Carbon storage and vertical distribution in three shrubland communities in Gurbantünggüt Desert, Uygur Autonomous Region of Xinjiang, Northwest China

This study was carried out in the Gurbantünggüt Desert,Uygur Autonomous Region of Xinjiang,Northwest China in August,2009.To quantify the storage,contribution and vertical distribution patterns of plant biomass carbon (PBC)and soil organic carbon(SOC)in the study area,we investigated the carbon concentrations and its vertical distribution in three different desert shrubland communities dominated by Reaumuria soongorica,Haloxylon ammodendron+R.soongorica and Tamarix ramosissima+R.soongorica,respectively.We analyzed vertical distribution of root biomass carbon and soil carbon contents by excavating soil profiles for each dominated community.The results show that SOC is considerably the larger carbon pool in the soil layers of 1.0-3.0 m(the mean value of three shrubland communities is 38.46%)and 3.0-5.0 m(the mean value is 40.24%).In contrast,70.74%of belowground biomass carbon storage in 0-1.0 m layer,and its content decrease with increasing soil depth.The Haloxylon ammodendron+R. soongorica shrubland community has the highest belowground biomass carbon among three selected communities. This study highlights the importance of SOC stored in deep soil layers(lower than 3.0 m from the surface)in arid shrubland communities in the global carbon balance.In addition,it provides the data support for revealing deep soil solid carbon potential,and offers scientific basis for the further research in the carbon cycle of terrestrial ecosystem.     

干旱生态系统净初级生产力估算及变化探测

1 Introduction Arid western China stretches from west of Helan Mountains to south of the piedmont of Kunlun Mountains, covering about 2.50×106 km2 or 26.08% of the total territorial area of China. Its unique geographic location in the hinterland of Euras…     

相似优先比法研究巴丹吉林沙漠及周边地区地下水补给

位于中国内蒙古西部的巴丹吉林沙漠东部存在高大固定沙丘与湖泊共存的景观,湖泊中存在上升泉,且沙丘内部潮湿．沙漠以北的拐子湖和古日乃草原也有上升泉的出现．本文采用聚类分析中的相似优先比法结合水化学因素对巴丹吉林沙漠及其周边地区不同地点的水样进行分析,由此得出祁连山上的冰川融水与沙漠湖泊及以北地区的地下水相关性良好．     

Disturbance of meromixis in saline Lake Shira (Siberia,Russia): Possible reasons and ecosystem response

Saline Lake Shira (Southern Siberia, Russia) was meromictic through the observation period 2002–2015. During the under-ice periods of 2015 and 2016, complete mixing of the water column was recorded for the first time, and hydrogen sulphide temporarily disappeared from the water column of the lake; i.e. in those years the lake turned to holomixis. In the summer of 2015, a sharp increase in chlorophyll a, organic carbon, zooplankton, and phytoflagellates was observed in the lake, which was probably due to the release of nutrients from the monimolimnion. Purple sulfur bacteria completely disappeared from the lake after the first mixing in 2015, and did not reappear despite the restoration of meromixis in 2017. Thus, it was demonstrated that purple sulfur bacteria are sensitive to the weakening of the stratification of Lake Shira. Based on the data of the seasonal monitoring of temperature and salinity profiles over the period 2002–2017, it was presumed that the main cause of deep mixing in 2015 was the weakening of the salinity gradient due to strong wind impact and early ice retreat in the spring of 2014. In addition, it was shown that in previous years a significant contribution to the maintenance of meromixis was made by an additional influx of fresh water, which caused a rise in the lake level in the period 2002–2007. Thus, we identified a relationship between the stratification regime of the lake and the change in its level, which provides valuable information both for the forecast of water quality and for reconstruction of the Holocene climate humidity in this region of Southern Siberia from the sediment cores of Lake Shira.     

宁夏固原古近系寺口子组砂岩成因探讨*

宁夏固原寺口子组砂岩是中国古近纪内陆古环境研究的重要载体。通过岩性、沉积构造、石英颗粒表面微结构和粒度分布特征研究,对其成因进行了深入探讨。结果表明,古近系寺口子组砂岩由3个成因段构成:段Ⅰ为河流相沉积;段Ⅱ,即砂岩主体,为典型风成砂岩,沉积环境为风成沙丘和丘间地;段Ⅲ,初步推断其为湖相沉积。结合中国古近纪气候背景、研究区域地形条件及古风向,推断寺口子组砂岩主体风成沉积为行星风系控制下的沙漠沉积。     

塔里木沙漠石油公路沿线沙丘移动规律

通过对肖塘南2km试验路段100m×100m沙丘移动监测区1991年10月、1992年10月及1993年10月的3次详测,总体上可以认为,沙丘各几何形态参数间存在着较好的相关性。但限于沙源供应不足,沙丘发育具有不成熟性,从而使有些沙丘几何形态参数间不存在理论上应具有的相关性。沙丘高度与宽度有较好的线性正相关关系,与底面积及体积存在较好的指数正相关关系。从而可以认为,沙丘高度是反映沙丘形成、规模及发育程度的较好示量指征。沙丘移动方向随主风向的改变而改变,并与落沙坡方向有明显的不一致性。沙丘移动强度与高度、底面积成线性负相关关系,而与体积成指数负相关关系。在不同时期,上述关系可用相似的多元线性方程表示。沙丘前移过程中,沙丘形态既有由不成熟到成熟的正向演变又有由成熟向不成熟的逆向演变过程。     

火干扰对内陆荒漠湿地芦苇群落特征的影响

采用人为起火的方法,通过对比敦煌西湖荒漠湿地干扰区域和未干扰区域火后第一年芦苇群落特征的变化,探讨内陆荒漠湿地植被对火干扰的响应机制。了解火干扰对内陆荒漠湿地芦苇群落特征的影响。结果表明: 火干扰能够延长植物青绿期,促进了植被的个体发育;火干扰对草本层植被盖度、高度均有显著的负面影响,而对密度有显著的正面影响,对灌木层植被群落盖度、高度及密度均有正面影响,但影响不明显;火干扰后植物群落Shannon-Wiener多样性指数H′、Simpson多样性指数D和Simpson优势度指数C均减少,而Margalef物种丰富度指数Ma和Pielou均匀度指数J均增加;火干扰致使草本层植物群落多样性指数与研究区植物群落总体多样性指数变化趋势一致,致使灌木层物种H′、D和J指数均减少,而Ma和C指数均增加;火干扰致使植物群落地上总的生物量降低,主要使灌木层生物量降低,而使草本层生物量有所增加。     

库布齐沙漠生态治理的生态经济系统耦合分析

以典型生态脆弱区—库布齐沙漠为研究区,基于耦合度模型与耦合协调度模型,对 2008— 2017 年库布齐沙漠生态治理的生态经济系统耦合状况进行动态定量分析。结果表明：（1）2008— 2017 年,库布齐沙漠生态治理的生态经济系统耦合发展呈现出较高水平的平稳态势,耦合度大多 维持在 0.819 8 ~ 1 之间,且表现为先下降、后上升交替变化态势。（2）2008—2010 年,库布齐沙漠生 态治理的生态系统参数贡献度小于其社会经济系统参数贡献度,而 2011—2017 年则正好相反,且 两个系统的参数贡献度时序变化呈逐年递增趋势。（3）2008—2017 年,库布齐沙漠生态治理的生态 经济系统耦合协调度逐年增长,其耦合模式经历了从失调衰退类、过度发展类到协调发展类的变 化,且不同年份耦合模式类型差异显著。（4）2008—2012 年,系统耦合度处于高位状态,但耦合协调 度却不处于高位。2013—2017 年系统耦合度与耦合协调度变化趋势基本一致。未来库布齐沙漠 化地区应以推进生态经济化、经济生态化为关键突破点,实现区域生态经济可持续发展。     

Culturable bacterial diversity in hypolithic and peripheral soils in the west of the Hexi Corridor desert and its influencing factors

Microbes inhabiting the desert respond sensitively to environmental changes and may be an indicator for changes in the desert ecosystem.Hypolithic microbial communities in the desert play a vital role in ecosystem processes such as soil formation and organic matter accumulation.This study investigated and compared the culturable bacterial community structure and diversity in hypolithic and peripheral soils,and the interaction between bacteria and environmental factors.The bacteria were isolated using four different kinds of media and identified by 16S rRNA gene-sequence analysis.The numbers of culturable bacteria in the hypolithic and peripheral soils ranged from 3.0×104 to 3.6×105 CFU/g and from 6.5×104 to 5.3×105 CFU/g,respectively,indicating that the bacteria number in peripheral soil was higher than that in hypolithic soil.A total of 98 species belonging to 34 genera were identified,among which Arthrobacter,Bacillus,and Streptomyces were found dominantly and widely distributed.The community of culturable bacteria had obvious sample specificity,and the diversity in hypolithic soil was higher than that in peripheral soil.On the regional scale,the distribution of culturable bacteria and the environmental factors showed regular changes.On the local scale,the high heterogeneity of the hypolithic environment determined the specificity of the number and species of culturable bacteria.     

模拟增雨对荒漠土壤古菌多样性的影响

为探讨生长季增雨对荒漠土壤中古菌群落结构的影响,根据内蒙古磴口多年平均降水量,设计了模拟增雨试验,包括对照、2个增雨时段（生长季前期与后期）、每个时段2个增雨梯度（50%与100%）共计5种处理。增雨后提取荒漠土壤总DNA,对古菌群落编码16S rRNA基因的V4区进行Hiseq测序,分析古菌群落丰度、多样性及结构组成等。结果表明：该地区荒漠土壤中古菌群落均以奇古菌门（Thaumarchaeota）和广古菌门（Euryarchaeota）为优势菌群。NMDS和3种非相似性分析（MRPP、ANOSIM和Adonis）表明,生长季前期增雨未显著改变古菌的群落结构,生长季后期增雨显著改变了古菌的群落结构,当生长季后期增雨量达到100%时,古菌丰富度和多样性显著降低。与氨氧化过程密切相关的奇古菌门（Thaumarchaeota）相对丰度在生长季后期100%增雨条件下显著增加,将促进荒漠土壤的硝化过程。Mantel检验发现荒漠土壤古菌群落结构受土壤湿度、土壤温度、土壤硝态氮含量的影响。未来全球变化背景下降水格局变化将会对荒漠土壤古菌群落结构产生影响,并可能影响氮循环过程。