Environmental Quality and Aquatic Invertebrate Metrics Relationships at Patagonian Wetlands Subjected to Livestock Grazing Pressures

Livestock grazing can compromise the biotic integrity and health of wetlands, especially in remotes areas like Patagonia, which provide habitat for several endemic terrestrial and aquatic species. Understanding the effects of these land use practices on invertebrate communities can help prevent the deterioration of wetlands and provide insights for restoration. In this contribution, we assessed the responses of 36 metrics based on the structural and functional attributes of invertebrates (130 taxa) at 30 Patagonian wetlands that were subject to different levels of livestock grazing intensity. These levels were categorized as low, medium and high based on eight features (livestock stock densities plus seven wetland measurements). Significant changes in environmental features were detected across the gradient of wetlands, mainly related to pH, conductivity, and nutrient values. Regardless of rainfall gradient, symptoms of eutrophication were remarkable at some highly disturbed sites. Seven invertebrate metrics consistently and accurately responded to livestock grazing on wetlands. All of them were negatively related to increased levels of grazing disturbance, with the number of insect families appearing as the most robust measure. A multivariate approach (RDA) revealed that invertebrate metrics were significantly affected by environmental variables related to water quality: in particular, pH, conductivity, dissolved oxygen, nutrient concentrations, and the richness and coverage of aquatic plants. Our results suggest that the seven aforementioned metrics could be used to assess ecological quality in the arid and semi-arid wetlands of Patagonia, helping to ensure the creation of protected areas and their associated ecological services.     

Relationships between National Wetlands Inventory maps and hydrophytic vegetation in Florida

This paper reports a preliminary investigation about National Wetlands Inventory (NWI) maps to see how they might be used in conjunction with other sources of information to provide offsite wetlands regulatory delineation. A geographic information system was used to overlay and compare NWI maps with ground-based tree species composition data from the US Department of Agriculture Forest Service Forest Inventory and Analysis program (FIA). Ninety plots located in the Apalachicola National Forest in northern Florida were used. The NWI mapped 42 of the 90 plots as wetlands. FIA data was used to calculate Prevalence Index (PI) scores. Twenty-four additional plots had PI < 3.0 and thus had hydrophytic vegetation. These plots may also have been wetlands by the Cowardin definition. The hypothesis that wetland identification did not differ between natural-origin versus planted forests was evaluated. NWI classified 61% of natural stands with PI <3.0 as wetlands, whereas 38% of planted stands with PI < 3.0 were mapped as wetlands. There were statistically significant differences (P < 0.05) in the relationships between hydrophytic vegetation and wetland status for plantations and natural-origin stands. FIA data was used to compare the actual frequency of species found in wetlands with the frequency ranges assigned for the NWI Regional Indicators. The observed frequency of occurrence in NWI-mapped wetlands agreed with the Regional Indicator frequency range for 6 of the 18 species. Most species not in agreement were reasonably close to their assigned frequency range, but some differed substantially. While this was a pilot-scale study, we believe that this technique can ultimately yield valuable new information on the tree characteristics of NWI wetlands, especially at larger spatial scales, such as states or regions.     

Contaminant Removal of Domestic Wastewater by Constructed Wetlands： Effects of Plant Species

A comparative study of the efficiency of contaminant removal between five emergent plant species and between vegetated and unvegetated wetlands was conducted in small-scale （2.0 m×1.0 m×0.7 m, lengthxwidthxdepth） constructed wetlands for domestic wastewater treatment in order to evaluate the decontaminated effects of different wetland plants. There was generally a significant difference in the removal of total nitrogen （TN） and total phosphorus （TP）, but no significant difference in the removal of organic matter between vegetated and unvegetated wetlands. Wetlands planted with Canna indica Linn., Pennisetum purpureum Schum., and Phragmites communis Trin. had generally higher removal rates for TN and TP than wetlands planted with other species. Plant growth and fine root （root diameter ≤ 3 mm） biomass were related to removal efficiency. Fine root biomass rather than the mass of the entire root system played an important role in wastewater treatment. Removal efficiency varied with season and plant growth. Wetlands vegetated by P. purpureum significantly outperformed wetlands with other plants in May and June, whereas wetlands vegetated by P. communis and C. indica demonstrated higher removal efficiency from August to December. These findings suggest that abundance of fine roots is an important factor to consider in selecting for highly effective wetland plants. It also suggested that a plant community consisting of multiple plant species with different seasonal growth patterns and root characteristics may be able to enhance wetland performance.     

人工湿地-微生物燃料电池耦合系统的研究进展

人工湿地-微生物燃料电池耦合系统(CW-MFC)是一种将人工湿地技术(CW)和微生物燃料电池技术(MFC)结合在一起的新型污水处理系统,其产电机理是产电微生物在底层湿地(阳极)的厌氧条件下生成电子,通过外电路传递到表面湿地(阴极)完成氧化还原反应。但是,近几年来,关于CW-MFC研究的文章较少且研究深度较浅。综述了电极材料、水力条件、湿地植物及微生物等条件对CW-MFC污水处理能力和产电能力的影响。在电极材料方面,选用导电性、吸附性及有效面积大的材料作为电极可有效提高CW-MFC产电与去污能力;在水利条件方面,在HRT为2-3 d的条件下,应选用升流式或升流-降流式的入水方式;湿地植物方面,种植湿地植物的CW-MFC在去污和产电能力上都要优于未种植植物的CW-MFC;微生物方面,阴极与阳极的微生物群落结构存在明显的差异,但存在的产电菌的种类却十分相似。CW-MFC中存在的常见产电微生物主要包括地杆菌属(Geobacter)、脱硫叶菌属(Desulfobulbus)、假单胞菌属(Pseudomona)和脱硫弧菌属(Desulfovibrio)等。最后对CW-MFC的研究方向进行了分析,以期为CW-MFC的实际应用提供理论依据。     

人工湿地在生态城市建设中的作用

生态城市的建设依赖于科学利用有限资源。随着我国城市化进程加快,水体污染日益严重,加剧了水资源的短缺。人工湿地是利用生物自净功能,低投入、低运行费、低能耗的环保型的污水处理技术。不仅可进行水资源的循环利用,而且美化环境、保护生物多样性。本文分析提出,人工湿地是生态城市建设中水资源利用的最有效模式,应大力发挥人工湿地在我国生态城市建设中的作用。     

Receding Water Line and Interspecific Competition Determines Plant Community Composition and Diversity in Wetlands in Beijing

Climate and human-induced wetland degradation has accelerated in recent years, not only resulting in reduced ecosystem services but also greatly affecting the composition and diversity of wetland plant communities. To date, the knowledge of the differences in community parameters and their successional trends in degraded wetlands remains scarce. Here based on remote sensing images, geographic information system technology, and statistical methods, we produced a successional gradient map of the Yeyahu Wetland Nature Reserve in Beijing, which has experienced a steady decline in water level in recent decades. In addition, we analyzed community composition and diversity along with each identified gradient. The results showed that community diversity decreases while dominance increases with the progress of succession, with the highest diversity occurring during the early stage of succession. Moreover, the community demonstrates greater similarity among subareas during later successional stages, and the similarity coefficients calculated from the important value (IV) of each species are more accurate. Correlation analysis showed that the impact of soil factors on diversity was not significant at a subarea scale, although these nutrients showed an increasing trend with the community succession. Furthermore, the IVs of the dominant species had a particularly significant impact on diversity, showing a significantly negative correlation with diversity indices and a significantly positive correlation with dominance indices. Further analysis showed that the retreat of water level resulted from sustained drought and local human activities was a major extrinsic driving force resulting in observed differences in the community successional stages, which resulted in differences in community composition and diversity. On the other hand, interspecific competition was the main intrinsic mechanism, which significantly influenced the IVs of the dominant species and community diversity. The results of this study could aid in improving the understanding of community composition, diversity, and its successional trends in degraded wetlands.     

植物体表与昆虫的关系

昆虫与植物的关系是当前昆虫学研究中十分活跃的领域。昆虫与植物之间的相互作用首先发生于植物体表。植物体表是植物与其生物和物理环境之间的界面,是一个功能器官,其结构的多样化是植物遭受环境压力多样化的反映。许多特性是植物与昆虫相互作用的结果［１５］。植物不...     

Rapid Seed Bank Development in Restored Tidal Freshwater Wetlands

Studies of seed bank development have rarely been included in evaluations of wetland restoration. We compared the seed bank of a recently restored tidal freshwater marsh in Washington, D.C., Kingman Marsh, with seed banks of another restored site (Kenilworth Marsh) and two reference marshes (Dueling Creek and Patuxent Marsh). The density and richness of emerging seedlings from Kingman Marsh seed bank samples increased from less than 4 seedlings and 2 taxa/90-cm² sample in 2000 (the year of restoration) to more than 130 seedlings and 10 taxa/90-cm² sample in 2003. The most important seed bank taxa at Kingman Marsh included Cyperus spp., Juncus spp., Lindernia dubia , Ludwigia palustris , and the non-native Lythrum salicaria . These taxa are not abundant in most mid-Atlantic tidal freshwater marshes but are almost identical to those described for a created tidal freshwater wetland in New Jersey. Seed banks of both the restored sites contained few seeds of several important species found at the reference sites. Flooding had a significant negative effect on emerging seedling density and taxa density, suggesting that slight decreases in soil elevation in restored wetlands will dramatically decrease recruitment from the seed bank. Because seed banks integrate processes affecting growth and reproduction of standing vegetation, we suggest that seed banks are a useful metric of wetland restoration success and urge that seed bank studies be incorporated into monitoring programs for restored wetlands.     

Relationships between Population Size, Genetic Diversity and Fitness Components in the Rare Plant Dictamnus albus in Central Germany

An increasing number of studies support the hypothesis that smaller populations face a higher risk of extinction, and declining population sizes are therefore one of the focal points in plant conservation. In small populations, loss of genetic diversity is often related to reduced reproductive fitness. For the rare Dictamnus albus in Central Germany, an earlier study had already confirmed a significant correlation between population size and genetic diversity. In order to assess whether these variables correlate with fitness components, plant height; flower, fruit and seed production; and germination were studied in a total of 11 populations of different size. In the seven populations that were sampled over two consecutive years, differences among populations and among years were tested using a Two-Way ANOVA. Co-linearity among variables was assessed using principal component analysis (PCA), followed by calculating correlations between ordination axes and both population size and genetic diversity. Plant height and flower number were uncorrelated to the other variables and, together with germination, did not show any correlation to either population size or genetic diversity. However, both size and genetic diversity of populations correlated significantly with other PCA axes that reflected reproductive components such as fruit number, seed number, seed fruit ratio, and seed mass. Our results support the idea that reproduction is hampered in small populations and raise concerns over the loss of genetic diversity in D. albus.     

Spatial Variation of Phosphorous Retention Capacity in Subsurface Flow Constructed Wetlands: Effect of Wetland Type and Inflow Loading

For verification of spatial distribution of phosphorous retention capacity in constructed wetlands systems(CWs), two horizontal subsurface flow(HSSF) CWs and two vertical subsurface flow(VSSF) CWs, using sand as substrate and Typha latifolia as wetland plants, were constructed and put into use for synthetic wastewater treatment. Five months later, significant spatial variations of TP and inorganic phosphorus(Ca-P, Fe-P and Al-P) were observed, which were found to be greatly affected by CWs type and hydraulic loading. The results revealed that though spatial distribution of Fe-P and Al-P displayed a similar order of substrate content as "rhizosphere" > "near-rhizosphere" > "non-rhizosphere" and "inflow section" > "outflow section" regardless of types and loading, the distribution of Ca-P was positively correlated to that of Fe-P and Al-P in HSSF CWs, while negative correlation was shown in VSSF CWs. As a result, TP spatial distribution in HSSF CWs demonstrated a greater dissimilarity than that in VSSF CWs. For HSSF CWs with low hydraulic loading, the lowest TP content was found in non-rhizosphere substrate of outflow section, while the highest one was discovered in rhizonsphere substrate of inflow section. The values in 6 parts of areas ranged from 0.138 g·kg^-1 to 2.710 g·kg^-1, which also were from -33.5% to 1209% compared to the control value. On contrast, spatial difference of TP content in substrates of VSSF CWs was insignificant, with a variation ranging from 0.776 g·kg^-1 to 1.080 g·kg^-1, that was 275% to 421% higher than the control value. In addition, when hydraulic loading was increased, TP content in VSSF CWs sharply decreased, ranging from 0.210 g·kg^-1 to 0.634 g·kg^-1. Meanwhile, dissimilarity of TP spatial distribution in HSSF CWs was reduced, with TP content ranging from 0.258 g·kg^-1 to 2.237 g·kg^-1. The results suggested that P spatial distribution should be taken into account for CWs design and operation.     

Site History and Edaphic Features Override the Influence of Plant Species on Microbial Communities in Restored Tidal Freshwater Wetlands

Restored wetland soils differ significantly in physical and chemical properties from their natural counterparts even when plant community compositions are similar, but effects of restoration on microbial community composition and function are not well understood. Here, we investigate plant-microbe relationships in restored and natural tidal freshwater wetlands from two subestuaries of the Chesapeake Bay. Soil samples were collected from the root zone of Typha latifolia, Phragmites australis, Peltandra virginica, and Lythrum salicaria. Soil microbial composition was assessed using 454 pyrosequencing, and genes representing bacteria, archaea, denitrification, methanogenesis, and methane oxidation were quantified. Our analysis revealed variation in some functional gene copy numbers between plant species within sites, but intersite comparisons did not reveal consistent plant-microbe trends. We observed more microbial variations between plant species in natural wetlands, where plants have been established for a long period of time. In the largest natural wetland site, sequences putatively matching methanogens accounted for ∼17% of all sequences, and the same wetland had the highest numbers of genes coding for methane coenzyme A reductase (mcrA). Sequences putatively matching aerobic methanotrophic bacteria and anaerobic methane-oxidizing archaea (ANME) were detected in all sites, suggesting that both aerobic and anaerobic methane oxidation are possible in these systems. Our data suggest that site history and edaphic features override the influence of plant species on microbial communities in restored wetlands.     

四种湿地植物在人工湿地的生长特性研究

研究了表面流人工湿地中香根草(Vetiveria zizanioides)、风车草(Cyperus flabelliformis)、芦苇(Phrogmites australis)和水鬼蕉(Hymenocallis littoralis)4种植物的根生物量和生长量、根系分布、地上部分的生长情况.风车草、香根草和水鬼蕉根系及地上部分的生长节律相似,9月或10月前生长较快,以后生长减慢甚至停止;芦苇则不同,7月以前生长缓慢,以后生长加速,冬季也保持较快的生长.全年根生长量和根生物量以水鬼蕉最大,显著高于其它植物(P<0.01),香根草最小,显著低于其它3种植物(P<0.01).香根草的根系垂直向下生长,分布较深,而其它3种植物的根系主要分布在浅层土壤中.风车草分株最多,叶面积指数最大.香根草叶面积指数最小.结果表明,在构建多种植物人工湿地群落时,可以考虑将芦苇与大多数湿地植物搭配以保证湿地全年保持较好的净化效果;水鬼蕉可以作为底层植物,和风车草等生长早、植株较高的植物构建多种湿地群落.     

合肥市不同类型湿地植物群落的物种多样性及群落特征研究

运用样地和样方相结合的调查方法,对合肥市不同演替进程的湿地类型进行调查研究,通过计算湿地植物的重要值与群落植物的α多样性与β多样性的相关指标分析了其群落多样性与群落特征.结果表明:合肥市典型的人工型湿地共有植物22科41属47种;半人工半自然型湿地共有植物10科21属21种;自然型湿地共有植物37科65属70种.湿地植物的多样性以及其群落特征与其人工性和自然性有关;在不同的外界干扰下,湿地的类型也不同,湿地处于不断的演替过程中.其群落的稳定性与物种多样性之间关系复杂,两者之间并非简单的正相关关系.在进行湿地群落和生态研究时,不仅要考虑其群落物种的多样性,也要考虑群落优势物种的组成,优势物种的优势度以及群落的演替趋势等因素.     

Desmids and Biofilms of Freshwater Wetlands: Development and Microarchitecture

Freshwater wetlands constitute important ecosystems, and their benthic, attached microbial communities, including biofilms, represent key habitats that contribute to primary productivity, nutrient cycling, and substrate stabilization. In many wetland biofilms, algae constitute significant parts of the microbial population, yet little is known about their activities in these communities. An analysis of wetland biofilms from the Adirondack region of New York (USA) was performed with special emphasis on desmids, a group of evolutionarily advanced green algae commonly found in these habitats. Desmids constituted as much as 23.7% of the total algal and cyanobacterial flora of the biofilms during the July and August study periods. These algae represented some of the first eukaryotes to colonize new substrates, and during July their numbers correlated with fluctuations in general biofilm parameters such as biofilm thickness and dry weight as well as total carbohydrate. Significant numbers of bacteria were associated with both the EPS sheaths and cell wall surfaces of the desmids. Colonization of new substrates and development of biofilms were rapid and were followed by various fluctuations in microbial community structure over the short- and long-term observations. In addition to desmids, diatoms, filamentous green algae and transient non-motile phases of flagellates represented the photosynthetic eukaryotes of these biofilms.     

Growth and Contaminant Removal Effect of Several Plants in Constructed Wetlands

The aim of the present study is to probe the relation between plant growth and its decontamination effect in constructed wetlands. Four species were studied in the small-scale mono-cultured constructed wetlands, which were fed with domestic wastewater. Plant growth indexes were correlated with contaminant removal performance of the constructed wetlands. Wetlands planted with Cyperus flabelliformis Rottb. showed the highest growth indexes such as shoot growth, biomass, root activity, root biomass increment, and the highest contaminant removal rates, whereas wetlands planted with Vetiveria zizanioides L. Nash had the lowest growth indexes and the lowest removal rates. Above-ground biomass and total biomass were significantly correlated with ammonia nitrogen removal, and below-ground biomass with soluble reactive phosphorus removal. Photosynthetic rate had higher correlation with nitrogen removal in these species. Root activity and root biomass increment was more correlated with 5 d biochemical oxygen demand removal. Chemical oxygen demand removal had lower correlations with plant growth indexes. All four species had higher removal rates in summer and autumn. The results suggest that the effect of plant growth on contaminant removal in constructed wetlands were different specifically in plants and contaminants.     

Growth and Contaminant Removal Effect of Several Plants in Constructed Wetlands

The aim of the present study is to probe the relation between plant growth and its decontamination effect in constructed wetlands.Four species were studied in the small-scale mono-cuitured constructed wetlands, which were fed with domestic wastewater. Plant growth indexes were correlated with contaminant removal performance of the constructed wetlands. Wetlands planted with Cyperus flabelliformis Rottb. showed the highest growth indexes such as shoot growth, biomass, root activity, root biomass increment, and the highest contaminant removal rates, whereas wetlands planted with Vetiveria zizanioides L. Nash had the lowest growth indexes and the lowest removal rates. Above-ground biomass and total biomass were significantly correlated with ammonia nitrogen removal, and below-ground biomass with soluble reactive phosphorus removal. Photosynthetic rate had higher correlation with nitrogen removal in these species. Root activity and root biomass increment was more correlated with 5 d biochemical oxygen demand removal.Chemical oxygen demand removal had lower correlations with plant growth indexes. All four species had higher removal rates in summer and autumn. The results suggest that the effect of plant growth on contaminant removal in constructed wetlands were different specifically in plants and contaminants.