Altitude Gradient Research Articles

GSI CTA evaluation of the vertebrobasilar artery in normal adults at high altitude.

Vascular geometry is influenced by several factors during its growth and development. Here, we compared the differences in vertebrobasilar geometry among residents of a plateau region at different altitudes and investigated the relationship between vascular geometry and altitude. Data of some adults in the plateau region who experienced vertigo and headache as the main symptoms but had no evident abnormalities found during imaging examination were collected. They were divided into three groups based on an altitude gradient: group A (1,800-2,500 masl), group B (2,500-3,500 masl), and group C (over 3,500 masl). They underwent head-neck energy-spectrum computed tomography angiography with a gemstone spectral imaging scanning protocol. The following indices were observed: (1) vertebrobasilar geometric configurations (walking, tuning fork, lambda, and no confluence), (2) vertebral artery (VA) hypoplasia, (3) the bending number of bilateral VA intracranial segment, (4) length and tortuosity of the basilar artery (BA), and (5) anteroposterior (AP)-mid-BA angle, BA-VA angle, lateral-mid-BA angle, and VA-VA angle. Of the 222 subjects, 84 of them were included in group A, 76 in group B, and 62 in group C. The number of participants in walking, tuning fork, lambda, and no confluence geometries was 93, 71, 50, and 8, respectively. As altitude increased, the tortuosity of the BA also increased (1.05 ± 0.06 vs. 1.06 ± 0.08 vs. 1.10 ± 0.13, P = 0.005), as did the lateral-mid-BA angle (23.18° ± 9.53° vs. 26.05° ± 10.10° vs. 31.07° ± 15.12°, P = 0.007) and the BA-VA angle (32.98° ± 17.85° vs. 34.51° ± 17.96° vs. 41.51° ± 19.22°, P = 0.024). There was a relatively weak positive correlation between the altitude and the tortuosity of the BA (rs = 0.190, P = 0.005), the lateral-mid-BA angle (rs = 0.201, P = 0.003), and the BA-VA angle (rs = 0.183, P = 0.006) which showed a significant difference. Compared with groups A and B, there were more multibending groups and fewer oligo-bending groups in group C (P < 0.001). There was no difference found in the vertebral artery hypoplasia, actual length of the BA, VA-VA angle, and AP-mid-BA angle among the three groups. As the altitude increased, the tortuosity of the BA and the sagittal angle of the vertebrobasilar arterial system also increased. The increase in altitude can lead to changes in vertebrobasilar geometry.

Soil bulk density and altitude are primary drivers of soil water content and soil temperature in the Three Rivers Headwaters Region, China

AbstractSoil water content (SWC) and soil temperature (ST) are important indicators of environmental change in permafrost regions. In this study, we conducted soil sampling at 89 locations in the Three Rivers Headwaters Region (TRHR) to investigate the individual and synergistic effects of environmental factors on SWC and ST. We used multivariable regression and random forest modelling to analyse the data. The results show that SWC and ST were higher in the southeast TRHR than in the northwest and higher in surface layers than deeper soil layers. The most important factors affecting SWC in the 0–20 cm and 20–40 cm soil layers were soil bulk density and precipitation, while bulk density was the most important factor in the 40–60 cm layer, and soil bulk density and steppe vegetation were the most important factors in the 60–80 cm layer. For ST, altitude, temperature and slope gradient were the drivers in the 0–20 cm surface layer, while altitude and temperature were the most critical drivers in the 20–40 cm, 40–60 cm and 60–80 cm layers. Overall, bulk density and altitude were the key environmental factors influencing SWC and ST values, respectively. The outcomes of this study provide valuable insights into the environmental factors that impact the SWC and ST in permafrost regions, which can guide decision‐making processes for sustainable soil management in the context of climate change.

Population structure analysis to explore genetic diversity and geographical distribution characteristics of wild tea plant in Guizhou Plateau

BackgroundTea, the second largest consumer beverage in the world after water, is widely cultivated in tropical and subtropical areas. However, the effect of environmental factors on the distribution of wild tea plants is unclear.ResultsA total of 159 wild tea plants were collected from different altitudes and geological types of the Guizhou Plateau. Using the genotyping-by-sequencing method, 98,241 high-quality single nucleotide polymorphisms were identified. Genetic diversity, population structure analysis, principal component analysis, phylogenetic analysis, and linkage disequilibrium were performed. The genetic diversity of the wild tea plant population from the Silicate Rock Classes of Camellia gymnogyna was higher than that from the Carbonate Rock Classes of Camellia tachangensis. In addition, the genetic diversity of wild tea plants from the second altitude gradient was significantly higher than that of wild tea plants from the third and first altitude gradients. Two inferred pure groups (GP01 and GP02) and one inferred admixture group (GP03) were identified by population structure analysis and were verified by principal component and phylogenetic analyses. The highest differentiation coefficients were determined for GP01 vs. GP02, while the lowest differentiation coefficients were determined for GP01 vs. GP03.ConclusionsThis study revealed the genetic diversity and geographical distribution characteristics of wild tea plants in the Guizhou Plateau. There are significant differences in genetic diversity and evolutionary direction between Camellia tachangensis with Carbonate Rock Classes at the first altitude gradient and Camellia gymnogyna with Silicate Rock Classes at the third altitude gradient. Geological environment, soil mineral element content, soil pH, and altitude markedly contributed to the genetic differentiation between Camellia tachangensis and Camellia gymnogyna.

Modulation of Anthocyanin Biosynthesis-Related Genes during the Ripening of Olea europaea L. cvs Carolea and Tondina Drupes in Relation to Environmental Factors.

Anthocyanins protect plants against various biotic and abiotic stresses, and anthocyanin-rich foods exert benefits on human health due to their antioxidant activity. Nevertheless, little information is available on the influence of genetic and environmental factors on the anthocyanin content in olive fruits. Based on this consideration, the total anthocyanin content, the genes involved in anthocyanin biosynthesis, and three putative R2R3-MYB transcription factors were evaluated at different ripening stages in the drupes of the Carolea and Tondina cultivars, sampled at different altitudes in the Calabria region, Italy. During drupe ripening, the total anthocyanin content and the transcript levels of analyzed genes gradually increased. In line with the anthocyanin content, a different level of expression of anthocyanin structural genes was observed in 'Carolea' compared to 'Tondina', and in relation to the cultivation area. Furthermore, we identified Oeu050989.1 as a putative R2R3-MYB involved in the regulation of anthocyanin structural genes correlated with the environmental temperature change response. We conclude that anthocyanin accumulation is strongly regulated by development, genotype, and also by environmental factors such as temperature, associated with the altitude gradient. The obtained results contribute to reducing the current information gap regarding the molecular mechanisms on anthocyanin biosynthesis regulation related to the environmental conditions in Olea europaea.

Characteristics, Drivers, and Development Modes of Rural Space Commercialization under Different Altitude Gradients: The Case of the Mountain City of Chongqing

The spatial commercialization of rural areas is essential to achieve rural reconstruction and promote overall rural rejuvenation. Through the use of a land use transfer matrix and kernel density, this study uncovers the pattern characteristics, driving forces, and development patterns of rural spatial commodification at various altitudes, providing a scientific reference for rural spatial usage at various altitudes. The main conclusions of this study are as follows: (1) rural spatial commercialization is the result of land use transformation, and the differences in rural spatial commercialization development patterns lead to different characteristics in the local land use changes; (2) the implementation of urbanization, industrialization, and rural revitalization strategies has promoted the development of rural spatial commercialization to some extent; (3) There are significant differences in the characteristics of the land use change and the development pattern of rural space commercialization at various altitudes. The areas below 500 m are mainly for recreational projects that have a repeatable consumption and that are distributed in a concentrated and continuous manner. For such areas, the agglomeration effect should be taken full advantage of, and thus they should be developed in groups. The areas between 500 and 1000 m serve mainly the surrounding residents; the mode is based on the leisure and recreational projects with a block-shaped spatial distribution. In such areas, branded rural spaces with special features should be created. The areas above 1000 m are used primarily to construct tourist attractions and are dispersed in a point pattern. In such areas, the transportation conditions should be improved and the rural resources revitalized by designing reasonable travel routes.

Vegetation restoration thresholds under different vegetation types and altitude gradients in the Sichuan-Yunnan ecological shelter, China

Determining the threshold for the response of ecosystem services (ESs) to vegetation change is critical for ecological restoration, and once the threshold is exceeded, ESs may be inhibited. Vegetation type and altitude are important factors affecting ESs. However, the nonlinear effects of vegetation change on ESs and their threshold under different vegetation types and altitude gradients are not clear. This study selected the Sichuan-Yunnan ecological shelter as the study area. Four ESs (water yield (WY), carbon storage (CS), soil conservation (SC), and water purification (WP)) were quantified by using the Integrated Valuation of Ecosystem Services and Trade-offs model. The differences in ESs among different vegetation types were identified. Variance analysis was used to explore the spatial differences in ESs under different altitude gradients. The inflection point of the promoting effect of vegetation cover on ESs was taken as the threshold, and elastic analysis was used to determine the impact threshold of fractional vegetation cover (FVC) on ESs. The threshold represents the inflection point at which vegetation cover promotes ESs. The results showed that the CS, SC, and WP of the natural forest were higher than those of the plantation, while the WY was lower than that of the plantation. WY, CS, and SC remained higher in the high-altitude regions, while nitrogen export was higher in the low-altitude regions. FVC was positively correlated with nitrogen export in the low-altitude regions and negatively correlated with WY in the high-altitude regions. FVC had a promoting effect on ESs, and the promoting effect was weakened beyond the threshold. The thresholds of FVC promoting ESs were 0.86, 0.79, 0.85, and 0.83 in natural forest, shrub, plantation, and grassland, respectively. The threshold of FVC promoting ESs in low-altitude regions was larger than that in high-altitude regions. This study can provide a theoretical basis for large-scale ecological management and moderate restoration.

Effects of Landscape Context on Bird Community in the Subtropical Evergreen Broad-Leaved Forest of Wuyishan National Park.

Landscape context can reflect the habitat structure and play an important role in bird species occurrences and abundance. For local biodiversity conservation and restoration, we examined the effects of landscape context on bird communities at different altitude gradients. Our study was conducted in four altitude gradients (<300 m, 300-599 m, 600-899 m, 900-1200 m) of subtropical evergreen broad-leaved forest in Wuyishan National Park, China. The bird survey was carried out in 115 transects in spring, summer, autumn and winter. We examined the effects of altitude, season and landscape context. The result showed that (1) species richness and abundance at <300 m altitude were highest among the four altitude gradients, and they showed more significant differences than those at other altitude gradients; (2) the species richness of birds was associated with altitude, season and landscape context, as the season is more significant than other explanatory variables; (3) at the landscape level, habitat configuration is more important. The average canopy height and contagion index positively correlated with the species richness and abundance of birds at all four altitude gradients. In particular, the average canopy height is significant at 300-599 m and 600-899 m altitude gradients. The study results can provide a theoretical basis and guidance for future national park conservation and management and ecological restoration in the subtropical evergreen broad-leaved forest regions.

Altitudinal Gradients Modify the Ecological Stoichiometry and Enzyme Activities of Soil in a Natural Secondary Quercus spp. Forest of the Dabie Mountains

Understanding the vertical distribution and driving mechanisms behind soil carbon (C), nitrogen (N), and phosphorus (P) contents and enzyme activities along elevation gradients is of great significance for the healthy and sustainable management of forest ecosystems. For this study, the 0–20 cm soil-layer samples of different natural Quercus spp. secondary forests from eight altitude gradients (ranging from 250 to 950 m) were investigated to quantify their physicochemical properties, ecological stoichiometry characteristics, and enzyme activities. The results indicated that the soil nutrient content of natural secondary Quercus spp. forests in the Dabie Mountains was low, with average soil organic carbon (SOC) and total phosphorus (TP) contents of 19.86 ± 3.56 g·kg−1 and 0.68 ± 0.10 g·kg−1, respectively, which were 19.14% and 12.82% lower, respectively, than the Chinese average. In terms of vertical spatial distribution, the SOC, total nitrogen (TN), and TP contents of the soil at high altitudes (≥750 m) were greater than those at middle- and low-altitude areas and reached the maximum value at or near the top of the mountain (850–950 m). The stoichiometric attributes of the soil ecosystem fluctuated with the higher altitudes in vertical space; however, the fluctuation range was not significant. The C:N, N:P, and C:P ratios reached their maximum values at altitudes of 250, 750, and 850 m, respectively. However, the overall average value remained generally lower than the national average; thus, in forest management, attention should be paid to the supplementation of the soil with C and P. The activities of soil sucrase, urease, acid phosphatase, and catalase were interconnected across the overall space, and increased with altitude. The SOC, TP, and pH were the main factors that influenced the changes in soil enzyme activities.

Patterns and driving factors of ecological stoichiometry in system of deadwood and soil in mountains forest ecosystem

The aim of our research was to identify the factors that most strongly determine the C, N and P cycles in the deadwood—soil system in mountains forest ecosystems. We assumed that the climatic conditions resulting from the location in the altitude gradient and rate of deadwood decomposition most strongly determine the C/N/P stoichiometry. A climosequence approach comprising north (N) and south (S) exposure along the altitudinal gradient (600, 800, 1000 and 1200 m a.s.l.) was set up. Spruce logs at different decomposition stages (III, IV and V) were selected for the analysis in Babiogórski National Park (southern Poland). We calculated the C/N/P stoichiometry for deadwood and soil samples to reflect the nutrient availability. Our research indicates a very strong influence of the location conditions in the altitude gradient on the C/N/P stoichiometry. The GLM analysis confirmed the importance of high elevation in shaping the C, N and P content. A strong correlation was confirmed between P content, N content and C/N ratio. A higher C/N/P ratio was found in deadwood compared to soil, regardless of location. Decaying wood is an important source of N and P and the degree of decomposition made a significant contribution to explaining the variability of C, N and P content. The obtained results indicate the need to leave deadwood in forest ecosystems in order to improve biogeochemical cycles. Deadwood, by having a beneficial effect on many components of the forest ecosystem, will improve its biodiversity and, consequently, its stability.

Influence of natural conditions of southern Dagestan on formation of food substances in fruits of Golden Delises apples

The results of studying the amino acid composition, macroand microelements, vitamins and other food substances in Golden Delicious apples grown in terroirs located at various altitudes above sea level in the south of Dagestan are presented in order to determine cultivation sites with natural conditions contributing to the greatest accumulation of these valuable components in fruits. The elemental composition of apples was studied using flame and atomic absorption photometry, mass concentrations of amino acids by HPLC methods, the content of sugars, titrated acids, pectins and vitamin C – titrimetrically, phenols and vitamin P colorimetrically. It was found that natural factors of the fruit zone located on the plain cause a high concentration of sugars in Golden Delicious apples – 11,3 %, soluble dry substances – 14,9 % and minerals: potassium (135.5 mg%), calcium (19.0 mg%), sodium (25.6 mg%), magnesium (12.6 mg%) and iodine (2.4 μg%), and the climatic conditions of the foothills are favorable for the synthesis of titrated acids (0,51%), vitamins C (6,8 mg %) and P (63,1 mg %), phenolic (362,1 mg %) and pectin substances (0,83 %), as well as iron, zinc and copper. The difference in the formation of minerals in apples, depending on natural conditions and the altitude gradient of the place of growth, was: for potassium – 7,2; sodium – 8,2; calcium – 9,5; magnesium – 9,4; iron – 10,9; copper – 10,2; zinc – 9,3, iodine – 8,3 %. The total amount of amino acids in apples, depending on the culture site, ranged from 683,2 to 696,9 mg/dm3. In fruits from the foothills, the total mass concentrations of replaceable and essential amino acids were 1,3 and 5,9% higher, respectively, than in apples grown on the plain. The results of the study can be taken into account in the rational use of agroecological resources of fruit zones that differ in soil-climatic conditions and altitude gradient, as well as to reveal the biological potential of the Golden Delicious apple variety.

Effects of Armillaria species on growth and quantity of active medicinal components of G. elata BL. f. elata tubers along an altitude gradient: Evidence from empirical experiments

Effects of Armillaria species on growth and quantity of active medicinal components of G. elata BL. f. elata tubers along an altitude gradient: Evidence from empirical experiments

Dendroclimatic response of Pinus tabuliformis Carr. along an altitudinal gradient in the warm temperate region of China.

Global climate change can affect the sensitivity of tree radial growth to climate factors, but the specific responses of tree radial growth to microclimate along the altitudinal gradient in the long term are still unclear. In this study, the tree-ring width chronologies of Pinus tabuliformis Carr. in Shanxi Province of China were studied at three altitude gradients (1200-1300m (low altitude), 1300-1400m (medium altitude) and 1400-1500m (high altitude)) during 1958-2017. The results showed that (1) the climate background could be divided into two periods based on the Mann-Kendall test analysis: 1958-1996 was a stable period (mean annual temperature (MAT)=10.25°C, mean annual precipitation (MAP)=614.39 mm), and 1997-2017 was a rapid change period (MAT=10.91°C, MAP=564.70 mm), indicating a warming and drying trend in the study region. (2) The radial growth of P. tabuliformis at different altitudes showed inconsistent variation patterns. The tree radial growth at low and medium altitudes (CV=27.01% for low altitude and CV=24.69% for medium altitude) showed larger variation amplitudes during the rapid change period than that in the stable period (CV=12.40% for low altitude and CV=18.42% for medium altitude). In contrast to the increasing trend, the tree radial growth rates at the high altitude showed a decreasing trend across years. (3) In the stable period, the radial growth of P. tabuliformis at the low altitude showed a significantly negative response to temperature and a positive response to precipitation in May and June. The tree radial growth at the medium altitude was positively related to precipitation in June and minimum temperature in February. The tree growth at the high altitude was mainly positively correlated with the temperature in May and August. In the rapid change period, the radial growth of P. tabuliformis at the low altitude was affected by more meteorological factors than that in the stable period. Medium-altitude trees were positively influenced by precipitation in June and minimum temperature in January, whereas high-altitude trees responded positively to wind speed in February. (4) Along altitudinal gradients, tree radial growth was more related to temperature than precipitation in the stable period. The tree radial growth at the high altitude during the rapid change period was only affected by wind speed in February, whereas the tree radial growth at low and medium altitudes was mainly affected by temperature to a similar extent during the two periods. The study indicated that tree growth-climate response models could help deeply understand the impact of climate change on tree growth adaptation and would be beneficial for developing sustainable management policies for forest ecosystems in the transition zone from warm-temperate to subtropical climates.

Stoichiometry Characteristics of C, N, and P of Soil Profiles along an Altitude Gradient in Luofu Mountain, Guangdong

Stoichiometry Characteristics of C, N, and P of Soil Profiles along an Altitude Gradient in Luofu Mountain, Guangdong

Vertical distribution differences of the understory herbs and their driving factors on shady and sunny slopes in high altitude mountainous areas

The vertical distribution understanding of undergrowth herbaceous plants in high altitude mountain areas is of great significance to reveal the environmental gradient change law of plant diversity. However, the species composition of herbaceous plants at different altitude gradients and the relationship between diversity and environmental factors is still vague. This study takes the Sejila Mountain in southeast Tibet at an altitude of 2,000–3,300 m as the study area to analyze the vertical distribution differences of the understory herbs and their driving factors on shady and sunny slopes. The results showed that: (1) The number of families, genera and species of herbaceous plants on sunny slope is greater than that on shady slope. Asteraceae on shady and sunny slopes has the largest number of species; (2) The α diversity index of the herbs on shady slope shows a U-shaped trend. The Cody heterogeneity index (βC) is negatively correlated with the β diversity index. The herb richness index (R) on sunny slope is unimodal. The β diversity index displays the same as that of shady slope; (3) Different environmental factors have different effects on herb diversity. The correlation between environmental factors and diversity indicators indicates that there is a certain degree of clustering among samples. The environmental factors of shady slope and sunny slope are separated; and (4) The difference of water and heat conditions caused by altitude and slope aspect is an important driving factor for the diversity of herbage species, followed by soil clay content, silt content and slope gradient. This study will help to understand the species diversity and ecosystem characteristics of the region, and provide a reference for the study of plant community structure and function and rational utilization of understory plant resources in high-altitude mountain areas.

Diversity, distribution, and conservation of the Trichoptera and their habitats in north‐eastern Algeria

Abstract Community patterns are generated by multiple processes and constraints generated at different spatial and temporal scales. A large‐scale study was carried out on the Trichoptera of four Algerian regions with contrasting climates, vegetation cover, and human pressures. Overall, 22 identified taxa were recorded, including nine families and 14 genera. The genus Hydropsyche was represented by eight species, with Hydropsyche maroccana and Hydropsyche lobata being the most abundant species. With one exception, localities in the subhumid Collo and the high‐altitude Batna were the most species rich, whereas localities in the semi‐arid Oum el Bouaghi were the most species poor. Nonmetric multidimensional scaling (NMDS) separated the caddisflies recorded into four assemblages organized by a set of constraining environmental factors (land use, altitude, water depth, helophyte cover, and flow velocity gradients) acting at different scales. As inadequate knowledge of insect biodiversity is a major limitation to their conservation, this article discusses how these results might help predict caddisfly communities in adjacent regions and enhance conservation efforts.

Revealing the main factors affecting global forest change at distinct altitude gradients

Anthropogenic activities and climate change play crucial roles in the productivity and sustainability of global forests. Although the impacts of anthropogenic activities and climate change on forests in specific regions have been reported in previous studies, their impact on the global forests along the elevation gradient remains poorly understood. Thus, here, we aimed to investigate anthropogenic activities and climate change effects on global forests by focusing on the drivers on the altitude gradient. To this end, we used spaceborne remote sensing and statistical methods to elucidate the forest areas experiencing significant change and the main factors governing the changes. Our analysis demonstrated that: (1) With respect to the altitude distribution of forest greening/browning, the higher the altitude is, the smaller is the indicated area of forest, and the smaller is the area of forest, the more significant is the greening/browning. In addition, although the area with significant forest greening was generally larger than that of browning, this trend was not consistent through the months or altitude gradients. (2) Except for the high-altitude areas in August and September (>2400 m), the impact of human global forest governance activities on the greening of forests in most altitude areas and months was greater than that of climate change. However, at most altitudinal gradients, the area of forest with significant browning caused by anthropogenic activities was smaller than that caused by climate change. This was because the scope of the impact of climate change was usually larger than that of anthropogenic activities. (3) Although temperature was the main factor responsible for significant monthly forest greening, it was not always the most crucial factor at specific altitudes. Temperature and sunshine duration were the most influential factors causing significant forest greening for the most months of the year in five terrestrial ecoregions. Sunshine duration, as the largest influencing factor causing significant forest browning, had the longest monthly impact in five terrestrial ecoregions. The findings of our study can provide a reference for better global forest management and sustainability.

Leaf morphology, functional trait and altitude response in perennial vetch (Vicia unijuga A. Braun), alfalfa (Medicago sativa L.) and sainfoin (Onobrychis viciifolia Scop.)

Species have plasticity across altitude gradients in leaf morphology and function, and their response to high altitude conditions was mainly reflected in leaf cell metabolism and gas exchange. Leaf morphological and functional adaptation to altitude has received research attention in recent years, but there are no studies for forage legumes. Here we report differences in 39 leaf morphology and functional traits of three leguminous forages (alfalfa, sainfoin and perennial vetch) at three sites in Gansu Province, China, ranging from 1768 to 3074m altitude to provide information for potential use in breeding programmes. With increasing altitude, plant water status increased, reflecting increase in soil water content and decreased average temperature, which lead to leaf intercellular CO2 concentration. Stomatal conductance and evapotranspiration increased significantly but water-use efficiency decreased. At high altitude, ΦPSII decreased but non-photochemical quenching and chlorophyll a:b ratio increased while spongy mesophyll tissue and leaf thickness increased. These changes may be due to UV or low-temperature damage of leaf protein and metabolic cost of plant protection or defence responses. Contrary to many other studies, leaf mass per area decreased significantly at higher altitude. This was consistent with predictions under the worldwide leaf economic spectrum on the basis that soil nutrients increased with increasing altitude. The key species differences were more irregularly shaped epidermal cells and larger stomatal size in perennial vetch compared to alfalfa or sainfoin that enhanced gas exchange and photosynthesis by generating mechanical force, increasing guard cell turgor, and promoting stomatal operation. The lower adaxial stomatal density also enhanced water-use efficiency. These adaptations might confer perennial vetch an advantage in environments with extreme diurnal temperature fluctuation or in frigid conditions.

In plateaus, land cover replaced climate as the vital environmental factor on the spatial composition of bumblebees with the altitude rising

Abstract Bumblebees show a series of advantages over other pollinating insects in offering pollination services for both the ecosystem and agricultural production, especially in high‐altitude areas. With climate warming, their diversity at high altitudes will be threatened. Therefore, more attention should be paid to the management of bumblebee resources at high altitudes to prevent their decline here. Discovering drivers responsible for the spatial variation of biodiversity is a benefit for developing appropriate management. Here, based on the bumblebee diversity on three plateau areas with an altitude gradient, the roles of different environmental factors, the climate, land cover, topography, habitat heterogeneity and soil, in the bumblebee composition were assessed by generalised dissimilarity modelling. And the relative importance of variables was evaluated by the impact on the magnitude of total biological change and the per cent change in deviance explained by models. According to the results, in the low‐altitude area, the climate played a vital role and the most important variable was the climate variable. Then, with the altitude rising, the effect of land cover continually increased. In the medium‐altitude area, the effects of different factors were detected to be similar, and the most important variables were a climate variable and a land cover variable. In the high‐altitude area, land cover finally replaced the climate as the most important factor, and one land cover variable was assessed as the most important variable. Our study revealed that the relative importance of different environmental factors on the biodiversity of bumblebees can differ as the altitude rises.

C:N:P stoichiometric characteristics of mosses in Picea crassifolia forest in Helan Mountains, Ningxia, China.

To explore the stoichiometric characteristics of C, N and P and adaptive mechanism of mosses in mountain forest ecosystems, we set up 15 plots along the altitude gradient in Picea crassifolia forest in Helan Mountains, Ningxia. We analyzed the C:N:P stoichiometry of moss aboveground tissues and its relationship with environmental factors. The results showed the mean values of C, N and P concentration in moss aboveground tissues were 336.67, 20.31 and 0.66 mg·g-1, respectively. The mean value of aboveground tissue N:P was 33.4, indicating that the growth of mosses was limited by P. The C concentration in the aboveground tissues of mosses was positively correlated with soil total nitrogen concentration and negatively correlated with soil total phosphorus concentration. The N concentration in aboveground tissues of mosses was significantly negatively correlated with soil organic carbon and soil total nitrogen concentrations. Results of redundancy analysis showed that the interpretation rate of environmental factors on the stoichiometry was 48.5%, with canopy closure, soil total nitrogen and soil total phosphorus as the main factors. Canopy closure was the main environmental factor affecting the growth of mosses in P. crassifolia forest in Helan Mountains. High canopy closure facilitated the growth of mosses.

Recent warming and its risk assessment on ecological and societal implications in Nepal

A predominantly mountainous country Nepal has a complex climatic pattern that varies from tropical in the south (Terai region) to arctic in the north (Himalayas). The gradual rise in temperature in the mountainous region has attracted great interest among the scientific community in general over recent years. However, recent warming in Nepal’s east-west and south-north temperature gradients and its implications for ecology and society based on facts and figures are still lacking. In this context, temperature data (1970–2016) of 76 meteorological stations from the Terai region to the Mountains were used in this study to analyze the annual and seasonal warming trends in the different physiographic regions of Nepal. We performed a hybrid analytical approach i.e. integrated statistical and theoretical tools to detect the warming trend and its ecological and societal implications across the country. The Eastern part of the country was found to be more warming than the Central and Western parts, showing an increased climatic sensitivity across the Khumbu (Mt. Everest region). The increasing trends of temperature have been found in all physiographic regions along an altitude gradient, i.e. Terai, Siwaliks, Lower Hills, and Upper Hills observed 0.15, 0.26, 0.68, and 0.57 °C per decade, respectively. Higher warming trend in Lower Hills than the Upper Hills showed that higher elevations experienced lesser degrees of warming trends than the lower elevations in the mountainous regions. Further, a higher warming trend was observed in the winter season than the other seasons in all regions except for Terai. Based on the warming trends in different physiographic regions, we also found a similar pattern of ecological impacts, where a higher warming region also experienced higher ecological impacts such as changes in water resources, phenology, etc. Lower Hills, Upper Hills, and Mountains experienced higher adverse impacts than the Terai and Siwaliks in the current global warming scenarios.