古尔班通古特沙漠生物结皮不同发育阶段中藻类的变化

通过在古尔班通古特沙漠南缘相同的地貌部位,选择裸沙、藻结皮、地衣结皮和苔藓结皮4种不同演替阶段中的生物结皮,研究了藻类的种类组成、优势种和生物量的变化.结果表明:(1)在结皮的不同演替阶段,藻类种类组成不同,其常见物种有一定的差异,如裸沙中藻类常见种是脆杆藻2(Fragilaria sp.2)、威利颤藻(Oscillatoria willei)和奥克席藻(Phormidium okenii),藻结皮的常见种是小聚球藻(Synechococcus parvus)、颗粒常丝藻 (Tychonema granulatum)、韧氏席藻(Phormidium retzli);同时在不同发育阶段亦存在一些特有种.(2)在裸沙发育到成熟生物结皮的过程中,藻类的优势物种也发生相应的变化.裸沙、藻结皮、地衣结皮和苔藓结皮的优势种分别是脆杆藻1(Fragilaria sp.1)、具鞘微鞘藻(Microcoleus vaginatus)、具鞘微鞘藻、眼点伪枝藻(Scytonema ocellatum)或集球藻(Palmellococcus miniatus).(3)藻类生物量在生物结皮不同演替阶段差异极显著(P<0.01),在裸沙中藻类生物量最低,随着生物结皮的逐渐发育,藻类生物量明显升高,地衣结皮最高,约是裸沙的8.3倍,当发育至苔藓结皮时,藻类生物量又有所下降.(4)在裸沙中基本为松散的沙粒,随着生物结皮的演替,丝状种类占明显的优势,尤其是具鞘微鞘藻,另外真菌菌丝和苔藓假根分别在地衣结皮和苔藓结皮中起着重要作用.     

北京怀沙河、怀九河自然保护区藻类组成及时空分布动态研究

于2004年3月至2005年3月,首次对北京怀沙河、怀九河自然保护区的藻类植物进行实地调查研究,通过对区内10个采样点360余份水生藻类植物标本鉴定、统计,分析了该区藻类植物的区系组成、藻类时空分布特点.研究表明,该区共分布有藻类植物9门105属226种,其中以硅藻、蓝藻、绿藻3门为主,并有少量裸藻、甲藻、黄藻、红藻、金藻等分布;藻类植物由于受水体化学物质组成和物理性质的影响,各采样点及不同月份的种类组成和数量均有差异.怀九河源头的物种丰度和硅藻多度均最大,洞台、黄坎丝状蓝藻占优势,怀柔水库绿藻占优势;在时间分布上,7月物种丰度和藻类多度最大.通过对区内藻类分布规律及大量污染指示藻类的分析表明,该保护区的水体已经受到了一定程度的污染.     

陕北黄土高原生物结皮中7种微藻的形态与分子生物学鉴定

陕北黄土高原实施退耕还林后,生物结皮成为其典型的地表覆盖类型,含有丰富的土生藻类,对固定土壤和促进养分循环具有极其重要的作用。该研究通过平板法与水滴稀释法对陕北黄土高原生物结皮土生藻类进行分离培养,采用光学显微镜观察结皮微藻的形态特征,并对单藻种进行分子鉴定,为黄土高原生物结皮藻类的研究奠定基础。结果显示:(1)共纯化获得7种结皮藻类,经光学显微镜初步确定,其中5株为绿藻、2株为蓝藻。(2)5株绿藻SM-2-1、DB-2-1、DB-2-2、SD-1和SD-2的序列长度分别为664 bp、663 bp、662 bp、589 bp和688 bp,GC含量分别为33.43%、49.47%、50.15%、50.76%和51.01%;2株蓝藻YJ-3、YJ-2的序列长度分别为570 bp和465 bp,GC含量分别为46.31%和49.03%。(3)序列比对并构建系统树分析发现,5株结皮绿藻可分为4个分支,分别为栅藻科(Scenedesmaceae)2株(DB-2-1和SM-2-1)、衣藻目(Chlamydomonadales)、环藻科(Sphaeropleaceae)、真眼点藻科(Eustigmataceae),但5株绿藻的5.8S+ITS2序列在属内差异小、非常保守,极易确定到属;2株蓝藻YJ-3和YJ-2聚在同一大类分支的伪鱼腥藻科(Pseudanabaenaceae)中,但分别归于不同的属。研究认为:5株结皮绿藻中DB-2-1藻株是Scotiellopsis属的一种、SM-2-1归于尖带藻属(Acutodesmus)、DB-2-2可能是红球藻属(Haematococcus)的一物种、SD-1是Ankyra属的一物种、SD-2归于真眼点藻属(Eustigmatos);2株生物结皮蓝藻中YJ-3可能是伪鱼腥藻科的一新物种、YJ-2可能是细鞘丝藻属(Leptolyngbya)亲缘关系较近的一新物种。     

半荒漠藻结皮中藻类的种类组成和分布

对宁夏沙坡头半荒漠藻结皮中２２种藻（其中蓝藻１０种,绿藻４种,硅藻６种,裸藻２种）进行了分离、鉴定;利用土壤磨片和电子探针揭示了藻体与基质间的结合方式;通过光镜、扫描电镜观察,从８个层次研究了藻类在结皮中的分布,并发现它们在微米间也呈“层片”分布规律,藻结皮由表及里依次为无机矿物质保护层（ｃａ．０．０２ｍｍ）、富藻层（ｃａ．０．０２～２．５ｍｍ）及疏藻层（２．５～５．０ｍｍ）;藻丝皮由表及里依次为     

宁夏沙坡头地区藻类及其分布

通过野外采样,室内培养、观察、鉴定,研究了沙坡头地区藻类多样性和分布特点,并为当地藻类资源利用提出建议。研究发现沙坡头地区藻类植物共计40种(包括1变型),其中蓝藻17种,绿藻10种,硅藻9种,裸藻4种,全为普生种,陆地生境中种类最丰富。亚气及陆地生境中蓝藻在种类数(除灌溉林地结皮)、生物量方面占主导地位;贫瘠水体生境中硅藻占主要地位,营养较丰富水体中绿藻处于优势地位。另外,陆生生境中多以具鞘微鞘藻Microcoleus vaginatus为优势种,小席藻Phormidium tenue为主要种。     

古尔班通古特沙漠生物土壤结皮对土壤种子库多样性与分布特征的影响

古尔班通古特沙漠地表广泛分布着生物土壤结皮,研究其覆盖下的土壤种子库,有利于了解生物土壤结皮的生态功能及当地植被更新与恢复的潜力。本文研究了该地区3种生物土壤结皮(藻结皮、地衣结皮、苔藓结皮)对土壤种子库分布特征和多样性的影响。结果表明:在种子库水平分布上,相比于裸沙,生物土壤结皮增加了种子库密度,且不同结皮类型对种子库的影响程度不同。地衣结皮土壤种子库的密度最大(5905±778粒·m~(-3)),其对种子的捕获作用最为明显,其次是苔藓结皮(1138±380粒·m~(-3)),藻结皮与裸沙无显著差异;水平分布上的差异与结皮的发育程度、种子的形态、不同生物土壤结皮空间分布的异质性有关。在垂直分布方面,结皮发育土壤,种子库集中分布在土壤浅层(0~2 cm),这与裸沙种子库的垂直分布特征基本一致,说明结皮的存在并没有显著改变种子库的垂直分布格局。此外,从裸沙到苔藓结皮,土壤种子库和地上植被的相似性不高(0.14~0.29),土壤种子库中的物种多样性和丰富度指数不及地上植被高。该研究区土壤种子库在植被恢复中的潜力可能较小,但相对于裸沙,生物土壤结皮的存在有益于土壤种子库的保持,对荒漠生态系统物种多样性的维持和稳定具有重要意义。     

杭州西湖浮游藻类变化规律与水质的关系

于2006～2007年对杭州西湖浮游藻类的种类及个体丰度进行初步研究,并依据<水和废水监测分析方法>对其水质现状进行了生物学评价.综合生物和理化指标数据,对杭州西湖的水质作一总体评估,并对西湖水中的物种多样性保护及水质的可持续利用提出了建议.共鉴定浮游藻类179种,其中蓝藻25种,隐藻1种,金藻3种,甲藻3种,黄藻5种,裸藻23种,硅藻41种和绿藻78种.分析了杭州西湖浮游藻类的组成和分布的特点,揭示出西湖浮游藻类的种类组成与西湖水质变化之间的关系.结果表明:藻类的组成和分布与水质变化规律基本吻合,西湖水质较整治前有明显的改善,一些清水藻类的物种逐步增多.     

基于克隆文库法研究古尔班通古特沙漠蓝藻多样性

该研究采用克隆文库法研究古尔班通古特沙漠藻类生物结皮中蓝藻多样性及分布。在古尔班通古特沙漠不同区域采集10份藻类结皮代表性土样,分别构建古尔班通古特沙漠蓝藻16S rRNA和psbA基因克隆文库,并进行系统发育分析,对蓝藻多样性和丰度与环境因子进行关联分析,研究蓝藻分布特点及影响因子。结果显示:(1)16S rRNA基因系统发育树中包括具有明确分类地位的蓝藻有6科10属(占总克隆文库的94.85%)和一个未分类蓝藻属,其中颤藻属(Oscillatoria)和微鞘藻属(Microcoleus)分别占克隆文库的42.54%和37.16%,为古尔班通古特沙漠蓝藻优势属;psbA基因系统发育树中仅鉴定有蓝藻类群4科4属,但优势属与前者结果一致。(2)10个样点藻类结皮中所含蓝藻种类不尽相同,但每个采样点都出现颤藻属和微鞘藻属,证明这二者是古尔班通古特沙漠藻类结皮中的优势属;且样点Gur2和Gur17中蓝藻种类较多,Gur3、Gur5和Gur9中种类较少,但Gur2、Gur3、Gur5和Gur17相对地理位置较近,表明地理位置不是影响蓝藻分布的主要因素。(3)RDA(Redundancy analysis)分析结果显示,微生物量氮(MBN)和土壤有机碳(SOC)对蓝藻多样性影响程度最大,其次是硝态氮(NO~-_3-N)、微生物量碳(MBC),全磷(TP)和全钾(TK)对其影响程度最小。研究表明,古尔班通古特沙漠不同区域沙漠蓝藻多样性和土壤理化性质具有空间异质性,综合分析可得沙漠中南部藻类结皮土壤营养最为丰富,蓝藻多样性较高,而东部和西部土壤营养较为贫瘠,蓝藻丰富度和多样性较低。     

新疆额尔齐斯河周丛藻类群落结构特征研究

周丛藻类是新疆跨境河流土著及特有鱼类重要的基础饵料资源,然而在该地区有关周丛藻类的研究目前尚属空白。有鉴于此,2012年7、8、10月对新疆跨境河流——额尔齐斯河全流域的周丛藻类群落结构进行了系统的调查分析。结果表明,周丛藻类隶属7门70属178种,由硅藻门、绿藻门、蓝藻门、裸藻门、黄藻门、金藻门和甲藻门组成,其中硅藻门有92种并占据绝对优势(51.7%),绿藻门49种(30.3%),蓝藻门20种(11.8%),裸藻门5种(2.8%),黄藻门3种(1.7%),金藻门2种(0.1%),甲藻门仅1种(0.6%),周丛藻类在不同月份的种类数存在显著差异(P0.01)。优势种主要为硅藻门的嗜盐舟形藻(Navicula halophila)、钝脆杆藻(Fragilaria capucina Desm)、极小桥弯藻(Cymbella perpusilla Cl)以及蓝藻门的皮状席藻(Phormidium corium Gom)等。研究期间,额尔齐斯河周丛藻类的密度和生物量的均值分别为1105.5×106 ind./m2和2692.0 mg/m2,不同月份间密度和生物量的分布差异不显著,但在空间分布上整体趋势为中下游地区高于上游地区。水温和营养盐成为影响其分布的主要环境因子。Simpson多样性指数、Shannon-Wiener多样性指数、Pielou均匀度指数和Margalef丰富度指数的平均值分别是0.38、3.04、0.66和2.55。运用多样性指数和藻类丰度对额尔齐斯河水质评价为轻度污染。     

稻鸭共育稻田水体藻类动态变化

稻鸭共育技术作为稻田复合种养模式,是有效控制常规稻作生态污染的重要技术途径.通过对不同时期稻田藻类群落种类、密度、生物量及环境因子进行测定,研究稻鸭共育稻田水体藻类动态变化规律.结果表明,稻田藻类群落包括蓝藻门、绿藻门、硅藻门、裸藻门,隐藻门及甲藻门共6门、38属、108种.随着水稻发育进程,藻类优势种单位生物量增加,前期皆以银灰平裂藻、栅藻等为优势种,后期对照以方鼓藻,灿烂颤藻,短小舟形藻等为优势种,而放鸭区优势种皆是裸藻门,包括绿色裸藻,尖尾裸藻,梭形裸藻等.稻鸭共育稻田水体藻类初期有个适应期,在放鸭后15d左右藻类密度及生物量显著下降,之后开始上升.与常规对照相比,稻鸭共育藻类密度及生物量较低,放鸭对稻田水体生态系统的影响主要体现在放鸭45d以后,表现为水体全P增加,全N减少,藻类多样性下降,优势种发生变化.环境因子与藻类相关分析表明,全磷与裸藻生物及藻类总生物量存在显著正相关,相关系数分别为0.697、0.625,而全N与藻类相关性不显著.     

新疆古尔班通古特沙漠南部沙垄不同部位藻类的垂直分布特征

 通过2005和2006年夏季两次对新疆古尔班通古特沙漠南部荒漠土壤中藻类植物进行采样、培养、鉴定和生物量测定，分析了该区沙漠沙垄不同部位藻类物种组成、优势种和生物量的垂直变化。结果表明：1）在不同地貌部位的不同层次中，藻类的种类组成均有所差异。2）藻类优势物种主要集中在0～2 cm层次中，2 cm以下的土层中藻类细胞很少，绝大部分土层以具鞘微鞘藻(Microcoleus vaginatus)为第一优势种，有些部位的土层中第一优势种是伪双点颤藻(Oscillatoria pseudogeminata)，如垄间低地和迎风坡的1～2 cm中。此外，大型集胞藻（Synechocystis crassa）、舟形藻 (Navicula sp.)、卵圆双眉藻(Amphora ovalis)数量也较多。3）除垄顶外，藻类生物量在其它3个部位不同层次的差异呈极显著水平（p<0.01），生物量由表及里锐减；在同一土层，藻类生物量基本表现为垄间低地最高，迎风坡与背风坡居中， 垄顶最低，不同地貌部位对藻类生物量影响呈显著或极显著水平。     

兰州五泉山的藻类及其分布

以兰州五泉山为该地藻种资源库,对其中水生、陆生生境中藻类的种类多样性、群落结构、分布特点进行了研究。结果发现该地藻类植物65种(含4变种),包括蓝藻、绿藻、硅藻和红藻,其中硅藻种类最多(29种),其它依次为蓝藻(24种)、绿藻(11种)和红藻(1种)。水体中共42种,硅藻最多,有26种,其次蓝藻8种,绿藻7种,红藻1种,不同水体中优势种和亚优势种不同。土壤生境中发现20种,蓝藻13种,绿藻4种,硅藻3种,且非洲席藻和小球藻分为优势种和亚优势种。7个种类在水、陆两大生境都有分布,而且它们主要是丝状蓝藻。     

柴达木盆地荒漠土壤蓝藻群落的初步研究

本文分析了柴达木盆地东部和中部具有代表性地区的丘陵、戈壁和沙丘的蓝藻种类组成、生物量及主要的土壤化学成分;采用了模糊聚类、系统聚类及多元线性回归等方法分析藻类的群落及其与环境因子的关系。共鉴定出21种蓝藻,其中6种为国内首次报道。研究表明:土壤含磷量、总盐量及与粘性和湿度有关的土壤结构是决定柴达木盆地蓝藻群落组成的重要因素。     

Chlorophytes of biological soil crusts in Gurbantunggut Desert, Xinjiang Autonomous Region, China

In this paper, chlorophytes collected from 253 biological soil crust samples in Gurbantunggut Desert in Xinjiang Autonomous Region, China were studied by field investigation and microscopical observation in lab. The flora composition, ecological distribution of chlorophytes in the desert and dynamic changes of species composition of chlorophytes in different developing stages of biological soil crusts are preliminarily analyzed. Results showed that there were 26 species belonging to 14 genera and 10 families, in which unicellular chlorophytes were dominant. There existed some differences in distribution of varied sand dune positions. The taxa of chlorophytes in leeward of sand dunes are most abundant, but the taxa in windward, interdune and the top of sand dunes reduced gradually. Chlorophytes were mainly distributed within the crust and the taxa of chlorophytes decrease obviously under the crust. In the devel-oping stages of the biological soil crust, species diversity of chlorophytes changed a little, but species composition pre-sented some differences. Chlorococcum humicola, Chlorella vulgaris, Chlamydomonas ovalis and Chlamydomonas sp. nearly existed in all developing stages of biological crusts. In several former stages of the biological soil crust there were spherical chlorophytes and filamentous ones. When moss crust formed, filamentous chlorophytes disappeared, such as Microspora and Ulothrix.     

Responses of the desert green algae,Chlorella sp. to drought stress

Desert algae are important components of the desert soil crust and play an essential role in desert soil ecosystem development. Owing to their special habitat, desert algae are often exposed to harsh environments, among which drought represents the most common stress. Green algae are considered to have drought tolerance potential; however, only a few studies have investigated this. In this study, we selected the green alga Chlorella sp., which was isolated from desert soil, and studied its physiological response to polyethylene glycol (PEG) 6000-induced drought stress. The results showed that drought stress can affect the photosynthetic efficiency of Chlorella sp., reduce its water retention ability, and destroy its ultrastructure. However, Chlorella sp. can cope with drought stress through a series of physiological regulatory strategies. Protective strategies include quick recovery of photosynthetic efficiency and increased chlorophyll content. In addition, induced synthesis of soluble proteins, lipids, and extracellular polysaccharide (EPS), and accumulation of osmotic regulatory substances, such as sucrose and trehalose, also contribute to improving drought tolerance in Chlorella sp. This study provides insights into the physiological responses of Chlorella sp. to drought stress, which may be valuable for understanding the underlying drought adaptation mechanisms of desert green algae.     

模拟降水对古尔班通古特沙漠生物结皮表观土壤碳通量的影响

水分是控制干旱区生态过程的重要环境因素,在水分受限制的生态系统中,降水通过改变土壤的干湿状态直接控制地下生物过程。生物结皮作为干旱区主要的地表覆盖物,能利用空气中有限的水分进行光合作用,其自身的碳交换是干旱区土壤碳通量的重要组成部分。通过模拟0(对照)、2、5 mm和15 mm 4个降水梯度,利用红外气体分析仪,对古尔班通古特沙漠中部生物结皮以及裸地表观土壤碳通量进行测量,探讨不同强度降水条件下生物结皮对表观土壤碳通量的影响,结果表明:(1)降水增加了生物结皮表观土壤碳释放量,2、5 mm和15 mm 3种降水处理累积碳释放量分别是对照的151.48%、274.97%、306.44%,并且随着降水后时间的延长,表观土壤碳通量逐渐减小直至达到降水前的水平;(2)生物结皮与裸地的表观土壤碳通量对降水的响应不同,对照和最大降水量下,生物结皮表观土壤碳通量大于裸地,但是2 mm和5 mm降水后,生物结皮表观土壤碳通量小于裸地,并且二者在2 mm降水时差异显著(P<0.05),而在其它降水处理下无显著差异;(3)连续两次降水事件,活性碳在初级降水后的大量释放使得二次降水后释放量下降,其中裸地碳释放量下降速率与降水强度正相关。本研究说明,在探求荒漠地区土壤碳交换对降水的响应规律时,应该考虑生物结皮的影响以及连续降水事件的差异。     

Effects of altered temperature and precipitation on desert protozoa associated with biological soil crusts

Biological soil crusts are diverse assemblages of bacteria, cyanobacteria, algae, fungi, lichens, and mosses that cover much of arid land soils. The objective of this study was to quantify protozoa associated with biological soil crusts and test the response of protozoa to increased temperature and precipitation as is predicted by some global climate models. Protozoa were more abundant when associated with cyanobacteria/lichen crusts than with cyanobacteria crusts alone. Amoebae, flagellates, and ciliates originating from the Colorado Plateau desert (cool desert, primarily winter precipitation) declined 50-, 10-, and 100-fold, respectively, when moved in field mesocosms to the Chihuahuan Desert (hot desert, primarily summer rain). However, this was not observed in protozoa collected from the Chihuahuan Desert and moved to the Sonoran desert (hot desert, also summer rain, but warmer than Chihuahuan Desert). Protozoa in culture began to encyst at 37 degrees C. Cysts survived the upper end of daily temperatures (37-55 degrees C), and could be stimulated to excyst if temperatures were reduced to 15 degrees C or lower. Results from this study suggest that cool desert protozoa are influenced negatively by increased summer precipitation during excessive summer temperatures, and that desert protozoa may be adapted to a specific desert's temperature and precipitation regime.     

Ecophysiological response and morphological adjustment of two Central Asian desert shrubs towards variation in summer precipitation

As part of global climate change, variation in precipitation in arid ecosystems is leading to plant adaptation in water-use strategies; significant interspecific differences in response will change the plant composition of desert communities. This integrated study on the ecophysiological and individual morphological scale investigated the response, acclimation and adaptation of two desert shrubs, with different water-use strategies, to variations in water conditions. The experiments were carried out on two native dominant desert shrubs, Tamarix ramosissima and Haloxylon ammodendron, under three precipitation treatments (natural, double and no precipitation, respectively), in their original habitats on the southern periphery of Gurbantonggut Desert, Central Asia, during the growing season in 2005. Changes in photosynthesis, transpiration, leaf water potential, water-use efficiency, above-ground biomass accumulation and root distribution of the two species were examined and compared under the contrasting precipitation treatments. There were significant interspecific differences in water-use strategy and maintenance of photosynthesis under variation in precipitation. For the phreatophyte T. ramosissima, physiological activity and biomass accumulation rely on the stable groundwater, which shields it from fluctuation in the water status of the upper soil layers caused by precipitation. For the non-phreatophyte H. ammodendron, efficient morphological adjustment, combined with strong stomatal control, contributes to its acclimation to variation in precipitation. On account of its positive responses to increased precipitation, H. ammodendron is predicted to succeed in interspecific competition in a future, moister habitat.