Dark septate endophyte and arbuscular mycorrhizal status of vegetation colonizing a bottomland hardwood forest after a 100 year flood

Levels of arbuscular mycorrhizal (AM) colonization and dark septate endophyte (DSE) colonization were assessed in the vegetation recolonizing a remnant bottomland hardwood forest in north central Texas following a 100 year flood. Thirty seven plant species representing 21 dicotyledonous and 2 montocotyledonous families established following floodwater recession. AM and/or DSE were found in all species. AM colonization was found in 31 out of the 37 species assessed including both monocotyledonous families (Poaceae and Cyperaceae) and 17 out of 21 dicotyledonous families (Acanthaceae, Asteraceae, Boraginaceae, Cucurbitaceae, Euphorbiaceae, Lamiaceae, Loganiaceae, Lythraceae, Malvaceae, Onagraceae, Pedaliaceae, Ranunculaceae, Sapindaceae, Scrophulariaceae, Solanaceae, Verbanaceae and Violaceae). DSE were found in 31 out of 37 species assessed including both monocotyledonous families and 15 out of 21 dicotyledonous families (Amaranthaceae, Asteraceae, Boraginaceae, Brassicaceae, Cucurbitaceae, Euphorbiaceae, Lamiaceae, Lythraceae, Malvaceae, Pedaliaceae, Phytolaccaceae, Polygonaceae, Ranunculaceae, Sapindaceae, Scrophulariaceae and Violaceae). There were no detectable differences in AM or DSE colonization levels among wetland indicator groups (p > 0.05). Levels of DSE colonization were negatively correlated with vesicular colonization and hyphal colonization for the obligate wetland species. There were no other significant relationships between AM and DSE colonization detected. Spearman rank order correlation coefficients did not differ significantly among wetland indicatory category for any level of AM or DSE colonization.     

Assessing the relationship between biomass and soil organic matter in created wetlands of central Pennsylvania, USA

Created wetlands are frequently structurally different from the natural wetlands they are intended to replace. With differences in structure might come differences in function. Most created wetlands in central Pennsylvania have very low amounts of soil organic matter relative to levels found in natural wetlands. However, anecdotal evidence also suggests that plant production is equivalent in created wetlands to natural wetlands. There is little evidence to indicate that this plant biomass in created wetlands is finding its way into the soil as organic matter. This might translate into a lack of function in the mitigation wetlands. To address this issue, we studied plant biomass production in seven created wetlands in central Pennsylvania (USA). We measured above- and below-ground biomass and compared results with known values of soil organic matter and hydrology for the same wetlands. We found biomass to be approximately equivalent to that produced in natural freshwater marshes, although the below-ground component was somewhat higher. We found no relationship of biomass to soil organic matter, even though site conditions were wet enough to retard plant decomposition.     

Developing a wetland-type classification system in the Republic of Korea

Though there are wetlands listed by the IUCN and wetland protection areas designated by the government, it is presumed that there would be more wetlands in Korea when they are surveyed and classified according to international wetland criteria, but a considerable amount of area is yet to be identified. Therefore, in order to conduct a systematic status survey on the wetlands of Korea, a wetland classification system needs to be developed first. The objectives of this paper include reviewing international wetland classifications and mapping systems of the USA, Germany, the Netherlands, Japan and North Korea and developing a wetland classification and mapping system appropriate to Korea based on an understanding of the major case examples of wetland types. Then, the developed system was applied to the Phanmun field watershed located at the western DMZ in Korea to conduct a case study. The overall process of a wetland classification and mapping system developed in this study is undertaken as the following from step 1 to step 5. First, wetlands are identified based on three parameters: hydrology, hydrophytes and hydric soil. Second, wetland delineation distinguished wetland areas and non-wetland areas by identifying wetlands through a field survey. Third, an ecological survey is conducted in order to classify wetland characteristics and types for the target area. Ecological survey items include the topography, landscape, biota, pollutant sources and land use status. Fourth, a wetland classification is developed through a hybrid approach based on HGM (the hydrogeomorphic method). Level 1 is classified into inland, estuarine and costal areas. Level 2, the target area, is classified as an eco-region at a watershed level, and level 3 is classified into depression, riverine, slope, flat and fringe areas based on a HGM approach. Level 4 is classified into detailed wetland types based on specific characteristics of wetlands. Level 5 is classified into marsh and swamp based on grasslands and shrubs and forest trees. Level 6 indicates the dominant vegetation communities.

Denitrification and N<Subscript>2</Subscript>O emission from forested and cultivated alluvial clay soil

Restored forested wetlands reduce N loads in surface discharge through plant uptake and denitrification. While removal of reactive N reduces impact on receiving waters, it is unclear whether enhanced denitrification also enhances emissions of the greenhouse gas N₂O, thus compromising the water-quality benefits of restoration. This study compares denitrification rates and N₂O:N₂ emission ratios from Sharkey clay soil in a mature bottomland forest to those from an adjacent cultivated site in the Lower Mississippi Alluvial Valley. Potential denitrification of forested soil was 2.4 times of cultivated soil. Using intact soil cores, denitrification rates of forested soil were 5.2, 6.6 and 2.0 times those of cultivated soil at 70, 85 and 100% water-filled pore space (WFPS), respectively. When NO₃ was added, N₂O emissions from forested soil were 2.2 times those of cultivated soil at 70% WFPS. At 85 and 100% WFPS, N₂O emissions were not significantly different despite much greater denitrification rates in the forested soil because N₂O:N₂ emission ratios declined more rapidly in forested soil as WFPS increased. These findings suggest that restoration of forested wetlands to reduce NO₃ in surface discharge will not contribute significantly to the atmospheric burden of N₂O.     

The hydrogeomorphic approach to functional assessment of riparian wetlands: evaluating impacts and mitigation on river floodplains in the U.S.A.

1. The ’hydrogeomorphic‘ approach to functional assessment of wetlands (HGM) was developed as a synthetic mechanism for compensatory mitigation of wetlands lost or damaged by human activities. The HGM approach is based on: (a) classification of wetlands by geomorphic origin and hydrographic regime (b) assessment models that associate variables as indicators of function, and (c) comparison to reference wetlands that represent the range of conditions that may be expected in a particular region. In this paper, we apply HGM to riparian wetlands of alluvial rivers. 2. In the HGM classification, riverine wetlands are characterized by formative fluvial processes that occur mainly on flood plains. The dominant water sources are overbank flooding from the channel or subsurface hyporheic flows. Examples of riverine wetlands in the U.S.A. are: bottomland hardwood forests that typify the low gradient, fine texture substratum of the south-eastern coastal plain and the alluvial flood plains that typify the high gradient, coarse texture substratum of western montane rivers. 3. Assessment (logic) models for each of fourteen alluvial wetland functions are described. Each model is a composite of two to seven wetland variables that are independently scored in relation to a reference data set developed for alluvial rivers in the western U.S.A. Scores are summarized by a ’functional capacity index‘ (FCI), which is multiplied by the area of the project site to produce a dimensionless ’functional capacity unit‘ (FCU). When HGM is properly used, compensatory mitigation is based on the FCUs lost that must be returned to the riverine landscape under statutory authority. 4. The HGM approach also provides a framework for long-term monitoring of mitigation success or failure and, if failing, a focus on topical remediation. 5. We conclude that HGM is a robust and easy method for protecting riparian wetlands, which are critically important components of alluvial river landscapes.     

The pelican scenario for nature restoration of Aral Sea wetland ecosystems

Sustainability of the wetland ecosystems in the Aral Sea region depends on the ecological dynamic processes resulting from shifting mosaic patterns along the ecotone. The Pelican Scenario, a natural dynamism-oriented nature restoration plan for the Aral Sea crisis, should be considered not only for achieving sustainable land use, but also for the conservation of Pelecanus crispus, a vulnerable species.An erratum to this article can be found at This revised version was published online in April 2005 with correction to the Revised date.     

Nitrate elimination by denitrification in hardwood forest soils of the Upper Rhine floodplain – correlation with redox potential and organic matter

Denitrification in floodplains is a major issue for river- and groundwater quality. In the Upper Rhine valley, floodplain forests are about to be restored to serve as flood retention areas (polders). Besides flood attenuation in downstream areas, improvement of water quality became recently a major goal for polder construction. Redox potential monitoring was suggested as a means to support assessment of nitrogen elimination in future floodplains by denitrification during controlled flooding. To elucidate the relationship between redox potential and denitrification, experiments with floodplain soils and in situ measurements were done. Floodplain soil of two depth profiles from a hardwood forest of the Upper Rhine valley was incubated anaerobically with continuous nitrate supply. Reduction of nitrate was followed and compared with redox potential and organic matter content. The redox potential under denitrifying conditions ranged from 10 to 300 mV. Redox potential values decreased with increasing nitrate reduction rates and increasing organic matter content. Furthermore, a narrow correlation between organic matter and nitrate reduction was observed. Experiments were intended to help interpreting redox potentials generated under in situ conditions as exemplified by in situ observations for the year 1999. Results obtained by experiments and in situ observations showed that monitoring of redox potential could support management of the flooding regime to optimize nitrogen retention by denitrification in future flood retention areas.     

Evaluating wetlands within an urban context

Coastal regions are among the most rapidly urbanizing places on earth. The numerous effects of urbanization on hydrology, geomorphology, and ecology make wetlands in urban regions function differently from wetlands in non-urban lands. Furthermore, wetlands in urban regions may take on human-related values that they lack in non-urban areas, as they provide some contact with nature, and some opportunities for recreations that are otherwise rare in the urban landscape. Evaluations of the success of restorations in urban regions require criteria first to determine the kinds, and intensities of urban influence on the site, and secondly to assess functional performance. The development of success criteria, at both the levels of assessment, depends on the proper definition of a reference domain (the set of wetlands to which success criteria will apply), and the documentation of a set of reference sites within the domain; both must be based within the urban context appropriate for the region of interest. An example is presented from a study of urban wetlands in New Jersey of a procedure for establishing the reference domain, the reference set of wetlands, and criteria for the assessment of urban influence.     

Early development of plant community in a created mitigation wetland as affected by introduced hydrologic design elements

The goal of this study was to investigate early plant community development in two sites (i.e., higher and lower elevation sites—LC1 and LC2, respectively) of the Loudoun County (LC) mitigation wetland created in the Virginia Piedmont. The effects of hydrologic design elements incorporated during the construction (i.e., disking-induced microtopography—MT and site level elevation difference) on vegetative and hydrologic attributes (e.g., species richness, biodiversity, plant cover, floristic quality assessment index, wetland indicator status, soil moisture content, and water table depths) were investigated. The study was conducted at the end of two growing seasons in 2008 and 2009 (i.e., second and third growing seasons). Drought conditions that persisted into the second growing season resulted in the abundance of a seeded cover grass, Lolium multiflorum (Italian ryegrass), intentionally planted during initial seeding for erosion control. L. multiflorum was subsequently phased out and replaced by facultative wet and obligate wetland species by the third growing season when above-average precipitation occurred, leading to a decrease in total percent cover. Prevalence index changed in both LC1 and LC2, dropping from overall facultative status in 2008 to obligate status in 2009 when obligate species such as Bidens cernua, Carex frankii, and Juncus effusus thrived and expanded with the change of hydrologic regime in 2009. Microtopographic treatment (i.e., disked or undisked) positively influenced vegetation development for LC1 site in 2008, but the positive influence was not consistent for LC2, which experienced an additional month of standing water conditions in the same year, nor for either site in 2009 when above-average precipitation occurred. The site differences in elevation, and thus hydrologic regime, seemed to overwhelm the effects on vegetation of disking-induced microtopography in each site when precipitation was at or above average range. Although shown on short spatial and temporal scales in this study, incorporation of micro- and macrotopographic design elements in creating a mitigation wetland can be beneficial to the early development of diverse vegetation communities wetland under varying climate conditions.     

三种生物质能源植物组织的乙醇提取液对烟粉虱生物活性的影响

为了探讨蓖麻、海滨锦葵等生物质能源植物组织的抽提物作为植物保护剂的可行性,用蓖麻种子、蓖麻叶片、海滨锦葵叶片等生物质能源植物组织的乙醇粗提物处理烟粉虱成虫,4、24、48、72和96 h后测定其体内的谷胱甘肽转移酶和羧酸酯酶活性,并利用Y型嗅觉仪测定烟粉虱对3种生物质能源植物组织的乙醇粗提物的嗅觉反应.结果表明:3种生物质能源植物组织的乙醇粗提物对烟粉虱谷胱甘肽转移酶和羧酸酯酶均有明显影响,随着浓度的提高,其作用增强,其中250倍液的作用与1.8%的阿维菌素3000倍液作用相当.3种提取液的250倍液对烟粉虱成虫具有明显的驱避作用,其中蓖麻种子、蓖麻叶片和海滨锦葵叶片等乙醇粗提物的驱避率分别为100.0%、96.7%和79.4%.表明蓖麻种子、蓖麻叶片和海滨锦葵叶片的乙醇粗抽提物对烟粉虱具有驱避作用和其他生物活性.     

Diversity of canopy and understorey spiders in north-temperate hardwood forests

1 We characterized and compared diversity patterns of canopy and understorey spiders (Arachnida: Araneae) on sugar maple ( Acer saccharum Marsh.) and American beech ( Fagus grandifolia Ehrh.) in hardwood forests of southern Québec, Canada.
2 We sampled canopies of 45 sugar maple and 45 American beech trees and associated understorey saplings in mature protected forests near Montréal. Samples were obtained by beating the crown foliage at various heights and by beating saplings around each tree.
3 Eighty-two species were identified from 13 669 individuals. Forty-eight species and 3860 individuals and 72 species and 9809 individuals were collected from the canopy and the understorey, respectively.
4 Multivariate analyses (NMDS ordination and NPMANOVA) showed the composition of canopy and understorey assemblages differed significantly, and canopy assemblages differed between tree species. Rank-abundance distribution models fitted to the canopy and understorey data indicated that different mechanisms structure the assemblages in both habitats. Three abundant spider species were significantly more common in the canopy; ten species were collected significantly more often in the understorey.
5 The forest canopy was shown to be an important reservoir for spider diversity in north-temperate forests.