赤水河上游典型植被中结皮苔藓的成土功能与总氮浓度特征

对赤水河上游典型植被中苔藓植物物种进行了调查,选取羽枝青藓(Brachythecium plumosum)、长帽绢藓(Entodon dolichocucullatus)、长喙灰藓(Hypnum fujiyamae)、皱叶麻羽藓(Claopodium rugulosifolium)和拟脆枝曲柄藓(Campylopus subfragilis)5种结皮苔藓进行成土功能与总氮浓度特征的研究。结果表明:(1)苔藓植物有14科18属26种(含变种、亚种),藓类植物占优势;(2)生物量为0.40~36.80 g·m-2,成土量为9.60~249.20 g·m-2,长喙灰藓的生物量和成土量高于其他结皮苔藓,对治理砂页岩区水土流失具有重要意义;(3)植物总氮(TN)浓度为1.20%~1.87%,土壤TN浓度为0.07%~0.50%,两者中长喙灰藓—土壤最高,拟脆枝曲柄藓—土壤最低,TN浓度随海拔的升高均出现先增大后减小的规律;(4)相关性分析表明,植物和土壤TN浓度差异大,最大相差倍数约17.14倍,但两者具有明显的正相关性。通过植物和土壤TN浓度特征的探究,为该地区生物地球化学作用的研究奠定了基础。     

固定沙丘结皮层藓类植物多样性及固沙作用研究

 根据对沙坡头固定沙丘生物结皮的物种调查、鉴定及盖度和生物量的研究,藓类植物共2科,7属,16种,以真藓（Bryum argenteum）为优势种。随着固沙时间的延长,生物结皮中藓类和藻类总盖度呈上升趋势;沿不同年代固定沙丘坡面向上等距离梯度,藓类盖度显著下降,而藻类盖度则平稳上升。对不同年代固定沙丘生物结皮优势种真藓的生物量和固沙量的测定表明,随沙丘固定年代的增加,真藓的生物量和固沙量增加,50年代固沙区结皮层真藓生物量是944.03 kg·hm-2,固沙量是3.925×104 kg·hm-2,但固沙率随时间的增加而减少。真藓的饱和吸水量与生物量呈正相关,50年代固定沙丘藓类结皮层可吸水7.06×103 kg·hm-2,说明藓类结皮层具有很强的吸水和保水能力,对于干燥少雨的沙漠地区具有十分重要的生态学意义。     

云南乃古石林5种藓类植物的水土保持作用

对云南乃古石林出现频度最高的5种藓类植物做了水土保持作用研究。5种藓类植物鳞叶藓（Taxiphyl-lum taxirameum（Mitt.）Fleisch.）、灰白青藓（Brachythecium albicans（Hedw.）B.S.G.）、小牛舌藓全缘亚种（Anomodon minor subsp.integerrimus（Mitt.）Iwats.）、中华细枝藓（Lindbergia sinensis（C.Muell.）Broth.）和拟扁枝藓（Homaliadelphus targionianus（Mitt.）Dix.et P.Varde）的生物量等测定结果显示：平均生物量为24.31～103.78 g/m2,平均饱和吸水率为818.24%～1462.02%,最高的达到1659.27%,最低的也达到了590.95%;平均饱和吸水量为216.92～791.80 g/m2,最高的达到1790.28 g/m2;平均成土率为47.32%～111.58%,最高的达到194.82%,最低的也达到19.33%;平均成土量为9.01～46.73 g/m2,最高的达到110.17 g/m2。小牛舌藓全缘亚种的平均饱和吸水量和平均生物量远远高于其他4种藓类,分别为：791.80 g/m2和103.78 g/m2。相关性分析表明,小牛舌藓全缘亚种的保水成土相关性最显著。它的干重与饱和吸水重、生物量与干重、生物量与饱和吸水量、生物量与成土量、饱和吸水量与成土量都是呈正极显著相关。研究结果表明,在乃古石林剑状喀斯特这种缺少土壤、干旱且保水能力弱的景区环境,藓类植物以其特有的生态功能在石林景观多样性、水土保持等方面具有十分重要的作用。     

黄土丘陵区藓结皮生物量测定方法及其随发育年限的变化

通过野外调查黄土丘陵区不同发育年限退耕地上藓结皮发育状况,结合室内测定,提出了藓类植物生物量测定的回归方程法.运用该方法测定了研究区9个不同发育年限藓类植物的生物量,并分析了其随发育年限的变化趋势.结果表明,研究区藓类植物个体微小,株高相同的藓类植物生物量变异很小,不同株高的藓类植物的株数与其生物量之间呈显著的线性相关关系(R2>0.96,n=7).因此,可以利用藓类植物株数与生物量之间的统计回归关系式估测生物结皮中藓类植物的生物量.用所建立的回归方程估测的研究区不同年限退耕地藓类植物生物量的绝对误差为1.3%～27.3%.研究区藓类植物生物量随结皮发育年限而变化,在退耕的前11年里,藓类植物生物量随发育年限的延长而增加,至11年时藓类植物生物量达到最大值(303.8g/m2),此后藓类植物生物量变化不大甚至还有下降趋势.     

黄土丘陵区藓结皮人工培养方法试验研究

以陕北黄土丘陵区自然发育的藓结皮为繁殖材料,通过室内人工培养研究了藓类植物孢子繁殖法(孢子法)、植物碎片营养繁殖(断茎法)以及生物结皮团块粉碎(碎皮法)接种等不同方法对藓结皮形成发育的影响,并对不同培养温度和土壤含水量条件下的藓结皮生长发育进行比较分析.结果表明,(1)相同培养条件下,碎皮法接种有利于藓结皮盖度的形成,在20℃、光照5 230 lx、光周期12 h/d条件下,经80 d培养,藓结皮盖度、密度分别达到76%和59株/cm2,且显著高于其他方法.(2)不同的接种量对藓结皮形成发育影响显著,采用碎皮法,接种量在500～750 g/m2水平下藓结皮的盖度和藓类植物的密度生长较高.(3)温度显著影响藓结皮的形成和发育,在试验条件下,17℃有利于藓结皮盖度、藓类植株密度和株高的生长.(4)土壤含水量只有>60%田间持水量时才有藓结皮形成,当土壤含水量达到超饱和含水量,并在近地面处有水汽存在时则更有利于藓结皮的形成和发育.     

荒漠结皮层藓类植物死亡对表层土壤水分蒸发和入渗的影响

水分是荒漠植物生长最主要的限制因子,藓类结皮作为荒漠土壤表层重要覆被物,对土壤水分蒸发入渗具有重要影响。研究表明,在全球气候变化背景下,不确定的降水格局变化导致结皮层藓类植物出现集群死亡现象,但这一过程对荒漠地表土壤水分蒸发与入渗过程的影响及其机理尚不清楚。以古尔班通古特沙漠齿肋赤藓结皮为研究对象,利用便携式渗透计和蒸发仪,研究了结皮层藓类植物死亡对土壤水分蒸发与入渗的影响。结果表明,与裸沙相比,藓类结皮的存在显著抑制了水分入渗,而藓类植物死亡的结皮层抑制作用最大,其初渗速率、稳渗速率和累积入渗量分别是活藓类结皮的39.89%、85.91%及64.48%,仅为裸沙的5.96%、13.13%及20.42%。在水分蒸发初期,裸沙的水分蒸发速率明显高于活藓类结皮和藓类植物死亡的结皮层,但藓类植物死亡的结皮层维持相对稳定的蒸发速率的时间长于裸沙和活藓类结皮,这也导致最终累计蒸发量以藓类植物死亡的结皮层最高、裸沙最低。可见,荒漠生物土壤结皮中藓类植物死亡会明显减少土壤水分入渗、增大水分蒸发,进一步影响荒漠表层土壤水分格局,从而影响生物土壤结皮与维管植物的水分利用关系。     

喀斯特石漠结皮细尖鳞叶藓的吸水机制及耐旱适应性

生物结皮是由隐花植物和相关土壤微小生物与表层土壤颗粒胶结而形成的复合体,与维管束植物覆盖一样,它是干旱区地表的重要覆盖类型。苔藓是荒漠植被演替过程中常见的一类先锋植物,同时也是生物结皮中生物量最大的2个类群之一。研究了结皮细尖鳞叶藓的吸水机制和耐旱适应性。结果表明:细尖鳞叶藓最大吸水量和持水率分别达到干重的9.74倍和700%以上,动力学总吸水过程的表观Km值和Vmax值分别为21.67g、10.42g·g-·1DW·min-1,外吸水过程为28.91g和8.56g·g-·1DW·min-1,内吸水过程为43.18g和1.76g·g-·1DW·min-1。可溶性糖含量从142.6mg·g-·1DW(CK)上升到344.3mg·g-·1DW,增长近2.4倍,而游离脯氨酸积累微弱。抗氧化酶SOD活性变化不明显,在0.04U·g-·1FW上下浮动;POD活性在PEG6000胁迫浓度在20%之前呈大幅度上升状态,以后趋于缓和,30%时达最高的131U·g-·1min-·1FW,增加近2倍;CAT活性的变化情况与POD变化趋势相同,但变化量较小。膜脂过氧化指标MDA先略有升高又逐步回落,说明细尖鳞叶藓抗氧化酶系统利用提高POD和CAT活性清除SOD在清除超氧阴离子自由基过程中产生的H2O2。因此,在喀斯特石漠化缺少土壤、极度干旱且保水能力弱的环境区域,结皮藓类植物以其特有的吸水特征、持水功能和抗旱机制等生态功能在石漠化治理、退化生态系统的恢复中具有十分重要的作用。     

喀斯特山区公路石漠化边坡苔藓生态功能

苔藓植物是喀斯特山区公路石漠化边坡的主要植物,其水分保持及重金属富集研究较少。选取黔S305省道石漠化边坡典型路段久长-开阳路段苔藓及其基质样品,研究苔藓对石漠化边坡水土保持能力及其对大气重金属(Pb、Zn、Cd)富集能力。结果显示:研究区内记录藓类植物5科12属33种,优势种为真藓、北地对齿藓、芽胞银藓、小酸土藓和缺齿小石藓,苔藓相对丰富度与石漠化边坡面积呈负相关。5种优势苔藓植物饱和吸水率为849%～1474%,成土率为464%～1025%,饱和吸水量是4.56×104～2.63×105kg·hm-2,成土量为4.01×104～2.45×105kg·hm-2。Pb、Zn、Cd在苔藓中的含量分别是基质中含量的2.25、3.98和2.49倍。基质中Pb、Zn、Cd的含量为16.86、54.58和0.30 mg·kg-1,均低于贵州省土壤环境背景值。相关分析显示,苔藓内Pb、Zn、Cd 3种元素与基质间相关性不显著(P0.05)。喀斯特石漠化边坡苔藓不仅具有较强的水土保持能力,而且对汽车尾气中重金属元素富集能力强,对喀斯特山区公路两侧生态环境及其环境净化具有重要作用。     

生物土壤结皮对雨滴动能的响应及削减作用

在野外调查采样的基础上,采用单滴雨滴法研究了黄土高原水蚀风蚀交错区不同类型生物结皮对雨滴动能的响应及削减作用.结果表明:生物结皮对雨滴动能的响应与其生物组成密切相关,击穿1 cm厚浅色藻结皮和80％盖度藓结皮的累积雨滴动能分别为0.99 J和75.56 J;相同组成的生物结皮对雨滴动能的响应与其生物量有关,生物量越大,击穿生物结皮所需累积雨滴动能越大;当藻结皮叶绿素a含量(表征藻结皮生物量)从3.32 μg·g-1增至3.73 μg·g-1时,对应的雨滴动能则由0.99 J增至2.17 J;当藓结皮的生物量从2.03 g·dm-2升至4.73 g·dm-2时,其对应的雨滴动能由6.08 J增至75.56 J;生物结皮演替过程中对雨滴动能的响应呈“S”形曲线变化.不同生物量的藻结皮对雨滴动能耐受能力的差异不显著;随单位面积苔藓生物量的增加,藓结皮对雨滴动能的耐受能力显著增加.藓结皮对雨滴动能的耐受能力在生物量2.03～4.73 g·dm-2之间呈线性增加;当藓结皮平均生物量达3.70 g·dm-2时,可以抗击62.03 J的雨滴动能.生物结皮对雨滴动能有显著的削弱作用,且这种削弱作用随着生物量的增加而增加.     

模拟氮沉降对鄂西南贫营养泥炭地两种藓类植物生长与分解的影响

以泥炭藓属(Sphagnum)植物为优势种的贫营养泥炭地是陆地生态系统重要的碳汇,其优势植物的生长与分解动态关系着贫营养泥炭地碳汇潜力,但有关氮沉降对贫营养泥炭地优势藓类植物生长与分解的影响还存在很大争议,并且氮沉降对亚热带贫营养泥炭地优势藓类植物生长与分解的研究鲜有报道。该研究以鄂西南贫营养泥炭地为研究对象,通过原位喷洒不同浓度的NH4Cl溶液,采用生物量收割法和分解袋法,探讨模拟氮沉降对泥炭藓(S.palustre)与金发藓(Polytrichumcommune)生长及分解的影响。研究结果表明:(1)氮沉降对两种藓类植物生长高度与生物量均有明显的影响,且两种藓类植物生长存在一定的氮沉降阈值,约为3g·m^–2·a^–1;(2)氮沉降对两种藓类植物生长影响程度不同,金发藓对氮沉降的响应灵敏度要大于泥炭藓;(3)高浓度氮沉降(6和12g·m^–2·a^–1)抑制了泥炭藓分解,低浓度氮沉降(3g·m^–2·a^–1)对泥炭藓分解的影响取决于分解时间,而所有浓度氮沉降均抑...     

黄土高原丘陵区生物结皮土壤的斥水性

采用滴水穿透时间法和酒精溶液入渗法,研究了黄土高原丘陵区浅色藻结皮、深色藻结皮、藻+少量藓结皮、藓+少量藻结皮、藓结皮5种不同发育阶段的原状生物结皮土壤的斥水性及其与土壤含水量的关系.结果表明: 生物结皮增加了土壤的斥水性,其斥水强度和持久性均显著增加.生物结皮土壤的斥水性随生物结皮的演替逐渐降低,当生物结皮中藓类植物盖度在20%以上时,斥水持久性显著低于藻结皮.生物结皮土壤的斥水性与土壤含水量及优势种密切相关,藓类生物结皮土壤的斥水性随着含水量的降低逐渐增加,藻类生物结皮土壤的斥水性随含水量的变化呈双峰曲线.     

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.     

Bacterial Communities in Soil Under Moss and Lichen-Moss Crusts

Biological soil crusts are symbiotic microbial communities formed by green algae, mosses, fungi, lichens, cyanobacteria and bacteria in different proportions. Crusts contribute to soil fertility and favour water retention and infiltration. However, little is known about the bacterial community structure in soil under the crusts. Soil was sampled under a moss crust (considered the MOSS group), lichen plus moss (considered the LICHEN group) and bare soil (considered the BARE group) and the microbial communities determined using nearly full 16S rRNA gene libraries. Bacteria belonging to seven different phyla were found and the Acidobacteria and Alphaproteobacteria were the dominant in each group. The crusts affected negatively the abundance of the Burkholderiales. The phylogenetic diversity and bacterial community membership were different in the LICHEN group compared to the BARE and MOSS groups, but not species richness and community structure. The beta diversity analysis also revealed a different bacterial community structure beneath the LICHEN and MOSS crusts, suggesting species-specific influence. This is a first insight into the effect of a biological soil crust on the bacterial community structure in an organic matter rich soil of a high altitude mountain forest.     

Germination and seed water status of four grasses on moss-dominated biological soil crusts from arid lands

Biological soil crusts dominated by drought-tolerant mosses are commonly found through arid and semiarid steppe communities of the northern Great Basin of North America. We conducted growth chamber experiments to investigate the effects of these crusts on the germination of four grasses: Festuca idahoensis, Festuca ovina, Elymus wawawaiensis and Bromus tectorum. For each of these species, we recorded germination time courses on bare soil and two types of biological soil crusts; one composed predominantly of the tall moss Tortula ruralis and the other dominated by the short moss Bryum argenteum. On the short-moss crust, the final germination percentage was about half of that on bare soil. Also, the mean germination time was 4 days longer on short-mosses than on bare soil. In contrast to the short-moss crust, the tall-moss crust did not reduce the final germination percentage but increased the mean germination time. Similar results were observed in the four grasses studied. To investigate the mechanism by which moss crusts affected germination, we analyzed the water status of seeds on bare soil and moss crusts. Six days after seeding, the water content of seeds on bare soil was approximately twice that of seeds on tall- or short-moss crust. Analysis of the time course of changes in seed weight and water potential in Bromus tectorum revealed that overtime seeds on tall mosses reached higher water content than those on short mosses. The increase in the water content of seeds on tall mosses occurred as the seeds gradually fell through the moss canopy. Taken together, our results indicate that biological soil crusts with distinct structural characteristics can have different effects on seed germination. Furthermore, this study revealed that a biological soil crust dominated by short mosses had a negative effect on seed water status and significantly reduced seed germination.     

Testate amoebae community structure in the moss biotopes of streams

The specific composition and community structure of testate amoebae in the moss biotopes of streams were studied in the Sura River basin (Middle Volga region). Twenty-nine species and forms were identified. The eurybiont species Trinema enchelys, Euglypha ciliata glabra, Centropyxis aerophila, Tracheleuglypha dentata, Crythion dubium, Centropyxis cassis, Trinema complanatum, and Trinema lineare are dominant. The species richness varies from 2 to 11 species per sample, the abundance is 100 to 4000 ind./g of absolutely dry moss. The degree of forest covering in the basin, hydrochemical peculiarities (the amount of biogenic elements and water hardness) of streams, the size of streams, and environmental contamination are possible factors that determine the specific character of the composition and structure of testate amoebae communities.     

Lentic macroinvertebrate assemblage structure along gradients in spatial heterogeneity, habitat size and water chemistry

Littoral zones of small water bodies are spatially heterogeneous habitats, harbouring diverse biotic communities. Despite this apparent heterogeneity, many studies have stressed the importance of water chemistry in determining the structure of littoral macroinvertebrate assemblages. The purpose of this study was to consider the relative importance of several spatial and water chemistry variables in explaining the patterns in the structure of macroinvertebrate assemblages in 21 lentic water bodies in northeastern Finland. Water bodies were selected to represent various habitat conditions ranging from small permanent bog ponds to small forest lakes. According to canonical correspondence analysis (CCA), the most important environmental factors related to assemblage composition were water body area, moss cover, total nitrogen and water hardness. In general, species composition in small bog ponds tended to differ from that in larger lakes with forested shoreline. Total species richness was best explained by a composite variable (PCA) describing physical habitat heterogeneity, species richness being lowest in small bog lakes with simple bottom structure and low amount of aquatic plants. Species numbers in dominant functional feeding groups were related to different environmental factors. Shredder species richness was best explained by a regression model incorporating total nitrogen and the amount of organic matter, both of which were negatively related to the number of shredder species. The number of gatherer species increased with mean substratum particle size. Scraper species richness was negatively affected by the abundance of detritus and positively affected by depth, and a model including both variables explained most of the variation. Variation in the number of predatory species was best explained by a regression model including moss cover and lake area.     

腾格里沙漠东南缘苔藓结皮对荒漠土壤种子库的影响

对腾格里沙漠东南缘沙坡头人工植被区和天然植被区苔藓结皮种子库进行了研究.结果表明,土壤种子库密度随着苔藓结皮的发育呈现增加的趋势,天然植被区是24年生人工植被区的3.4倍.种子库中共发现12种植物种子,分属于6科,其中1年生草本植物占70%以上.人工植被区未发现有多年生草本的植物种子,天然植被区多年生草本占20%,半灌木植物在人工植被区和天然植被区分别占20%和10%.人工植被区土壤种子库物种丰富度指数相对较低,而天然植被区物种丰富度指数是人工植被区的2倍;人工植被区土壤种子库物种多样性指数随着结皮的发育略有下降,天然植被区的多样性指数最高,为0.693;人工植被区土壤种子库物种相似性指数为1,相对较高,而人工植物区与天然植被区的物种相似性指数为0.4.苔藓结皮的出现增加了地表粗糙度,有利于对种子的捕获,同时显著地改善了土壤环境,有利于更多植物的定居.     

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.     

黄土丘陵区生物土壤结皮层水稳性

采用改进的土壤水稳性团聚体数量测定方法,研究了黄土丘陵区不同组成和生物量的生物结皮层水稳定性.结果表明：生物结皮层的水稳定性与其生物组成有关,苔藓结皮的水稳定性显著高于藻结皮,震荡390次后,苔藓结皮的厚度和质量损失率仅分别是藻结皮损失率的47.3%和40.1%;生物结皮层水稳定性与生物结皮的生物组成有关,60%以上苔藓覆盖度的生物结皮的稳定性最高,质量和厚度损失率分别是藻结皮（无苔藓覆盖）损失率的28.6%和22.7%;生物结皮层水平方向结构水稳定性显著大于垂直方向,震荡390次后,苔藓结皮的面积损失率仅为厚度损失率的6.4%.试验分析证实,生物结皮层是一种水平方向稳定性极强的层状结构体,这一结构特性增强了其抗风蚀和水蚀的能力.