High-elevation Sites Research Articles

Spatial Difference of Interactive Effect Between Temperature and Daylength on Ginkgo Budburst.

Climate warming-induced shifts in spring phenology have substantially affected the structure and function of terrestrial ecosystems and global biogeochemical cycles. Spring phenology is primarily triggered by spring temperature and is also affected by daylength and winter chilling, yet the relative importance of these cues across spatial gradients remains poorly understood. Here, we conducted a manipulative experiment with two daylength and three temperature treatments to investigate spatial differences in the response of ginkgo budburst to temperature and daylength, using twigs collected at three sites across a spatial gradient: a control site at a low latitude and low elevation on Tianmu Mountain (TMlow), a low latitude and high elevation site on Tianmu Mountain (TMhigh), and a high latitude site on Jiufeng mountain (JF). The mechanisms were also tested using in situ phenological observations of ginkgo along latitudes in China. We found that, compared to TMlow individuals, budburst dates occurred 12.6 (JF) and 7.7 (TMhigh) days earlier in high-latitude and high-elevation individuals when exposed to the same temperature and daylength treatments. Importantly, daylength only affected budburst at low latitudes, with long days (16 h) advancing budburst in low-latitude individuals by, on average, 8.1 days relative to short-day (8 h) conditions. This advance was most pronounced in low-elevation/latitude individuals (TMlow = 9.6 days; TMhigh = 6.7 days; JF = 1.6 days). In addition, we found that the temperature sensitivity of budburst decreased from 3.4 to 2.4 days °C−1 along latitude and from 3.4 to 2.5 days °C−1 along elevation, respectively. The field phenological observations verified the experimental results. Our findings provide empirical evidence of spatial differences in the relative effects of spring temperature and daylength on ginkgo budburst, which improved our understanding of spatial difference in phenological changes and the responses of terrestrial ecosystem to climate change.

Interactions between Geomorphology and Production Chain of High-Quality Coffee in Costa Rica

High-altitude coffee has an international reputation due to its high quality, especially in countries with a long production history, such as Costa Rica. Specific geographical characteristics determine the regions where high-altitude coffee can be cultivated. Over the last two decades, new production conditions have promoted the growth of smallholder coffee farms in the Upper Buenavista Catchment (UBC) in the South of Costa Rica. To understand this phenomenon’s process, we initially performed a detailed geomorphological mapping of the high-elevation production sites in the UBC. Then, we used remote sensing to determine the coffee land cover (2005, 2012, and 2018) to compare their landforms. Furthermore, we analyzed the production–processing–market chain that has promoted coffee plantations since 2005. Our results show that coffee farmers chose more unstable and erosive areas with short-term production prospects to cultivate premium-priced coffee. Moreover, farmers have changed their role in the coffee sector, evolving from small producers to entrepreneurs with specialized knowledge. These actions may reduce economic risks and improve the household incomes of smallholder coffee producers. However, limited research has been conducted along the tropics about the relationships between landforms, socioeconomic drivers, and high-altitude coffee yield. Therefore, our results are essential to present geomorphology and applied geography as baselines in land-use planning for agricultural landscapes.

Floristic and functional diversity of ferns and lycophytes at three elevational zones in the eastern slopes of the northern Andes, Ecuador

ABSTRACT The northeastern slope of the Andes is an area of high diversity of ferns and lycophytes. In this study we assessed the diversity patterns of ferns and lycophytes in ten 250 m x 2 m plots installed at three elevational zones, from 418 to 3447 m.a.s.l., in the Napo province of Ecuador. Floristic diversity was measured using Hill numbers and by partitioning species diversity. Three functional diversity indices were calculated from a set of five leaf traits and weighted by species abundance: functional richness (FRic), evenness (FEve) and divergence (FDiv). To disentangle functional diversity from species richness, the standardized effect size (SES) of each index was also calculated. We recorded 148 species, Polypodiaceae and Dryopteridaceae being the most representative families. Species richness continuously decreased with elevation. Floristic composition was highly heterogeneous among elevation zones, with total species turnover found between 1500 and 2000 m.a.s.l. SES-FDiv and SES-FEve were higher than the null expectation for plots at mid-elevations, suggesting that deterministic mechanisms, such as biotic or abiotic filters, could explain assemblage composition at these sites. However, SES-FEve, SES-FRic and SES-FDiv did not differ from the null expectations at low and high elevation sites, suggesting the predominance of a stochastic process. By combining floristic and functional diversity, we were able to infer the observed community patterns with the resource-use strategies of fern and lycophytes in a mountain area, an approach that can be used to understand how assemblages might react to changing environmental conditions.

Particulate organic nitrates at Mount Tai in winter and spring: Variation characteristics and effects of mountain-valley breezes and elevated emission sources

Particulate organic nitrates, among the major components of secondary organic aerosols and fine particles, play important roles in regional nitrogen cycle, ozone budget, and cloud condensation nuclei formation. However, the pollution characteristics of particulate organic nitrates at mountain areas and the effects of anthropogenic pollutant transport remain poorly understood. In this study, field sampling and measurements were conducted at a high-elevation mountain site over North China Plain in winter and spring. Total five kinds of particulate organic nitrates in fine particles were determined by ultra-high performance liquid chromatography-electrospray mass spectrometry. The average total concentrations of particulate organic nitrates were 330 ± 121 ng m-3 and 247 ± 63 ng m-3 in winter and spring. The monoterpene-derived organic nitrates were the dominant components in both seasons with their contribution higher than 70%, accounting for 1.2 ± 0.8% and 2.0 ± 1.0% in organic aerosols in winter and spring, respectively. The significantly higher levels of particulate organic nitrates in winter than spring was ascribed to the strong effects of mountain-valley breezes and coal combustion plumes. The increasing concentrations of NOx and particulate matters brought by the valley breeze at daytime facilitated the formation of MHN215, OAKN359, and OAHN361, while the rising SO2 abundance and the sulfate aerosols transported by elevated emission sources affected the formation of MDCN247 at nighttime.

Climate and energy balance of the ground in University Valley, Antarctica

AbstractWe report 3 years of data from one meteorological and three smaller stations in University Valley, a high-elevation (1677 m) site in the Dry Valleys of Antarctica with extensive dry permafrost. Mean air temperature was -23.4°C. Summer air temperatures were virtually always < 0°C and were consistent with the altitude lapse rate and empirical relationships between summer temperature, distance from the coast and elevation. The measured frost point (-22.5°C) at the 42 cm deep ice table is equal to the surface frost point and above the atmospheric frost point (-29.6°C), providing direct evidence that surface conditions control ground ice depth. Observed peak surface soil temperatures reach 6°C for ice-cemented ground > 15 cm deep but stay < 0°C when it is shallower. We develop an energy balance model tuned to this rocky and dry environment. We find that differences in peak soil surface temperatures are primarily due to the higher thermal diffusivity of ice-cemented ground compared to dry soil. Sensitivity studies show that expected natural variability is insufficient for melt to form and significant excursions from current conditions are required. The site's ice table meets the criteria for a Special Region on Mars, with 30% of the year > -18°C and water activity > 0.6.

Regional variability of diatoms in ice cores from the Antarctic Peninsula and Ellsworth Land, Antarctica

Abstract. The presence of marine microfossils (diatoms) in glacier ice and ice cores has been documented from numerous sites in Antarctica, Greenland, as well as from sites in the Andes and the Altai mountains, and attributed to entrainment and transport by winds. However, their presence and diversity in snow and ice, especially in polar regions, are not well documented and still poorly understood. Here we present the first data to resolve the regional and temporal distribution of diatoms in ice cores, spanning a 20-year period across four sites in the Antarctic Peninsula and Ellsworth Land, Antarctica. We assess the regional variability in diatom composition and abundance at annual and sub-annual resolution across all four sites. These data corroborate the prevalence of contemporary marine diatoms in Antarctic Peninsula ice cores, reveal that the timing and amount of diatoms deposited vary between low- and high-elevation sites, and support existing evidence that marine diatoms have the potential to yield a novel palaeoenvironmental proxy for ice cores in Antarctica.

An hourly ground temperature dataset for 16 high-elevation sites (3493–4377 m a.s.l.) in the Bale Mountains, Ethiopia (2017–2020)

Abstract. Tropical mountains and highlands in Africa are under pressure because of anthropogenic climate and land-use change. To determine the impacts on the afro-alpine environment and to assess the potential socio-economic consequences, the monitoring of essential climate and environmental variables at high elevation is fundamental. However, long-term temperature observations on the African continent above 3000 m are very rare. Here we present a consistent multiannual dataset of hourly ground temperatures for the Bale Mountains in the southern Ethiopian Highlands, which comprise Africa's largest tropical alpine area. The dataset covers the period from January 2017 to January 2020. To characterise and continuously monitor the mountain climate and ecosystem of the Bale Mountains along an elevation gradient from 3493 to 4377 m, ground temperature data loggers have been installed at seven sites at 2 cm depth; at four sites at 10 cm depth; and at five sites at 2, 10, and 50 cm depth. The statistical analysis of the generated time series reveals that ground temperatures in the Bale Mountains are subject to large daily fluctuations of up to 40 ∘C and minor seasonal variations on the order of 5 to 10 ∘C. Besides incoming short-wave radiation, ground moisture, and clouds at night, slope orientation and the type of vegetation coverage seem to be the main factors controlling daily and seasonal ground temperature variations. On the central Sanetti Plateau above 3800–4000 m, the mean annual ground temperature ranges from 9 to 11 ∘C. However, nocturnal ground frost down to a depth of 5 cm occurs frequently during the dry season from November to February. At the five sites where ground temperature is measured at three depths, the monitoring will be continued to trace long-term changes. To promote the further use of the ground temperature dataset by the wider research community dealing with the climate and geo-ecology of tropical mountains in eastern Africa, it is made freely available via the open-access repository Zenodo: https://doi.org/10.5281/zenodo.6047457 (Groos et al., 2022).

Ancient genomes from the Himalayas illuminate the genetic history of Tibetans and their Tibeto-Burman speaking neighbors

Present-day Tibetans have adapted both genetically and culturally to the high altitude environment of the Tibetan Plateau, but fundamental questions about their origins remain unanswered. Recent archaeological and genetic research suggests the presence of an early population on the Plateau within the past 40 thousand years, followed by the arrival of subsequent groups within the past 10 thousand years. Here, we obtain new genome-wide data for 33 ancient individuals from high elevation sites on the southern fringe of the Tibetan Plateau in Nepal, who we show are most closely related to present-day Tibetans. They derive most of their ancestry from groups related to Late Neolithic populations at the northeastern edge of the Tibetan Plateau but also harbor a minor genetic component from a distinct and deep Paleolithic Eurasian ancestry. In contrast to their Tibetan neighbors, present-day non-Tibetan Tibeto-Burman speakers living at mid-elevations along the southern and eastern margins of the Plateau form a genetic cline that reflects a distinct genetic history. Finally, a comparison between ancient and present-day highlanders confirms ongoing positive selection of high altitude adaptive alleles.

Rock temperature variability in high-altitude rockfall-prone areas

In a context of cryosphere degradation caused by climate warming, rock temperature is one of the main driving factors of rockfalls that occur on high-elevation mountain slopes. In order to improve the knowledge of this critical relationship, it is necessary to increase measurement capability of rock temperature and its variability in different lithological and slope/aspect conditions, and also to increase local scale studies, increasing the quality and the comparability of the data. This paper shows an example of metrological characterization of sensors used for rock temperature measurement in mountain regions, by means of the measurement uncertainty. Under such approach, data and results from temperature measurements carried out in the Bessanese high-elevation experimental site (Western European Alps) are illustrated. The procedures for the calibration and field characterization of sensors allow to measure temperature in different locations, depths and lithotypes, within 0.10 °C of overall uncertainty. This work has highlighted that metrological traceability is fundamental to asses data quality and establish comparability among different measurements; that there are strong differences between air temperature and near-surface rock temperature; and that there are significant differences of rock temperature acquired in different aspect conditions. Finally, solar radiation, slope/aspect conditions and lithotype, seem to be the main driving factors of rock temperature.

Evapotranspiration across the rain–snow transition in a semi‐arid watershed

AbstractThe snowpack regime influences the timing of soil water available for transpiration and synchrony with the evapotranspiration (ET) energy demand (air temperature, VPD, and shortwave radiation). Variability of snowmelt timing, soil water availability, and the energy demand results in heterogeneous ET rates throughout a watershed. In this study, we assessed how ET and growing season length vary across five sites on an elevational gradient in the Dry Creek Watershed, ID, USA. We compared trends of daily and annual ET between 2012 and 2017 to environmental parameters of soil moisture, air temperature, vapour pressure deficit, snow cover, and precipitation. Trends between parameters and ET were evaluated at each site and compared between sites. We observed three trends in ET across the watershed. The first trend is at the low elevation site where the snow cover is not continuous throughout the winter and rain is the dominant precipitation form. The first day of the growing season and ET occurs early in the season when the energy demand is low and soil water is available. Annual ET at the low elevation site is a balance between spring precipitation providing soil water into the summer season and limiting the ET energy demand. The second trend occurs at the middle elevation site located in the rain–snow transition. At this site, ET increases with snow depth and spring precipitation extending the soil water availability into the summer season. At the higher elevation sites, ET is aligned with the energy demand and limited by growing season length. At the high elevation sites, decreasing snow depth and spring precipitation and increasing spring air temperatures result in greater annual ET rates. The observations from this study highlight the influence of environmental parameters and the potential sensitivity of ET to climate change.

The dynamics of warming during the last deglaciation in high-elevation regions of Eastern Equatorial Africa

Tropical mountain environments, such as the Rwenzori Mountains in equatorial Africa, are thought to be particularly sensitive to climate change. Ongoing warming in the Rwenzori is impacting local environments and communities through glacial retreat, fires, and flooding. Paleoclimate reconstructions from elsewhere in Africa suggest considerable warming accompanied glacier retreat during the last glacial termination, from ∼21 thousand years before present (ka) through the early to mid-Holocene. Quantifying these changes has been difficult but could help to assess future impacts in the Rwenzori. Here, we present a ∼21 thousand-year (kyr) temperature reconstruction based on the relative abundance of branched glycerol dialkyl glycerol tetraethers (brGDGTs) from Lake Mahoma (2,990 m above sea level; m asl) in the Rwenzori Mountains, Uganda. Our record, paired with existing Rwenzori glacial moraine 10Be exposure ages, suggests that deglacial warming and glacial retreat began by ∼20 ka and accelerated at ∼18–18.5 ka. The timing of the onset of rapid warming matches the timing of the post-glacial rise in radiative forcing from atmospheric greenhouse gases (GHGs) from Antarctic ice cores (Brook et al., 1996; Marcott et al., 2014; Monnin et al., 2004; Schilt et al., 2010). Our temperature reconstruction registers ∼4.9 °C warming from the Last Glacial Maximum (LGM) to the late Holocene. This increase is larger than the average ∼2-4 °C warming observed in records from lower elevation sites in tropical East Africa, but similar to that observed at other high-elevation sites in this region. The increased warming at higher elevations thus confirms that the temperature lapse rate steepened during the LGM over this region. Our results also indicate ∼3 °C of warming during the mid-Holocene relative to the late Holocene. This suggests that the freezing-level height rose above Rwenzori summit elevations at that time, likely causing complete deglaciation of the Rwenzori Mountains from ∼5 to 7 ka. The mid-Holocene is thus a potential analog for the glacial and environmental changes that these mountains are likely to experience in the coming decades. Overall, the timing and magnitude of temperature change observed in our record has important implications for climate model projections of future warming in tropical Africa.

Discovery of frogs of the Stumpffia hara species group (Microhylidae, Cophylinae) on Montagne d’Ambre in northern Madagascar, with description of a new species

The stump-toed frogs of the Madagascar-endemic genusStumpffiaare mostly diminutive in size, but there is one group of comparatively large frogs within the genus, which we herein refer to as theStumpffia haraspecies group. Each of the four known members of this species group is endemic to a single location of deciduous dry forest with exposed karstic limestone rock. Here, we report on the discovery of members of this species group on Montagne d’Ambre, a rainforest-covered extinct volcano in the North of Madagascar that has a richStumpffiafauna but has been thought to lack members of theS. haraspecies group until now. We found two members of the species group, one at the peak, and one in transitional and dry deciduous forest on the west and northern slopes of the mountain. The high-elevation species is new to science, and we here describe it asStumpffia bishopisp. nov.It occupies a highly distinct position in the phylogeny of these frogs, characterized by ≥ 9.8% uncorrected pairwise distance from all other nominalStumpffiain a fragment of the mitochondrial 16S rRNA gene. It is also the smallest of the members of theS. haraspecies group. Our genetic results show that the low-elevation species isStumpffia megsoni, constituting a range expansion of that species and considerably expanding our understanding of its morphology and ecology. We report its advertisement call for the first time. Our results highlight the importance of continued surveys of even well-sampled localities, with special attention on the high elevation sites of northern massifs and collection of voucher specimens, and how much there still remains to understand about even the largest of Madagascar’s small frogs.

Cloud and fog deposition: Monitoring in high elevation and coastal ecosystems. The past, present, and future

Deposition of pollutants by cloud water exceeds deposition by precipitation and dry deposition in many high elevation settings. This larger loading of pollutants in these environments is due to a combination of factors such as high frequency of cloud immersion, high wind speeds, orographic enhancement of precipitation, and large leaf area of tree species typical in these environments. Fog-impacted coastal ecosystems also experience increased pollutant deposition similar to cloud-impacted high elevation sites. Therefore, development of meaningful critical load values and total nitrogen budgets for high-elevation and fog-impacted sites requires reliable cloud and fog water deposition estimates. The cost and labor intensity of cloud/fog water sample collection have made it difficult to conduct long-term studies that would provide the data needed to develop accurate estimates. Current understanding of fog formation, transport, and the role of fog and cloud deposition in hydrogeological and biogeochemical cycles is incomplete due, in part, to lack of a concerted interdisciplinary approach to the problem. Historically, these obstacles have limited interest in and collection of cloud and fog water samples. In addition to measurements of cloud/fog chemical composition, documenting fog/cloud deposition fluxes of pollutant and nutrient species requires knowledge of cloud/fog physical properties, frequency and duration of fog/cloud interception with landscapes, properties of vegetation on those landscapes, and properties of the wind that drive droplet/vegetation interactions. Because drop deposition efficiency is dependent on drop size, it is also important to consider variations in fog/cloud drop composition with drop size as species enriched in larger/smaller drops will experience enhanced/reduced deposition rates.This paper presents summary results from a small U.S. cloud water monitoring network that operated from the mid-nineties through 2011, as well as a brief qualitative review of other cloud and fog water studies conducted in the United States (including Puerto Rico), Europe, South America/Pacific, and Asia. Current collection methods are also reviewed. Recent scientific efforts by the National Atmospheric Deposition Program's (NADP) Total Deposition Science Committee and NADP's Critical Loads of Atmospheric Deposition Science Committee have identified occult (cloud/fog) deposition as a “need” in developing critical loads for ecosystems that experience significant cloud and fog impaction. To this end, remaining knowledge gaps and suggestions for future research to investigate these gaps are explored.

Lithic cyanobacteria as bioindicators for dewless habitats within a dew desert

While previous measurements in a small drainage basin in the Negev Desert (Sede Boqer) discovered dewless habitats (<0.03 mm of non-rainfall water, NRW), which are inhabited by lithic cyanobacteria, it is not clear whether these findings can be generalized to other locations in the Negev. The question is especially relevant for high elevation sites (1000 m above msl) where previous measurements recorded high amounts of dew and fog and lush cover of lichens. Towards this end, measurements along an elevational gradient were carried out, at Nizzana (NIZ), 250 m above msl, Sede Boqer (SB), 550 m above msl, and Har Harif (HH), 1000 m above msl. The measurements included (a) cover and biomass (chlorophyll a) of the cyanobacteria and lichens on bedrocks along a 30 m transect at the south-facing slopes, (b) simultaneous monitoring of the surface temperatures of bedrocks inhabited by cyanobacteria and lichens, and (c) periodic measurements of NRW at these habitats using the cloth-plate method (CPM) and cloths attached to rock surfaces inhabited by both lithobionts. A significant decrease in minimum temperatures and increase in NRW (as recorded by the CPM) with elevation was recorded following the pattern: NIZ (0.12 mm) < SB (0.20 mm) < HH (0.29 mm). A significant increase in NRW with elevation was also recorded at the lichen habitat (with NRW of up to 0.51 mm), but yet NRW at the cyanobacteria habitat was always <0.04 mm, i.e., below the necessary threshold required for their activation. The findings point to the fact that variability in rock temperatures dictates the amount of NRW, and regardless of the general increase in NRW with elevation, cyanobacteria are confined to dewless habitats. A prokaryote–eukaryote partition in accordance with NRW is thus apparent, with cyanobacteria serving as useful bioindicators for dewless habitats in the Negev.

Co-Occurring Wyoming Pinus Species Exhibit Differing Climate–Growth Relationships

The North American Dendroecological Field week (NADEF) is an intensive dendrochronology workshop, funded in part by the National Science Foundation. The 2019 Introductory Group at NADEF developed two precisely dated tree-ring width chronologies for Pinus contorta (lodgepole pine) and Pinus flexilis (limber pine) at the Wolf Knob site ca. 5 km west of Beartooth Lake, WY, within the bounds of the Shoshone National Forest (SNF), in the Greater Yellowstone Ecosystem (GYE). Wolf Knob is a semi-arid, S- to SW-facing, mid- to high-elevation site, making it an ideal location to examine the climate sensitivity of annual tree-ring width increments. Here, we show that two co-located Pinus species exhibit differing climate–growth relationships, with P. contorta exhibiting relatively weak correlations with precipitation (r = 0.37; p < 0.01) and temperature (r = –0.23; p < 0.05) during the late summer, and P. flexilis exhibiting stronger overall correlations with both cool-season (r = 0.48; p < 0.01) and warm-season precipitation (r = 0.51; p < 0.01) as well as with snowpack records (r = 0.45; p < 0.05). Our results suggest these two Pinus species may face disparate threats in the face of regional climate change, with P. flexilis being particularly vulnerable to drought conditions and declining snowpacks in the GYE. The differing seasonal climate sensitivities of the two species is likely caused by microsite conditions (e.g. soil moisture capacity, incoming solar radiation) and distinct species-climate responses, underscoring the importance of not only site selection, but also microsite and individual selection in dendroclimatological sampling. Finally, this work contributes to identifying Snow Water Equivalent (SWE)-sensitive tree-ring proxies in the GYE, critical for understanding ongoing warming-induced snowpack declines across western North America, particularly given the projections of a largely snow-free (April 1) GYE by 2075.

Global tree-ring response and inferred climate variation following the mid-thirteenth century Samalas eruption

The largest explosive volcanic eruption of the Common Era in terms of estimated sulphur yield to the stratosphere was identified in glaciochemical records 40 years ago, and dates to the mid-thirteenth century. Despite eventual attribution to the Samalas (Rinjani) volcano in Indonesia, the eruption date remains uncertain, and the climate response only partially understood. Seeking a more global perspective on summer surface temperature and hydroclimate change following the eruption, we present an analysis of 249 tree-ring chronologies spanning the thirteenth century and representing all continents except Antarctica. Of the 170 predominantly temperature sensitive high-frequency chronologies, the earliest hints of boreal summer cooling are the growth depressions found at sites in the western US and Canada in 1257 CE. If this response is a result of Samalas, it would be consistent with an eruption window of circa May–July 1257 CE. More widespread summer cooling across the mid-latitudes of North America and Eurasia is pronounced in 1258, while records from Scandinavia and Siberia reveal peak cooling in 1259. In contrast to the marked post-Samalas temperature response at high-elevation sites in the Northern Hemisphere, no strong hydroclimatic anomalies emerge from the 79 precipitation-sensitive chronologies. Although our findings remain spatially biased towards the western US and central Europe, and growth-climate response patterns are not always dominated by a single meteorological factor, this study offers a global proxy framework for the evaluation of paleoclimate model simulations.

Low germination rate of Pinus hartwegii seeds from trees growing at high elevations: Vulnerability to climate change?

• In Pinus hartwegii seeds germinability decreased with increasing elevation. • Pinus hartwegii seeds from uppermost elevations germinated under limited temperature and humidity conditions, showing their susceptibility to conditions of water and thermal stress. • Pinus hartwegii seeds from low and medium elevations constitute a potential source of seeds for higher elevation sites.

Variability in Soil Moisture by Natural and Artificial Snow: A Case Study in Mt. Balwang Area, Gangwon-do, South Korea

Soil moisture is an important variable for understanding hydrological processes, and the year-round monitoring of soil moisture and temperature reflect the variations induced by snow cover and its melt. Herein, we monitored the soil moisture and temperature in high (two sites) and low (two sites) elevation regions with groundwater sampling near the Mt. Balwang area in Gangwon-do, South Korea from Sep 2020 to May 2021. This study aims to investigate the temporal and spatial variations in soil moisture and temperature due to snow (natural and artificial snow) and its melt. A ski resort has been operating in this area and has been producing artificial snow during winter periods; thus, the spring snowmelt comprises both natural and artificial snow. The effect of soil freezing and thawing, wind conditions, vegetation covers, the timing and intensity of snow cover and snowmelt were differed in the monitoring sites. The high elevation sites 1 and 2 exhibit the relatively longer and consistent snow cover than the low elevation sites. Particularly, site 2 show late (May 8) snow melting even this site is in south slope of the Mt. Balwang. The relatively steady and moist soil layers at sites 1, 2, and 3 during the warm period can be considered as influential points to groundwater recharge. Moreover, the differences between the mean δ18O (−9.89‰) of the artificial snow layers and other samples were low: in the order of surface water (0.04‰) &amp;gt;groundwater (−0.66 and −1.01‰) &amp;gt;natural snow (1.34 and −3.80‰). This indicates that the imprint of artificial snow derived from surface water and with decreasing amount of natural snow around the Mt. Balwang region, the results support the assumption that the potential influence of artificial snowmelt on groundwater quality. This study helps to understand the snow dynamic and its influence on the hydrological processes in this region by combining the hydro-chemical and isotopic analysis.

Neotropical stingless bees display a strong response in cold tolerance with changes in elevation.

Tropical pollinators are expected to experience substantial effects due to climate change, but aspects of their thermal biology remain largely unknown. We investigated the thermal tolerance of stingless honey-making bees, the most ecologically, economically and culturally important group of tropical pollinators. We assessed changes in the lower (CTMin) and upper (CTMax) critical thermal limits of 17 species (12 genera) at two elevations (200 and 1500m) in the Colombian Andes. In addition, we examined the influence of body size (intertegular distance, ITD), hairiness (thoracic hair length) and coloration (lightness value) on bees' thermal tolerance. Because stingless beekeepers often relocate their colonies across the altitudinal gradient, as an initial attempt to explore potential social responses to climatic variability, we also tracked for several weeks brood temperature and humidity in nests of three species at both elevations. We found that CTMin decreased with elevation while CTMax was similar between elevations. CTMin and CTMax increased (low cold tolerance and high heat tolerance) with increasing ITD, hair length and lightness value, but these relationships were weak and explained at most 10% of the variance. Neither CTMin nor CTMax displayed significant phylogenetic signal. Brood nest temperature tracked ambient diel variations more closely in the low-elevation site, but it was constant and higher at the high-elevation site. In contrast, brood nest humidity was uniform throughout the day regardless of elevation. The stronger response in CTMin, and a similar CTMax between elevations, follows a pattern of variation documented across a wide range of taxa that is commonly known as the Brett's heat-invariant hypothesis. Our results indicate differential thermal sensitivities and potential thermal adaptations to local climate, which support ongoing conservation policies to restrict the long-distance relocations of colonies. They also shed light on how malleable nest thermoregulation can be across elevations.

Variation in Tree Layer Composition Across Mid and Higher Elevation Forest Sites in Kumaun Himalayan Region, Uttarakhand

The Himalayan forests are rich in biodiversity and distributed over a large extent from lower to higher elevations. The dependence of the locals for their daily requirements of fuel, fodder and medicinal plants is high on these forests. The study was conducted at altitude varied between 1725 and 3250 masl (above sea level) in Kumaun region. The study deals with the comparison of tree layer vegetation in higher elevation sites (HES) and mid elevation sites (MES) with reference to Diversity, Richness, Basal area (BA), Dominance and Important Value Index. The MES were dominated by mixed Quercus leucotrichophora and Pinus roxburghii forests where as HES sites were dominated by Quercus semecarpifolia and Aesculus indica forests and Rhododendron campanulatum in the understory. Across all the sites the tree species richness ranged between 9 and 15. Tree density was maximum (1400 trees/ha) at MES. Tree diversity and total basal area were maximum at HES. The study will be useful in developing baseline data for carrying out future studies. The data generated will be helpful for the conservation of biodiversity of the region.