Subspecies in Przewalski’s gazelle Procapra przewalskii and its conservation implication

Przewalski’s gazelle Procapra przewalskii is an endangered species endemic to China. A question remains about subspecific variation in this species. Skulls of Przewalski’s gazelle collected from its current remnant ranges around the Qinghai Lake in combination with those collected prior to the 20th century were measured and analyzed using Hierarchical Cluster Analysis in order to clarify the question. Unexpectedly, P. p. diversicornis, extirpated from its historic range, has spread to the Qinghai Lake region where it has replaced nominotypical P. p. przewalskii and is now restricted to a few small isolated populations around the lake. We discuss the causes of this unexpected replacement. In this study, we discuss the possibility of a new form, possibly a new subspecies, in the Guide Basin, adjacent to Qinghai Lake; it is unclear whether the new form has long existed and was only discovered in recent years, or whether it evolved in recent times due to the geographical isolation and anthropogenic landscape features. The study sheds light on the processes of microevolution and subspeciation in Procapra przewalskii, and based on the findings, we propose measures for conservation strategies for Przewalski’s gazelle.     

Food-Chain Model of Grassland Degradation and Its Restoration Process in Northern Tibet Plateau：A Case Study in Nierong County

Based on the model of grassland climate ecological productivity, the process of grassland degradation and its restoration mechanism in northern Tibetan Plateau were discussed by the model of food-chain in which the environmental and human factors were corrected. The results of case study in Nierong County showed that： ① the climate trend of becoming warmer, more droughts and gales were conflicted with the restoration of grassland degradation, even under level of perfect management the climate ecological productivity was declined from 89. 3 kg/m^2 of 1983 to 71.8 kg/m^2 of 2003; ② from 1983 to 2003, the population increased fast, while the variation of livestock on hand was little, and the cost of its maintaining is rapid grassland degradation; ③ on the present condition of overgrazing, the livestock on hand can be maintained on the level of theoretical carrying capacity in 2033 by applying the mechanism of food-chain in grassland ecological system controlled with expected coefficients, so that to realize the policy of determining the quantity of livestock according to grass growth.     

Evaluating the influences of measurement time and frequency on soil respiration in a semiarid temperate grassland

Soil respiration(Soil R)is one of the largest CO2fluxes from terrestrial ecosystems to the atmosphere.The largely seasonal and daily patterns of Soil R in semiarid grassland ecosystems indicate that measurement time and frequency would have significant influences on the assessment of seasonal soil carbon release.Based on a three-year continuous measurement of Soil R in a semiarid grassland,we found that the Soil R value measured at around 10:00 o’clock local time was the closest to its daily mean,while the value at 14:00 o’clock was found to be the highest daily rate.A measurement frequency higher than every 10 days was necessary for estimating the seasonal Soil R and its temperature sensitivity(Q10)reasonably.Our study would be useful as guidelines for manual Soil R measurements and model data selection in semiarid temperate grasslands.     

Study on Landscape Pattern in the Jinshajiang Xerothermic Valley Using RS and GIS——Taking Yuanmou of Yunnan as an Example

Based on the data of Landsat-TM in 1986 and 2000 and with the applied indices of landscape pattern, an analysis is carried out on the landscape pattern with its evolution in Yuanmou County of Yunnan Province inside the Jinshajiang Xerothermic valley area and a forecast is given on the changing tendency of the landscape pattern in the county with Markov Chain Model. The result shows that the production landscape like irrigated farmland and construction land in town and country as well as ecological building landscape in boondocks were enlarged during 1986-2000. Also the patch shape was regularized and the patch shape index and dimensionality were degraded. The landscape pattern was tattered and the heterogeneity index and Evenness degree were increased but the dominance degree was degraded. The key elements with lower stability cover grassland, water body and bush land. The future transformation of landscape pattern will centralize in construction land‘‘s occupation in irrigated farmland, non-irrigated farmland and grassland, the transformation of non-irrigated farmland to irrigated farmland, forest and sparse wodland or orchard, construction land‘‘s occupation in grassland and cultivation of it into sloping non-irrigated farmland and forest‘‘s degeneracy to bush land, sparse woodland and grassland. The main measures to improve virtuous development of landscape in the xerothermic valley are suggested.     

Comprehensive eco-environmental effects of the shelter-forest ecological engineering along the Tarim Desert Highway

In this work, we report a comprehensive study about the eco-environmental effects of the shelter forest along the Tarim Desert Highway, including the effects on aeolian environment, soil, micro-climate, biodiversity, and groundwater. The results show that: (1) The movement of windblown sand near the ground surface was affected by the shelter forest. The wind speed and sediment transport rate in the shelter forest decreased by 64%―80% and 87.45%―99.02%, respectively. In addition, there were also significant changes in the sand flux structure, the sand grain size, and the deflation and deposition on the ground surface. (2) Compared to the natural mobile sand, the soil bulk density in the forest area decreased while the total salt content, the total porosity, and the water content increased. In addition, the soil fertility was significantly improved in the forest area, and showed the "first rapid, then slow" variation pattern. (3) The shelter forest showed positive effects on the micro-climate. Within the 6 m height above the ground, the air temperature in the shelter forest at different heights was lower than that in the mobile sand, while the air humidity was higher, while, the soil temperature was also lower in the shelter forest than mobile sand. (4) The number of soil microbial species increased significantly with the improvement of habitat in the shelterbelt. However, the population of different species was not distributed evenly across the surveyed area. (5) Currently, no significant effects of groundwater-pumping and forest-irrigation water have been found on the groundwater level and its salinity. The variation amplitude of both groundwater level and salinity was at the level of centimeters and 1g/L, respectively. No obvious variation trend has been observed.     

Glacier changes during the last forty years in the Tarim Interior River basin, northwest China

By comparing digitized glacier outlines from the Chinese Glacier Inventory (CGI) during the 1960s–1970s and Landsat Enhance Thematic Mapper (ETM+) images from 1999 to 2001, we investigated changes for about 7665 alpine glaciers among 11665 glaciers in seven sub-basins of the Tarim Interior River basin (TIRB). The results showed that the total glacier area was reduced by 3.3% from the 1960s/ 1970s to 1999/2001 and area losses for 1–5 km2 glaciers accounted for 48.3% of the total glacier area loss in the TIRB. However, the glacier area reductions varied from 0.7% to 7.9% among the seven sub-basins of the TIRB during the study period. The glacier area changing with altitude showed that the maximum contribution of area shrinkage occurred at 4900–5400 m. Data from 25 meteorological stations in the TIRB showed increases in both the annual mean air temperature and annual precipitation during 1960–2000. This indicates that the glacier shrinkage in the TIRB over the last 40 years was largely due to regional climate warming that enhanced glacier ablation and overcame the effects of increased precipitation on the glacier mass balance.     

Typical severe dust storms in northern China during 1954 —2002

Based on China抯 available daily observation data from 681 national meteorological stations from 1954 to 2002, a time series of typical severe dust storms in northern China is constructed in terms of the weather process, and the temporal and spatial distribution, and their evolution ten-dency is analyzed. The results indicate that there were 223 relatively typical severe dust storms in northern China from 1954 to 2002, among which the event on April 10—12, 1979 had the largest affected area. Closely associated with the geographical distribution of deserts, sandy lands and the tracks of strong cold air outbreaks, severe dust storms mainly occurred in the Tarim Basin, the eastern part of Northwest China and the northern part of North China. The season with the most frequent severe dust storms was spring, in which the frequency accounts for 82.5% in the whole year, while the least occurrence was in summer and autumn. Dur-ing the past 49 years, the highest frequency of severe dust storms occurred in the 1950s and the lowest was in the 1990s with a general descending tendency, but during 2000—2002 the occurrence was relatively increasing. On the average, the duration of severe dust storms was shortest in the 1990s, about 0.5—1 h shorter than that in the other 4 decades.     

Effect of microparticle properties on erosion in solid-steam mixtures

Based on a custom-built experimental apparatus, irregular microparticles of different sizes and microparticles of the same size but of different shape were added to wet steam, and erosion experiments were performed on polished medium carbon steel specimens. After the experiments, the eroded surfaces were analyzed by scanning electron microscopy and the degree of damage was evaluated by area loss. The results indicated that microparticle size significantly affects the degree of erosion damage. With an increase in size, variations in the method of damage mainly cause different degrees of damage on an eroded surface. Microparticle shape hardly affects the number of craters. Compared with spherical microparticles, irregular microparticles cause indentations more easily and result in more severe abrasion on the material’s surface.     

Mixed Frequency Ultrasound Phased Array

A mixed frequency ultrasonic phased array (MPA) was developed to improve the focus, in which the element excitation frequencies are not all the same as in a normal constant frequency phased array. A theoretical model of the mixed frequency phased array based on the interference principle was used to simulate the array‘s sound distribution. The pressure intensity in the array focal area was enhanced and the scanning area having effective contrast resolution was enlarged. The system is especially useful for high intensity focused ultrasound (HIFU) with more powerful energy and ultrasound imaging diagnostics with improved signal to noise ratios, improved beam forming and more uniform imaging quality.     

Experimental study on soil respiration of temperate grassland in China

Understanding of CO2 source and sink characteristics of terrestrial ecosystem is one of the most critical prob-lems at present, but till now, most studies concerning the natural terrestrial ecosystem carbon cycle are concentrated on the forest ecosystem. Not enough attention is paid to the natural grassland, especially to the temperate natural grassland, whose area is almost equal to that of tropical forest in the world. Little is known about the role of the grassland, which takes about 25% of…     

Spatial prisoner’s dilemma games with increasing size of the interaction neighborhood on regular lattices

We studied the evolution of cooperation in the prisoner’s dilemma game on a square lattice where the size of the interaction neighborhood is considered. Firstly, the effects of noise and the cost-to-benefit ratio on the maintenance of cooperation were investigated. The results indicate that the cooperation frequency depends on the noise and cost-to-benefit ratio: cooperation reaches a climax as noise increases, but it monotonously decreases and even vanishes with the ratio increasing. Furthermore, we investigated how the size of the interaction neighborhood affects the emergence of cooperation in detail. Our study demonstrates that cooperation is remarkably enhanced by an increase in the size of the interaction neighborhood. However, cooperation died out when the size of the interaction neighborhood became too large since the system was similar to the mean-field system. On this basis, a cluster-forming mechanism acting among cooperators was also explored, and it showed that the moderate range of the neighborhood size is beneficial for forming larger cooperative clusters. Finally, large-scale Monte Carlo simulations were carried out to visualize and interpret these phenomena explicitly.     

Natural diet and food habitat use of the Tarim red deer,Cervus elaphus yarkandensis

In order to determine the natural diet and food habitat use of Tarim red deer (Cervus elaphus yarkandensis), a study was carried out in Qiemo, Xinjiang , China from October 2000 to June 2001. Direct observation combined with faecal analysis method was used to determine the natural diet of red deer. 15 different species of plant were identified as food items. Among them, 13 species of plants were identified in winter diet and 9 species in summer. Red deer consumed a wider range of species in winter because of their nutrient requirement as well as the shortage of food and the scarcity of high-quality forage in the study area. Phragmites communis, Glycyrrhiza inflata and populus diversifo-lia were frequently present in the deer's diet whenever in winter and summer. Among them, Phragmites communis was the most abundant plant in the area and was included in the deer's diet. Observation on food selection frequency of captive Tarim red deer showed that Populus diversifolia was the first preferred species. However, this food was limited in the study area. Five food habitat types were found in the study area according to plant association: (1) Phragmites communis-Tamarix ramosissima association, (2) Tamarix ramosissima-Halostachys cas-pica association, (3) Tamarix ramosissima-Phragmites communis association, (4) Populus diversifolia-Phragmites communis association, (5) Burned area. Among them, Phragmites communis-Tamarix ramosissima association (reed meadow and reed marsh) was preferred to other types within the study area whenever in summer and winter. Dense reed cover could reduce the chance of detection from predator and obstruct attack from predator. Furthermore, under the cover of the reed, Tarim red deer was protected from direct solar radiation during the hours of hot day in summer. The reed meadow and marsh was preferred, presumably because the red deer could minimize their movements while searching for food, water and cover.     

Mapping wetland changes in China between 1978 and 2008

Four wetland maps for all China have been produced,based on Landsat and CBERS-02B remote sensing data between 1978 and 2008 (1978,1990,2000 and 2008).These maps were mainly developed by manual interpretation and validated by substantial field investigation in 2009.Based on these maps,we analyzed the 2008 wetland distribution in China and discussed wetland changes and their drivers over the past 30 years.(i) There were about 324097 km 2 of wetlands in 2008,for which inland marshes or swamps were the most common wetland type (35%),with lakes (26%) second.Most of the wetlands were in Heilongjiang,Inner Mongolia,Qinghai and Tibet,occupying about 55% of the national wetland area.(ii) From 1978 to 2008,China’s wetland area continually and significantly decreased,by about 33% based on changes in the wetland map.This was in sharp contrast to the increase in artificial wetlands,which increased by about 122%.Inland marshes accounted for the main loss of total wetlands from 1978 to 2000.From 2000 through 2008,riverine and lacustrine wetlands constituted the main wetland loss.Fortunately however,the rate of wetland loss decreased from 5523 to 831 km 2 /a.(iii) The change ratio of lost natural wetlands (including inland and coastal wetlands) to non-wetlands has decreased slightly over the past 30 years.From 1978 to 1990,nearly all natural wetlands (98%) lost were transformed into non-wetlands.However,the ratio declined to 86% from 1990 to 2000,and to 77% from 2000 to 2008.(iv) All Chinese provinces were divided into three groups according to patterns of wetland changes,which could relate to the driving forces of such changes.Tibet was completely different from other provinces,as it was one representative example in which there was a net wetland increase,because of global warming and decreased human activity since 1990.Increased economic development caused considerable wetland loss in most eastern provinces,and artificial wetlands increased.     

Analysis of the ecological environment around 10000 a BP in Zhaitang area,Beijing: A case study of the Donghulin Site

The transition from Paleolithic to Neolithic around 10000 a BP was a significant event in human history. We have analyzed the paleoenvironment in the Zhaitang area (Beijing) based on samples from an early Neolithic site at Donghulin. This site is considered to demonstrate the Paleolithic-Neolithic transition in this area. The site yielded burials with several human skeletons, known as "Donghulin man". We conducted a geomorphological and quaternary geological investigation in the Donghulin area, and also analyzed sediments and pollen, enabling us to discuss the living environment of the local people. Donghulin man lived mainly from 11100-9600 cal a BP; a period of warming following the Younger Dryas. The climate was good, the land was covered by dry temperate grassland, and later, wet temperate meadow steppe. "Donghulin man" usually inhabited the floodplain; this was flat, warm, and wet, with abundant plants and animals for a favorable living environment. Our research helps to rebuild the living environment of humans in the Beijing area around 10000 a BP, and to understand more about the environmental setting in north China during the Paleolithic-Neolithic transition.     

Natural diet and food habitat use of the Tarim red deer, Cervus elaphus yarkandensis

In order to determine the natural diet and food habitat use of Tarim red deer （Cervus elaphus yarkandensis）, a study was carried out in Qiemo, Xinjiang , China from October 2000 to June 2001. Direct observation combined with faecal analysis method was used to determine the natural diet of red deer. 15 different species of plant were identified as food items. Among them, 13 species of plants were identified in winter diet and 9 species in summer. Red deer consumed a wider range of species in winter because of their nutrient requirement as well as the shortage of food and the scarcity of high-quality forage in the study area. Phragmites communis, Glycyrrhiza inflata and populus diversifolia were frequently present in the deer＇s diet whenever in winter and summer. Among them, Phragmites communis was the most abundant plant in the area and was included in the deer＇s diet. Observation on food selection frequency of captive Tarim red deer showed that Populus diversifolia was the first preferred species. However, this food was limited in the study area. Five food habitat types were found in the study area according to plant association： （1） Phragmites communis-Tamarix ramosissima association, （2） Tamarix ramosissima-Halostachys caspica association, （3） Tamarix ramosissima-Phragmites communis association, （4） Populus diversifoliaPhragmites communis association, （5） Burned area. Among them, Phragmites communis-Tamarix ramosissima association （reed meadow and reed marsh） was preferred to other types within the study area whenever in summer and winter. Dense reed cover could reduce the chance of detection from predator and obstruct attack from predator. Furthermore, under the cover of the reed, Tarim red deer was protected from direct solar radiation during the hours of hot day in summer. The reed meadow and marsh was preferred, presumably because the red deer could minimize their movements while searching for food, water and cover.     

Molecular demographic history of the Hainan Peacock Pheasant (Polyplectron katsumatae) and its conservation implications

Knowledge of the historical responses of animal species to climate changes is critical for understanding their evolutionary history and conservation.During the late Quaternary period,Southeast Asia had a larger land area than today due to lower sea levels,and its terrestrial landscape was covered by extensive forests and savannah.To date,however,the general fluctuations in landscape distribution and their impacts on the demographics history of native species during the late Quaternary periods are still disputed.Specifically,the responses of animals on Hainan Island,which is located in the northernmost region of Southeast Asia,to historical climate changes,are poorly understood.Here,we performed a series of demographic analyses based on mitochondrial DNA genes to examine the response of the resident Hainan Peacock Pheasant(Polyplectron katsumatae) to climate change.Unlike the pattern of population collapse during the ice age and expansion during the warming period,we detected a historical expansion pattern in the demographic history of Hainan Peacock Pheasant through the late Quaternary period.It was concluded that the Hainan Peacock Pheasant survived through the late Quaternary periods,despite of its currently limited distribution and population size on Hainan Island.Anthropogenic influences must be considered in conservation planning due to their impacts on currently fragmented habitats and populations.     

Mechanism and operation parameters of a plasma-driven micro-particle accelerator

There is a large amount of micro debris ranging between millimeters and micrometers in space, which has significant influence on the reliability and life of spacecrafts through long-duration integrated impacts and has to be considered in designing a vehicle’s suitability to the space environment. In order to simulate the micro-impacts on exposed materials, a plasma-driven micro-particle accelerator was developed. The major processes, including the acceleration, compression and ejection of plasmas, were mode...     

Obtaining the best possible predictions of habitat selection for wintering Great Bustards in Cangzhou,Hebei Province with rapid machine learning analysis

Great Bustards （Otis tarda dybowskii） are one of the world＇s heaviest flying birds, occupying grassland hab- itats in Eastern Asia. Our study is located at the most eastern Chinese wintering site in Cangzhou, Hebei Province, where approximately 100 individuals are concentrated in a small area （17.53 km2）. Solid information is still lacking about the wintering areas for this subspecies in its eastern range and specifically for China. The study area consists of intensely used farmland in proximity to humans and is lacking con- servation areas and wild, open fields. Here, we present our results from two years of field data collection on habitat selection. We choose a machine learning model approach based on a rapid assessment methodology for the winter habitat of the Great Bustard. It is based on a spatial analysis of the best available environmental data, which were col- lected relatively quickly. These relatively new methods in ecology are based on an ensemble of decision trees and include algorithms such as TreeNet, Random Forest and CART used in parallel. In this study, we collected bustard droppings （presence only） from 48 locations between December 2011 and January 2012 and used the sites as training data. Droppings from 23 locations were collected in November 2012, and those sites were used as test data. We used eight environmental variables as predictor layers for the response variable of bustard presence/availability. We employed a Geographic Information System （ArcGIS 10.1and Geospatial Modelling Environment） and Google Earth. Compared with the other three models, we found that pre- dictions from Random Forest obtained a significant differ- ence between presence and absence. According to this model, the three most important factors for wintering Great Bustards are distance to residential area, distance to water pools, and farmland area. Our model shows that wintering Great Bustards prefer locations that are over 400 m away from residential areas, within 900 m of water pools and on areas o     

Wafer-scale graphene on 2 inch SiC with uniform structural and electrical characteristics

Wafer-scale graphene on SiC with uniform structural and electrical features is needed to realize graphene-based radio frequency devices and integrated circuits.Here,a continuous bi/trilayer of graphene with uniform structural and electrical features was grown on 2 inch 6H-SiC (0001) by etching before and after graphene growth.Optical and atomic force microscopy images indicate the surface morphology of graphene is uniform over the 2 inch wafer.Raman and transmittance spectra confirmed that its layer number was also uniform.Contactless resistance measurements indicated the average graphene sheet resistance was 720 /with a non-uniformity of 7.2%.Large area contactless mobility measurements gave a carrier mobility of about 450 cm2 /(V s) with an electron concentration of about 1.5×10 13 cm2.To our knowledge,such homogeneous morphology and resistance on wafer scale are among the best results reported for wafer-scale graphene on SiC.     

Simulation study of discharge processes in thunderstorm

The discharge characteristics in thunderstorm have been calculated by using a numerical cloud model. The results indicate that discharge processes occur when simulated thunderstorm developed at the stage of 30-45 min and initial locations of discharge mainly distributes between 4.4-4.8 km and 6.4-6.8 km above the ground (corresponding to ambient temperature of - 10℃ and -25℃. In simulated thunderstorm with a tripole electric structure, 10% of discharges occur between upper positive charge area and middle negative charge area and propagate upwards (from middle negative charge area to upper positive charge area); while, 90% of discharges occur between lower positive charge area and middle negative charge area and propagate downwards (from negative charge area to lower positive charge area). There is a positive correlation between updraft and discharge. The occurrence of discharge process needs hydrometer with a specified concentration and size in cloud (corresponding to ≥ 5 mm/h for precipitation on the ground). The maximum value of precipitation lags the peak of discharge number by a period of about several minutes. The discharge and its variation in thunderstorm are an important factor for monitoring and forecasting thunderstorm.