Cold Alpine Research Articles

Geographical differences in maternal basking behaviour and offspring growth rate in a climatically widespread viviparous reptile

In reptiles, the thermal environment during embryonic development affects offspring phenotypic traits and potentially offspring fitness. In viviparous species, mothers can potentially manipulate the embryonic thermal environment through their basking behaviour and, thus, may be able to manipulate offspring phenotype and increase offspring fitness. One way in which mothers can maximise offspring phenotype (and thus potentially affect offspring fitness) is by fine-tuning their basking behaviour to the environment in order to buffer the embryo from deleterious developmental temperatures. In widespread species, it is unclear whether populations that have evolved under different climatic conditions will exhibit different maternal behaviours and/or thermal effects on offspring phenotype. To test this, we provided extended or reduced basking opportunity to gravid spotted skinks (Niveoscincus ocellatus) and their offspring from two populations at the climatic extremes of the species' distribution. Gravid females fine-tuned their basking behaviour to the basking opportunity, which allowed them to buffer their embryos from potentially negative thermal effects. This fine-tuning of female basking behaviour appears to have led to the expression of geographical differences in basking behaviour, with females from the cold alpine regions being more opportunistic in their basking behaviour than females from the warmer regions. However, those differences in maternal behaviour did not preclude the evolution of geographic differences in thermal effects: offspring growth varied between populations, potentially suggesting local adaptation to basking conditions. Our results demonstrate that maternal effects and phenotypic plasticity can play a significant role in allowing species to cope in changing environmental conditions, which is particularly relevant in the context of climate change.

藏北高寒草甸植物群落对土壤线虫群落功能结构的影响

2011年5-11月,对西藏北部高寒草甸3种典型植物群落下0-30cm范围内不同深度土层的土壤线虫群落进行调查,采用浅盆法分离线虫,土壤性质指标,如pH、含水量、电导率分别采用电位法、烘干法、电导率仪法进行测定,应用营养类群组成、c-p类群结构及营养结构特征指数,以及营养类群、c-p类群与土壤性质之间的关系等特征值分析高寒环境下土壤线虫群落的功能结构特征,以了解高寒环境下植被对土壤线虫群落功能结构的影响。调查共分离得到33038条土壤线虫,隶属于2纲6目51科93属;线虫个体密度平均为847条/100g干土;表聚性明显。研究结果表明,高寒草甸不同植物群落的土壤线虫群落营养类群组成及分布特征均存在一定差异,植食性线虫和食细菌性线虫是调查区域的主要营养类群,不同植物群落间植食性线虫和杂食/捕食性线虫的相对多度差异明显。c-p类群组成结构特征结果表明:3种植物群落的土壤线虫cp2类群均为优势类群,生活策略以r-对策为主;高山嵩草植物群落土壤中的线虫食物资源在3种植物群落中最丰富;藏北嵩草群落土壤线虫数量低的可能原因是线虫食物资源的减少限制了cp1、cp2类群的增殖。<em>PPI</em>值表明:委陵菜群落受扰动的影响程度大于其余两种植被类型,而<em>MI、PPI/MI</em>值及cp5类群数量的结果则表明:委陵菜群落的稳定性较高,受到的干扰在3种植物群落中最少。<em>F/B</em>及<em>NCR</em>值均说明了3种植物群落的土壤有机质分解均主要依靠细菌分解途径。相关性分析结果表明:杂食/捕食性线虫在枯草期明显受到土壤含水量的影响;食真菌性线虫与土壤pH之间的关系密切,在盛长期则明显受到土壤电导率的影响;食细菌性线虫仅在返青期与pH有相关性。不同植物群落下土壤线虫群落功能结构特征的分异显示出线虫指示环境因子影响土壤生态系统的潜力。;Northern Tibet lies within the remote regions of the Tibetan Plateau, features a dry and cold climate, and forms a broad strip of land sensitive to global warming. Meadows are the largest and most important ecosystems in northern Tibet. Alpine meadows are extensively distributed in the northern Tibetan Plateau and are typical features of the region. The alpine meadow soil type in the study area is seasonally frozen. We chose three representative plant communities as samples areas, which we identified as <em>Potentilla</em> spp., <em>Kobresia pygmaea</em>, and <em>Kobresia littledalei</em> based on the dominant species of each community to study soil nematode communities. The plots are situated at Dejixiangdaga village at N31°31'38″-31°32'02″, E92°04'03″-92°04'16″ in Naqu County in the Naqu region of the Tibet Autonomous Region, China. Soil nematode communities in the upper 0-30 cm soil were investigated in three typical plant communities in alpine meadows of northern Tibet from May to November 2011. The soil nematodes were collected using the shallow basin method. The following soil chemical properties were tested: pH, potentiometry, soil water content (oven drying method), and electricity conductivity. The trophic composition, c-p group structure and functional structure index, as well as the characteristic values between trophic groups, c-p groups and soil properties, were analyzed to understand the effect of cold alpine conditions on soil nematode functional diversity. A total of 33038 nematodes, which were classified to nematode phylum, 2 classes, 6 orders, 51 families and 93 genera, were collected during the surveys. Average individual density was 847 nematodes per 100g dry soil. The results were mostly within the scope of previous reports, and nematodes obviously appeared to aggregate in the upper soil layers. The research indicated soil nematode tropic composition varied from one plant community to another in alpine meadows. Herbivorous and bacterivorous nematodes were the major nematode communities in the area. The relative abundance of herbivorous to omnivorous and/or predatory nematodes obviously varied in different plant communities. An analysis of the constitution of the c-p groups showed all cp2 groups were the predominant groups in all three plant communities, and all c-p groups were mainly <em>r</em>-strategists. <em>Kobresia pygmaea</em> was the most common food source for nematodes. <em>Kobresia littledalei</em> had the lowest nematode density, possibly because limited food availability limits the reproduction of cp1 and cp2 nematodes. The result of analysis of the plant parasite index indicated the <em>Potentilla</em> community was easier for nematodes to populate when compared to the other two vegetation types, whereas the data from the maturity index (<em>MI</em>), <em>PPI/MI</em> and cp5 demonstrated nematode stability in <em>Potentilla</em> was highest among three vegetation types. The fungal to bacterial feeder ratio and Nematode Channel Ratio showed bacterial decomposition was the major decomposition pathway in the soil organic substance decomposition system. Correlation of nutritional groups and environmental factors showed omnivorous/predatory nematodes were affected significantly by water content during dry periods, while a close relationship was found between soil pH and fungivorous nematodes, which was obviously affected by electrical conductivity (<em>EC</em>) during periods of rapid growth. The abundance of bacterivorous nematodes was only correlated to pH during the dry season. The presence of different plant communities leads to effects on water content, soil formation and the distribution of nutrients. The analysis related to water content, pH and <em>EC</em> reveals plant communities have important influences on the functional structure of nematode communities. Differences in nematode community structure in different meadows preliminarily indicate the potential for using nematodes as environmental indicator species.

Wireless Sensor Network Applications in Cold Alpine Area of West China: Experiences and Chanllenges

Abstract Wireless sensor network (WSN) shows unique advantages in cold alpine area comparing with traditional in-situ monitoring approaches. This paper presents two WSN applications in cold alpine area, one in the Hulugou watershed and the other in the Babaohe watershed, both of which are situated in the upper mountainous reach of the Heihe River Basin of West China. Apart from introductions to the two WSN applications and experimental results, experiences learned and challenges met during designing, testing and deployment of WSN are discussed. The paper concludes a promising future of WSN in environment monitoring in cold alpine areas.

Soil Enzyme Activities in Permafrost Regions of the Western Qinghai-Tibetan Plateau

Enzyme activities play key roles in the biochemical functioning of soils, in processes such as soil organic matter formation and degradation, and nutrient cycling. They are indicators of soil quality and key to soil ecosystem functioning. In this study, the effect of vegetation communities and soil properties on the activities of invertase, alkaline phosphatase, amylase, urease, cellulose, and catalase were investigated in permafrost regions of the middle and western Qinghai-Tibetan Plateau. This area is characterized by cold, arid steppe, with an active layer thicker than 2 m. The results demonstrated that soil enzyme activities were higher in Stipa roborowskyi Roshev. vegetation communities than those of Carex moorcroftii Falconer ex Boott communities. Soil enzyme activities were lowest in the alpine cold desert area. The activities per unit soil were primarily positively related to soil organic C (SOC) and moisture contents, and when activities were expressed as per unit C, they were primarily positively related to gravel content and negatively to moisture content. Results demonstrated that the vegetation communities, SOC, and moisture contents were important factors influencing soil enzyme activities, while permafrost, vegetation cover, and topographic factors played less important roles in the cold, arid area of the northwestern part of Qinghai-Tibetan Plateau. Potential SOC changes in this area were also investigated with regard to future climate change.

Soil Organic Carbon and Its Relationship to Vegetation Communities and Soil Properties in Permafrost Areas of the Central Western Qinghai‐Tibet Plateau, China

ABSTRACTSoil organic carbon (SOC) contents were examined beneath two grassland vegetation communities and cold desert sites in permafrost areas of the central western part of the Qinghai‐Tibet Plateau. Mean SOC stocks in the top 150 cm were 7.73 kg m‐2 for Stipa roborowskyi communities and 3.72 kg m‐2 for Carex moorcroftii communities, but only 1.84 kg m‐2 for cold alpine desert. More than 80 per cent of SOC stocks beneath the grasslands were in the top 100 cm. Correlation analyses showed that SOC stocks in the top 150 cm are linked to soil moisture content, and the vertical distribution of SOC is mainly affected by depth and soil moisture content. Moisture content and vegetation communities are therefore important factors associated with SOC content in this cold, arid area, while active‐layer thickness, vegetation cover and topographical factors play non‐significant roles in SOC distribution. Copyright © 2012 John Wiley &amp; Sons, Ltd.

Intergenomic rearrangements after polyploidization of Kengyilia thoroldiana (Poaceae: Triticeae) affected by environmental factors.

Polyploidization is a major evolutionary process. Approximately 70–75% species of Triticeae (Poaceae) are polyploids, involving 23 genomes. To investigate intergenomic rearrangements after polyploidization of Triticeae species and to determine the effects of environmental factors on them, nine populations of a typical polyploid Triticeae species, Kengyilia thoroldiana (Keng) J.L.Yang et al. (2n = 6x = 42, StStPPYY), collected from different environments, were studied using genome in situ hybridization (GISH). We found that intergenomic rearrangements occurred between the relatively large P genome and the small genomes, St (8.15%) and Y (22.22%), in polyploid species via various types of translocations compared to their diploid progenitors. However, no translocation was found between the relatively small St and Y chromosomes. Environmental factors may affect rearrangements among the three genomes. Chromosome translocations were significantly more frequent in populations from cold alpine and grassland environments than in populations from valley and lake-basin habitats (P<0.05). The relationship between types of chromosome translocations and altitude was significant (r = 0.809, P<0.01). Intergenomic rearrangements associated with environmental factors and genetic differentiation of a single basic genome should be considered as equally important genetic processes during species' ecotype evolution.

Reconstructing the origins of high-alpine niches and cushion life form in the genus Androsace S.L. (Primulaceae).

Relatively, few species have been able to colonize extremely cold alpine environments. We investigate the role played by the cushion life form in the evolution of climatic niches in the plant genus Androsace s.l., which spreads across the mountain ranges of the Northern Hemisphere. Using robust methods that account for phylogenetic uncertainty, intraspecific variability of climatic requirements and different life-history evolution scenarios, we show that climatic niches of Androsace s.l. exhibit low phylogenetic signal and that they evolved relatively recently and punctually. Models of niche evolution fitted onto phylogenies show that the cushion life form has been a key innovation providing the opportunity to occupy extremely cold environments, thus contributing to rapid climatic niche diversification in the genus Androsace s.l. We then propose a plausible scenario for the adaptation of plants to alpine habitats.

Melting and shrinkage of cryosphere in Tibet and its impact on the ecological environment

Global warming is having a profound impact on global ecological systems, and has inevitably induced changes in the cryosphere, one of the five layers of the earth. Major changes include the shrinking and reduction in the area and volume of both the mountain glaciers and the ice caps covering the North and South poles, and the melting of permafrost and thickening of the active frost layer. Swift changes in the cryosphere have inevitably in- duced ecological and environmental changes in its zone. While some of these changes are beneficial to mankind, such as an increase in water circulation, short term increases in water volumes and the enlargement of the culti- vatable area, others are extremely hazardous, like the flooding of lowlands caused by an increased sea level ele- vation, debris flow caused by glaciers, glacier lake bursts, undermined building safety caused by permafrost melting, the deterioration of alpine cold meadows, and the surface aridization and desertification of land. Tibet, having a major part of the cryosphere in China, is home to the most widely spread glaciers and permafrost, which play a vital role in regulating water resources, climate, environment and the ecological safety in China and Asia. However, due to global warming, the glaciers and permafrost in Tibet have recently changed dramatically, exhibiting shrinkage and melting, which threatens long-term water resources, and the ecological and environmental safety of China. Based on existing research, this paper discusses the relationship between global warming and the melting and shrinkage of the cryosphere. The results show that the cryosphere's melting and shrinkage in Tibet are the direct result of global warming. The melting of glaciers has led to a series of disasters, such as changes in river runoff, the heightened frequency of debris flows induced by glaciers and the outbursts of glacier lakes. The melting of the permafrost also resulted in a series of ecological and environmental problems in Tibet, such as the degradation and population succession of the alpine grassland and meadows, the aridization of the land surface, and the occurrence of freeze-thaw erosion.

Hydrological processes in the different landscape zones of alpine cold regions in the wet season, combining isotopic and hydrochemical tracers

AbstractStudies on hydrological processes are often emphasized in resource and environmental studies. This paper identifies the hydrological processes in different landscape zones during the wet season based on the isotopic and hydrochemical analysis of glacier, snow, frozen soil, groundwater and other water sources in the headwater catchment of alpine cold regions. Hydrochemical tracers indicated that the chemical compositions of the water are typically characterized by: (1) CaHCO3 type in glacier snow zone, (2) MgCaSO4 type for surface runoff and CaMgHCO3 type for groundwater in alpine desert zone, (3) CaMgSO4 type for surface water and CaMgHCO3 type for groundwater in alpine shrub zone, and (4) CaNaSO4 type in surface runoff in the alpine grassland zone. The End‐Members Mixing Analysis (EMMA) was employed for hydrograph separation. The results showed that the Mafengou River in the wet season was mainly recharged by groundwater in alpine cold desert zones and shrub zones (52%), which came from the infiltration and transformation of precipitation, thawed frozen soil water and glacier‐snow meltwater. Surface runoff in the glacier‐snow zone accounted for 11%, surface runoff in alpine cold desert zones and alpine shrub meadow zones accounted for 20%, thawed frozen soil water in alpine grassland zones accounted for 9% of recharge and precipitation directly into the river channel (8%). This study suggested that the whole catchment precipitation did not produce significant surface runoff directly, but mostly transformed into groundwater or interflow, and finally arrived in the river channel. Copyright © 2011 John Wiley &amp; Sons, Ltd.

Niche breadth, rarity and ecological characteristics within a regional flora spanning large environmental gradients

AbstractAim Species specialization, which plays a fundamental role in niche differentiation and species coexistence, is a key biological trait in relation to the responses of populations to changing environments. Species with a limited niche breadth are considered to experience a higher risk of extinction than generalist species. This work aims to measure the degree of specialization in the regional flora of the French Alps and test whether species specialization is related to species rarity and ecological characteristics.Location This study was conducted in the French Alps region, which encompasses a large elevational gradient over a relatively limited area (26,000 km2).Methods Specialization was estimated for approximately 1200 plant species found in the region. Given the inherent difficulty of pinpointing the critical environmental niche axes for each individual species, we used a co‐occurrence‐based index to estimate species niche breadths (specialization index). This comprehensive measurement included crucial undetermined limiting niche factors, acting on both local and regional scales, and related to both biotic and abiotic interactions. The specialization index for each species was then related to a selection of plant typologies such as Grime strategies and Raunkiaer life‐forms, and to two measurements of plant rarity, namely regional area of occupancy and local abundance.Results Specialist species were mainly found in specific and harsh environments such as wetlands, cold alpine habitats and dry heathlands. These species were usually geographically restricted but relatively dominant in their local communities. Although none of the selected traits were sufficient predictors of specialization, pure competitors were over‐represented amongst generalist species, whereas stress‐tolerant species tended to be more specialized.Main conclusions Our results suggest that co‐occurrence‐based indices of niche breadth are a satisfactory method for inferring plant specialization using large species samples across very heterogeneous environments. Our results are an empirical validation of the tolerance–dominance trade‐off and also provide interesting insights into the long‐standing question of which biological properties characterize species with narrow niche breadth that are potentially threatened by global changes in the environment.

Hydrologic processes in the different landscape zones of Mafengou River basin in the alpine cold region during the melting period

Summary Hydrologic processes of glacier, snow, frozen soil, groundwater, surface water and precipitation have always been the common concern of hydrologists. The purpose of this study is to identify the hydrologic processes in different landscape zones, based on the isotopic and hydrochemical analysis of glacier, snow, frozen soil and groundwater. The chemical compositions were characterized by Ca–HCO 3 in the glacier snow zone, Mg–Ca–SO 4 –HCO 3 in the alpine cold desert zone, Ca–Mg–HCO 3 in the marsh meadow zone, Ca–Mg–HCO 3 in the alpine shrub zone, and Na–Ca–SO 4 in the mountain grassland zone. The end-member mixing model was employed for hydrograph separation. The results showed that during the melting period Mafengou River water was recharged by glacier–snow melt water about 34%, thawed frozen soil water in each of the landscape zones about 12%, and groundwater about 54%. This study suggested that Mafengou River water during the melting period was mainly recharged by glacier–snow melt water, groundwater and thawed frozen soil water.

Hydrochemical and hydrological processes in the different landscape zones of alpine cold region in China

Investigation of water sources and flow pathways is crucial to understand and evaluate the characteristics of surface water and groundwater systems. This article aims to identify the hydrochemical and hydrological processes in different landscape zones based on hydrochemical analyses of various samples, including samples from glacier, snow, frozen soil meltwater, surface water, groundwater, and precipitation, in the alpine cold region of China. Hydrochemical tracers indicated that chemical compositions are characterized by the Ca-HCO3 type in the glacier-snow zone; the Mg-Ca-SO4 type in the alpine cold desert zone; the Ca-HCO3-SO4 type in the marsh meadow zone; the Ca-Mg-HCO3 type in the alpine shrub zone; and the Ca-Na-SO4 type in the mountain grassland zone. An end-member mixing model was used for hydrograph separation. The results showed that the Mafengou River in the wet season was recharged by groundwater in the alpine cold desert and alpine shrub zones (67%), surface runoff in the glacier-snow zone (11%), surface runoff in the alpine cold desert zone (8%), thawed water from frozen soil in the marsh meadow and mountain grassland zones (9%), and direct precipitation on the river channel (5%). This study suggests that precipitation from the whole catchment yielded little direct surface runoff; precipitation was mostly transformed into groundwater or interflow and was then concentrated into the river channel. This study provides a scientific basis for evaluation and management of water resources in the basin.

Spatial variability of soil moisture at typical alpine meadow and steppe sites in the Qinghai-Tibetan Plateau permafrost region

Permafrost degradation has the potential to significantly change soil moisture. The objective of this study was to assess the variability of soil moisture in a permafrost region using geostatistical techniques. The experiment was conducted in August 2008 in alpine steppe and meadow located in the Qinghai-Tibetan Plateau permafrost region. Four soil depths (0–10, 10–20, 20–30 and 30–40 cm) were analyzed using frequency domain reflectometry, and sampling made of 80 points in a 10 m × 10 m grid were sampled. Soil moisture was analyzed using classical statistics to appropriately describe central tendency and dispersion, and then using geostatistics to describe spatial variability. Classical statistical method indicated that soil moisture in the permafrost region had a normal distribution pattern. Mean surface soil moisture in alpine meadow was higher than that in alpine steppe. The semivariograms showed that soil moisture variability in alpine cold steppe was larger than that in alpine meadow, which decreased with depths. Nugget values in alpine steppe were low (0.1–4.5), in contrast to alpine cold meadow. Soil moisture in alpine steppe had highly structured spatial variability with more than 93.4% spatial heterogeneity, and the range decreased with depth. Soil moisture content in alpine cold meadow had a moderate spatial dependence with a range of 51.3–169.2 m, increasing with depth.

Hydrology, ecology and climate significance and its research progress of the Alpine cold desert

Alpine cold desert broadly distributed in the high-altitude of mountain area accounts for about 20%~30% of area in Tibet Plateau and Tianshan Mountain regions.It is an important hydrological functional area owing to high precipitation,rapid infiltration and the high runoff coefficient.It is also the ecological fragile region,due to the high altitude,low air temperature,steep terrain and the sparse vegetation.Moreover,the sparse vegetation and the cold-adapted microorganism in the alpine cold desert is the important signal to climatic change.However,the relevant research on alpine cold desert is rare.Furthermore,human activities give little impact on alpine cold desert thanon lower altitude area.Therefore,it is suitable for us to monitor the climatic change effect in the high mountain region.In this paper,the authors summarize the importance of alpine cold desert for cryospheric hydrology,ecology and climate in China and its relevant research progress,and suggest that the alpine cold desert should be a special research area in cryospheric sciences.

Composition and origin of amber ice and its influence on the behaviour of cold glaciers in the McMurdo Dry Valleys, Antarctica

AbstractThis paper examines the basal ice sequence of Rhone Glacier, a cold-based glacier in the McMurdo Dry Valleys, Antarctica, using isotopic and solute chemistry data. Three different ice facies are identified: englacial, amber and stratified. The englacial facies is clean, bubbly ice of meteoric origin and is underlain by an amber facies. Amber ice is a characteristic of cold alpine glaciers in the McMurdo Dry Valleys and is distinctive for its high solute concentrations and much higher strain rates compared with the overlying englacial ice and the underlying stratified ice. Analysis of the stratified facies reveals an isotopic signature indicative of melt then refreeze processes and it is most likely associated with apron entrainment at the margin. By contrast, the amber facies has a co-isotopic slope of 8 and plots on a meteoric waterline. The inclusion of impurities in the amber ice reveals prolonged contact with the bed, and its depleted isotopic signature is consistent with ice formed during a cooler period. Comparison of the basal sequence of Rhone Glacier with other cold-based glaciers in the McMurdo Dry Valleys reveals strong similarities between valley-side glaciers (e.g. Meserve and Rhone Glaciers), whereas valley-floor glacier basal sequences (e.g. Suess Glacier) are characterized by structurally complex amalgamations of ice and debris.

Effects of permafrost thawing on vegetation and soil carbon pool losses on the Qinghai–Tibet Plateau, China

Bearing a total organic carbon (TOC) content of 9.3–10.7 kg C/m 2, alpine grassland soils of the Qinghai–Tibet plateau's permafrost region bear a greater organic carbon pool than do grassland soils in other regions of China or than tropical savannah soils. The easily released light fraction organic carbon (LFOC) accounts for 34–54% of the TOC and is particularly enriched in the topsoil (0–0.10 m). The LFOC in the organic carbon pool of alpine cold meadow and alpine cold steppe soils decreased at exponential and quadratic rates, respectively, as the vegetative cover decreased. When the vegetative cover of alpine cold meadows decreased from > 80 dm 2/m 2 to 60 dm 2/m 2, the topsoil TOC and LFOC dropped by 20.4% and 38.4%, respectively. Similarly, when the vegetative cover of alpine cold meadow decreased from 50 dm 2/m 2 to 30 dm 2/m 2 and < 15 dm 2/m 2, the topsoil LFOC content dropped by 60% and 86.7%, respectively. Under climatic warming, the degradation of permafrost and vegetation have resulted in serious soil organic carbon (SOC) loss from the carbon pool. Land cover changes that occurred between 1986 and 2000 are estimated to have resulted in a 1.8 Gg C (120 Mg C/yr) loss in SOC, and a concomitant 65% decrease in the LFOC, in the 0–0.30 m soil layer in the Qinghai–Tibet plateau's permafrost regions. Since the region's ecosystems are quite sensitive to global climate changes, if global warming persists, alpine cold grassland ecosystems are expected to further degrade. Hence, the influence of global climatic change on soil carbon emissions from alpine grasslands should receive more attention.

Biological spectrum of Nubra Valley (Ladakh)

The Nubra valley of Ladakh (Jammu and Kashmir) is situated to the North of Leh and constitutes a part of the Indian cold desert of trans-Himalaya. The life forms of the flora of Nubra valley (including Pteridophytes, gymnosperms and angiosperms) belonging to 65 families, 257 genera and 439 species have been studied and the biological spectrum has been compared with that of Raunkiaer’s normal spectrum. The thero-hemicryptophytic phytoclimate of the area is characteristic of cold alpine zones.

Influences of alpine ecosystem responses to climatic change on soil properties on the Qinghai–Tibet Plateau, China

Alpine ecosystems are quite sensitive to global climatic changes. Drawing from two sets of remote sensing data (1986 and 2000) and field investigations, the ecological index method was used to document ecosystem changes in the Yangtze and Yellow River source regions of central Qinghai–Tibet. Although crucial to understanding alpine ecosystem responses to global climatic changes, and in assessing the potential for their rehabilitation, the impact of such changes on alpine soil characteristics, including structure, composition, water retention, as well as chemical and nutrient contents, is poorly understood. Over a 15-year period (1986–2000), climatic changes led to considerable degradation of alpine meadows and steppes. In the meadows, the surface layers of the soil became coarser, bulk density, porosity and saturated hydraulic conductivity rose, while water-holding capacity decreased. In comparison, steppe soils showed little changes in soil physical properties. Degradation of alpine ecosystems led to large losses in soil available Fe, Mn and Zn. Important losses in soil organic matter (SOM) and total nitrogen (TN) occurred in badly degraded ecosystems. Climate warming in the Qinghai–Tibet Plateau, caused by the impact of greenhouse gas, has resulted in changes of cold alpine ecosystem such as the significant alteration of the soil C and N cycles.

Impacts of permafrost changes on alpine ecosystem in Qinghai-Tibet Plateau

Alpine cold ecosystem with permafrost environment is quite sensitive to climatic changes and the changes in permafrost can significantly affect the alpine ecosystem. The vegetation coverage, grassland biomass and soil nutrient and texture are selected to indicate the regime of alpine cold ecosystems in the Qinghai-Tibet Plateau. The interactions between alpine ecosystem and permafrost were investigated with the depth of active layer, permafrost thickness and mean annual ground temperature (MAGTs). Based on the statistics model of GPTR for MAGTs and annual air temperatures, an analysis method was developed to analyze the impacts of permafrost changes on the alpine ecosystems. Under the climate change and human engineering activities, the permafrost change and its impacts on alpine ecosystems in the permafrost region between the Kunlun Mountains and the Tanggula Range of Qinghai-Tibet Plateau are studied in this paper. The results showed that the permafrost changes have a different influence on different alpine ecosystems. With the increase in the thickness of active layer, the vegetation cover and biomass of the alpine cold meadow exhibit a significant conic reduction, the soil organic matter content of the alpine cold meadow ecosystem shows an exponential decrease, and the surface soil materials become coarse and gravelly. The alpine cold steppe ecosystem, however, seems to have a relatively weak relation to the permafrost environment. Those relationships resulted in the fact that the distribution area of alpine cold meadow decreased by 7.98% and alpine cold swamp decreased by 28.11% under the permafrost environment degradation during recent 15 years. In the future 50 years the alpine cold meadow ecosystems in different geomorphologic units may have different responses to the changes of the permafrost under different climate warming conditions, among them the alpine cold meadow and swamp ecosystem located in the low mountain and plateau area will have a relatively serious degradation. Furthermore, from the angles of grassland coverage and biological production the variation characteristics of high-cold ecosystems in different representative regions and different geomorphologic units under different climatic conditions were quantitatively assessed. In the future, adopting effective measures to protect permafrost is of vital importance to maintaining the stability of permafrost engineering and alpine cold ecosystems in the plateau.

Land-Cover Changes and Its Impacts on Ecological Variables in the Headwaters Area of the Yangtze River, China

Land cover changes affect ecological landscape spatial pattern, and evolving landscape patterns inevitably cause an evolution in ecosystem functionality. Various ecological landscape variables, such as biological productivity (plant biomass and stock capacity), soil nutrients (organic matter and N content) and water source conservation capacity are identified as landscape function characteristics. A quantitative method and digital model for analyzing evolving landscape functionality in the headwaters areas of the Yangtze River, China were devised. In the period 1986-2000, patch transitions of the region's evolving landscapes have been predominantly characterized by alpine cold swamp meadow, with the highest coverage tending to be steppified meadow or steppe, and desertification landscape such as sand and bare rock land expansion. As the result of such changes, alpine swamp areas decreased by 3.08 x 10(3) km2 and the alpine cold sparse steppe and bare rock and soil land increased by 6.48 x 10(3) km2 and 5.82 x 10(3) km2, respectively. Consequently, the grass biomass production decreased by 2627.15 Gg, of which alpine cold swamp meadows accounted for 55.9% of this loss. The overall stock capacity of the headwaters area of the Yangtze River decreased by 920.64 thousand sheep units, of which 502.02 thousand sheep units decreased in ACS (Alpine cold swamp) meadow transition. Soil organic matter and N contents decreased significantly in most alpine cold meadow and swamp meadow landscape patches. From 1986 to 2000 the total losses of soil organic matter and total N in the entire headwaters region amounted to 150.2 Gkg and 7.67 Gkg. Meanwhile, the landscape soil water capacity declined by 935.9 Mm3, of which 83.9% occurred in the ACS meadow transition. In the headwater area of the Yangtze River, the complex transition of landscape resulted in sharp eco-environmental deterioration. The main indication for these changes involved the intensity of the climate in this region is becoming drier and warmer, resulting in a gradual degradation of the permafrost.