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Treelines and treeline species are being studied the world over because of their sensitivity to climate change but most of these studies have not focused on the essential belowground mutualists which could influence the outcome of the interaction between treeline species and climate change, such as the treeline shift. To fill this knowledge gap, we processed 27 root samples of Betula utilis from two sites in the Kashmir Himalaya and identified 590 species of root-associated fungi belonging to 158 genera, 80 families, 38 orders, 15 classes and 3 phyla from a total of 9157 quality reads. Most of the identified species belonged to Basidiomycetes. Papiliotrema, Humaria, Sphaerobolus, Sebicina, Inocybe, Cryptococcus, Lactarius and Laccaria were the dominant taxa. Symbiotroph, Saproptroph-Symbiotroph and Saprotrophs were the dominant trophic modes of the identified root-associated fungi and most of the identified species belonged to the Ectomycorrhizae (ECM) guild. Differences in the species richness between the two sites were noted and a total of 511 taxa were recovered from root samples at the Sinthan Top site in south Kashmir whereas only 302 taxa were recovered from root samples at the Apharwat site in north Kashmir. Papiliotrema and Inocybe with > 75% prevalence represented the core microbiome. Our study provides the first detailed and comprehensive account of the diversity of fungi associated with the roots of B. utilis and paves way for exploring their functional role in the growth of this treeline species, particularly under changing climate. [ABSTRACT FROM AUTHOR]

Treeline patches are among Earth’s most sensitive and are important model ecosystems for assessing climate change trends. To explore ecological factors that limit the species’ survival in treelines, the treeline patch of Li Mountain National Nature Reserve was selected as the research site. Pinus armandii (P. armandii), Betula albo-sinensis (B. albo-sinensis), and Betula utilis (B. utilis) were selected as research species based on their dominance. Two 50 m × 50 m plots were established separately from the upper and lower limits of the highest treeline patch for point pattern analysis. Five 10 m × 10 m quadrats per plot were sampled to investigate the flora and environmental factors. The results showed that: (1) Slope and community composition at tree layer in quadrates had significant differences between upper and lower limits. Pinus armandii had a greater population size at the upper limit. Seedling recruitment restricted population development for B. albo-sinensis at the lower limit and B. utilis at the upper limit and less regeneration of B. albo-sinensis at the upper limit. (2) More aggregation scales occurred at the upper limit, and P. armandii had more aggregation scales than the other two species at 0–25 m. The heterogeneity caused by density distribution affected P. armandii pattern at the upper limit, and heterogeneity of seed dispersal could explain species patterns in both limits. Distinctness of size difference may have an influence on inter-specific species correlations. [ABSTRACT FROM AUTHOR]

Traditional wound dressings have a limited capacity to absorb exudates, are permeable to microbes, and may adhere to wounds, which leads to secondary injuries. Hydrogels are promising alternative dressings to overcome the above challenges. In this study, we developed sodium alginate-based hydrogel films loaded with Betula utilis bark extract. These films were prepared via solvent-casting crosslinking method and evaluated for wound healing activity. Prepared films were 0.05–0.083 mm thick, flexible with folding endurance ranging from 197–203 folds, which indicates good physical properties. Optimized formulations exhibited successful loading of extract in the film matrix without any interaction as confirmed by FTIR. Maximum zone of inhibition against Gram-positive and Gram-negative bacteria was achieved by optimum formulation (B6), i.e., 19 mm and 9 mm, respectively, with > 90% scavenging activity. Furthermore, this optimum formulation (B6) was able to achieve 93% wound contraction in rats. Histograms of the optimized formulation treated group also revealed complete reepithelization of wounds. Conclusively, our extract-loaded hydrogel dressing successfully demonstrated its potential for cutaneous wound healing.

The present study aimed to analyse the population structure, forest composition and regeneration dynamics of Betula utilis D.Don in two core zone of Nanda Devi Biosphere Reserve. A total of 346 plants species belonging to 198 genera and 82 families were recorded dominated by Asteraceae (24) followed by Rosaceae (21 species) and Ranunculaceae (19 species), respectively. The total tree stand density was ranged between 1133 ind.ha−1 and 2137 ind.ha−1 in the south and north aspect of the each sites. Among tree species B. utilis was showed the dominant tree species with highest density ranged between 663 ind.ha−1 and 1525 ind.ha−1 at north and south aspects of both sites. Highest seedling density (1033 saplings ha−1 and 1783 seedlings ha−1) and sapling density (1033 saplings ha−1 and 1470 saplings ha−1) was recorded for B. utilis in north and south aspects. The density-diameter curve of B. utilis forest resembled a reverse J-shape which exhibits good regeneration with higher number of individuals in seedling and sapling stages, followed by a sharp decline in tree classes. This study suggests urgent need of long term ecological monitoring of timberline zone to assess the significant change in timberline vegetation and development of sustainable management plans.

The sensitivity and response of climatic treelines in the Himalayas to climate change is still being debated. Regeneration of tree species in the treeline ecotone is considered a sensitivity indicator and thus of great scientific interest. The aim of this study is to detect predictor variables for regeneration densities of the major tree species in central Himalayan treeline ecotones (Abies spectabilis, Betula utilis, Rhododendron campanulatum), analysing five development stages from seedling to mature tree. We applied negative binomial generalized linear models with predictors selected from a wide range of soil, topography, climate and stand characteristic variables. We found considerably varying predictors across the tree species and their stages of development. Soil conditions, topography and climate, as well as competing and facilitating tree species, had high predictive power for population densities. These predictors were clearly species- and development stage-specific. Predictors' spatial- and development-specific heterogeneity induce a high degree of complexity and diversify any potentially linear response of tree population densities and treeline position to changing climatic conditions. [ABSTRACT FROM AUTHOR]

A simple, rapid, sensitive, and reliable ultra‐high‐performance liquid chromatography‐hybrid linear ion trap triple quadrupole mass spectrometry method was developed and validated for simultaneous determination of 10 bioactive compounds in stem bark of Betula utilis grown in high altitude of Himalaya, India. The objective of the study is to develop and validate ultra‐high‐performance liquid chromatography‐hybrid linear ion trap triple quadrupole mass spectrometry for investigation of geographical variations of triterpenoids, phenolics, and flavonoids contents in stem bark of B. utilis. The validated method was successfully applied to investigate geographical variations of triterpenoids, phenolics, and flavonoids in stem bark of B. utilis. The contents of betulinic acid and oleanolic acid were detected higher among selected analytes. The present variation study reveals great importance for the application and overall assessment of B. utilis. [ABSTRACT FROM AUTHOR]

The present study was conducted in Hamta Pass area of Kullu district, Himachal Pradesh, India with a focus on Betula utilis populations. Totally 16 populations of B. utilis representing four habitats and three aspects were studied. The maximum sites were represented by moist and moist, shaded habitats with northwestern aspect. Totally 188 plant species representing trees, shrubs and herbs were recorded. Acer acuminatum, Abies pindrow, Prunus cornuta and Quercus semecarpifolia were the major associated species of B. utilis in the subalpine zone of Hamta Pass. Based on importance value index five tree communities, namely A. acuminatum, A. pindrow, B. utilis, Q. semecarpifolia and B. utilis--P. cornuta mixed were identified. Among the communities, total density of trees, shrubs and herbs was recorded from 160 to 270, 300 to 515 and 21 to 33 individuals m--2 respectively. The total basal area recorded was 6.94--42.10 m2 ha--1, species richness 15--127, and species diversity for trees 0.4--0.9, shrubs 0.0--2.1 and herbs 1.7--4.2. The density and regeneration (i.e. seedlings and saplings) of B. utilis in most of the populations revealed that this species will continue to grow in the area. However, continued anthropogenic activities, climate change and other factors may cause population depletion in the study area. [ABSTRACT FROM AUTHOR]

The sensitivity and response of climatic treelines in the Himalayas to climate change is still being debated. Regeneration of tree species in the treeline ecotone is considered a sensitivity indicator and thus of great scientific interest. The aim of this study is to detect predictor variables for regeneration densities of the major tree species in central Himalayan treeline ecotones (Abies spectabilis, Betula utilis, Rhododendron campanulatum), analysing five development stages from seedling to mature tree. We applied negative binomial generalized linear models with predictors selected from a wide range of soil, topography, climate and stand characteristic variables. We found considerably varying predictors across the tree species and their stages of development. Soil conditions, topography and climate, as well as competing and facilitating tree species, had high predictive power for population densities. These predictors were clearly species- and development stage-specific. Predictors’ spatial- and development-specific heterogeneity induce a high degree of complexity and diversify any potentially linear response of tree population densities and treeline position to changing climatic conditions.

Question: Tree growth at high altitude in the Himalayan region is limited by cold temperatures and also strongly influenced by the seasonality of the Asian monsoon. Understanding whether the ongoing increase in temperatures and changes in precipitation regimes in the Himalayan region can stimulate or limit tree growth is of particular importance to predict the local treeline dynamics. Location: Altitudinal treeline (~4000 m a.s.l.) in the Sagarmatha (Mt. Everest) National Park (Central Himalaya, Eastern Nepal). Methods: We assessed the relationships between ring widths and monthly precipitations and mean temperatures, and analysed cellulose stable isotopes (δ13C and δ18O) and their derived C discrimination (Δ13C), and intrinsic water use efficiency (iWUE) in Abies spectabilis and Betula utilis at the Himalayan treeline. Results: Growth of A. spectabilis strongly depended on summer temperatures, whereas that of B. utilis on spring precipitation. δ13C and iWUE increased with time in both species, especially in A. spectabilis. The long‐term decrease in Δ13C was accompanied by an increase in δ18O in both species, thus suggesting an increase in photosynthetic efficiency rather than a stronger stomatal control of transpiration. Conclusions: Climate change is progressively reducing the physiological limitations due to low temperatures and low spring precipitations at the Central Himalayan treeline, thus potentially facilitating a further altitudinal forest advance. [ABSTRACT FROM AUTHOR]

Increase in endemism with elevation is a common feature in Himalayas because of increased isolation of higher areas like treelines. To protect species of treeline, we at least need to record their numbers and distribution. We estimated that the total number of tree species in Himalayan treeline is 58, and they belong to 14 genera and 8 families. It is impressive, given that globally alpine treeline species richness is unlikely to be considerably higher than 100. While estimating the species number, we confronted uncertainties in some cases concerning synonyms of species, weak demarcation between species and incorrect identification. Because of a high species differentiation in the Hengduan Mountains and Western Sichuan Province in Tibet, the eastern part of the Himalayan arc (88°E and more) has much higher species richness than the western part (less than 88°E), despite similar number of genera. These areas of high species differentiation accounted for nearly half of the total species. The dominant genera in terms of geographical distribution are Juniperus, Abies, Rhododendron, and Betula. Among the families, Pinaceae, Cupressaceae, Ericaceae, Betulaceae, and Rosaceae were prominent. Because of global climatic change, species shifts are predicted to occur along an altitudinal gradient (representing temperature gradient) as well as along the 31º longitudinal range, representing a moisture gradient. The Himalayan treelines are relatively species-rich, largely because of variations in precipitation, topography, continentality, and cultural factors, among others along the east-to-west arc. There is a need to undertake additional taxonomic studies, using tools such as molecular techniques to provide solution to confusion relating to incorrect identification of some species. [ABSTRACT FROM AUTHOR]

Aim: The spatial patterns of tree populations reflect multiple ecological processes. However, little is known on whether these patterns mediate responses to climate in marginal tree populations such as those forming alpine tree lines. We examined the influence of tree‐to‐tree interactions on the responsiveness of tree lines to climate warming. Location: Central Himalayas. Taxon: Betula utilis; Abies spectabilis. Methods: We analysed a network of 17 tree line sites located across the central Himalayas, encompassing a wide longitudinal gradient characterized by increasing precipitation eastwards. We quantified the changes in density and the spatial patterns of three 50‐year age classes of the two main tree species found at the tree line (Betula utilis and Abies spectabilis), and related them to reconstructed shifts in tree line elevation. Results: Younger trees showed clustering near the tree line, while older trees tended to show random spatial distribution. Clustering decreased as climate conditions ameliorated, that is, in the wetter eastern sites. Lower rate of tree line elevation change was observed at the sites with higher clustering intensity. Main Conclusions: Our study indicates that tree aggregation weakens tree line responsiveness to climate warming, and thus warming‐induced drought stress tends to lower tree line shift rates by enhancing clustering. It also highlights the complexity and contingency of site‐dependent tree line responses to climate. Hence, to advance our understanding of tree line processes, we should consider both direct and indirect influences of relevant biotic (tree‐to‐tree interactions) and abiotic (climate) drivers of tree line dynamics. [ABSTRACT FROM AUTHOR]

Betula utilis D. Don. is an important species of alpine Himalaya and forms the major treeline component of western Himalaya. The different populations of B. utilis are declining and are under high risk. In the present study, novel expressed sequence tag–simple sequence repeat (EST–SSR) primers were developed from expressed sequence tag (EST) data of different Betula species. Of the 10,796 designed primers, the percentages of di-, tri-, tetra-, penta-, and hexa-repeats were 36%, 35%, 15%, 5.5% and 7.7%, respectively. For validation, 50 primers were synthesized randomly and were characterized in 20 different B. utilis accessions from north-western Himalaya. Of these, 45 primers amplified fragments in a range of 1–6. The 24 polymorphic primers produced 111 fragments in aggregate with 4.6 fragments on average. Polymorphism information content (PIC) ranged from 0.288 in marker BUMS-24 to 0.497 in BUMS-3 and BUMS-7, with an average of 0.447 among polymorphic markers. Dendrogram based on Jaccard's similarity coefficient and UPGMA method showed that newly developed SSR markers distinguished twenty accessions of B. utilis into two groups. As no SSR markers were available in this species, the newly developed markers will foster molecular genetics research and conservation efforts for this species. [ABSTRACT FROM AUTHOR]

• Study was conducted to determine the best medium for in vitro pollen germination of B. utilis. • An effect of sucrose, boric acid, calcium nitrate, magnesium sulfate, potassium nitrate and time of incubation on pollen germination and tube growth was investigated. • The germination rate and pollen tube length varied significantly with different concentrations and incubation time. • Pollen grains collected immediately after anther dehiscence showed the best germination ability however steadily decreased with time. The study was conducted to determine the optimum medium for in vitro pollen germination for B. utilis based on germination percentages and length of the pollen tube. Studies about pollen germination and tube growth of B. utilis are limited. Therefore, this study aimed to investigate the effects of sucrose (1, 3, 5, 10 and 15%), boric acid (25, 50, 100 and 200 ppm), calcium nitrate (50, 100, 200, 300 and 400 ppm), magnesium sulfate (50, 100, 200 and 300 ppm) and potassium nitrate (50, 100 and 200 ppm) and time of incubation on pollen germination and tube growth. Pollen germination rates and tube growth were recorded periodically at 2, 4, 6, and 10 h. The length varied significantly with different concentrations and incubation time. The germination rate and pollen tube length varied significantly with different concentrations and incubation time. Pollen germination was maximal (98 ± 6.1%) when the germination medium contained 10% sucrose solution supplemented with 100 ppm H 3 BO 3 , 300 ppm Ca(NO 3) 2 , 200 ppm MgSO 4 and 100 ppm KNO 3, after 6 h of incubation. In addition, results revealed that pollen grains collected immediately after anther dehiscence showed the best germination ability but gradually decreased with time. [ABSTRACT FROM AUTHOR]

Himalayan Silver Fir (Abies spectabilis) and Himalayan Birch (Betula utilis) are tree species often found coexisting in sub-alpine forests of the Nepal Himalayas. To assess species-specific growth performances of these species, tree-ring samples were collected from the subalpine forest in the Dhorpatan Hunting Reserve, Nepal. Standard ring width chronologies of both species were correlated with climatic variables in both static and running windows. Differential and contrasting temporal responses of radial growth of these species to climate were found. Warmer and drier springs appeared to limit birch radial growth. Whereas radial growth of fir showed weakened climate sensitivity. Moving correlation analyses revealed divergent influences of spring climate on both fir and birch. Significant warming that occurred in the 1970s coincided with growth declines in birch and an increase in fir, as indicated by basal area increment. In summary, recent warming has been unfavorable for birch, and favorable to fir radial growth.

Psoriasis is a chronic autoimmune pathological condition characterized by hyperactivation of proinflammatory cytokines (IL-6, TNF-α, IL-17, IL-23, etc.). Severe drug-associated toxicities like hepatotoxicity and nephrotoxicity (Methotrexate), teratogenicity (Tazarotene), hypercholesterolemia (Cyclosporine) and hypercalcemia (tacalcitol), are the forefront challenges that demand an alternative approach for the treatment of psoriasis. In the present study, a natural lead molecule 'Betulin' (BE, lup-20(29)-ene-3b,28-diol) was isolated from Betula utilis and subsequently, structure-based molecular docking was employed to identify the molecular target for psoriasis. The computational analysis reflects better affinity of BE towards pro-inflammatory cytokine as compared to standard drugs. Apart from this BE shows a greater affinity towards the overexpressed Glut-1 receptor in comparison to standard drug Metformin (Met). Based on the in silico screening the isolated lead compound was further processed for the evaluation of anti-psoriatic activity via imiquimod (IMQ 5%) induced psoriasis-like skin inflammation model. In vivo screening models were characterized by different parameters (psoriasis area and severity index (PASI) scores, macroscopically and behavioral evaluation, splenomegaly, cytokine levels and histological changes) and compared among the experimental groups. The experimental finding reflects comparable results of PASI score, i.e., 57.14% and 61.9% recovery of test BE-solution (180 mg/kg) and standard Betamethasone di-propionate ointment (BD-oint.0.5 mg/g), respectively. Focusing on other parameters, BE shows relative results such as an enhanced macroscopically with behavioral conditions, reducing the expression of proinflammatory cytokine as well as restoring histological changes with that of BD. These findings suggest that BE-isolated phytoconstituents from Betula utilis could be a potential agent and a step closer to psoriasis treatment. HIGHLIGHTPsoriasis is a multifaceted, immunologically mediated disease consequences production of high levels of proinflammatory mediators and overexpression of Glut-1 transporters that trigger keratinocyte proliferation and inflammatory cascades.A Himalayan silver birch, Betula utilis (Bhojpatra) contains many steroidal terpenes which are responsible for various pharmacological activities that could be exploited in drug development in psoriasis.The computational analysis of BE reflects a better affinity toward the proinflammatory cytokines with their target receptors and indicates a satisfactory range with a slight deviation from Jorgensen and Lipinski's rule and possesses a significant drug choice for psoriasis.Preclinical findings of BE-solution (BE-sol) give a positive response towards IMQ-induced psoriasis-like skin inflammation model.[Figure: see text]Communicated by Ramaswamy H. Sarma.

In this study on treeline phenology in Tungnath, Garhwal Himalaya (altitude, 2955-3334 m asl), we (i) collected data on micro-climatic conditions, timing of major phenophases, leaf and shoot growth phenology and leaf nitrogen resorption in four major tree species (Abies spectabilis, Betula utilis, Quercus semecarpifolia, Rhododendron arboreum) and a krummholz species (R. campanulatum); and (ii) compared the treeline species phenology with mid-altitude forest tree species phenology of this region. Meteorological data reported for this site revealed that the mean monthly atmospheric temperature during growing period (July-September) has increased at the rate of 0.11 °C yr-1 in the last two decades. Leaf bud-break occurred in all the species in May, however, the proportion of marked tree population in bud-break phase at the time of first observation in May varied considerably across the species from 10% in Q. semecarpifolia to 50% in R. arboreum. Leaf initiation and leafing in the treeline species was delayed by about two months, compared to the mid-altitude tree species. Also, the leaf expansion within one month of leafing was conspicuously slower in treeline species than mid-altitude species (43% vs. 83% in Quercus spp. and 49% vs. 76% in R. arboreum). The treeline species were characterized by short growing period (2-4 months), lower period of steady-state in peak leaf mass and rapid leaf mass loss, low nitrogen concentration in leaves (1.7% vs. 2.5%), slow shoot growth, lower shoot length (5.6 cm vs. 9.5 cm) and shoot growth period, and higher leaf density in shoots (1.2 vs. 0.8 leaves cm-1 shoot length) than the mid-altitude forest trees. It is expected that with the increasing rate of warming in Tungnath the phenological behaviour of treeline species would change markedly in future leading to changes in ecosystem properties. [ABSTRACT FROM AUTHOR]

The Himalayas is one of the most ecologically sensitive and fragile areas in the world. The climate of the region is dominated by the monsoon seasonality, with typical dry winters and abundant summer precipitations. Here, forest vegetation spreads up to the world’s highest elevations, where cold temperatures and early spring droughts represent the main limiting factors for growth. In this study, we applied a dendro-anatomical approach to assess xylem trait chronologies and their association to local climate variability in the diffused broadleaved Betula utilis D Don close to the treeline (above 3900 m a.s.l.). We measured tree-ring width on increment cores from 73 trees. On seven cores, we prepared 12 μm thick sections, which were analysed with ROXAS for the assessment of ring-based xylem parameters. We then built up the corresponding trait chronologies and analyzed them against the time series of monthly temperatures and precipitations. Mean ring width (MRW), mean vessel area (MCA_V) and ring-specific hydraulic conductivity (Kr) positively correlated with summer temperatures in the previous and current year. In addition, MCA_V was significantly associated with March precipitations. Instead, fibres’ area showed a widely negative correlation only with temperatures during the previous and current season suggesting that fibres get narrower when vessels are wider. These results revealed that Himalayan birch is well adapted to the monsoon seasonality and is responding positively to atmospheric warming, thus suggesting the potential for this species to further expand in altitude under the forecasted climate change scenarios. [ABSTRACT FROM AUTHOR]

A treeline can respond to climate change by shifting position, infilling, increasing recruitment, and increasing radial growth. More studies from understudied areas and their associated species are needed to understand treeline structure and dynamics. We established two transects of 20 m width and 120 m length (100 m above and 20 m below the forestline) in the Betula utilis subalpine forest of the Dhorpatan Hunting Reserve in Western Nepal. All individuals of B. utilis within the transects were classified into three height classes - trees (>2 m), saplings (0.5-2 m), and seedlings (<0.5 m) - and measured for morphometric features. Tree-ring cores were collected for age structure analysis. B. utilis forms an abrupt treeline in the region, and the mean forestline and treeline elevations were 3893 and 3898 m, respectively. The average age (57 yr) of trees at the treeline ecotone suggests a young stand. Poor regeneration was observed above the forestline in both transects when compared to below the forestline. Low regeneration at the treeline ecotone suggests site-specific biotic and abiotic controlling factors. Seedling and sapling establishment above the forestline is limited by a lack of moisture, absence of suitable microsites, and presence of herbivores. [ABSTRACT FROM AUTHOR]

Betula utilis, commonly known as Himalayan birch is an important tree species of fragile ecosystem of Himalayas placed in endangered category. In the present study genetic diversity, structure and interrelationships of B. utilis accessions from North-western Himalayan regions were analyzed using Random Amplified Polymorphic DNA (RAPD) and Inter Simple Sequence Repeat (ISSR) markers. 15 RAPD and 16 ISSR primers collectively amplified 109 polymorphic fragments with an average of 3.51 fragments in a size range of 300-1300 bp. Polymorphism Information Content (PIC) ranged from 0.21 to 0.5 with an average of 0.43. Dendrogram grouped all the accessions into two major clusters. Factorial analysis showed three groups for all the analyzed accessions. Bayesian clustering using STRUCTURE grouped all the accessions in two clusters and separated majority of accessions belonging to Jammu & Kashmir Himalaya (cluster-II) from other accessions of Himachal Pradesh and Uttarakhand Himalaya (cluster-I). Exceptionally, four accessions namely, Sinth-12, Sinth-20, Son-06 and Son-16 from Kashmir grouped in Cluster-I. Structure analysis showed that two genetic stocks were contributing in genetic makeup of all the analyzed accessions. Results of the present study can be useful for selection of diverse accessions as well as can be useful in designing conservation and management strategies in North-western Himalayan regions. [ABSTRACT FROM AUTHOR]

This article enfolds a rapid and sensitive high-performance thin-layer chromatographic (HPTLC) method for the estimation of four triterpenoids, namely, betulin (BU), betulinic acid (BA), lupeol (LU), and oleanolic acid (OA), from the bark, roots, and leaves of Betula utilis D. Don, an endangered Himalayan tree. All the four phytoconstituents have high therapeutic value. Separation was performed on thin-layer chromatography (TLC) aluminum plates precoated with silica 60 F254 (20 × 20 cm) followed by detection of betulin, lupeol, and oleanolic acid carried out by derivatizing the plate with ceric ammonium sulfate followed by heating at 110°C for 5 min. For betulinic acid, the plate was dried and visualized after spraying with Liebermann-Burchard reagent. CAMAG TLC Scanner 4 equipped with winCATS software was used for densitometric scanning at 500-550 nm. The proposed technique was further validated in terms of linearity, precision, accuracy, and sensitivity as per the International Conference on Harmonisation (ICH) guidelines. A good linear relationship was obtained for the calibration plots with r² = 0.9994, 0.9995, 0.9969, and 0.9998 for betulin, lupeol, oleanolic acid, and betulinic acid, respectively. Accuracy of the method was checked by recovery study conducted at three different levels with the average recovery between 98.9% and 99.3% for all the four markers. [ABSTRACT FROM AUTHOR]

Seedling establishment is a crucial factor for spatial dynamics of treelines. However, safe sites for successful tree regeneration which is a basic prerequisite for a supposed treeline advance in response to climate warming have not been fully characterised, especially in the Himalayas. In this study, we aim at analysing safe sites of the tree species Abies spectabilis, Betula utilis and Rhododendron campanulatum, dominating the near-natural treeline ecotone in Rolwaling Himal, Nepal. We investigated microhabitat ground cover of established seedlings in rectangular plots along the treeline ecotone from subalpine forest stands via the krummholz belt to alpine dwarf shrub heaths (3800-4200 m). We examined protective elements that potentially ameliorate seedlings' growth conditions and quantified the distance of seedlings to the nearest protective element. Our results showed species-specific microhabitat preferences for seedling establishment. While A. spectabilis seedlings establish on ground that is covered in average by 70% with litter, B. utilis and R. campanulatum seedlings primarily emerge on bryophyte mats (mean site cover 80%). Microhabitat structure did not vary significantly in relation to different vegetation types encompassing the treeline ecotone. The majority of seedlings of all species grew in maximum 2 m distance to at least one potentially protective element. Geomorphic elements and deadwood were the most important shelters for seedling establishment. Our results emphasise the importance of safe sites for successful tree regeneration in harsh environments. As growth conditions in high mountain ecosystems may substantially alter under contemporary climate change, the necessity of safe sites may increase to buffer potential extremes. [ABSTRACT FROM AUTHOR]

Betula utilis is a major constituent of alpine treeline ecotones in the western and central Himalayan region. The objective of this study is to analyse for the first time the performance of different climatic predictors in modelling the potential distribution of B. utilis in the subalpine and alpine belts of the Himalayan region. Using Generalized Linear Models (GLM) we aim at examining climatic factors controlling the species distribution under current climate conditions. We evaluate the predictive ability of climate data derived from different statistical methods GLMs were created using least correlated bioclimatic variables derived from two different climate data sets: 1) interpolated climate data (i.e. WORLDCLIM; Hijmans et al., 2005), and 2) quasi-mechanistical statistical downscaling (i.e. CHELSA; Karger et al., 2016). Model accuracy was evaluated using threshold-independent (Area Under the Curve) and threshold-dependent (True Skill Statistics) measures. Although there were no significant differences between the models in AUC, we found highly significant differences (p ≤ 0.01) in TSS. We conclude that models based on variables of CHELSA climate data had higher predictive power, whereas models using WORLDCLIM climate data consistently overpredicted the potential suitable habitat for B. utilis . Although climatic variables of WORLDCLIM are widely used in modelling species distribution, our results suggest to treat them with caution when topographically complex regions like the Himalaya are in focus. Unmindful usage of climatic variables for environmental niche models potentially causes misleading projections. [ABSTRACT FROM AUTHOR]

Changes in the position of altitudinal treelines and timberlines are considered useful indicators of climatic changes on tree growth and forest dynamics. We sought to determine if recent warming is driving contrasting growth responses of Himalayan birch, at moist treeline (Lete Lekh) and semi-arid timberline (Chimang Lekh) sites in the Trans-Himalayan zone of central Nepal. We used dendrochronological techniques to measure tree ring width (TRW) and basal area increment (BAI) of birch trees from climatically contrasting but nearby sites. The TRW series were correlated with climate records from nearby meteorological stations, and BAI was compared between populations to explore growth trends over recent decades. We found contrasting precipitation trends between nearby sites such that the wet site (Lete) is getting warmer and wetter, and the dry site (Chimang) is getting warmer and drier in recent decades. The radial growth of birch in both moist and semi-arid sites are positively correlated to spring (March-May) rainfall, and negatively correlated to mean and maximum temperature for the same period. The growth climate analysis indicated that moisture availability in early growing season is crucial for birch growth at these locations. The BAI of birch is declining more rapidly at the dry timberline than at the moist treelines in the recent decades, indicating that climatic warming might negatively impact birch radial growth where warming interacts with increasing spring drought in the region. Our work highlights contrasting growth response of birch to climate change at moist and semi-arid forests indicating that local climatic variation must be accounted for when assessing and forecasting regional patterns of tree growth in topographically complex regions like Trans-Himalaya, in order to make accurate predictions of vegetation responses to climate change. [ABSTRACT FROM AUTHOR]

Objective: The present study investigated the comparative analysis of fatty acid and antioxidant activity from the bark of Betula utilis, collected from Kashmir and Sikkim coded as BUK and BUS respectively. Methods: Fatty acid constituents were analyzed by GCMS (gas chromatography mass spectroscopy) in BUK and BUS bark. B. utilis bark extracts of both the locations were phytochemically investigated and radical scavenging activity was evaluated by DPPH in all solvent fractions. Results: Phenolic content were found to be higher in methanolic extracts of BUK bark, 5.8 ± 0.1 mg/gm and flavonoid content were higher in the water extract of BUK bark, 6.16 ± 0.2 mg/gm. The radical scavenging activity was found to be higher methanolic, alcoholic and water extracts of BUK bark. The lowest IC50 value for radical scavenging activity of methanolic and water extracts of B. utilis bark collected from Kashmir were found 18.7 ± 1.1 and 18.2 ± 0.3 µg/mL, respectively. Thirteen fatty acids were identified in the sample BUK as well as BUS in which the major fatty acids were found-Palmitic acid, linoleic acid and oleic acid. BUK possess the highest amount of Palmitic acid (18.07%) in oily portion of the bark. Conclusion: The present study concluded that BUK and BUS extracts have shown significant antioxidant activity in comparison to standard but BUK possess potent radical scavenging activity over BUS, and higher amounts palmitic acid, linoleic acid and oleic acid was present in the extract, and may a play an important role in nutritional and pharmaceutical applications. [ABSTRACT FROM AUTHOR]

A rapid and reliable method was developed and validated for determining betulin and betulinic acid in bark inBetula utilisby high-resolution magic angle spinning1H nuclear magnetic resonance (HR-MAS NMR) spectroscopy. HR-MAS NMR spectroscopy clearly distinguished the resonances of betulin and betulinic acid in the bark of all accessions ofB. utilis. The concentrations of betulin and betulinic acid were calculated and added to the spectra. The determination of the targeted metabolites in chloroform extract of bark of each accession ofB. utiliswas performed by high-performance liquid chromatography (HPLC). Quantitatively, betulin was present at higher concentrations than betulinic acid in all accessions. The HR-MAS NMR and HPLC results showed that betulin and betulinic acid varied significantly among accessions ofB. utilis. Principal component analysis of the NMR and HPLC results provided classification into three metabolic groups in which the betulin concentration was high, moderate, or low. The results show that HR-MAS NMR is rapid for fingerprinting of betulin and betulinic acid in the bark ofB. utilis, while minimizing the drawbacks associated with solvent extraction. [ABSTRACT FROM PUBLISHER]

The phenological events, height class distribution, volume and biomass of Himalayan birchor bhojpatra (B. utilis D. Don) were monitored along the altitudinal gradient in distinct ecological settings at Sindh and Tangmarg forest divisions in western Himalayas, Kashmir. The observations recorded revealed high synchrony throughout the altitudinal gradients, especially for bud set, bud burst, peak flowering and seed maturation. All the phenological events began early at lower elevation as compared to higher elevation. The timing of phenophases along the altitude was governed by the timing of snow-melt which is usually responsible for early phenological changes in the northern alpine habitats. The height, volume and biomass showed a decreasing trend with increasing altitude at both the sites. Higher number of trees (116.71 trees/ha) with maximum height, volume (112.38 m3/ha) and biomass (57.31 tonnes/ha) were recorded at 3 000-3 200 m asl. The values for all these parameters decreased with increasing altitude from 3 200-3 400 and 3 400-3 600 m amsl, respectively. The short growing seasons, reduced air and soil temperature (an adiabatic effect), increased exposure to wind, lower availability of nutrients and increased exposure to frost are some of the common features of high altitude niches which greatly influences the growth of the existent vegetation.

Modelling ecological niches across vast distribution ranges in remote, high mountain regions like the Himalayas faces several data limitations, in particular nonavailability of species occurrence data and fine-scale environmental information of sufficiently high quality. Remotely sensed data provide key advantages such as frequent, complete, and long-term observations of land surface parameters with full spatial coverage. The objective of this study is to evaluate modelled climate data as well as remotely sensed data for modelling the ecological niche of Betula utilis in the subalpine and alpine belts of the Himalayan region covering the entire Himalayan arc. Using generalized linear models (GLM), we aim at testing factors controlling the species distribution under current climate conditions. We evaluate the additional predictive capacity of remotely sensed variables, namely remotely sensed topography and vegetation phenology data (phenological traits), as well as the capability to substitute bioclimatic variables from downscaled numerical models by remotely sensed annual land surface temperature parameters. The best performing model utilized bioclimatic variables, topography, and phenological traits, and explained over 69% of variance, while models exclusively based on remotely sensed data reached 65% of explained variance. In summary, models based on bioclimatic variables and topography combined with phenological traits led to a refined prediction of the current niche of B. utilis, whereas models using solely climate data consistently resulted in overpredictions. Our results suggest that remotely sensed phenological traits can be applied beneficially as supplements to improve model accuracy and to refine the prediction of the species niche. We conclude that the combination of remotely sensed land surface temperature parameters is promising, in particular in regions where sufficient fine-scale climate data are not available.

Traditional wound dressings have a limited capacity to absorb exudates, are permeable to microbes, and may adhere to wounds, which leads to secondary injuries. Hydrogels are promising alternative dressings to overcome the above challenges. In this study, we developed sodium alginate-based hydrogel films loaded with Betula utilis bark extract. These films were prepared via solvent-casting crosslinking method and evaluated for wound healing activity. Prepared films were 0.05-0.083 mm thick, flexible with folding endurance ranging from 197-203 folds, which indicates good physical properties. Optimized formulations exhibited successful loading of extract in the film matrix without any interaction as confirmed by FTIR. Maximum zone of inhibition against Gram-positive and Gram-negative bacteria was achieved by optimum formulation (B6), i.e., 19 mm and 9 mm, respectively, with > 90% scavenging activity. Furthermore, this optimum formulation (B6) was able to achieve 93% wound contraction in rats. Histograms of the optimized formulation treated group also revealed complete reepithelization of wounds. Conclusively, our extract-loaded hydrogel dressing successfully demonstrated its potential for cutaneous wound healing., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Ishfaq, Khan, Khalid and Asghar.)

Compounds having antimicrobial activity obtained from plant sources are useful because they are new sources against antibiotic resistance. The present study is based on the evaluation of antimicrobial activity of the essential oil of the fresh bark ofBetula utilisand to identify the chemical constituents responsible for antimicrobial potential, grown in high altitude of Himalaya, India. The chemical constituents of essential oil were identified by gas chromatography-mass spectrometry (GC-MS). The essential oil was evaluated for the antimicrobial potential against human pathogenic bacteria and fungi by using a micro-dilution assay. GC-MS analysis revealed that the major constituents of the essential oil were geranic acid (11.38 %), β-seleneol (10.98 %), β-linalool (10.91 %), terragon (10.61 %), β-sesquiphellendrene (8.02 %), champacol (6.33 %) and 1,8-cineol (5.49 %). Result showed thatB. utilisessential oil has a strong antimicrobial activity against the fungusCandida albicansand Gram (+) and Gram (-) human pathogenic bacteria (MIC: 60.5-240 µg/ml). [ABSTRACT FROM AUTHOR]

The unavailability of weather records from the orography dominated high Himalayas restricts our understanding in long term perspective. However, remote high-altitude regions of Himalaya silently testify the regional climate and can provide valuable insights of real climatic challenges in the absence of instrumental observatories. The tree-species over such high-altitude regions with negligible anthropogenic pressure have the potential to reveal the clear climate upheavals in long-term perspective. In the present study tree-ring samples of Himalayan birch from a high-altitude cold-arid region of Lahaul-Spiti, Himachal Pradesh were analysed and two ring-width chronologies were developed. The response function analyses showed direct relationship between the summer temperature and ring-width chronologies of Himalayan birch. Using the relationship we have reconstructed mean summer temperature (June-July) back to AD 1752 for the Lahaul-Spiti region of Himachal Pradesh. We have developed the first record of summer temperature from the Indian western Himalaya using tree-ring-width chronologies that have direct relationship with summer temperature. Further, our study in accordance with instrumental as well as other tree-ring based summer temperature records suggested that the high-altitude western Himalaya is not warming unprecedently during summers. However, slight warming pattern have been observed in the summer temperature in the later part of the reconstruction. The temperature reconstruction also reflects strong spatial correlation with gridded temperature for the western Himalaya. [ABSTRACT FROM AUTHOR]

Birch (Betula) trees and forests are found across much of the temperate and boreal zones of the Northern Hemisphere. Yet, despite being an ecologically significant genus, it is not well studied compared to other genera like Pinns, Picea, Larix, Juniperus, Quercus, or Fagus. In the Himalayas, Himalayan birch (Betula utilis) is a widespread broadleaf timberline species that survives in mountain rain shadows via access to water from snowmelt. Because precipitation in the Nepalese Himalayas decreases with increasing elevation, we hypothesized that the growth of birch at the upper timberlines between 3900 and 4150 m above sea level is primarily limited by moisture availability rather than by low temperature. To examine this assumption, a total of 292 increment cores from 211 birch trees at nine timberline sites were taken for dendroecological analysis. The synchronous occurrence of narrow rings and the high interseries correlations within and among sites evidenced a reliable cross-dating and a common climatic signal in the tree-ring width variations. From March to May, all nine treering- width site chronologies showed a strong positive response to total precipitation and a less-strong negative response to temperature. During the instrumental meteorological record (from 1960 to the present), years with a high percentage of locally missing rings coincided with dry and warm pre-monsoon seasons. Moreover, periods of below-average growth are in phase with well-known drought events all over monsoon Asia, showing additional evidence that Himalayan birch growth at the upper timberlines is persistently limited by moisture availability. Our study describes the rare case of a drought-induced alpine timberline that is comprised of a broadleaf tree species. [ABSTRACT FROM AUTHOR]

Tree rings of Birch (Betula utilis) growing along moraines around Bhojbasa, close to the snout of Gangotri glacier, Garhwal Himalaya have been analysed to assess relationships among tree growth/climate vis-à-vis glacial fluctuations. It has been noted that the growth of this tree has negative relationship with temperature of January, March and April, and direct relationship with precipitation of March, April and June, and temperature of February. Moreover, increased tree growth in recent years has also been recorded coinciding with the rapid retreat of Gangotri glacier. It could be hypothesized that the fast retreat of this glacier might be the cumulative effect of several climatic parameters which enhance tree growth, i.e. increased precipitation of March, April and June associated with increased winter temperature and low snowfall. [ABSTRACT FROM AUTHOR]

Himalayan Silver Fir (Abies spectabilis) and Himalayan Birch (Betula utilis) are tree species often found coexisting in sub-alpine forests of the Nepal Himalayas. To assess species-specific growth performances of these species, tree-ring samples were collected from the subalpine forest in the Dhorpatan Hunting Reserve, Nepal. Standard ring width chronologies of both species were correlated with climatic variables in both static and running windows. Differential and contrasting temporal responses of radial growth of these species to climate were found. Warmer and drier springs appeared to limit birch radial growth. Whereas radial growth of fir showed weakened climate sensitivity. Moving correlation analyses revealed divergent influences of spring climate on both fir and birch. Significant warming that occurred in the 1970s coincided with growth declines in birch and an increase in fir, as indicated by basal area increment. In summary, recent warming has been unfavorable for birch, and favorable to fir radial growth. [ABSTRACT FROM AUTHOR]

Litter decomposition plays a vital role in carbon and nutrient budget of forest ecosystems, but our understanding of this process for high altitude ecosystems, especially the timberline zone, is not very clear. We studied leaf litter decomposition of Betula utilis , which is the main timberline species of Western Himalaya. We placed 144 litterbags (each containing 10 g of oven dried litter) at three 'spatially well separated sites' in Oct 2014, to study the direction and magnitude of change in key variables associated with leaf litter decomposition and to test for generality of decomposition process across these spatially distant sites. The results revealed that initial nutrient concentration and lignin content of litter was significantly different for the sites. Further, magnitude of mass loss and decay rate was found to be greater for up to 34 weeks (19.03 ± 4.55% and 0.35 ± 0.06 yr−1 respectively), which reached 47.01 ± 1.98% and 0.17 ± 0.01 yr−1 respectively, after 4 years. N, P and K concentrations showed sharp decease for up to 34 weeks, after which N consistently increased with incubation time, whereas P and K concentrations were relatively stable. The lignin and cellulose contents decreased consistently with incubation time (from 12.29 ± 1.21% to 5.21 ± 0.50% and from 16.87 ± 1.01% to 8.25 ± 0.50% respectively). There were significant increases in C:N and lignin:N ratios for up to 34 weeks, followed by a continuous decrease thereafter. The change in various variables associated with litter decomposition was not consistent among the sites and the magnitude of change was greater during initial stages due to leaching of labile components. The increase in N and decreases in C:N and lignin:N ratios with incubation time might be due to microbial immobilization of N and are important for nutrient conservation in timberline ecosystems, as such changes are related to faster decomposition of recalcitrant fraction of litter, N mineralization and building of soil nutrient pool. • We assessed leaf litter decomposition at three distantly located sites in timberline zone of western Himalaya. • Betula utilis leaf litterbags were placed on forest floor and consequently sampled for up to 206 weeks (4 years). • Leaf litter decomposition rate in timberline forest was considerably slow and differed among sites. • Nitrogen content increased, whereas C:N and lignin:N ratios gradually decreased in later stages of decomposition. • Slow litter decomposition could be a key process in nutrient release and efficient nutrient recycling in timberline forests. [ABSTRACT FROM AUTHOR]

Biological processes in soil are driven and mediated by root and soil microbiome (microbial communities) and are sensitive to many environmental variations. Soil microbial communities compete for nutrient and space and form mutualistic associations with host plants. Rhizosphere, the connecting site of plant roots with soil, influences the soil health and plant-microbe interactions. Soil enzyme activity, which is considered to be the biological indicator of soil health, is significantly influenced by microbial functioning. Betula utilis D. Don is a dominant treeline forming species that has been extensively studied for the impact of climate-mediated variations in sub-alpine Himalayan region. However, the microbial ecology of this species remains almost unexplored. Therefore, the present study aims to assess the endophytic communities associated with B. utilis roots along with the status of enzymes, nutrients, and microbial communities in rhizosphere soil in two seasons from three sites in North-Western Himalaya. Activity of soil enzymes (acid and alkaline phosphatase, aryl sulfatase, β-glucosidase, urease and dehydrogenase) varied statistically with respect to seasons. Except dehydrogenase, the soil enzymes activity correlated with pH, organic carbon, and phosphorus content in soil. High dehydrogenase activity is attributed to high microbial activity in dormant season. B. utilis roots were found to be colonized with a range of microbial communities namely, mycorrhizae, dark septate endophytes (DSE), bacterial endophytes and unidentified nematode like structures (NLS). While, in general, DSE colonization was higher during growing season, mycorrhizae dominated the roots during dormant season. Significant differences were obtained only in mycorrhizal colonization with respect to seasons and sites. Further, significant correlations were obtained among soil nutrients, enzyme activity, and microbial counts during growing season. B. utilis roots exerted negative rhizosphere effect on microbial communities. The study will have implications in understanding plant-microbe interactions under sub-alpine Himalayan region. Microbial endophytes and soil enzymes with respect to B. utilis rhizosphere. Unlabelled Image • Assessment of physico-chemical properties and enzyme activity in B. utilis rhizosphere soil • Assessment of microbial colonization with respect to mycorrhizae and dark septate endophytes • Presence of B. utilis roots – nematode association under sub-alpine location • Occurrence of negative rhizosphere effect by B. utilis roots [ABSTRACT FROM AUTHOR]

Betula utilis (BU), an important medicinal plant that grows in high altitudes of the Himalayan region, has been utilized traditionally due to it's antibacterial, hepatoprotective, and anti-tumor properties. Here, we demonstrated the longevity and amyloid-β toxicity attenuating activity of B. utilis ethanolic extract (BUE) in Caenorhabditis elegans. Lifespan of the worms was observed under both the standard laboratory and stress (oxidative and thermal) conditions. Effect of BUE was also observed on the attenuation of age-dependent physiological parameters. Further, gene-specific mutants and green fluorescent protein (GFP)-tagged strains were used to investigate the molecular mechanism underlying the beneficial effects mediated by BUE supplementation. Our results showed that BUE (50 μg/ml) extended the mean lifespan of C. elegans by 35.99% and increased its survival under stress conditions. The BUE also reduced the levels of intracellular reactive oxygen species (ROS) by 22.47%. A delayed amyloid-β induced paralyses was observed in CL4176 transgenic worms. Interestingly, the BUE supplementation was also able to reduce the α-synuclein aggregation in NL5901 transgenic strain. Gene-specific mutant studies suggested that the BUE-mediated lifespan extension was dependent on daf-16 , hsf-1 , and skn-1 but not on sir-2.1 gene. Furthermore, transgenic reporter gene expression assay showed that BUE treatment enhanced the expression of stress-protective genes such as sod-3 and gst-4. Present findings suggested that ROS scavenging activity, together with multiple longevity mechanisms, were involved in BUE-mediated lifespan extension. Thus, BUE might have potential to increase the lifespan and to attenuate neuro-related disease progression. Unlabelled Image • Betula utilis ethanolic extract (BUE) extends the lifespan of Caenorhabditis elegans under normal and stress conditions. • BUE enhances stress resistance (oxidative, thermal): reduces lipofuscin in C. elegans. • BUE enhances the expression of both SOD-3 and GST-4 transgenic strains of C. elegans. • BUE enhances the neuroprotection in transgenic C. elegans. [ABSTRACT FROM AUTHOR]

A simple, rapid, sensitive, and reliable ultra-high-performance liquid chromatography-hybrid linear ion trap triple quadrupole mass spectrometry method was developed and validated for simultaneous determination of 10 bioactive compounds in stem bark of Betula utilis grown in high altitude of Himalaya, India. The objective of the study is to develop and validate ultra-high-performance liquid chromatography-hybrid linear ion trap triple quadrupole mass spectrometry for investigation of geographical variations of triterpenoids, phenolics, and flavonoids contents in stem bark of B. utilis . The validated method was successfully applied to investigate geographical variations of triterpenoids, phenolics, and flavonoids in stem bark of B. utilis . The contents of betulinic acid and oleanolic acid were detected higher among selected analytes. The present variation study reveals great importance for the application and overall assessment of B. utilis ., (© 2020 The Authors. Analytical Science Advances published by Wiley‐VCH GmbH.)

To better understand the response and adaptation of plants to altitudinal changes, four sites at the altitude of 2200 m, 2500 m, 3100 m and 3400 m on Balang Mountain were selected to test and calculate the eco-physiological parameters in leaves of Betula utilis, including photosynthetic nitrogen use efficiency (PNUE), CO 2 diffusion conductance (stomatal conductance g s and mesophyll conductance g m ) and nitrogen allocation in each component (fractions of leaf nitrogen allocated to Rubisco P R , to bioenergetics P B , to light-harvesting components P L , and to cell wall P CW ). Their changes with altitudinal variations and the relationships between leaf PNUE and the other parameters were analyzed. The results showed that PNUE, P R , and P B of the leaves were relatively higher at 2500 m and 3100 m. With the increases of altitude, g s and g m increased and P L decreased. The correlations between P R , P B and PNUE were significant, indicating that P R and P B were the main factors driving the changes in leaf PNUE in response to altitudinal variations. Besides, the fraction of leaf nitrogen allocated to photosynthetic apparatus (P P ) was relatively higher at 2500 m and 3100 m. With increasing altitude, P CW decreased and the fraction of leaf nitrogen allocated to the other components (P other ) increased, which suggested that B. utilis leaves tended to allocate more nitrogen to the other components instead of the photosynthetic apparatus and cell wall with the increasing altitude to well adapt environmental changes.

Modelling ecological niches across vast distribution ranges in remote, high mountain regions like the Himalayas faces several data limitations, in particular nonavailability of species occurrence data and fine-scale environmental information of sufficiently high quality. Remotely sensed data provide key advantages such as frequent, complete, and long-term observations of land surface parameters with full spatial coverage. The objective of this study is to evaluate modelled climate data as well as remotely sensed data for modelling the ecological niche of Betula utilis in the subalpine and alpine belts of the Himalayan region covering the entire Himalayan arc. Using generalized linear models (GLM), we aim at testing factors controlling the species distribution under current climate conditions. We evaluate the additional predictive capacity of remotely sensed variables, namely remotely sensed topography and vegetation phenology data (phenological traits), as well as the capability to substitute bioclimatic variables from downscaled numerical models by remotely sensed annual land surface temperature parameters. The best performing model utilized bioclimatic variables, topography, and phenological traits, and explained over 69% of variance, while models exclusively based on remotely sensed data reached 65% of explained variance. In summary, models based on bioclimatic variables and topography combined with phenological traits led to a refined prediction of the current niche of B. utilis, whereas models using solely climate data consistently resulted in overpredictions. Our results suggest that remotely sensed phenological traits can be applied beneficially as supplements to improve model accuracy and to refine the prediction of the species niche. We conclude that the combination of remotely sensed land surface temperature parameters is promising, in particular in regions where sufficient fine-scale climate data are not available. [ABSTRACT FROM AUTHOR]