大型浅水湖泊鄱阳湖湿地微生物的研究现状

鄱阳湖是我国第一大淡水湖泊,同时也是一个典型的季节性通江浅水湖泊,独特的水文特征和多样的湿地景观类型形成了复杂多样的微生物群落。本文综述了鄱阳湖水文节律、营养盐及重金属含量对湖泊微生物群落组成的影响,以及水位高程和湿地围垦对鄱阳湖湿地土壤微生物分布特征的影响,同时还探讨了未来湖泊湿地微生物的研究方向和鄱阳湖所拥有的独特研究条件,以期为未来湖泊微生物研究提供重要参考。     

Identification and siting of native vegetation types on disturbed land: demonstration of statistical methods

Question: How does one best choose native vegetation types and site them in reclamation of disturbed sites ranging from cropland and strip mines? Application: World‐wide, demonstrated in SE Montana. Methods: We assumed that pre‐disturbance native communities are the best targets for revegetation, and that the environmental facet each occupies naturally provides its optimal habitat. Given this assumption, we used pre‐strip‐mine data (800 points from a 88 km² site) to demonstrate statistical methods for identifying native communities, describing them, and determining their environments. Results and conclusions: Classification and pruning analysis provided an objective method for choosing the number of target community types to be used in reclamation. The composition of eight target types, identified with these analyses, was described with a relevé table to provide a species list, target cover levels and support the choice of species to be seeded. As a basis for siting communities, we modeled community presence as a function of topography, slope/aspect, and substrate. Logistic GLMs identified the optimal environment for each community. Classification and Regression Tree (CART) analysis identified the most probable community in each environmental facet. Topography and slope were generally the best predictors in these models. Because our analyses relate native vegetation to undisturbed environments, our results may apply best to sites with minimal substrate disturbance (i.e. better to abandoned cropland than to strip‐mined sites).     

The Monstering of Tamarisk: How Scientists made a Plant into a Problem

Dispersal of biota by humans is a hallmark of civilization, but the results are often unforeseen and sometimes costly. Like kudzu vine in the American South, some examples become the stuff of regional folklore. In recent decades, “invasion biology,” conservation-motivated scientists and their allies have focused largely on the most negative outcomes and often promoted the perception that introduced species are monsters. However, cases of monstering by scientists preceded the rise of popular environmentalism. The story of tamarisk (Tamarix spp.), flowering trees and shrubs imported to New England sometime before 1818, provides an example of scientific “monstering” and shows how slaying the monster, rather than allaying its impacts, became a goal in itself. Tamarisks’ drought and salt tolerance suggested usefulness for both coastal and inland erosion control, and politicians as well as academic and agency scientists promoted planting them in the southern Great Plains and Southwest. But when erosion control efforts in Arizona, New Mexico and Texas became entangled with water shortages, economic development during the Depression and copper mining for national defense during World War Two, federal hydrologists moved quickly to recast tamarisks as water-wasting foreign monsters. Demonstrating significant water salvage was difficult and became subsidiary to focusing on ways to eradicate the plants, and a federal interagency effort devoted specifically to the latter purpose was organized and continued until it, in turn, conflicted with regional environmental concerns in the late 1960s.     

中水技术污水处理工艺去除病毒的效果

中水技术开发既可缓解水资源的紧缺,又能改善城市环境。本文报道用石英粉吸附/洗脱和浓缩棒脱水的二步浓集水病毒技术(回收率为25.4～37.3％),研究中水技术不同处理工艺去除病毒的效果。结果,二级处理可去除掺入病毒的98.9％,结合三级处理的混凝沉淀和过滤,可去除99.976％,再加活性炭吸附或加氯消毒,所得中水分别去除掺入病毒的99.986％和99.991％。经首都机场中水道试验厂水样检测表明,中水中未检测到病毒(<0.23PFU/L)。     

Nitrogen accumulation in Kaolin wastes in Cornwall

Summary Nitrogen accumulation and nitrogen mineralisation rates were measured in a series of waste heaps, produced by the china clay mining industry, which had been reclaimed at different times with a sward ofAgrostis tenuis, Festuca rubra, andTrifolium repens. The best swards tended to have high ammonification rates and rapid N turnover (which is represented by a nitrogen turnover index) —nitrification rates or nitrogen accumulation were not such good predictors of sward quality. Ammonification increased with pH and with organic nitrogen accumulation whereas N turnover was not related to these factors. Nitrification levels were generally low and it was concluded that nitrification was not important to sward health. Organic nitrogen increased with age in all swards, ammonification in certain types only and nitrification not at all. Levels of all are well short of those in adjacent grazing land. Rates of turnover had however a tendency to decline towards those in the grazings owing probably to the build up of resistant humus. The proportion of the total nitrogen which is in the biomass (30%) is also higher than in adjacent grazings (6%). Rapid nitrogen cycling is thus needed to maintain productivity and greenness, and the disadvantages of this are discussed. The adequacy of nitrogen cycle development to date is considered, and possible future strategies outlined.     

Ectomycorrhiza communities of red oak (<Emphasis Type="BoldItalic">Quercus rubra</Emphasis> L.) of different age in the Lusatian lignite mining district,East Germany

Ectomycorrhizal (ECM) communities were assessed on a 720 m² plot along a chronosequence of red oak (Quercus rubra) stands on a forest reclamation site with disturbed soil in the lignite mining area of Lower Lusatia (Brandenburg, Germany). Adjacent to the mining area, a red oak reference stand with undisturbed soil was investigated reflecting mycorrhiza diversity of the intact landscape. Aboveground, sporocarp surveys were carried out during the fruiting season in a 2-week interval in the years 2002 and 2003. Belowground, ECM morphotypes were identified by comparing sequences of the internal transcribed spacer regions from nuclear rDNA with sequences from the GenBank database. Fifteen ECM fungal species were identified as sporocarps and 61 belowground as determined by morphological/anatomical and molecular analysis of their ectomycorrhizas. The number of ECM morphotypes increased with stand age along the chronosequence. However, the number of morphotypes was lower in stands with disturbed soil than with undisturbed soil. All stands showed site-specific ECM communities with low similarity between the chronosequence stands. The dominant ECM species in nearly all stands was Cenococcum geophilum, which reached an abundance approaching 80% in the 21-year-old chronosequence stand. Colonization rate of red oak was high (>95%) at all stands besides the youngest chronosequence stand where colonization rate was only 15%. This supports our idea that artificial inoculation with site-adapted mycorrhizal fungi would enhance colonization rate of red oak and thus plant growth and survival in the first years after outplanting.     

Salvaged-Wetland Soil as a Technique to Improve Aquatic Vegetation at Created Wetlands in Wyoming,USA

Aquatic plants usually establish following wetland creation from a variety of mechanisms including animal transport, inflows from nearby wetlands, wind dispersal, and seed banks if they are available. However, at created wetlands that are isolated from natural wetlands, aquatic plant communities may not establish even after 10 or more years. One method of improving the establishment of aquatic plants is through the use of salvaged-marsh soils. Using this method, wetland soil from a donor site is collected and spread across the basin of the created wetland. When the proper hydrologic regime is reached at the created site, the seed bank from the donor soil is then present to take advantage of the uncolonized site. Over 1500 wetlands have been created in northeast Wyoming, USA from bentonite mining and most of them have not developed submersed and emergent plant communities due to isolation from plant sources. Our goal was to evaluate the effectiveness of using salvaged-wetland soil as a tool for improving plant growth at created wetlands. Our study took place at 12 newly created wetlands that were isolated from other wetlands by >5 km. Six wetlands were treated as reference wetlands, with no introductions of seeds or propagules. At the other six wetlands we spread ≈10–15 cm of salvaged soil from a donor wetland during the winter of 1999–2000. To identify the potential plants in donor soil, we collected 10 random samples from the donor wetlands and placed them within wetland microcosms in a greenhouse where they were treated to either moist-soil conditions (water at or just below the soil line) or submersed conditions (water levels maintained at 15–30 cm). Treatment wetlands were evaluated for plant growth during the fall of 2000 and 2001, whereas the greenhouse samples were grown for two growing seasons then harvested. Our results show that using salvaged wetland soil increases: (1) the number of plant species present at a wetland over time, (2) the total vegetation coverage in a treated wetland over time, and (3) the total plant biomass in a treated wetland. The species pool available in the salvaged wetland soil was limited to 10 obligate wetland species, but several of them are considered valuable to waterfowl and other wildlife. Furthermore, salvaged-wetland soil could be useful for ameliorating poor substrate conditions (i.e., bentonite) and improving conditions for the establishment of additional species. One concern with this technique is the introduction of invasive or exotic species that could form monocultures of undesirable plants (e.g., cattail [Typha spp.]); introducing more desirable species during the application of salvaged soil could reduce this probability. We believe incorporating salvaged-wetland soil during basin construction could be used to increase the value and productivity of created wetlands in this region.     

Reclamation of coalmine overburden dump through environmental friendly method

Coal mine spoils (-the previous overburden of coal seams, inevitable by-product in the mining process) which are usually unfavorable for plant growth have different properties according to dumping years. The reclamation of overburden dumps (OBDs) through plantation by using efficient microbes with suitable bio-inoculants is an environmental friendly microbial technique for significant improvement in fertility status and biological activities of the OBD soil. A systematic greenhouse pot experiment program followed by field trial was conducted to investigate the influence of arbuscular mycorrhizal (AM) and NFB on the performance of plant growth which have resulted in the development of environmental friendly bio-inoculant package for soil reclamation of abandoned mine land by revegetation.     

Delayed inoculation and starter nitrogen for enhancing early growth and nitrogen status ofLespedeza cuneata

Summary Two growth chamber experiments were conducted to determine the response ofLespedeza cuneata (Dumont) G. Don. (sericea lespedeza) to delayed inoculation and low levels of nitrogen fertilization. Nitrogen was supplied either as NH ₄ ⁺ or as NO ₃ ^– in solution. At 0.5 and 5.0 ppm nitrogen early growth and N₂(C₂H₂) fixation was inhibited by NH ₄ ⁺ and promoted by NO ₃ ^– . Inoculation at seeding did not negatively affect growth prior to the onset of N₂(C₂H₂) fixation. Delayed inoculation until the trifoliate stage thus did not increase growth or N₂ fixation during the first 40 days of growth. After 40 days, specific nitrogenase activity was highest for plants inoculated at the first trifoliate stage of growth. In contrast, growth and total shoot nitrogen accumulation were higher in plants inoculated at planting. The experimental results suggest that delaying inoculation is not a useful technique for improving early growth ofL. cuneata for surface mine reclamation.     

The relation between geomorphology and forest community types of the Haut-Saint-Laurent,Quebec

The highly disturbed community types of the Haut-Saint-Laurent in southern Quebec were classified using an hierarchic approach with three levels: geomorphology, pedology and vegetation. Considered as distinct entities were, on the one hand, the herbaceous and shrub species that made up ecological groups as defined by Meilleur et al. (1992), and, on the other hand, individual tree species. Great importance was given to geomorphological variables because they are one of the most stable ecological factors of the region. We identified 47 community types from 452 sites sampled, based on a TWINSPAN analysis of the vegetation data. Binary Discriminant Analysis (BDA) showed the importance of disturbance on community composition, especially for sites included in the forest mosaic. Other important abiotic parameters included morphogenic features, topography and drainage. The BDA showed that 24 community types were found to be significantly associated with at least one morphogenic feature. The results indicate that the Beech-Hemlock association is a more stable state for mesic sites than the often cited Sugar Maple with Hickory. On glacial deposits, the presence of Thuja occidentalis is significantly associated with grazing practices. The other 23 community types are not significantly associated with any morphogenic features. On one hand, these types tend to be ubiquitous on different deposits with the same drainage class and reveal that their composition was altered through disturbances. On the other hand, some community types are more associated with microclimates as is the case of Sugar Maple with Striped Maple, or with their ecological amplitude limits as is the case of Sugar Maple with Ironwood and Aspen or Sugar Maple with Red Maple and Black Ash. A classification of the stands, given the high number of disturbed communities within the territory, appears difficult to use as a basis for ecological units.