六种湿地植物根际氧化还原电位的日变化

在野外条件下,研究人工湿地植物根际氧化还原电位(ORP)随时间的变化及其与主要环境因子的关系。研究了美人蕉(Canna indica Linn.)、风车草(Cyperus flabelliformis Rottb.)、芦苇(Phragmites australis Trin.ex Steud.)、水鬼蕉(Hymenocallis littoralis(Jack.)Salisb.)、紫芋(Colocasia tonoimo Nakai.)和鸢尾(Iris tectorum Maxim.)6种植物在潜流人工湿地中的根际ORP及其日变化。6种湿地植物的根际ORP日变化曲线相似,均为双峰型,双峰值出现在11:00—14:00之间,最大值出现在14:00。各植物的根际ORP日变化基本在130—350 m V之间,以水鬼蕉的变幅最大,风车草和芦苇的变幅较小。不同植物的根际ORP有较大差异,风车草和紫芋的日平均值最大,显著高于鸢尾、美人蕉和水鬼蕉(P0.05);芦苇显著高于鸢尾和美人蕉(P0.05)。ORP与光照强度和气温呈正相关,尤与气温的正相关最为显著。ORP日平均值与植物生物量有显著的正相关性,尤与地下部分生物量相关性最显著。结果表明,人工湿地植物根际ORP因不同植物、一天中不同的时间有较大差异,后者与光照和气温等环境因子密切相关。     

Metal content in higher aquatic plants in a small siberian water reservoir

The dynamics of metal content in higher aquatic plants (macrophytes) in a small Bugach water reservoir in 1998–2006 was studied. A comparative estimation of the metal content in six macrophyte species (Typha latifolia L., Typha angustifolia L., Polygonium amphibium L., Potamogeton perfoliatus L., Potamogeton pectinatus L., Phragmites australis (Cav) Trin. Ex Steud.) showed that their metal concentrations do not generally exceed those known from the literature. Cluster analysis showed that the macrophyte species under study form two ecological groups with respect to the metal content, i.e., submerged plants (hydrophytes) and emergent aquatic plants (heliophytes).     

测定潜流人工湿地根系生物量的新方法

设计了一种新方法研究潜流人工湿地植物根系的分布和生物量。采用自制的圆柱形的不锈钢网柱,安放在潜流湿地的碎石基质中,定期分层取出网柱内的碎石,可观察根系的分布特点;收获网柱内的根,可测定根系的生物量和生长量。网柱的直径20cm,高50cm,网孔直径1．80cm,不锈钢丝粗1．38mm。安装时,使网柱垂直,上端达碎石表面,下端靠近湿地床底。安装好后,装入碎石基质,观察测定时,把基质取出,观察完后,再把基质放回。用该方法,对碎石基质的潜流人工湿地中植物根系的分布和生物量进行了1a的实验测定,认为该方法是测定潜流人工湿地根系生长和分布的有效方法,它易于安装、测定方便、准确。7月和12月份两次测定的湿地根系生物量之和为331．8gm^-2,其中分布于0—5cm的根生物量为174．4gm^-2,5～15cm为142．1gm^-2,15cm以下为15．3gm^-2。种问根系生物量的差异很大,根系生物量最大的是美人蕉,为182．4gm^-2,最小的是水鬼蕉,为1．38gm^-2。根生物量似乎呈不同的季节格局,象草7月份根系生物量较大,而其他种12月份的较大。不同种根系生物量的垂直分布也有显著的差异,具根状茎的芦苇和较粗根的水鬼蕉以直径大于1mm的根为主,它们的根分布较深,而浅层根较少;象草、美人蕉和风车草,直径1mm以内的根占根生物量的80％以上甚至100％,它们的根分布较浅。     

上海金泽水库典型挺水植物碳、氮、磷化学计量特征的季节变化

为探究不同水生植物碳(C)、氮(N)、磷(P)含量及其化学计量比随季节的变化特征,本研究以上海金泽水库库区四种典型挺水植物旱伞草(Cyperus alternifolius),芦苇(Phragmites australis),千屈菜(Lythrum salicaria),水葱(Scirpus validus)为例,开展了季节性取样及室内分析,结果显示:(1)四种植物碳氮磷含量的变化规律不同。其中,对于植物碳含量,旱伞草和芦苇均无显著差异,千屈菜和水葱仅在冬季显著降低。对于植物氮含量,除旱伞草外,其他植物均在春季生长初期显著降低,在夏季生长旺盛时期显著升高,而旱伞草四季无显著差异。对于植物磷含量,水葱在四季均无显著差异,芦苇和千屈菜在冬季植物休眠期显著降低,旱伞草和芦苇磷含量在夏季显著降低。(2)四种植物C/N/P的季节性变化特征不同。其中,旱伞草C/N四季间无显著差异,其他3种植物C/N在春季生长初期显著升高;在C/P方面,水葱四季间无显著差异,芦苇和千屈菜在春季显著降低,旱伞草和芦苇C/P在夏季显著升高;常绿植物旱伞草N/P在四季无显著差异,其他3种植物N/P均在冬季生物量低时显著升高,春季N/P显著降低,而夏季生物量增长时N/P显著升高。(3)季节变化对四种植物C、P、N/P的影响远大于物种差异的影响,而植物N、C/N、C/P受物种差异的影响程度略大于季节变化。(4)四种植物C/N和C/P分别与N和P呈显著负相关,表明植物C/N和C/P分别受N和P主导;植物C与N、P二者在夏、秋季均无显著相关性,表明起支撑作用的C元素在夏、秋季独立于起生化作用的N、P元素;而营养元素N、P二者含量仅在植物生长的春、夏季显著相关。综上所述,不同植物碳氮磷含量及其化学计量比的季节变化特征不尽相同。今后的研究,可结合相关的生境因子,更好地探究其变化的内在机理。     

Distribution and impact of exotic gall flies (Lipara sp.) on native and exotic Phragmites australis

Two exotic gall fly species infest stems of native and exotic Phragmites australis (Cav.) Trin. ex Steudel in northeastern North America. In this study, we determined the distribution of Lipara similis Schiner and L. rufitarsis Loew in native and exotic P. australis in Rhode Island. We also studied the within-stand distributions of each fly species and their effects on flowering of native and exotic P. australis. We collected stems from populations throughout southern Rhode Island and measured stem length and diameter, and percent flowering. Stems were then dissected to determine Lipara infestation. L. similis and L. rufitarsis were found throughout Rhode Island infesting both native and exotic P. australis, but their presence and abundance varied among sites. Within stands, L. similis infests the taller, thicker interior stems and L. rufitarsis infests the shorter, thinner exterior stems. Lipara similis reduces stem length by 6%; L. rufitarsis infestation reduces stem length by 37%. The flowering rate of uninfested stems is significantly lower in native P. australis stems than in exotic stems. Both Lipara species prevent infested stems from flowering. In adjacent stands of native and exotic P. australis, L. rufitarsis infests significantly more native stems than exotic stems, possibly further reducing the reproductive potential of the native plants relative to the exotic. Lipara species may play a role in facilitating the displacement of native P. australis by the exotic genotype.     

Probable effects of algal bloom on the growth ofPhragmites australis (Cav.) Trin. ex Steud.

The effects of blue-green algal blooms on an emergent reed plant,Phragmites australis (Cav.) Trin. ex Steud., were investigated in a eutrophic lake in central Japan. The plants showed conspicuous withering of bottom leaves in spring of 1982, after an early occurrence of the bloom. In June, the plants in the area of algal infestation had about half the shoot length and dry weight of normalP. australis without the algal infestation. Reductions in water transparency, dissolved oxygen in bottom water and redox potentials of surface soil corresponded to the presence of algal bloom and plant damage.     

Variabilité morphologique,caryologique et enzymatique chez quelques populations dePhragmites australis (Cav.)Trin. exSteud.

Use of morphological, karyological and enzymatic approaches in the study of 11 populations ofPhragmites australis (Cav.) Trin. exSteud. originating from different geographic areas, climates and ecological conditions reveals a spatial differentiation of populations. There is no relationship between the two levels of ploidy, 2n=48 and 2n=96, and the habitat. In contrast, the climate and environmental conditions act to the selection of the well-adapted genotypes. So, the considerable phenotypic variability ofP. australis is due to a high adaptability and an important genetic diversity.     

What is the role of Phragmites australis in experimental constructed wetland filters treating urban runoff?

The aim of this research was to assess the role of the macrophyte Phragmites australis (Cav.) Trin. ex Steud. in experimental temporarily flooded vertical-flow wetland filters treating urban runoff. For 2 years, hydrated nickel and copper nitrate were added to sieved road runoff to simulate contaminated primary treated urban runoff. During the first year, 5-day biochemical oxygen demand (BOD) removal efficiencies were lower in planted filters than in unplanted filters. However, the BOD removal performances of all filters were virtually similar irrespective of the planting regime during the second year. The nutrient removal performance of planted filters was more efficient and stable throughout the season particularly after the filters matured compared to that of unplanted filters. A substantial amount of nitrogen was also removed by harvesting P. australis, though metals were not, when compared to those retained in the filters. Furthermore, higher concentrations of nickel in the effluent were recorded in the planted filters, despite their ability to take up the heavy metals. P. australis provided undesirable conditions for precipitation of Ni by lowering the pH in the processes. Finally, after applying shock loadings of Cu, higher Cu outflow concentrations were recorded for planted in comparison to unplanted filters.     

The effect of nutrients on seedling growth of native and introduced Phragmites australis

Differing responses to abiotic stresses and increased nutrient availability may play a role in the invasion and spread of introduced Phragmites australis Cav. (Trin.) ex. Steud. and the decline of native P.a. americanus Saltonstall, P.M. Peterson & Soreng in North America. We present results from an outdoor experiment where native and introduced P. australis seedlings were grown under two nutrient treatments. Both subspecies responded positively to increased nutrients but introduced plants clearly outperformed natives, growing taller, producing more stems, and had three to four times higher biomass. The biomass of introduced P. australis growing in low nutrients was similar to that of the native in high nutrients. Aboveground:belowground biomass ratios were nearly 1.25 for both native and introduced plants across treatments and reflect the high investment P. australis seedlings place on shoot production in their first year of growth. Our results also demonstrate that introduced P. australis can have explosive growth over a single growing season, even when established from seed. This implies that management of young, newly established populations may be prudent where introduced P. australis is considered undesirable, irregardless of whether eutrophication is an issue.     

不同植物构成的人工湿地对生活污水中氮的去除效应

测定由不同植物构成的人工湿地的氨态氮、硝态氮和亚硝态氮含量,对比不同植物对生活污水中氮的去除效率.结果表明,与不种植物的人工湿地相比,由风车草[Cyperus alternifolius L. ssp. flabelliformis (Rottb.) Kiikenth.]、香根草[Vertiveria zizanioides (Linn.) Nash]、芦苇(Phragmitas communis Trin.)和美人蕉(Canna indica Linn.)构成的人工湿地对氨态氮去除率分别提高6%、8%、11%和14%;对硝态氮去除率分别提高5%、6%、13%和9%;对亚硝态氮去除率分别提高5%、7%、10%和7%,说明种植芦苇和美人蕉的人工湿地对生活污水中的氮具有较好的去除效果.     

Soil water status influences plant nitrogen use: a case study

We studied differences in nitrogen use efficiency (NUE) among six species [Calamagrostis epigejos (L.) Roth., Carex duriuscula C.A. Mey., Phragmites communis (L.) Trin., Salix gordejevii Y.L. Chang, Salix cheilophila Schneid., and Typha minima Funk.] growing in two contrasting habitat types, i.e., a riverine wetland with high water supply and a riparian zone with low water supply. The two sites were different in soil water supply, but not in nitrogen supply. Here, NUE was defined as the total net primary production per unit nitrogen absorbed. There was no significant difference in NUE between the species growing in the riverine wetland (Carex duriuscula, P. communis, S. cheilophila, T. minima) and the species growing in the river bank (Carex duriuscula, Calamagrostis epigejos, P. communis, S. gordejevii). We further analyzed NUE as the product of the nitrogen productivity (A, the rate of dry matter production per unit of nitrogen in the plant) and the mean residence time of nitrogen (MRT, the period of time a unit of nitrogen is present in the plant). The species growing in the riverine wetland had larger A but lower MRT than the species growing in the river bank. There was an inverse relationship between A and MRT. Consequently, NUE was similar among species and habitats. These results suggested that environmental factors, such as soil water supply, can influence N use by plants.     

Shoot development and production studies of phragmites Australis (Cav.) Trin. Ex Steudel in Scottish Lochs

Studies were made on the development and production of Phragmites australis (Cav.) Trin. ex Steudel (= Phragmites communis Trin.) stands from Forfar Loch-polytrophic, Balgavies Locheutrophic and Loch of the Lowes-mesotrophic. Differences were detected in the shoot height, shoot dry weight, standing crop biomass, leaf area index, crop growth rate and net efficiency of solar energy conversion among the three lochs. Such differences were partly due to the different nutrient levels of the three locations. The percentage ratio of leaf to shoot weight, leaf area ratio, relative growth rate and net assimilation rate for the reed stands in the three lochs were also calculated and were compared with values from other study areas.     

Phenotypic and phenological plasticity of an aquatic macrophyteMenyanthes trifoliata L.

Phenotypic and phenological properties ofMenyanthes trifoliata L. were investigated within and outside of aPhragmites australis (Cav.) Trin. ex. Steud. canopy in a floating peat mat in Mizorogaike Pond, Central Japan. Under theP. australis canopy,M. trifoliata adjusted its phenotypic properties to the conditions of decreased light by increasing leaf blade area, decreasing leaf blade thickness and elongating petioles. The earlier expansion of leaves ofM. trifoliata within theP. australis community than outside the community was advantageous in terms of allowing the plant in the mixed community to produce as much dry matter as possible before the foliage ofP. australis could overgrow it. Despite the harmful effect ofP. australis onM. trifoliata's vegetative growth and reproduction, the latter species can persist in aP. australis community by changing its phenotypic and phenological properties.     

New methods and allelopathic considerations of riparian buffer zones using Phragmites australis (Cav.) Trin.

Recently, the riparian buffer zone using Phragmites australis (Cav.) Trin. has frequently been installed in the ecotone, and young shoots of P. australis have been produced worldwide using seeds and/or rhizomes. However, the expenditures of labor, time, and money related to this technique have been enormous. In this paper, therefore, a new method which enables the reduction of the above-mentioned expenditure is developed and proposed. Using this method, we were able to install an area where P. australis flourished without the production of young shoots, by simply placing segments of P. australis culms by the water, and were able to reduce the above-mentioned usual expenditure. On the other hand, hydrophytes such as Scirpus tabernaemontani Gmel., Zizania latifolia Turcz. and Typha latifolia L. have frequently been planted with P. australis as a riparian buffer zone material. In this study, therefore, the care required in the mix planting of the above-mentioned four hydrophytes was also examined on the basis of the allelopathic potential of the interspecies. As a result, the allelopathic inhibition of root elongation was observed between the interspecies. Therefore a sufficient planting interval is required in order to ensure the elongation of the roots of the above-mentioned hydrophytes in the case of mix planting.     

Roots of the wetland plants Typha latifolia and Phragmites australis are inhabited by methanotrophic bacteria in biofilms

Wetland plants create partly aerobic conditions in the rhizosphere by releasing oxygen to the waterlogged substrate. The present study was conducted to characterise the arrangement of rhizobacteria, especially those active in methane oxidation, in root-associated biofilms of wetland plants. Root cross sections sampled from Typha latifolia L. (broadleafed cattail) and Phragmites australis (Cav.) Trin. ex Steud. (common reed) were scanned using light and electron microscopy. Methane-oxidising bacteria were identified and quantified by immunological labelling of the α-subunit of the methanol dehydrogenase (α-MDH; encoded in mxaF). On roots of both species there was a diverse subset of bacteria arranged in a microbial biofilm around the roots’ exodermis. Similar bacterial densities in the root-associated biofilm were detected in more basal regions and closer to the root tip. Many microbes carried notable internal membrane systems that are characteristic of methanotrophic bacteria. This morpho-anatomical characterisation was confirmed by immunogold labelling with α-MDH antibodies. Quantification of labelled bacteria revealed that 34–43% of the biofilm bacteria were potentially capable of methane turnover. These findings confirm the presence of methane-oxidising bacteria in the root-associated biofilms of the two common macrophytes T. latifolia and P. australis. This implies that the methanotrophs participate essentially in the microbial processes related to oxygen-releasing roots of wetland plants.     

Practical applications of a shading material for macrophytes control in watercourses

The use of a light-weight gas-permeable opaque material (Typar: Du Pont's registered trademark for its spunbonded polypropylene) for the control of rooted macrophytes in flowing waters is described for areasnormally subject to mechanical control. Submerged macrophytes were more rapidly controlled that emergent ones, primarily because the build up to detdritus on submersed material reduced the light penetration. The period required for control varied — Ranunculus penicillatus var. calcareus (R.W. Butcher) C.D.K. Cook 5–8 weeks; Nasturtium officinale R.Br. and Apium nodiflorum (L.) Lag. 6–9 weeks; Elodea spp., Sparganium erectum L. and Phragmites australis (Cav.) Trin. 12 weeks. Shorter periods give partial control whereas extended periods require macrophytes to reinvade controlled sites. This technique, i.e., the planned cycle of movement of material during the plant growing season, is considered economically competitive with other methods and could be applied to a wide variety of sites currently being managed by techniques which stress the biological system.     

Role of plant aeration in zonation of Zizania latifolia and Phragmites australis

The emergent plants Phragmites australis (Cav.) Trin. ex Steud and Zizania latifolia (Griseb.) Stapf. are distributed along a gradient of increasing water depth, with P. australis restricted to shallow water and Z. latifolia to deeper water. The lower limits of the two vegetational zones were discussed from the view-point of oxygen supply from aerial shoots. The oxygen influx to the underground organs from aerial shoots is proportional to the gradient between oxygen concentrations in atmosphere and inside the basal stem (C). The proportional constant (Q), called here the ventilation coefficient, expresses the efficiency of the diffusion of oxygen. An attempt was made to measure Q and C. The values of Q for the two species in their dominant niches are higher in Z. latifolia than in P. australis, corresponding to the natural distribution with increasing depths of water. Q in Z. latifolia and P. australis first increased and then decreased. Corresponding to such changes of Q, the oxygen concentration inside the basal stem (C) fell to low values for Z. latifolia at the greatest water-depth. Since in Z. latifolia a low value of C in deeper waters was accompanied by a decline in standing crop of aerial shoots, it was concluded that oxygen is the limiting factor for the distribution of Z. latifolia in the deeper waters.     

Exotic plant species of the St Lawrence River wetlands: a spatial and historical analysis

Aim To evaluate the importance (number of species, plant cover) of the exotic flora in seven well‐defined sectors of one of the most important transportation waterways in North America. To determine the impact of exotic species on wetland plant diversity and reconstruct the spread of some invasive species. Location St Lawrence River, southern Québec. Methods The exotic flora (vascular plants) of wetlands bordering the St Lawrence River was studied using 713 sampling stations (25 m²) along a 560‐km long corridor. Results Exotic species represent 13.7% of the vascular flora of the St Lawrence wetlands. The relative plant cover occupied by exotic species is high in some of the fluvial sectors (42–44%), but low (6–10%) in the estuarine sectors. Wetlands (marshes) surrounding islands were particularly susceptible to invasion by exotic plants. Historical, abiotic and landscape factors may explain the differences observed between sites. Purple loosestrife (Lythrum salicaria L.) is the most common exotic species of the St Lawrence wetlands, but other species, namely flowering‐rush (Butomus umbellatus L.) and reed canary grass (Phalaris arundinacea L.) are much more invasive. There is no linear relationship between the exotic species cover and the diversity of wetland plants; low diversity sites can be dominated by either exotic or native plant species. In the other sites, exotic species generally have little impact on plant communities and can contribute to increase diversity. Common reed (Phragmites australis (Cav.) Trin. ex Steudel) and reed canary grass, both considered as exotic species in this study, clearly have a stronger impact on plant diversity than flowering‐rush and purple loosestrife. Main conclusions This study shows that the global impact of an invader cannot be adequately evaluated with only a few highly invaded sites. While nationwide strategies have been developed to control exotic species, large surveys are essential to adapt them to regional particularities.     

Screening of the essential oil composition of wild Sicilian thyme

Thirty samples of wild thyme collected from as many Sicilian locations have been analysed for their qualitative and quantitative essential oil profiles. The oils, obtained by hydrodistillation, have been analysed by a combination of GC-FID-MS; in all, 46 components, representing more than 98% of the oils, were fully characterized. Monoterpenes, both hydrocarbons and oxygenated, were the most highly represented components: the former with a range of 8–61% and the latter with a range of 31–86%. Carvacrol was the main compound in 29 samples, ranging between 49 and 83%, suggesting that Thymus capitatus Hoff. et Link. [syn. Coridothymus capitatus (L.) Rchb.f., Satureja capitata L., Thymbra capitata (L.) Cav.] is the most widespread wild species in the Sicilian area. Only one sample, identified as Thymus longicaulis C. Presl., collected from the North-East of Sicily showed a different composition, p-cymene and thymol being the main compounds with 40 and 16%, respectively. Statistical analyses allowed establishing a single broad group, confirming the substantial compositional uniformity of the essential oil profiles of the wild Sicilian thyme.     

三种湿地植物的生长及根系溶解性有机碳分泌物研究

研究了美人蕉(Canna indica Linn.)、风车草(Cyperus flabelliformis Rottb.)和水鬼蕉(Hymenocallis littoralis (Jack) Salisb.)3种湿地植物在人工气候室水培条件下的根系溶解性有机碳分泌物分泌量及其与生长的关系.结果表明,风车草和美人蕉的植...