineralisation in forest soils along an elevational gradient

AbstractSoil net nitrogen (N) mineralisation, the difference between organic nitrogen mineralisation and mineral nitrogen immobilisation, changes with elevation, thereby determining plant productivity and soil N cycling along elevation gradients. However, it has yet to be established how different microbial functional genes influence the rate of soil net N mineralisation along such gradients. To address this deficiency in our current knowledge, we performed metagenomic sequencing to identify soil microbial functional genes encoding enzymes involved in N cycling at five forest sites along an elevational gradient spanning a range from 1503 to 3182 m above sea level. Our results indicate that the rate of net N mineralisation follows a unimodal pattern with increasing elevation, with a peak (0.18 mg kg−1 d−1) being detected at the mid‐high elevation site. Further, we detected a significant correlation between the abundance of genes encoding enzymes involved in denitrification and ammonia assimilation pathways and net N mineralisation rate (p < 0.05). Moreover, we established that microbial species in the phyla Cyanobacteria, Acidobacteria and Planctomycetes, harbouring keystone functional genes, play a predominant role in determining the rate of net N mineralisation. Our findings also revealed soil substrate content (ammonium nitrogen and nitrite nitrogen, soil organic carbon, and C:N ratio) and soil environment (soil temperature and soil moisture) to be the major drivers of net N mineralisation in soil via their regulatory effects on the composition of microbial communities and functional genes. Our characterisation of the microbial metagenomic basis of net N mineralisation in forest soils accordingly highlights the importance of the combined contributions of soil microbial functional genes, soil substrate, and environmental factors in determining the cycling of N in forest soils at different elevations.Highlights Net N mineralisation rate followed a unimodal pattern along an elevational gradient. Denitrification and ammonia assimilation genes were correlated with net N mineralisation rate. Cyanobacteria play a dominant role in determining net N mineralisation rate. Soil substrate and environment determine microbial functional gene distribution.

Sucker Shapes, Skeletons, and Bioinspiration: How Hard and Soft Tissue Morphology Generates Adhesive Performance in Waterfall Climbing Goby Fishes.

Many teleost fish, such as gobies, have fused their paired pelvic fins into an adhesive disc. Gobies can use their pelvic suckers to generate passive adhesive forces (as in engineered suction cups), and different species exhibit a range of adhesive performance, with some even able to climb waterfalls. Previous studies have documented that, in the Hawaiian Islands, species capable of climbing higher waterfalls produce the highest passive pull-off forces, and species found at higher elevation sites are likely to have more rounded suction discs than those found in the lowest stream segments. Morphology of the pelvic girdle also varies between species, with more robust skeletons in taxa with superior passive adhesion. To investigate what factors impact the passive adhesive performance of waterfall climbing gobies, we tested biomimetic suction cups designed with a range of shapes and embedded bioinspired "skeletons" based on micro-CT scans of goby pelvic girdles. We found that while the presence of an internal skeleton may provide some support against failure, the performance of suction cups may be more strongly affected by their external shape. Nonetheless, factors besides external shape and skeletal morphology may still have a stronger influence on sucker tenacity. Our results suggest that the relationship between suction disc morphology and adhesive performance may be influenced by a variety of physical factors, and live animal performance likely is further complicated by muscle activation and climbing behavior. These results have implications for the evolution of suction disc shape in adhesive fish and for improving the design of biomimetic suction cups.

Citizen science reveals broad-scale variation of calling activity of the Mediterranean tree frog (Hyla meridionalis) in its westernmost range

Abstract Population monitoring is essential to determine different aspects of the ecology and conservation of the species. In anurans, recording the acoustic activity of choruses allows surveying populations. Therefore, knowing the timing of male calls is fundamental to achieve this goal. Here we monitored calling activity of the Mediterranean tree frog (Hyla meridionalis) at eight localities in southern Iberian Peninsula and western North Africa in the frame of a citizen science program. Subsequently, after summarizing call activity with Non-metric Multidimensional Scaling, we aimed to identify the geographic and environmental variables that associate with the calling activity of frogs. The results of the 258-hour census showed that male tree frogs called mainly from December to July, although the duration and intensity of choruses varied, depending on the elevation and seasonality of the water bodies. Males sang earlier and had more durable call activities at lower elevation sites, which are sites with higher and more stable ambient temperatures. Also, calling activity was lower in sites where water fluctuates more over the annual cycle. Our results provide a first overview of the calling activity of the Mediterranean tree frog over a relatively large set of populations encompassing a wide variety of environmental conditions in its westernmost range of distribution. However, further studies relying on more intensive sampling, likely using automatic recorders, would be desirable to achieve a full understanding of the calling activity of tree frogs in the region.

Brain Activation Site of Laryngeal Elevation During Swallowing: An fMRI Study.

The object of this study is to investigate dysphagia caused by reduced laryngeal elevation in patients poststroke. The central mechanism of laryngeal elevation during swallowing was explored by comparing the brain activation area before and after treatment with that of healthy subjects. The treatment group included patients diagnosed with dysphagia poststroke that showed reduced laryngeal elevation. They were treated with electrical stimulation at the motor points of the muscles related to laryngeal elevation. Functional magnetic resonance imaging (fMRI) using the blood oxygenation level-dependent (BOLD) was used to observe brain activation of the normal healthy control group and treatment group during voluntary swallowing. Independent sample t test and paired sample t test were used to analyze the differences in brain activation between and within the groups. Compared with the control group, no activation was observed in the brainstem and putamen regions of the experimental group before treatment. Statistics showed that the experimental group had a wider range of brain activation than the control group pretreatment, including the left supplementary motor area, the cingulate gyrus, the inferior frontal gyrus, the right thalamus, and the right putamen. After the electrical stimulation, the brain stem subregion, the left cerebellar lobule IV and V, and parts of the cerebral cortex were more active, while the left supplementary motor area, paracentral lobule, and occipital lobule were less active post-treatment. (1) The brainstem and putamen are the specific brain regions that control laryngeal movement. (2) The enhanced activation of the cortical-basal ganglia-thalamic circuit after stroke is a compensatory mechanism. (3) The improvement of hyoid bone elevation was related to the enhanced activation of the IV and V lobes of the cerebellar hemisphere. The over-activation of the supplementary motor area poststroke would subside once the motor function improved.

Environment-Driven Changes in the Functional Traits of Milk Thistle [Silybum marianum (L). Gaertn.] Along an Altitudinal Gradient in the Semi-Arid Environment: Perspective on Future Plant Invasion.

The elevation is an important gradient across which the environmental variables and plant traits vary and is considered as a barrier to the recent global problem of plant invasion. However, certain invasive plants show plasticity traits to adapt and cope with the changes across the elevation. Silybum marianum (S. marianum) is one such invasive species widely spread in Khyber Pakhtunkhwa, Pakistan. Therefore, this study investigates the traits plasticity and invasive behaviors of this plant species across the elevation gradient. Plant functional traits (PFTs) and environmental variables were recorded in forty different low, middle, and high elevation sites. The plant shows a decrease in plant functional traits, i.e., above-ground plant height/plant, leaf length/leaf, leaf width/leaf, leaf dry weight/plant, vegetative dry weight/plant, and number of capitula/plant having the significance of p < 0.05. In contrast, the dry reproductive weight does not change significantly with elevation, while the root length increases across the elevation. The soil and environmental variables such as organic matter, lime percentage, and latitude significantly affected the PFTs. The importance value index of the species was also related to elevation and diversity indices, i.e., species richness, Shannon–Wiener diversity index, and evenness index, indicating that the invasion has strong effects on diversity. This study concludes that S. marianum has traits plasticity across the elevation and affects community diversity. Further investigation is required to understand the invasion and diversity parameters in a better way.

Tree-Ring Patterns and Growth Response of Abies jaliscana to Climate along Elevational Gradients in the Mountains of Western Jalisco, Mexico

Jalisco fir (Abies jaliscana) is an endemic tree with restricted distribution, and is considered a Pliocene relict inhabiting the cloud montane forests in the humid-temperate upper zone of western Jalisco Mountains. Despite its ecological importance, to date, there are no studies for this taxon aimed to understand its vulnerability to regional climate variability. We used dendrochronological techniques to investigate tree-ring patterns and the effects of climate variability on the radial growth of Jalisco fir through its elevational range in both southern and northern aspects. We developed tree-ring series that ranged in length from 79 to 152 years. High-elevation trees (2400 m.a.s.l.) showed higher annual radial growth compared to those present in low-elevation sites. Over the last 150 years, Abies jaliscana trees have had higher annual radial growth rates compared to those exhibited by other Abies species. Both winter and early spring precipitation are the main factors determining the growth rates at all the elevation sites for both aspects. In the cold season, mean maximum temperature negatively affected ring-width growth at most of the elevation zones except for two study sites. We conclude that the radial growth of A. jaliscana appears to be smaller during lower rainfall periods in the dry seasons (winter and early spring), and A. jaliscana annual radial growth responds differently to regional climate variability along the elevational gradient and mountain aspects.

Primary production responses to extreme changes in North American Monsoon precipitation vary by elevation and plant functional composition through time

Abstract Primary production in dryland ecosystems is limited by water availability and projected to be strongly affected by future shifts in seasonal precipitation. Warm‐season precipitation derived from the North American Monsoon contributes 40% of annual precipitation to dryland ecosystems in the southwestern United States and is projected to become more variable. However, there is large uncertainty on whether this variability will be expressed as either extreme wet or dry years and how primary production of different plant functional types will respond across widespread elevation gradients in this region. We experimentally imposed extreme drought and water addition treatments from 2016 to 2020, during which ambient warm‐season precipitation declined to reach historic lows, to understand production sensitivity of dominant plant functional types along a 1000 m elevation gradient. We found that the production responses of plant functional types to monsoon precipitation extremes were dependent on the number of treatment years that occurred across sites along the elevation gradient. C4 perennial grasses were most responsive to precipitation manipulation treatments, followed by C3 perennial grasses and annuals, while perennial forbs and shrubs had weak or no responses. C4 perennial grass reductions due to extreme drought were generally stronger or occurred earlier at low elevation sites, while multi‐year extreme drought extended negative effects to C3 perennial grasses at high elevation, and all sites showed delayed responses to multi‐year water addition. We found that the sensitivity of C3 perennial grass production differed for extreme drought and water addition compared to ambient precipitation at one site, but other sites and plant functional types had similar sensitivities to the different treatment types. Synthesis. The upward advance of primary production responsiveness from single‐ to multi‐year extreme changes in warm‐season precipitation suggests more immediate shifts in functional composition and carbon cycling at low elevation, while high elevation ecosystems may become less resistant as the effects of extreme precipitation compound through time.

Recent evolution of glaciers in the Cocuy‐Güican Mountains (Colombian Andes) and the hydrological implications

AbstractThis study extends knowledge of the evolution of glacier shrinkage in the Cocuy‐Güican Mountains since the maximum glacier extent of the Little Ice Age (LIA). Mass balance data for the Ritacuba Glacier since 2009 were acquired and compared with available data for the Conejeras Glacier (Los Nevados National Park). This study also investigated the hydrological significance of Colombian glaciers, which is still largely unknown because the available information is very limited. Glaciers in the Cocuy‐Güican Mountains covered 13.2 km2 in 2019 compared with 127.8 km2 during the maximum LIA, representing a shrinkage of 89.7%. Analysis of glacier cover observations made in 1955, 1994, 2010, and 2019 revealed that the rate of ice loss was greatest from 1994 to 2010 (0.59 km2 yr−1), and was then almost halved from 2010 to 2019 (0.34 km2 yr−1). This slowing of glacier retreat is consistent with the moderate negative mass balance measured for 2009–2019, and an accumulated loss of 1766 mm w.e. (mm water equivalent). The progressive confinement of glaciers to higher elevations, ice accumulation in topographic locations providing shelter from solar radiation, and an absence of recent marked climatic anomalies could explain why the Cocuy‐Güican glaciers have temporally reached a near equilibrium state conditions. This contrasts with the Conejeras Glacier, where 47,000 mm w.e. has been lost in the same period. The available data on runoff and isotope tracers of streamflow and precipitation suggest that precipitation rather than glacier melt water exerts primary control over the hydrological variability at high elevation sites.

Elevational changes in productivity of saplings relate to distribution of two congeneric tree species.

Elevational changes in vegetation are associated with changes in environmental factors, an example of which is provided by the shade-tolerant Abies mariesii and less shade-tolerant Abies veitchii, which dominate forests at high and low elevations, respectively, in subalpine zones of central Japan. In this study, we sought to establish the factors underlying the differential elevational dominance of these two species from the perspective of sapling growth and survival. It is assumed that the growth and survival of saplings is greater at higher rates of surplus production (the value obtained by subtracting the minimum net production to maintain the current sapling leaf mass from the total net production), as sapling leaf mass gradually declines with time if saplings cannot maintain the current sapling leaf mass, thereby increasing the risk of premature mortality. In this regard, we aimed to verify the following two hypotheses: (1) at low elevations, the surplus production rate of A. veitchii is greater than that of A. mariesii in canopy gaps, and vice versa in the forest understory; and (2) at high elevation, the surplus production rate of A. mariesii is greater than that of A. veitchii in both forest understory and canopy gaps. The results obtained in this study were consistent with our two stated hypotheses. In addition, at the low elevation site, the rate of the growth in height of A. veitchii in canopy gaps was greater than that of A. mariesii, indicating that A. veitchii can dominate after disturbance at low elevations. The findings of this study indicate that the differential elevational distribution of the two Abies species can be attributed to interspecific differences in surplus production rates. We believe that these findings will be useful for predicting changes in the distribution of vegetation in response to climate change.

Direct and Indirect Effects of Long-Term Field Warming Methods on the Physical Environment and Biological Responses in a Subtropical Forest

Tree growth may be affected by rising temperature. We conducted two long-term, independent warming experiments in a subtropical forest; one experiment used translocation warming and one experiment used infra-red (IR) warming. Both warming techniques are designed to increase air and soil temperatures (Tair and Tsoil), but may also differentially affect other environmental variables, including soil volumetric water content (SVWC), air relative humidity (RH) and vapor pressure deficit (VPD). Hence, tree response ascribed to Tair and Tsoil may be dependent on the indirect effects of the warming techniques. We experimentally tested these ideas on three native tree species (Machilus breviflora, Syzygium rehderianum, and Schima superba), which occurred at all experimental sites, in subtropical China. We translocated trees from higher elevation sites to lower elevation sites in the coniferous and broadleaf mixed forest (Tair was 0.68 ± 0.05°C higher; 8 years) and mountain evergreen broadleaf forest (Tair was 0.95 ± 0.06°C and 1.63 ± 0.08°C higher; 8 years). IR warming was imposed at an experimental site in a monsoon evergreen broadleaf forest (Tair was 1.82 ± 0.03°C higher; 5 years). We found that both methods directly increased Tair and Tsoil (although to varying degrees), while translocation warming indirectly dried the soil (lower SVWC) and IR warming indirectly dried the air (lower RH and higher VPD). Machilus breviflora exposed to translocation warming exhibited lower photosynthesis due to higher Tsoil and lower SVWC, leading to declining growth. Higher Tair and Tsoil due to translocation warming increased photosynthesis and growth for S. superba. Trees exposed to IR warming exhibited reduced photosynthesis due to lower RH (M. breviflora) and to lower stomatal conductance (gs) as a function of higher Tair (S. rehderianum and S. superba). This study highlights the potential direct and indirect effects of different warming techniques on the physical environment of forest ecosystems, and subsequently their impacts on biological traits of trees. Hence, different warming techniques may provide different outcomes when assessing the impact of warming on trees in future climates.

Review: Modern Architecture, Empire, and Race in Fascist Italy

Review: <i>Modern Architecture, Empire, and Race in Fascist Italy</i>