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1.
南亚热带气候下三种树木径向生长季节节律研究   总被引:15,自引:2,他引:13  
用带状测树器对南亚热带气候条件下的落叶树柚木(Tectona grandis L.f.)、喜树(Camptotheca acuminata Decne)和常绿树火烧花(Mayodendron igeum Kurz)16年生(测定开始时年龄)的立木的径向生长进行了6a的测定。研究结果表明,所测立木的年均胸围生长量在1.5~2.5cm(胸径生长量为0.48~0.80cm)之间,年间有一定的差异。年生长  相似文献   

2.
华北落叶松树干主要营养元素的空间分布   总被引:2,自引:0,他引:2  
用标准地-标准木-分层分割法测定了华北落叶松(Larix principis-rupprechtii Mayr)树干主要营养元素的分布规律,结果为:树干木质部水平方向N、P、K质量分数随年龄增加逐渐增大,Ca、Mg的逐渐减少。树干木质部垂直方向N、P、K质量分数随圆盘高度增加而增加,Ca、Mg变化较小。树皮N、P、K、Mg质量分数随圆盘高度的增加而增大,Ca有减小的趋势,但梢部质量分数较高;树干主要营养元素的质量分数大小排序为:K〉Ca〉N〉Mg〉P。不同个体不同组分质量分数之比分别为,皮/木 N:4.1~6.3,P:2.8~4.8,K:2.1~2.7,Ca:2.3~4.1,Mg:2.1~3.1;皮/心,N:4.9~8.6,P:5.2~7.5,K:2.2~2.7,Ca:2.6~3.8,Mg:2.0~3.2;边/  相似文献   

3.
小麦族几种近缘植物细胞在长期离体培养中的染色体变异   总被引:7,自引:0,他引:7  
对小麦及其4种近缘属间禾草进行了长时间(0.5~5.7年,个别8.6年)的愈伤组织培养,在继代过程中染色体数目的变异在染色体倍性低的簇毛麦(Haynaldia villosa,2n=2x=14)及新麦草(Psathyrostachys juncea,2n=2x=14)倾向于数目的增大;染色体倍性高的小麦(Triticun aestivun,2n=6x=42)趋向于数目的减少;而倍性居中的羊草  相似文献   

4.
利用植物他感作用灭螺效果的研究   总被引:60,自引:4,他引:56  
通过调查有螺滩地林下植被的演变和乌柏(Sapiumsebiperum)、枫杨(Pterocaryastenoptera)等滩地造林树种的灭螺效果发现,鸡矢藤(Paederiascandens)、水芹(Oenanthejavanica)的个体数量与钉螺的数量呈正相关关系,X2分别为12.8和11.2(a<0.02),而益母草(Leonurusartemisia)、问荆(Equisetumarvense)、酸模叶蓼(Rumexacetosa)、打碗花(Calystegiahederacea)、紫云英(Astragalussinicus)等与钉螺的数量呈负相关关系(a<0.02)经过一个汛期,枫杨、乌柏叶片使钉螺死亡率从草滩对照的2%升至43.3%和44.1%  相似文献   

5.
以小集水区定位测定方法,系统地测定了海南尖峰岭热带山地雨林更新林系统水文分量及水化学组成,分析比较了热带林生态系统降水化学含量及冠层的淋溶效应;其本实验区年降水量在1822.2mm~3225.8mm林冠层年均截留率为14.3%,年径流系数在0.33~0.71之间,降水养分元素输入总量均值为85.81kg/hm^2,a.林层的淋溶效应使养分元素增加57.04kg/hm^2,a。5~10月是降水,不化  相似文献   

6.
芋的组织培养   总被引:12,自引:1,他引:11  
1植物名称芋(Colocasiaesculenta)品种江汉芋(多子芋类型)。2材料类别茎尖及微芽。3培养条件分化培养基:(1)MS+6-BA3.0~5.0mg·L-1(单位下同)+NAA0.5;(2)MS+6.BA1.0~2.0+NAA0.5。诱导生根培养基:(3)MS+6-BA1.0~2.0+NAA0.1。培养基(1)、(2)中另加蔗糖30g·L-1,培养基(3)中加蔗糖10g·L1,琼脂6~7g·L-1,pH5.8~6.0,121℃高温高压灭菌15min左右。光照度155~2000lx,光…  相似文献   

7.
银王亮丝草的试管微繁殖   总被引:2,自引:0,他引:2  
1植物名称银王亮丝草(Aglaonema com-mutatumcv."SilverKing”),又名银王粗肋草、银王万年青、银皇帝。2材料类别带腋芽的茎段。3培养条件以MS为基本培养基。芽诱导培养基附加6-BA2.0~2.5mg·L-1(单位下同);芽增殖培养基附加6-BA4.0~4.5及NAA0.01~0.02;生根培养基采用3/4MS附加IBA3.0~3.5及GA33,0。所有培养基蔗糖及琼脂含量分别为3%和0.75%,pH值均调至5.8。培养温度26~28℃,光照8~10h·d-1,光照…  相似文献   

8.
香叶树果挥发油的化学成分和抗菌活性研究   总被引:9,自引:0,他引:9  
本文利用GC-MS技术确定了香叶树(Lindera communis)果挥发油18种成分的化 学结构和相对含量,这些化合物多为倍半萜烯类或其含氧衍生物,优势成分为双(2-羟乙 基)月桂酰胺(43.5%)和正癸酸(35.82%)。体外对12种真菌和细菌的药敏实验表明,该 挥发油具有很好的抑制活性,其中,对致病真菌的 MIC为 0. 03~0. 5 μl/ml,对污染霉菌 的 MIC为 1. 0~2. 0 μl/ml,对细菌的 MIC为 0. 02~0. 03 μl/ml。  相似文献   

9.
采用赖氨酸缺陷型酿酒酵母(Saccharomyces cerenisiae)L1原生质与肌醇缺陷型粟酒裂殖酵母(Schizosaccharomyces pombe)PM-5原生质体事例选育了葡萄酒发酵性能良好且具有降解苹果酸能力的酵母菌株。对融合子菌落形态、遗传稳定性、降解苹果酸能力和葡萄酒发酵性能进行了研究。结果表明:用促融合剂「30%聚乙二醇(MW6000)、0.02mol/L CaCl2和1  相似文献   

10.
对青海海北地区高山草甸主要植物群落小嵩草(Kobresiapygmaea)草甸、矮嵩草(K.humilis)草甸、藏嵩草(K.tibetica)沼泽化草甸地上生物量动态和能量分配的研究结果表明,不同植物群落年地上净生产量及其年际动态和主要植物类群生物量季节动态具明显的差异,其生物量季节动态可由如下模型表示:Wi=Ki/(1+exp(Ai-Bit))植物群落地上、地下生物量的垂直分布呈典型的金字塔和倒金字塔模式。小嵩草草甸、矮嵩草草甸和藏嵩草沼泽化草甸的地上净生产量依次为368.4gm-2a-1、418.5gm-2a-1和518.4gm-2a-1,所固定的太阳能值依次为6655.16kJm-2a-1、7610.09kJm-2a-1、9488.77kJm-2a-1。光能利用率分别为0.1097%、0.1256%、0.1568%。  相似文献   

11.
Substantial amounts of algal crusts were collected from five different desert experimental sites aged 42, 34, 17, 8 and 4 years, respectively, at Shapotou (China) and analyzed at a 0.1 mm microscale of depth. It was found that the vertical distribution of cyanobacteria and microalgae in the crusts was distinctly laminated into an inorganic-layer (ca.0.00–0.02 mm, with few algae), an algae-dense-layer (ca.0.02–1.0 mm) and an algae-sparse-layer (ca.1.0–5.0 mm). It was interesting to note that in all crusts Scytonema javanicum Born et Flah (or Nostoc sp., cyanobacterium), Desmococcus olivaceus (Pers ex Ach., green alga) Laundon and Microcoleus vaginatus Gom. (cyanobacterium) dominated at the depth of 0.02–0.05, 0.05–0.1 and 0.1–1.0 mm, respectively, from the surface. Phormidium tenue Gom. (or Lyngbya cryptovaginatus Schk., cyanobacterium) and Navicula cryptocephala Kutz.(or Hantzschia amphioxys (Ehr.) Grun. and N. cryptocephala together, diatom) dominated at the depth of 1.0–3.0 and 3.5–4.0 mm, respectively, of the crusts from the 42 and 34 year old sites. It was apparent that in more developed crusts there were more green algae and the niches of Nostoc sp., Chlorella vulgaris Beij., M. vaginatus, N. cryptocephala and fungi were nearer to the surface. If lichens and mosses accounted for less than 41.5% of the crust surface, algal biovolume was bigger when the crust was older, but the opposite was true when the cryptogams other than algae covered more than 70%. In addition to detailed species composition and biovolume, analyses of soil physicochemical properties, micromorphologies and mineral components were also performed. It was found that the concentration of organic matter and nutrients, electric conductivity, silt, clay, secondary minerals were higher and there were more micro-beddings in the older crusts than the less developed ones. Possible mechanisms for the algal vertical microdistribtion at different stages and the impact of soil topography on crust development are discussed. It is concluded that biomethods (such as fine species distribution and biovolume) were more precise than mineralogical approaches in judging algal crust development and thus could be a better means to measure the potentiality of algal crusts in desert amelioration.  相似文献   

12.
Wu L  Lan S  Zhang D  Hu C 《Microbial ecology》2011,62(3):715-724
Although many studies have been conducted on the ecological functions and ecophysiological characteristics of lichen soil crusts (LSCs), no explanation of these results has been provided based on crust structures. Using algae soil crusts (ASCs) as comparison, this work studied the small-scale vertical distribution of algal biomass and stratification in two types of LSCs, by combining the binocular stereomicroscope observations, microscope observations, plate cultures, chlorophyll analysis, and polysaccharides analysis. The results showed an obvious difference in the proportion but not the composition of the algae species between the ASCs and the two LSCs. Approximately 60% and 80% of the total algal biomass were concentrated in the top 1 mm of the soil profile and thalli in the ASCs and LSCs, respectively. This implies that symbiotic algae are the dominant species and primary organic carbon producers in LSCs, and the algal biomass decreased with the depth in both the ASCs and LSCs. The small-scale vertical distributions of the crustal algal biomass and polysaccharides were characterized by obvious successional stage, whereas these were unrelated to the crust type within the successional stage. Additionally, a large amount of fungi, which were always piercing the entire crusts, were observed in the LSCs, but only occasionally in the ASCs. These special structures are purported to cause the LSCs to achieve specific ecological functions, such as higher carbon fixation and greater compressive strength. High biomass, large living space, and advantageous resource utilization privilege suggest that the lichen association is mutualistic and the direction from ASCs to LSCs is developmental.  相似文献   

13.
Cyanobacteria and green algae present in biological soil crusts are able to colonize mineral substrates even under extreme environmental conditions. As pioneer organisms, they play a key role during the first phases of habitat colonization. A characteristic crust was sampled 3 years after installation of the artificial water catchment “Chicken creek”, thus representing an early successional stage of ecosystem development. Mean annual rainfall and temperature were 559 mm and 9.3°C, respectively. We combined scanning electron microscopy (SEM/EDX) and infrared (FTIR) microscopy to study the contact zone of algal and cyanobacterial mucilage with soil minerals in an undisturbed biological soil crust and in the subjacent sandy substrate. The crust was characterized by an approximately 50 μm thick surface layer, where microorganisms resided and where mineral deposition was trapped, and by an approximately 2.5 mm thick lower crust where mineral particles were stabilized by organo-mineral structures. SEM/EDX microscopy was used to determine the spatial distribution of elements, organic compounds and minerals were identified using FTIR microscopy and X-ray diffraction (XRD). The concentration of organic carbon in the crust was about twice as much as in the parent material. Depletion of Fe, Al and Mn in the lower crust and in the subjacent 5 mm compared to the geological substrate was observed. This could be interpreted as the initial phase of podzolization. Existence of bridging structures between mineral particles of the lower crust, containing phyllosilicates, Fe compounds and organic matter (OM), may indicate the formation of organo-mineral associations. pH decreased from 8.1 in the original substrate to 5.1 on the crust surface 3 years after construction, pointing to rapid weathering of carbonates. Weathering of silicates could not be detected.  相似文献   

14.
在水分极度匮乏的荒漠生态系统,凝结水是除降雨之外最重要的水分来源之一,它对荒漠生态系统结构、功能和过程的维持产生重要的影响。为探明半干旱沙区生物结皮表面的凝结水形成和蒸发特征,采用自制的微型蒸渗计(直径7 cm、高5 cm的PVC管)实验观测了不同类型地表(裸沙、浅灰色藻类结皮、黑褐色藻类结皮和苔藓结皮)对凝结水形成和蒸发的影响。结果表明:(1)观测期间共有20次凝结水形成记录,除降雨天气外,几乎每天都能观测到水分凝结现象;(2)不同类型地表凝结水总量依次为(1.998±0.075),(2.326±0.083),(2.790±0.058)和(3.416±0.068) mm,生物结皮表面的凝结水总量显著大于裸沙(P < 0.05);随生物结皮的发育,不同类型生物结皮表面的凝结水总量呈增加的趋势,凝结水总量之间差异显著(P < 0.05);观测期间不同类型地表日平均凝结水量依次为(0.100±0.003),(0.116±0.004),(0.140±0.002)和(0.171± 0.003) mm,不同类型地表日平均凝结水量之间差异极显著(P < 0.01);(3)凝结水形成过程的观测结果显示,凝结水19:00开始形成,23:00-凌晨1:00形成不明显,1:00-7:00继续形成,除浅灰色藻类结皮外,太阳升出后在黑褐色藻类结皮和苔藓结皮表面继续形成少量的凝结水;凝结水7:30开始蒸发,10:30到11:00之间结束蒸发,凝结水在裸沙和浅灰色藻类结皮中的保持时间显著大于黑褐色藻类结皮和苔藓结皮中的保持时间(P < 0.05);(4)凝结水的形成受大气温度、地表温度、空气相对湿度和大气地表温度差等气象因素的影响,但其形成过程不与某一个气象因素呈简单的线性关系。  相似文献   

15.
古尔班通古特沙漠生物结皮不同发育阶段中藻类的变化   总被引:6,自引:2,他引:4  
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.  相似文献   

16.
Red algae of the family Peyssonneliaceae typically form thin crusts impregnated with aragonite. Here, we report the first discovery of brucite in a thick red algal crust (~1 cm) formed by the peyssonnelioid species Polystrata dura from Papua New Guinea. Cells of P. dura were found to be infilled by the magnesium‐rich mineral brucite [Mg(OH)2]; minor amounts of magnesite and calcite were also detected. We propose that cell infill may be associated with the development of thick (> ~5 mm) calcified red algal crusts, integral components of tropical biotic reefs. If brucite infill within the P. dura crust enhances resistance to dissolution similarly to crustose coralline algae that infill with dolomite, then these crusts would be more resilient to future ocean acidification than crusts without infill.  相似文献   

17.
于作物生长季对东北黑土区典型农田中生物结皮的发育特征(类型、物种、厚度、覆盖度、生物量)进行分析,并使用数显推拉力计测定比较了无结皮土壤与不同生物量(以叶绿素含量表征,分别为5~15、15~25、25~35、35~50 mg·g-1)生物结皮层中土壤的崩解差异。结果表明: 1)东北黑土区农田中发育有藻和藓两类生物结皮,其中,毛枝藻和细叶真藓最为多见;藻结皮的厚度和生物量显著小于藓结皮,并总体上呈现由藻结皮逐渐向藓结皮演替的趋势。2)农田生物结皮的覆盖度、厚度和生物量与耕作扰动的频率和强度呈负相关,传统耕作农田中其平均覆盖度、厚度和叶绿素含量仅为27.8%、1.52 mm和6.49 mg·g-1,但在免耕地中可增加至83.5%、2.74 mm和34.16 mg·g-1。3)生物结皮显著削弱了土壤崩解作用,与无结皮土壤相比,4种生物量下生物结皮的土壤崩解速率分别显著降低了43.1%、50.1%、55.5%和59.8%,土壤最大崩解率分别显著降低了11.4%、17.7%、33.2%和36.6%。4)土壤崩解速率和最大崩解率均与生物结皮的厚度和生物量呈显著负相关,即生物结皮对土壤崩解的影响主要缘于其在发育过程中自身特性的改善及其覆盖后对表层土壤物理性质的改变。综上,随着保护性耕作技术推广后耕作扰动的减少,生物结皮在东北黑土区农田中有较高的发育潜力,它们发育后能削弱表层土壤崩解、提高土壤抗冲性,对农田土壤侵蚀防治具有积极意义。  相似文献   

18.
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。  相似文献   

19.
生物结皮粗糙特征——以古尔班通古特沙漠为例   总被引:1,自引:0,他引:1  
王雪芹  张元明  张伟民  杨东亮 《生态学报》2011,31(14):4153-4160
摘要:空气动力粗糙度可以反映地表气流与下垫面的相互作用。古尔班通古特沙漠是我国最大的固定、半固定沙漠,其间广泛分布的生物结皮在稳定地表和改善环境方面意义重大。对未经扰动的4种类型生物结皮进行表面微形态观察,并通过风洞实验确定动力粗糙度Z0和摩阻风速u*,结果表明:(1)不同生物结皮类型,其组成和表面微形态等都具有明显差异。藻结皮以表面致密光滑为显著特征,由藻类分泌物和藻丝体粘结细粒物质所形成;地衣结皮表面藻类和真菌形成的叶状体匍匐沙面生长,呈现三维生长方式,形成有明显凹凸的壳状覆被;苔藓结皮以苔藓植物体密集丛生为特点,地上部分出现了茎叶分化,有一定的柔韧性。(2)就动力粗糙度的大小而言,是按地衣结皮>藻类-地衣结皮>苔藓结皮>藻结皮的顺序排列的,Z0平均值依次为(6.5890.850)mm、(4.1790.239)mm、(2.5420.357)mm和(0.3930.220)mm,与定床裸沙面的(0.0420.019)mm相比,生物结皮Z0值提高了10—150倍。随着风速的增大Z0值有所减小,其中以地衣结皮的减小趋势较为明显。(3)由风速廓线对比发现,四类生物结皮对气流阻滞作用的差异主要局限于4 cm以下的高度范围,风速越大这种差异也越大。各类生物结皮摩阻风速u*随风速增大而增大,其中藻结皮的增大速率明显低于其它三类结皮,说明藻结皮随风速增大的阻滞效应较其它三类结皮要差。(4)在净风条件下,地衣结皮具有最好的防风效果,其次为藻类-地衣结皮和苔藓结皮,藻结皮最差。当生物结皮破损后,床面结构和气流性质将发生变化,对空气动力学粗糙度和摩阻风速产生的影响将有待于进行更深入的研究。  相似文献   

20.
抵抗风力胁迫是荒漠藻类适应干旱区环境的重要生物学机制,也是藻结皮能够拓殖流沙的必要条件之一,但有关藻类对风力胁迫的响应机理国内外尚无研究报道。以具鞘微鞘藻(Microcoleus vaginatus Gom.)人工结皮为实验对象,研究了不同强度风力吹蚀对结皮含水量、藻类活力、生物量、及其光合活性的影响。结果表明:不论低于当地起沙风(3m/s)还是高于起沙风(5m/s和7m/s)的风力吹蚀,结皮中藻类生物量均明显下降,而且结皮生物量的变化与风速大小和吹蚀时间呈线性关系(y=14.78+0.035a-1.48b,a风速,b时间,r2=0.79)。进一步分析发现,风力吹蚀后结皮中藻类活力并没有降低但主要光合色素和天线色素的含量普遍降低,叶绿素荧光(Fv/Fm)、表观电子传递速率(ETR)和净光合速率(Pn)明显下降,并且风速越大,降幅越大。这些结果说明风力胁迫对藻结皮生长和光合活性的影响主要是通过影响光合色素代谢合成和电子传递速率引起的,对其生命力没有明显影响。  相似文献   

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