外来种互花米草和土著种芦苇空中凋落物氮动态的比较研究

土壤氮含量是限制植物生长的重要因素, 所以入侵植物要入侵成功必须突破土壤氮限制的瓶颈。近年来, 外来种互花米草(Spartina alterniflora)在中国海岸带盐沼中快速取代土著种芦苇(Phragmites australis), 引起了多方面的生态学后果。为了解互花米草与本地种芦苇空中凋落物的氮含量是否存在差异及产生这种差异的机制, 2003年11月至2004年4月, 作者在长江口九段沙湿地对互花米草与芦苇空中凋落物氮含量(单位面积凋落物的总氮量, N g/m²)进行了测定, 结果表明互花米草的氮含量比芦苇高。在空中分解过程中, 互花米草茎(包括叶鞘与秆)凋落物的氮含量显著上升, 但芦苇茎凋落物的氮含量显著降低。2006年1月, 又对中国海岸带6个地点的盐沼中互花米草的凋落物进行取样和氮浓度测定, 发现互花米草空中叶鞘与秆的老凋落物(2004年冬季产生)的氮浓度均显著高于其新产生的凋落物(2005年冬季产生), 表明在空中分解过程中, 互花米草叶鞘与秆凋落物氮含量增加具有普遍性。进一步的温室受控实验结果表明, 互花米草凋落物氮含量增加可能是由腐生固氮微生物引起的。以上结果表明,互花米草取代芦苇后, 改变了空中凋落物的氮动态, 增加了生态系统中氮的输入, 可能有利于互花米草的快速扩张。     

Common Reed Phragmites australis: Control and Effects Upon Biodiversity in Freshwater Nontidal Wetlands

Phragmites australis (common reed) has expanded in many wetland habitats. Its ability to exclude other plant species has led to both control and eradication programs. This study examined two control methods—herbicide application or a herbicide‐burning combination—for their efficacy and ability to restore plant biodiversity in non‐tidal wetlands. Two Phragmites‐dominated sites received the herbicide glyphosate. One of these sites was burned following herbicide application. Plant and soil macroinvertebrate abundance and diversity were evaluated pre‐treatment and every year for four years post‐treatment using belt transects. The growth of Phragmites propagules—seeds, rhizomes, and rooted shoots—was examined in the greenhouse and under bare, burned, or vegetated soil conditions. Both control programs greatly reduced Phragmites abundance and increased plant biodiversity. Plant re‐growth was quicker on the herbicide‐burn site, with presumably a more rapid return to wetland function. Re‐growth at both sites depended upon a pre‐existing, diverse soil seed bank. There were no directed changes in soil macroinvertebrate abundance or diversity and they appeared unaffected by changes in the plant community. Phragmites seeds survived only on bare soils, while buried rhizomes survived under all soil conditions. This suggests natural seeding of disturbed soils and inadvertent human planting of rhizomes as likely avenues for Phragmites colonization. Herbicide control, with or without burning, can reduce Phragmites abundance and increase plant biodiversity temporarily. These changes do not necessarily lead to a more diverse animal community. Moreover, unless Phragmites is eradicated and further human disturbance is prohibited, it will likely eventually re‐establish dominance.     

Accumulation of Metals and Boron in Phragmites australis Planted in Constructed Wetlands Polishing Real Electroplating Wastewater

The concentration of metals (Al, Cu, Fe, Mn, Ni, Zn) and B were determined in the above- and belowground biomass of Phragmites australis collected from the microcosm constructed wetland system used for the polishing of real electroplating wastewater. Translocation factor and bioconcentration factor were determined. Pearson correlation test was used to determine correlation between metal concentration in substrate and above- and belowground parts of Phragmites australis. The obtained results suggested that Phragmites australis did not play a major role as an accumulator of metals. It was observed also that the substrate could have exerted an effect on the translocation of Ni, Cu, Zn and Mn. The analysed concentrations of metals and B in biomass were in the range or even below the concentrations reported in the literature with the exception of Ni. The aboveground biomass was found suitable as a composting input in terms of metals concentrations.     

芦苇生态型研究进展

芦苇生态幅极广,适生于多种生境类型。不同的环境选择压力如水深、盐度、养分、气候等交互影响致使芦苇个体及种群间发生不同程度的分化和变异,形成了形态、生理或遗传上互有差异、异地性的不同生态型。尽管基于芦苇表型变异以及遗传变异进行生态型划分的研究已开展很多,但针对芦苇生态型变异规律及其可能的形成机制的认知仍存在较多分歧。在总结近年来有关芦苇生态型研究文献的基础上,通过对影响芦苇生态型变异的主要因素——环境因素和遗传因素的分析,以期为芦苇生态型的划分及其可能的形成机制提供新的研究思路。(1)空间尺度的选择应成为研究者分析、划分芦苇生态型的首要定位。在较大的地理空间尺度上,高度异质性的生境导致某些性状的变异式样具有相对的不连续性,可作为不同芦苇生态型鉴别与描述的主要依据;(2)在合理的尺度定位、取样设计和统计分析的基础上开展的表型变异研究,及进一步基于种群水平的分子标记研究(分子指纹特征或特有等位基因),可为芦苇生态型的鉴定、划分提供更为可靠的参考数据,并且可以甄别生境差异(环境响应)和遗传变异对芦苇不同生态型分化的贡献;(3)应同时进行不同生态型的特定性状与功能(株高、茎粗、生物量、生理抗逆性、水体污染物净化能力等)的定位,推动优良基因型的选育与扩繁。     

北京地区芦苇资源状态及其多样性

为探明北京地区芦苇(Phragmites australis)的资源状态和多样性, 实地考察北京主要河流、湿地和水库, 发现北京地区芦苇总生长面积已超过600 hm²。芦苇染色体倍性以八倍体为主, 四倍体次之。在面积较大的湿地内, 八倍体单一芦苇群落占据优势地位; 而在城市的浅河内有形态和遗传性多样的混合种群。研究表明, 植物性状和倍性水平之间无显著相关性。在小清河发现了6种形态各异的芦苇克隆, 均属于叶绿体DNA片段的P单倍型; 其单倍体基因组大小为(0.499±0.019) pg, 变异系数为3.8%。这表明表型与单倍型之间也不具相关性。此外, 发现1个具有变叶特性的芦苇, 将其命名为金条芦苇。北京地区芦苇形态和遗传多样性为研究芦苇基因型与环境适应性之间的关系提供了珍贵的资源。     

长江口九段沙盐沼湿地芦苇和互花米草生物量及碳储量

2010-2012年,采用野外采样和实验室测定相结合的方法,研究了长江口九段沙芦苇、互花米草植被带生物量的季节动态和碳储存能力.结果表明:两种植物生物部分(地上、地下、枯立物生物量之和)的有机碳储量均为秋季最高、春季最低.地上活体互花米草单位面积的平均碳储量(445.81 g·m-2)高于芦苇(285.52 g·m-2),芦苇枯立物的平均碳储量(203.15 g·m-2)低于互花米草(315.28 g· m-2),但芦苇区土壤表层(0 ～30 cm)有机碳储量(1048.62 g·m-2)约为互花米草区(583.33 g· m-2)的2倍.芦苇区的碳储存能力(3212.96g· m-2)总体上高于互花米草区(2730.42 g·m-2).表明保护芦苇群落对于维护盐沼湿地的碳汇功能具有重要意义.     

Morphology and Genetic Diversity of Phragmites australis in Beijing

为探明北京地区芦苇(Phragmites australis)的资源状态和多样性, 实地考察北京主要河流、湿地和水库, 发现北京地区芦苇总生长面积已超过600 hm²。芦苇染色体倍性以八倍体为主, 四倍体次之。在面积较大的湿地内, 八倍体单一芦苇群落占据优势地位; 而在城市的浅河内有形态和遗传性多样的混合种群。研究表明, 植物性状和倍性水平之间无显著相关性。在小清河发现了6种形态各异的芦苇克隆, 均属于叶绿体DNA片段的P单倍型; 其单倍体基因组大小为(0.499±0.019) pg, 变异系数为3.8%。这表明表型与单倍型之间也不具相关性。此外, 发现1个具有变叶特性的芦苇, 将其命名为金条芦苇。北京地区芦苇形态和遗传多样性为研究芦苇基因型与环境适应性之间的关系提供了珍贵的资源。     

Leaf litter decomposition in an ephemeral karst lake (Chaney Lake,Kentucky, U.S.A.)

Litter decomposition in temporary aquatic environments has not been experimentally studied as much as it has in perennial systems. However, litter is likely a critical resource for organisms inhabiting ephemeral aquatic habitats. In this study, we used litterbags under different conditions of submergence and water physical and chemical properties/characteristics to study mass and nutrient losses of terrestrial materials in an ephemeral karst lake in south-central Kentucky (USA). In the first experiment, which was designed to compare decomposition rates in submerged and dry sites, total mass and carbon declined more rapidly in the litter at fully submerged sites than in dry sites. In the second experiment, which was designed to compare decomposition rates in two different submerged environments, total mass and carbon showed similar decomposition trends between the two submerged areas with different seasonal temperature patterns. Nitrogen patterns were variable but in general nitrogen levels increased in the litter in both experiments over a period of several months. These results are similar to those found in some perennially inundated systems and indicate that litter decomposition dynamics in this temporary lake can be greatly affected by lake hydrology. Year-to-year variations in hydrology may thus have strong impacts on nutrient and energy release within this system, which may affect the organisms within this karst lake and in other areas of the karst ecosystem that are ecologically connected to it.     

有机螯合剂在芦苇富集转运铅中的作用

近年来,随着人口的激增和工农业生产的迅猛发展,土壤和水体的重金属污染日益加重。植物提取技术作为一种新兴的修复重金属污染的治理方法,以其潜在的高效、经济及其生态协调性等优势被广泛关注。其研究主要是利用对某些重金属具有超富集能力的超积累植物或耐性植物,配合添加一定量的鳌合剂来进行修复。由于超富集植物一般生长缓慢且生物量小,因此利用对重金属有一定耐性的生长快速、生物量大的植物来进行修复更具有广阔的应用前景。芦苇作为一种多年生禾本科植物,具有生物量大、耐受性强和分布广泛的特点,已经被研究和应用到环境治理的多个领域。本文通过户外盆栽沙培试验,研究了铅胁迫下,分别在 2-10 mmol·L-1共 5 个浓度梯度的 EDTA 和柠檬酸两种鳌合剂处理下,芦苇生长对铅的响应以及对铅在植物体内的富集转运的影响。初试结果表明∶在 4mmol·L-1 Pb(NO3)2胁迫下,施加 EDTA 对芦苇的生长具有一定的抑制作用。当 EDTA 浓度为 10 mmol·L-1 时,透灌 7 d 后,其芦苇根和地上部(茎和叶)干重分别是空白试验(未加螯合剂)的 68.0% 和 72.3%,而柠檬酸对植物生物量的影响较小。同时,EDTA 和柠檬酸对铅在芦苇体内的富集和转运,都起到了促进作用。分别施加 10 mmol·L-1的 EDTA 和柠檬酸,其植物根部和地上部的铅浓度分别为空白试验的 7.4 倍、10.7 倍、2.5 倍、3.5 倍。EDTA 在促进植物体内铅的吸收和从根部到地上部的转运效率方面要比柠檬酸更为有效。尽管像 EDTA 和柠檬酸这样的鳌合剂能够在一定程度上提高植物的富集效率,但考虑到螯合剂自身对植物的毒害性、对环境的潜在威胁以及运行成本等方面因素,目前,寻找高效、廉价、可生物降解的鳌合剂以及大生物量的耐性植物成为植物提取技术的研究重点。     

东北地区芦苇植硅体的变化特征

深入研究芦苇(Phragmites australis)不同生长期植硅体的形态变化规律, 对提高古植被重建精度、探讨植硅体形成机理具有重要意义。该文对东北地区12个样点的芦苇叶片进行研究, 选取长势相近、叶片大小一致的芦苇叶片, 用湿式灰化法提取植硅体并对其进行分类和命名。研究发现, 芦苇植硅体主要有5种类型, 在不同生长期内和不同温湿度组合下, 其植硅体类型组合基本无变化, 说明同种植物的植硅体类型组合具有稳定性, 据此可以有效地恢复古植被; 同时芦苇鞍型植硅体百分含量的峰值出现在7月份, 随后稍有减少, 而芦苇扇型植硅体百分含量和浓度的峰值出现在8或9月份, 谷值在7月份。由此推测芦苇鞍型植硅体的形成可能更多地受控于植物的光合作用和蒸腾作用, 芦苇扇型植硅体的形成可能与机动细胞的支撑作用关系密切。实验结果还表明芦苇植硅体浓度并不是随着时间逐渐积累的, 其在8月份达到峰值, 9月份达到谷值, 因此推测植物植硅体浓度的变化规律可能与植物在不同生长期其自身对硅的需求规律相一致。鞍型植硅体浓度的峰值也出现在8月份, 谷值也在9月份, 其浓度变化与芦苇植硅体总浓度的变化趋势相似。     

Aluminium and phosphate uptake by Phragmites australis: the role of Fe,Mn and Al root plaques

Aluminium, a potentially phytotoxic metal, is an important constituent of many mine water discharges but has largely been neglected in the literature. The behaviour of this element in the rhizosphere of the wetland plant Phragmites australis was investigated in the laboratory in the presence and absence of Mn and Fe root plaques. Electron microscopy and chemical extraction techniques were utilized to determine the physico-chemical properties of the plaques and any association of Al. Both Mn and Fe plaques occurred as amorphous coatings on root surfaces with uneven distributions. Al was not adsorbed onto the surface of either plaque type but formed a separate phosphate deposit closely resembling the Fe and Mn plaques. Phosphorus was also found to be adsorbed to the surface of the Fe plaques (but not the Mn plaques). Both mechanisms were found to immobilize P at the root surface but this did not significantly reduce the concentration of P in aerial plant tissues that was sufficient to ensure adequate growth.     

Isoprene emission and primary metabolism in Phragmites australis grown under different phosphorus levels

Aquatic plants are generally used for wastewater purification and phytoremediation, but some of them also emit large amounts of isoprene, the most abundant biogenic volatile organic compound. Since isoprenoid biosynthesis requires high amounts of phosphorylated intermediates, the emission may also be controlled by inorganic phosphorus concentration (Pi) in leaves. We carried out experiments to determine the emission of isoprene from Phragmites australis plants used in reconstructed wetlands to phytoremediate elevated levels of phosphorus contributed by urban wastes. Four groups of plants were grown hydroponically in water containing different levels of KH(2)PO(4). High levels of phosphorus in the water resulted in high Pi in the leaves. High Pi stimulated photosynthesis at intercellular CO(2) concentrations lower and higher than ambient, implying higher ribulose 1,5-bisphosphate carboxylase (Rubisco) activity and higher ribulose 1,5-bisphosphate regeneration rates, respectively. However, isoprene emission was substantially lower at high Pi than at low Pi, and was not associated to photosynthesis rates at high Pi. This surprising result suggests that isoprene is limited by processes other than photosynthetic intermediate availability or by energetic (ATP) requirements under high Pi levels. Irrespective of the mechanism responsible for the observed reduction of isoprene emission, our results show that Phragmites plants may effectively remove phosphorus from water without concurrently increase isoprene emission, at least on a leaf area basis. Thus, Phragmites used in reconstructed wetlands for phytoremediation of urban wastes rich of phosphates will not contribute high loads of hydrocarbons which may influence air quality over urban and peri-urban areas.     

扎龙芦苇湿地生长季的甲烷排放通量

为研究高寒地区天然淡水芦苇湿地的甲烷排放特征,采用静态箱-气相色谱法,测定了扎龙不同水位芦苇湿地生长季的甲烷排放通量.结果表明:观测期内,扎龙芦苇湿地甲烷排放通量平均为7.67 mg·m^-2·h^-1（-21.18～46.15 mg·m^-2·h^-1）,其中深水区(平均水深100 cm)和浅水区(平均水深25 cm)的平均甲烷排放通量分别为5.81和9.52 mg·m^-2·h^-1,排放峰值分别出现在8月和7月,最低值均出现在10月.深水区夏季(6-7月)的甲烷排放通量显著低于浅水区,而春(5月)、秋(8-10月)季节显著高于浅水区.生长季甲烷排放通量的变化为夏季>秋季>春季;昼夜排放量为12:00和14:00最高,0:00最低.温度和水位是高寒地区淡水芦苇湿地甲烷排放通量变化的主要影响因子.     

敦煌阳关盐沼湿地芦苇种群小尺度空间分布格局

植物种群的空间分布格局是研究连接植物与外界环境关系的重要桥梁,是植物种群稳定性和生活史策略的表现形式。本研究以敦煌阳关盐沼湿地克隆植物芦苇(Phragmites australis)为对象,设置湿生区、轻度盐化区、重度盐化区和荒漠区采样梯度,应用Ripley K(d)函数分析法研究了芦苇种群的小尺度空间分布格局特征及生态适应对策。结果表明:(1)随着从湿生到荒漠区环境梯度的变化,芦苇种群的盖度、密度、高度、地上生物量及种群领地面积都呈现出显著下降的趋势,空斑面积呈现出显著增加的趋势,而种群领地密度则呈现出先增加后下降的趋势;(2)从湿生到荒漠生境,芦苇种群的小尺度空间拓展策略主要表现为由聚集分布为主、非聚集分布(随机分布或均匀分布)为辅,转变为随机分布为主、非随机分布(聚集分布或均匀分布)为辅的特征。研究结果明晰了干旱区内陆河湿地中芦苇种群的空间分布格局特点及其影响因素,为进一步理解克隆植物的生态适应机制提供了案例研究,为科学保护和管理干旱区内陆河湿地生态系统提供了理论依据。     

扎龙芦苇遗传多样性ISSR分析

采用ISSR分子标记技术对扎龙湿地的5个野生芦苇居群进行了遗传多样性研究.从75条ISSR引物中筛选出10个特异性强、稳定性好的引物进行ISSR分析.共获得96个位点,其中多态位点94个,多态位点百分率为97.92％.PopGene分析结果表明:居群的平均多态位点百分率为56.46％,Shannon's多样性指数(J)...     

Pyrosequencing Reveals Bacterial Diversity in the Rhizosphere of Three Phragmites australis Ecotypes

Here we present the use of high-throughput DNA pyrosequencing to assess bacterial diversity in the rhizosphere of three Phragmites australis ecotypes from the Hexi Corridor, China. In total, 43404 sequences were obtained for the three ecotypes, representing 31 phyla and a small amount of unclassified bacteria. The predominant bacterial groups in the rhizosphere of P. australis were Proteobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Gemmatimonadetes and Planctomycetes. The bacterial community structure varied with the different degrees of wetland degradation, which were exhibited by the three P. australis ecotypes in the study area. At the phylum level, the Caldiserica, Chlamydiae, Deferribacteres, Lentisphaerae, and candidate division WS3 were only detected in the swamp reed (SR) sample. Then, δ-proteobacteria, Acidobacteria, Cyanobacteria and Fusobacteria decreased, the Actinobacteria increased with the degree of degradation from SR through salt meadow reed (SMR) to dune reed (DR). The functional bacterial genera also varied with wetland degradation. The sulfur and sulfate-reducing, nitrifying and nitrogen-fixing bacteria were more abundant in the rhizosphere of the SR sample. Methane-oxidizing bacteria were abundant in the SR and DR samples but less so in the SMR. In our study, pyrosequencing of different P. australis ecotypes provided insight into the structural variation of the rhizosphere bacterial community. This study gave a database for the use of bacteria in the protection and ecological restoration of wetland.     

中国滨海沼泽湿地芦苇种子功能性状的纬度梯度变异

种子功能性状反映了植物适应环境变化的繁殖对策,这是植物在自然环境选择和遗传上的一种进化行为,对深入认识植物及种子对环境的长期适应性进化意义重大。本研究对中国滨海6个省市9个地区的滨海沼泽湿地(21°29′—40°57′ N)主要土著植物芦苇种子功能性状(包括种子大小、重量、结实率和产量)进行研究,分析其纬度变异规律。结果表明: 我国滨海湿地芦苇种子各功能性状在不同纬度差异显著,各功能性状间具有显著的相关性。芦苇种子大小(种长、种宽、种形指数、长宽比、种子表面积)和百粒重与纬度呈显著的二次函数关系,随着纬度升高先降后升,而种子结实率呈现先升后降的规律,芦苇种子数量与大小间存在着权衡关系。单位面积种子产量随着纬度升高显著增加。逐步回归分析显示,气候因素是影响不同纬度间芦苇种子功能性状差异的主要因素,土壤孔隙水的pH和盐度次之。     

Die-back of Phragmites australis: influence on the distribution and rate of sediment methanogenesis

Methanogenesis was measured during the summer of 1994, in sediment coresand bulk samples from a Phragmites australis wetland in northern Jutland,Denmark. We compared sediment from healthy reed and dying-back reed, andan open lagoon resulting from die-back. Cores revealed variability withdepth and between sites, with the highest rates coinciding with layers oforganic gyttja, and negligible methane production from the underlying sandbase. Methanogenesis rates in the lagoon and die back sites were higher(up to 100–150 nmol h^-1 g^-1dry wt. sediment) than in the healthy reed (50–80 nmolh^-1 g^-1), with the highest rates being recordedfrom May to July. At these times, methanogenesis was markedly temperature-limited; samples incubated at 30 °C anon-limiting temperature, gave rates as high as 200–400nmol h^-1 g^-1 for the lagoon and die-backareas and 150 nmol h^-1 g^-1 for the healthyarea. Addition of 8 mM acetate and H₂/CO₂headspace suggested that both acetate-fermenting andCO₂-reducing bacteria were present. Acetate additions suggested some co-limitation by substrate availability, with acetate limitation occurring in the healthy site during July and in the die-back site during August. Lower rates during August, especially in the healthy area, were associated with low water levels which resulted in more oxidized sediments. The data reveal highly variable methanogenesis in the sediment which, when considered with sediment depths, indicates that sites of Phragmites die-back have significantly greater rates of anaerobic mineralization than surrounding healthy wetland, and may be intense sources of methane.     

用芦苇恢复受损河岸生态系统的工程化方法

我国中小河流的护岸工程只考虑工程的耐久性多采用混凝土护岸。忽略了河流的生态功能,破坏了河流的各种生态过程,导致河流污染严重,生态作用越来越小。本研究提出一种用芦苇恢复受损河岸的工程化方法,以解决恢复受损河岸时成本高,破坏了芦苇原生地的生态环境和芦苇不便于运输的问题。其优点在于：在保证能够达到防止河岸崩塌及侵蚀的同时,在河岸工程设计中纳入生态学原理．创造出动植物及微生物能够生存的多孔隙河岸工程生态结构;可以减少对芦苇原生地的破坏。并且能够快速、大量繁殖芦苇幼苗。快速恢复受损河岸的芦苇群落及其生态环境;此方法在减少劳力、时间和成本的基础上,能够更容易恢复浅水带和河岸缓冲带芦苇群落,构建出一个芦苇繁茂的水域。