Cold-dry Conditions Research Articles

8000-year monsoonal record from Himalaya revealing reinforcement of tropical and global climate systems since mid-Holocene

We provide the first continuous Indian Summer Monsoon (ISM) climate record for the higher Himalayas (Kedarnath, India) by analyzing a 14C-dated peat sequence covering the last ~8000 years, with ~50 years temporal resolution. The ISM variability inferred using various proxies reveal striking similarity with the Greenland ice core (GISP2) temperature record and rapid denitrification changes recorded in the sediments off Peru. The Kedarnath record provides compelling evidence for a reorganization of the global climate system taking place at ~5.5 ka BP possibly after sea level stabilization and the advent of inter-annual climate variability governed by the modern ENSO phenomenon. The ISM record also captures warm-wet and cold-dry conditions during the Medieval Climate Anomaly and Little Ice Age, respectively.

Modelling of equilibrium working capacity of PSA, TSA and TVSA processes for CO2 adsorption under direct air capture conditions

In this study, direct air capture performance of polymeric adsorbent was studied by determining CO2-isotherms in very dilute conditions (CO2 partial pressure up to 5mbar). The effect of cold conditions (0°C and −10°C) and humidity on the CO2 capacity was also studied. The experimental isotherms were used in temperature-dependent equilibrium modelling to simulate equilibrium CO2 working capacities in pressure-swing adsorption (PSA), temperature-swing adsorption (TSA) and temperature-vacuum swing adsorption (TVSA). Experimental adsorption capacities of 0.80mmolCO2/gsorbent and 0.89mmolCO2/gsorbent were obtained from 400ppmv CO2 in dry cold conditions and at 25°C in humid conditions, respectively. The highest experimental capacity gained from 400ppmv CO2 was 1.06mmolCO2/gsorbent in humid cold conditions. In terms of the working capacity, PSA was found not to be a viable process option. Humidity promoted TSA working capacity up to by 0.36mmolCO2/gsorbent (78%). TSA could produce larger than 0.5mmolCO2/gsorbent working capacity levels even with very low regeneration temperatures (50–60°C) when adsorbing either in dry cold conditions or humid warm conditions. Such EWC levels with dry TVSA could only be achieved using 90°C regeneration temperature with adsorption in either cold conditions or from compressed air. Based on these results, TVSA should only be considered in PtX applications requiring high-purity CO2.

Seasonal dynamics with compensatory effects regulate populations of tropical forest marsupials: a 16-year study.

The conditions that a population experiences during one season can affect the strength of density dependence in the following season. In the tropics, many populations face their biggest challenges in the dry season due to limited food and cold-dry conditions. Seasonal environmental changes can be especially problematic for small, short-lived, seasonally breeding endotherms. To investigate the effects of seasonality on population dynamics, we studied five marsupial species in the Brazilian Atlantic Forest, using a 16-year dataset. We tested if (1) compensatory density feedback is stronger in the dry season, due to the high population sizes and limited food; (2) lower temperatures and the overall abundance of small mammals negatively affect dry season population growth rates; and (3) rainfall, a proxy for food availability, is positively related to wet season population growth rates. Population growth rates were regressed against seasonal population sizes and exogenous variables, and analyzed with linear autoregressive models. Seasonal compensatory density feedback occurred in both seasons, with compensation processes in just one season being sufficient to allow population persistence. Rainfall and the overall abundance of small mammals had little influence on populations, while colder temperatures decreased population growth rate of smaller species in both seasons. Although the study marsupials share similar life histories and phylogeny, they varied with respect to the season when compensatory density feedback was strongest. Our results demonstrate that seasonality plays a key role in driving marsupial population dynamics, and highlight the need to account for seasonality in demographic studies even in tropical environments.

Daily rhythms of colonic temperature and circulating blood enzymes, urea and calcium in Japanese quail (Coturnix coturnix japonica) under natural cold-dry (harmattan) and hot-dry conditions

The influence of cold-dry (harmattan) and hot-dry seasons on daily rhythmicity of colonic temperature (CT) and blood biochemical variables were investigated in 340 male Japanese quails under natural light–dark circle. Rhythm characteristics analysed using cosinor and the application of the periodic model showed a daily rhythm of CT, creatinine phosphate kinase (CPK), aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase (ALP) and urea in both seasons, while calcium did not exhibit any rhythmicity. The rhythmic parameters of mesor, amplitude and acrophase analysis showed significant (p < 0.05) effects of season. The amplitudes, except for ALP, were greater during the harmattan. The acrophase, except for CPK and urea, were all restricted to the light phase of the light-dark cycle. The results, demonstrated strong seasonal changes on the daily rhythmicity of CT and blood biochemical parameters of quails under natural light-dark circle, which could be useful for researchers, clinicians and agriculturists under different climatic conditions.

Climate change and social vicissitudes in China over the past two millennia

The relation between climate change and historical rhythms has long been discussed. However, this type of study still faces the lack of high-resolution data concerning long-term socio-economic processes. In this study, we collected 1586 items of direct and proffered evidence from 29 Chinese history books. We used semantic analysis to reconstruct a quantitative series of the social vicissitudes of the past 2000 yr with a 10-yr resolution to express the phase transition of the social vicissitudes of the dynasties in China. Our reconstruction demonstrates that social vicissitudes have clear cyclical features on multiple time scales. Analysis of the association of social rise and fall with climate change indicates that temperature displayed more significant effects on social vicissitudes in the long term, while precipitation displayed more significant effects on the social vicissitudes in the short term. There are great overlaps between social and climatic variables around the predominant or periodic bands. Social rise mostly occurred in the centennial-scale warm periods, whereas social decline mostly occurred in the centennial-scale cold periods. Under warm-wet conditions, social rise occurred over 57% of the time; under cold-dry conditions, the social decline occurred over 66% of the time.

Highway deicing salt dynamic runoff to surface water and subsequent infiltration to groundwater during severe UK winters

Dynamic impact to the water environment of deicing salt application at a major highway (motorway) interchange in the UK is quantitatively evaluated for two recent severe UK winters. The contaminant transport pathway studied allowed controls on dynamic highway runoff and storm-sewer discharge to a receiving stream and its subsequent leakage to an underlying sandstone aquifer, including possible contribution to long-term chloride increases in supply wells, to be evaluated. Logged stream electrical-conductivity (EC) to estimate chloride concentrations, stream flow, climate and motorway salt application data were used to assess salt fate. Stream loading was responsive to salt applications and climate variability influencing salt release. Chloride (via EC) was predicted to exceed the stream Environmental Quality Standard (250mg/l) for 33% and 18% of the two winters. Maximum stream concentrations (3500mg/l, 15% sea water salinity) were ascribed to salt-induced melting and drainage of highway snowfall without dilution from, still frozen, catchment water. Salt persistance on the highway under dry-cold conditions was inferred from stream observations of delayed salt removal. Streambed and stream-loss data demonstrated chloride infiltration could occur to the underlying aquifer with mild and severe winter stream leakage estimated to account for 21 to 54% respectively of the 70t of increased chloride (over baseline) annually abstracted by supply wells. Deicing salt infiltration lateral to the highway alongside other urban/natural sources were inferred to contribute the shortfall. Challenges in quantifying chloride mass/fluxes (flow gauge accuracy at high flows, salt loading from other roads, weaker chloride-EC correlation at low concentrations), may be largely overcome by modest investment in enhanced data acquisition or minor approach modification. The increased understanding of deicing salt dynamic loading to the water environment obtained is relevant to improved groundwater resource management, highway salt application practice, surface-water - ecosystem management, and decision making on highway drainage to ground.

火星表面の永久凍土と周氷河作用

Following the development of high-resolution imaging, digital elevation models, thermal and hydrological data, and onsite ground information during the early period of the 21st century, the periglacial geomorphology of the Martian surface advanced rapidly. Images can even resolute meter-scale landforms, enabling identification of most periglacial features and analysis of their global distributions and detailed morphologies. This review focuses on progress in research covering permafrost distribution, patterned ground, possible heave and subsidence features, lobate debris forms, and slope-lineated features during the last decade. Most of the Martian high-latitude surface is underlain by ice-rich ground called the latitude-dependent mantle (LDM), which favors permafrost-related features possibly developed under warm-humid conditions during past high-obliquity periods or partially s,till active under the present cold-dry conditions. Thermal contraction cracking is likely to prevail in the LDM, resulting in high-centered, flat-top polygons, possibly underlain by sublimation-type wedges or sand wedges that prevail at high latitudes. The surface patterns change into subdued or peak-top polygons toward the mid-latitudes, probably reflecting long-term sublimation of the LDM. Some researchers attribute stone circles to sorting due to freeze-thaw, but the features are much larger than candidates on the Earth. Small isolated domes with concentric cracks or craters at the top may include pingos, which also prevail at high- to mid-latitudes. Asymmetrical scalloped depressions may result from sublimation or thawing of the LDM, but there is a debate between pole-ward and equator-ward slope retreats. Lobate debris aprons may originate from creep of ice-rock mixtures or debris-covered glaciers, but the distinction between the two origins is unclear, as in the long-lasting debate on terrestrial candidates. Some thin, smaller debris lobes at high latitudes resemble stone-banked solifluction lobes on the Earth, which may indicate the occurrence of seasonal freeze-thaw cycles in the recent past. Time-series images indicate active slope features, including gullies, slope streaks, and recurrent slope lineaes that develop below cliffs. These active features may originate from outflows of brine that thaws far below the melting point of water ice.

Clay mineralogical characteristics and the palaeoclimatic significance of a Holocene to Late Middle Pleistocene loess–palaeosol sequence from Chaoyang, China

ABSTRACTChanges in soil chemistry in response to varying climatic regimes can alter the equilibria of soil systems and result in different clay minerals. Variations in phyllosilicate clay composition can reflect temporal and spatial climatic changes, such as summer/winter monsoon cycles. The objective of this research was to investigate the mineralogy of the clay fractions as a proxy for determining variations in the East Asian monsoon climate, based on a section at Chaoyang in China spanning the last 0.423 Ma BP. The clay mineralogy record in the Chaoyang section was compared with other proxies as recorded in this section and with other palaeoclimatic indicators, including oxygen isotopes from oceanic sediments and loess–palaeosol sections on the Chinese Loess Plateau (CLP). The results from clay mineralogy and related climatic studies show that the summer monsoon has a trend of four increased stages and four decreased stages; whereas the winter monsoon displays the opposite trend. During the last 0.423 Ma BP, the strongest winter monsoon occurred around 0.243–0.311 Ma BP. During this period, which included an intense winter monsoon, the soil in the section had the least illite, one of the smallest kaolinite and illite/Chlorite (I/C) indices and an overall decreasing clay content. The period 0.225–0.243 Ma BP had the strongest summer monsoon over the last 0.423 Ma BP. This period had the greatest amount of illite, the highest I/C index, greater overall clay content and the strongest magnetic susceptibility signal. Additionally, this section contained the smallest mean grain size. The multi-monsoon climate cycles of alternating cold-dry and warm-moist conditions as recorded in the Chaoyang section corresponded well with multiple glaciation cycles based on deep sea sediments. This indicates that the Chaoyang section provides a record of palaeoclimate changes in northeast China that can be linked to mineralogical suites to assist in reconstructing the palaeoclimate over the Late Middle Pleistocene, and complements the global palaeoclimate records in the CLP.

Wheel damage on the Swedish iron ore line investigated via multibody simulation

The Swedish iron ore company LKAB uses freight wagons with three-piece bogies to transport iron ore from its mines in Kiruna and Malmberget to the ports at Luleå and Narvik. A simulation model of the freight wagon is built using the multibody simulation code GENSYS. The objective is to investigate possible sources of rolling contact fatigue (RCF) of the wheels given the high level of observed damage. A parameter study is performed on the effects of vertical track stiffness and viscous damping that occur as a result of seasonal variations of the track condition. Another parameter study is carried out on the influence of the wheel/rail friction coefficient as in winter time the climate is very dry along most parts of the Malmbanan line. The impact of track gauge, track quality and cant deficiency on RCF is also studied. Comparing the calculated and observed RCF locations on wheels, attempts are made to find a relation between wear number and RCF damage. To detect the surface-initiated fatigue a so-called shakedown map is used. It is shown that RCF occurs on the tread of the inner wheels while negotiating curves with below an approximately 450 m radius. It is also shown that cant deficiency can be helpful for the vehicles to negotiate curves and to reduce the risk of RCF, however, on the other hand it may increase the track forces and in severe cases result in flange climbing. Lateral track irregularities and a large track gauge result in small contact areas and can lead to a higher risk of RCF. In cold dry climate conditions, as the water content in air drops significantly, the wheel/rail friction coefficient increases and when the material in the wheel begins to behave in a brittle manner, the risk of RCF is significantly increased, especially when the wear rate is not high enough to remove the initiated cracks.

Antimicrobial Properties of 39 Essential Oils against Thirteen Food-borne Microorganisms; Efficacy and Environmental Hygiene of Prunus armeniaca in Raw Food Preservation under Cold Storage

Aim: The present study investigated the antimicrobial properties of 39 diversified essential plant oils (EOs). The most bioactive EO was selected and tested for its environmental hygiene efficacy in the preservation of stored raw food. Methods: The antimicrobial efficacy of 39 EOs was examined against 13 representative food-borne microorganisms. Minimal inhibitory concentration (MIC) of extracted apricot (Prunus armeniaca) seed EO was evaluated. Different concentrations of extracted oil were applied to four types of low-fat raw foods under cold dry storage. Results: The results of the microbial sensitivity assay showed considerable positive responses to only 23 out of 39 EOs. Pru. armeniaca exhibited the most significant antimicrobial efficacy. Different MIC values of extracted Pru. armeniaca oil were documented as a result of strain variability of representative food-borne microorganisms. Extracted apricot EO concentration delayed bacterial food spoilage at 1000 μgml-1 while fungal spoilage delayed at 2000 μgml-1. Total bacterial viable count (TVC) of raw food samples treated with 1000 μgml-1 oil decreased sharply when compared with TVC of samples not treated with oil. Fungal growth was completely inhibited in samples treated with 2000 μgml-1 oil. Statistical analysis showed a significant association between the minimal inhibitory concentrations (MIC) of Pru. armeniaca EO and the growth of the 13 representative food-borne microorganisms, it was mostly 500μgml-1. Conclusion: The achieved study results support using of Pru. armeniaca EO in controlling shelf-life of raw foods stored under dry cold conditions.

Loess deposits in the northern Kyrgyz Tien Shan: Implications for the paleoclimate reconstruction during the Late Quaternary

Loess deposits on the northern slopes of the Kyrgyz Tien Shan were examined. Their particle size characteristics show silt size dominancy (>80%) with minor contribution from sand (12%) and clay (7%). The loess was dated using optically stimulated luminescence (OSL) and radiocarbon methods to define the timing of deposition. The OSL ages of fine and coarse quartz fractions were consistent with each other within 2σ uncertainty level, except several samples deposited during MIS 2. Based on the OSL ages, four major loess depositional periods are recognized in the northern Kyrgyz Tien Shan during the Late Quaternary: the Holocene, MIS 2, MIS 3, and MIS 4. The rate of dust accumulation in the northern Tien Shan during MIS 2 was greater than that during MIS 3 or MIS 4. This implies that cold–dry conditions varied significantly during the Late Quaternary in the study area. The accumulation patterns of the Kyrgyz loess deposits in the northern Tien Shan are closely related to climate fluctuations during the Late Quaternary, influenced by changes in the mid-latitude westerlies, Asian summer monsoons, and Siberian High Pressure (SHP) systems, during which there was no significant cessation of deposition.

Germination capacity and seed storage behaviour of threatened metallophytes from the Katanga copper belt (D.R.Congo): implications for ex situ conservation

Background and aims – Plant species adapted to metalliferous soil are of high conservation value, and actions for preserving these species (some of them are endemics) are urgent given the threat of mining activities. In the framework of an integrated conservation programme of cuprophytes (plants that tolerate a soil with a high level of copper) in Katanga (D. R. Congo), this study aims at: (1) providing new data on species whose germination has never been studied so far; (2) gaining new insight into the storage behaviour of these species; (3) discussing implications for ex situ conservation of these highly threatened species. Methods – Germination tests were conducted on fresh seeds of nineteen species. These tests were repeated after 6, 12 and 24 months of storage in dry-cold conditions. Key results – Most species kept or increased their germination capacity after 2 years storage in dry-cold conditions. Nine species showed a slight decrease in their viability (from 100% to &gt; 80%) after 2 years storage in dry-cold conditions. The present study gives evidence that at least six of the 19 studied species are desiccation-tolerant (orthodox). Among these, two are strict endemics, Haumaniastrum robertii and Faroa malaissei, and two are broad endemics, Diplolophium marthozianum and Gladiolus robiliartianus . This means that ex situ seed banking of these species could form a useful part of a more comprehensive conservation strategy. Only two species have been identified as desiccation-sensitive (recalcitrant), i.e.inappropriate for conservation in standard seed bank conditions. An orthodox behaviour has not been ruled out for the other species tested, but their response was less clear and needs further investigation.

Characteristic of Seed Germination of Dendropanax morifera According to Temperature and Light Factors for Estimating Change of Habitat Area in Global Warming

The plant habitat is moved by change of growth environment due to global warming. And it have to need seed germination and successful settlement of seedling in new habitat. This study aims to supply basic data for predicting change of habitat of Dendropanax morbifera Lev., warm temperate tree in Korea, by global warming. Characteristics of seed germination of D. morbifera was studied in different temperature and light conditions. Firstly, fruit and non-fleshed seed were saw without cold treatment. Second, each fruit and non-f leshed seed were treated in wet cold and dry cold conditions at 4°C for 3 months, and it were saw in 10, 15, 20, 25, 30°C conditions. After cold treatment at 4°C, non-fleshed seed shows high germination ratio of 87%, 53%, 77%, 63%, 23% in 10°C, 15°C, 20°C, 25°C, and 30°C, respectively. Also, in filed test, non-fleshed seed was high in 69.2% and in non-light condition. However, it did not shown germinated seed in light condition. In conclusion, germination of D. morbifera mainly controlled by non-light condition in temperature after cold treatment for about 3 months on 4°C.

Correlation of the Late Pleistocene paleogeographical events of the Caspian Sea and Russian Plain

The present work shows the author's concept of paleogeographic development of the Caspian Sea in the Late Pleistocene, based on the comprehensive analysis of the Caspian deposits and their relation and synchronization with glacial–interglacial cycles on the Russian Plain, based on published materials. Global climate changes were fundamental for both the transgressive-regressive state of the Caspian basins, as well as for glacier formation and retreat on the Russian Plain. At the same time, glaciers influenced the Caspian basin development on a regional level. The long-term low Caspian Sea level, complicated by the double-stage “minor” Late Khazar transgression, corresponded to the Mikulino (Eemian) interglacial with two endothermals. This warm stage in the Caspian history encompassed the interval corresponding to Marine Isotope Stage (MIS) 5. This is in agreement with the point of view of researchers who correlate the Mikulino interglacial with the entire MIS 5. The “cold” vast Khvalynian transgression and preceding to it the Atel regression developed during the Valday glaciation (MIS 4–2). The Atel regression corresponds to cold MIS 2 and the beginning of MIS 3. Its lower boundary in the Lower Volga region is marked with ice wedges. A transgressive tendency began to show in the second half of the interstadial (second half of MIS 3) and continued into early stages of the Late Valdai cooling, but it was interrupted during the dry and cold Glacial Maximum (peak of MIS 2) by the regressive stage. Further transgression development occurred during the degradation of the glaciation. Its course was impacted by transgressive-regressive events of lower magnitude linked to oscillations of climatic parameters: i.e., cold dry conditions of the Middle Dryas by the Enotaevka regression, and the continentalization of the Boreal period of the Holocene by the Mangyshlak regression.

Reconstructing the distribution and depositional history of the sedimentary deposits of Arabia Terra, Mars

The sedimentary deposits of Meridiani Planum formed during the martian climate transition at the Noachian–Hesperian boundary between warm–wet and cold–dry conditions, and give valuable insight into how and when this transition occurred. We show that these deposits share characteristics with sedimentary outcrops across Arabia Terra. Despite near-ubiquitous dust cover across much of Arabia Terra, spectral signatures of polyhydrated sulfate minerals resembling those in Meridiani were identified in Schiaparelli and another unnamed crater. An erosional morphology analysis using both image and topographic data was then used to identify morphologies characteristic of Meridiani-type deposits and catalogue their occurrences throughout Arabia Terra. The occurrences of deposits with compositions and morphologies resembling the Meridiani deposits throughout Arabia Terra suggest that Meridiani-type sedimentary rocks were once more widespread. Elevations of the eroded remnants were used to reconstruct the pre-erosional paleo-surface of the deposits. Within this study area, these deposits once covered ∼2.5–3.6×106km2 and represent an eroded volume of 0.9–1.7×106km3 of sediment. Crater retention ages using craters of a range of preservation states and stratigraphic levels reveal that the deposits were laid down and subsequently eroded during a ∼270Myr period between ∼3.83 and 3.56Ga. The deposits formed following the transition from fluvial dissection to evaporite deposition at the end of the Noachian. The high erosion rates (∼3×10−6m/yr) suggest that Mars may have maintained a thick atmosphere relative to today even as it dried out in the Early Hesperian.

A 28,000 year history of vegetation and climate from Lower Red Rock Lake, Centennial Valley, Southwestern Montana, USA

A sediment core extending to 28,000calyrBP from Lower Red Rock Lake in the Centennial Valley of southwestern Montana provides new information on the nature of full-glacial vegetation as well as a history of late-glacial and Holocene vegetation and climate in a poorly studied region. Prior to 17,000calyrBP, the eastern Centennial Valley was occupied by a large lake (Pleistocene Lake Centennial), and valley glaciers were present in adjacent mountain ranges. The lake lowered upon erosion of a newly formed western outlet in late-glacial time. High pollen percentages of Juniperus, Poaceae, Asteraceae, and other herbs as well as low pollen accumulation rates suggest sparse vegetation cover. Inferred cold dry conditions are consistent with a strengthened glacial anticyclone at this time. Between 17,000 and 10,500calyrBP, high Picea and Abies pollen percentages suggest a shift to subalpine parkland and warmer conditions than before. This is attributed to the northward shift of the jet stream and increasing summer insolation. From 10,500 to 7100calyrBP, pollen evidence of open dry forests suggests warm conditions, which were likely a response to increased summer insolation and a strengthened Pacific subtropical high-pressure system. From 7100 to 2400calyrBP, cooler moister conditions promoted closed forest and wetlands. Increases in Picea and Abies pollen percentages after 2400calyrBP suggest increasing effective moisture. The postglacial pattern of Pseudotsuga expansion indicates that it arrived later on the Atlantic side of the Continental Divide than on the Pacific side. The Divide may have been a physical barrier for refugial populations or it delimited different climate regions that influenced the timing of Pseudotsuga expansion.

Friction and noise of rubber belt in low temperature condition: The influence of interfacial ice film

Abstract The friction of rubber belt on pulley was examined under cold conditions. Special emphasis was given to the investigation of the influence of interfacial ice film on friction and noise. A test rig was constructed to study the friction and noise behavior of rubber belt with interfacial ice film under low temperatures. Belt friction and noise were measured using the test rig in the field as well as in a cold environmental chamber. The temperatures used for room testing and cold testing were respectively 23 °C and − 20 °C. It is found that the rubber belt friction is strongly dependent on temperature and the presence or absence of interfacial ice film. The belt friction is found to increase under dry-cold conditions when compared to room temperature conditions. The wet belt under cold conditions could form a thin ice film leading to high static friction and low kinetic friction. The belt sound associated with dry-cold friction is a continuous squeal with a distinct frequency of 9 kHz and associated harmonics, whereas the sound associated with wet-cold friction is impulsive with wideband spectrum stretching up to 20 kHz.

Effect of storage conditions on germination of seeds of 489 species from high elevation grasslands of the eastern Tibet Plateau and some implications for climate change

Little is known about the effect of environmental conditions on seed dormancy break at the community level or how it could be affected by climate change. This study tested the effects of storage conditions on germination of 489 species from high-elevation natural grasslands on the Tibet Plateau. We stored seeds in dry cold, dry warm, and wet cold environments to test the effect of these conditions on germination. Germination responses were classified with the use of cluster analysis. The effect of phylogeny on germination response to storage conditions was determined. Compared with results of wet cold conditions, storing seeds at dry warm or dry cold conditions decreased the mean community germination percentage by 17.93% and 16.07%, respectively. Storing seeds at dry warm vs. dry cold conditions decreased the community mean germination percentage by 4.61%. The germination response to moisture conditions during storage showed significant phylogenetic patterns, whereas the germination response to storage temperature did not. On the basis of the germinability of seeds of the same species stored under different conditions, germination may increase, decrease, or stay the same. Within the high-elevation Tibetan grassland community, the different responses in dormancy breaking and germination behavior to the same storage conditions may have implications for understanding how this community might respond to climate change. In particular, some species may increase in the community, whereas others may decrease or remain the same. However, the potential for such change can be detected only by studying the responses of many species.

Ostracod-based environmental reconstruction over the last 8,400 years of Nam Co Lake on the Tibetan plateau

From a 332-cm long lacustrine core taken at 60 m water depth and 25 surface sediment samples taken at different water depth sites in Nam Co lake (4,718 m a.s.l.) in the middle-south part of the Tibetan Plateau, we identified nine species of ostracods (Crustacea: Ostracoda) belonging to six genera. Using lithological data, auto-ecological information of the recovered taxa and an ostracod-based transfer function for water depth reconstruction, we distinguished three main environmental stages over the past 8,400 years: during Stage I (8,400–6,800 yr BP), the climate changed from warm-humid to cold-humid, and eventually to cold-arid. The water depth of the site was much lower than today and changed from an estimated 50 to 20–30 m. During Stage II (6,800–2,900 yr BP), environmental conditions were again warm-humid, turning into a cold-arid episode. The lake water depth initially stayed much shallower than today, but then gradually deepened to around 50 m. At the earlier period of Stage III (2,900 yr BP–present), the climate became again warm-humid from cold-arid status. There was a cold-dry event between 1,700 and 1,500 yr BP, which intensified afterward while the surface run off weakened. Early in this stage, lake depth decreased slightly, but then it continuously deepened to 60 m. Our results revealed that central Tibet experienced wavily warm toward tendency in early Holocene, a shift from warm-humid to cold-dry conditions in the middle Holocene, and from warm-humid to cold-dry conditions in the late Holocene. They also show that ostracod assemblages are not only indicative of cold-warm conditions, but are also usable to imply the dry–wet status of a lake area by the inferring water depth variations. Finally, this study provides baseline data on (natural) climate change in this mountain region against which to compare global change impacts.

Cyanobacteria in Biological Soil Crust of Chadormalu Area, Bafq Region in Central Iran

Arid and semi-arid regions are characterized by sparse vegetation or absence of vegetation cover. The absence of a dense distribution of macrophytes (higher plants), much of arid and semi-arid surfaces are covered by microphytic communities of small non-vascular plants. An important group of organisms comprising soil crusts in such habitats are cyanobacteria. In this research the genus and species of cyanobacteria were detected at the Chadormalu desert, Yazd Province of Iran. The study showed that cyanobacteria (Microcoleous vaginatus, Nostoc.sp, Microcystis.sp, Ocillatoria.sp, Chroococcuss.sp, Chroococcidiopsis, Ocillatoria.sp, Chroococcuss.sp, Microcystis.sp) at Chadormalu Desert are comparable with other Deserts in cold and warm dry conditions.