离岸消浪堰式湖滨带生态修复工程对水质的影响

离岸消浪堰式湖滨生态修复工程系采用离湖岸线一定距离的桩基消浪堰,在湖堤硬质化、湖滨植被带缺失的湖滨带实现控浪促淤,形成半封闭型的人工湖湾以恢复湖滨植被带的工程措施.修复工程形成了堰内挺水植物区、堰内沉水植物区和堰外开阔水体3个生境梯度带.本文以无锡市太湖贡湖湾离岸消浪堰式生态修复工程为研究对象,于2010年6月至2011年5月对工程区3个生境梯度带的水质状况进行了研究.结果表明:消浪堰内亚硝态氮与硝态氮总体上低于堰外,但铵态氮和总氮总体上高于堰外.秋冬季磷素指标堰内浓度低于堰外,但春夏季多高于堰外.堰内水体亚硝态氮和正磷酸盐浓度的变异系数减小,硝态氮、亚硝态氮和正磷酸盐的年最高浓度值低于堰外;但铵态氮和总氮的变异系数增加,且堰内铵态氮、总氮的年最高浓度值高于堰外.修复工程在生长季末期可在一定程度上加剧铵态氮、总氮等水质指标的恶化.     

Landscape scale assessment of stream channel and riparian habitat restoration needs

Human modifications of streams and rivers have caused extensive stream channel and riparian degradation. Cost-effective, rapid assessment tools can be used to better manage such areas by identifying the status of habitats for restoration planning and protection. We used a spatially explicit, reach-scale geographic information system modeling strategy to examine stream channel and riparian condition and prioritize restoration actions. The stream channel condition index uses information on land use, road and railroad density, and sinuosity. The riparian condition index uses calculations of percent forest, patch density, and convexity based on land cover in the floodplain. Reaches were classified into restoration categories based on stream channel and riparian condition model results, land ownership, slope, position in the subwatershed, and adjacency to high-quality habitat. We compared modeled restoration priority rankings with those in the management plan for the East Credit subwatershed in Ontario, Canada. Predicted stream channel restoration priority rankings matched field-based classifications for 86% of the reaches in the East Credit subwatershed. Predicted riparian restoration priority rankings matched field-based classifications for 81% of the reaches. Our methods replicate with fairly good accuracy the results obtained using intensive field surveys and stakeholder input. Managers can use these cost-effective strategy development tools to identify candidate reaches for further study and prioritize stream channel and riparian restoration actions over large regions.     

The restoration of gravelly floodplain vegetation and endemic plants to riparian habitat in a Japanese river

Aster kantoensis, an endangered and monocarpic perennial plant species, is endemic to the gravelly floodplain of a few rapid flowing rivers in eastern central Japan. In recent years, an extreme declining trend in the species has been accelerated due to the strong negative influence by invasion of an alien grass, Eragrostis curvula. A restoration project aimed at recovering the original condition of the floodplain in the Kinu River, central Japan, has been started. To determine the possibility of successful restoration as well as its habitat preferences, I carried out some seed sowing experiments. In April 2003, seeds collected from a seminatural habitat were sown (54,000 seeds) in the restoration site (1.2 ha), where flood frequency, substrate condition, and control of alien plants are combined to form different habitat conditions. Seedling survival, flowery, and seed production were subsequently monitored from 2003 to 2005. Seed cohorts completed their life cycles within 3 years, and mean fitness of 927 was achieved. Performance of A. kantoensis seedlings was generally greater for environmental variables of sandy-type substrate and/or with control of alien plants. In addition, there were significant negative correlations between percentage survival, percentage flowery, and seed production with vegetation cover and coverage of E. curvula. The results confirm that, if safe sites with sparse vegetation exist, irrespective of their substrate condition, as well as seed sources of river endemics in natural habitats, restoration of riparian vegetation including river endemics is possible. The aggressive alien species E. curvula should be taken into consideration.     

Fast but ephemeral effects of ecological restoration on forest beetle community

Many protected areas have a long history of human intervention before being protected. In protected forests, the past land use has reduced the amount of natural structures, which are crucial substrates for thousands of species. We evaluate the short-term ecological effect of forest restoration (dead wood creation) on conifer-associated saproxylic (dead-wood dependent) beetles. More specifically, we analyze the effect of dead wood creation on the number of beetle species and individuals 1 and 5 years after restoration in spruce and pine forests, using a large-scale monitoring network over Finland. The number of saproxylic beetle species and individuals was larger at restored than at control plots both 1 and 5 years after restoration in both spruce and pine forests. Community composition in restored plots was different from control plots 1 year after restoration, but had returned towards the control plot composition 5 years after restoration, while control plots remained largely unchanged. Both in spruce and pine forests, there were more red-listed and rare saproxylic beetles in restored than in control plots 1 and 5 years after restoration. Our results indicate that restoration has an overall positive influence on saproxylic beetle diversity immediately after dead wood creation, but this effect is rather short-lived. Long term monitoring of restored dead wood is crucial in investigating successional pathways as well as biotic communities in advanced decay stages, and in fully evaluating the ecological effect of dead wood creation as a forest restoration measure.     

Estimating the ecological status and change of riparian zones in Andalusia assessed by multi-temporal AVHHR datasets

Following the European Commission's Water Framework Directive all surface waters in EU's Member States must reach a good status by 2015. The evaluation of this status will be partly based on ecological criteria, such as the hydro-morphological quality criteria which also evaluate the structure and condition of the riparian zone. Riparian zones with undisturbed or nearly undisturbed condition are given high-ecological status. The agri-environmental measures in the EU promote an extensive use of land to protect the farmed environment and its biodiversity. Recent studies in Andalusia and elsewhere suggest that extensification leads to riparian zones with higher ecological status compared to intensively used areas. We suggest that extensification and thus better ecological status of the riparian zone can be partly approximated by the amount of vegetation permanently present on the area. For this the so-called permanent vegetation fraction was derived from a multi-temporal advanced very high-resolution radiometer (AVHRR) dataset and was used (1) to classify the ecological status of the riparian zone into two classes, favourable and unfavourable, and (2) to assess the effect of agricultural practices on these areas. The classification was validated by field observations in the Guadalquivir river basin while detailed information on farming practices helped to assess the effect of agriculture on the riparian zone. The assessment was carried out in olive land cover because erosion control in olive cultivations is the most widely implemented measure in Andalusia. Results suggest that the remotely sensed permanent vegetation fraction is a good indicator of the favourable and unfavourable ecological status of the riparian zone. Furthermore, extensification of agricultural practices expressed in terms of increasing permanent vegetation cover was shown to have positive effect on the riparian zone as opposed to areas where no measures were implemented.     

Native and introduced land snail species as ecological indicators in different land use types in Java

We investigated the effects of different land use types and environmental parameters on the number and abundance of native and introduced land snail species in East Java. 2919 specimens were sampled and assigned to 55 species of which 8 are introduced. Whereas species richness was highest in primary forest, the highest number of introduced species was found in agroforest. The snail assemblages in different habitat types differ much clearer in composition than in total species richness. Plantations and agroforest are dominated by introduced pulmonates with regard to number of individuals, while primary forest is dominated by native prosobranchs. The habitat requirements of the introduced pulmonates differ from those of the native species. In the study area, the abundance of native as well as introduced pulmonate species increased with increasing human impact. However, the abundance of introduced pulmonate species decreased with increasing density of the canopy cover, whereas the abundance of native pulmonate species increased with increasing canopy cover. The abundance of native prosobranch land snails also tends to increase with increasing canopy cover and with the availability of deadwood, but decreased with increasing human impact. Improving the canopy cover and retaining deadwood in plantations and agroforests might help to control the populations of introduced species or even prevent their establishment in these habitats. Land snails are good indicators for the long-term stability of natural habitats, because several species are restricted to undisturbed natural habitats and because of their low dispersal abilities. However, complete inventories of land snail species are costly. Therefore we propose two indices that can be scored with much less effort, namely the percentage of prosobranch individuals and the percentage of individuals of introduced species. Both indices are significantly correlated with the number of native species. Dense plantations and agroforests bordering primary forests may protect the latter from introduced species and help to conserve the native fauna by reducing desiccation and buffering the human impact on the primary forests.     

Hydrologic effects on riparian vegetation in a boreal river: an experiment testing climate change predictions

Climate change is expected to alter the magnitude and variation of flow in streams and rivers, hence providing new conditions for riverine communities. We evaluated plant ecological responses to climate change by transplanting turfs of riparian vegetation to new elevations in the riparian zone, thus simulating expected changes in water‐level variation, and monitored the results over 6 years. Turfs moved to higher elevations decreased in biomass and increased in species richness, whereas turfs transplanted to lower elevations gained biomass but lost species. Transplanted plant communities responded slowly to the new hydrologic conditions. After 6 years, biomass of transplanted turfs was statistically indistinguishable from target level controls, but species richness and species composition of transplants were intermediate between original and target levels. By using projections of future stream flow according to IPCC climate change scenarios, we predict likely changes to riparian vegetation in boreal rivers. Climate‐driven hydrologic changes are predicted to result in narrower riparian zones along the studied Vindel River in northern Sweden towards the end of the 21st century. Present riparian plant communities are projected to be replaced by terrestrial communities at high elevations as a result of lower‐magnitude spring floods, and by amphibious or aquatic communities at low elevations as a result of higher autumn and winter flows. Changes to riparian vegetation may be larger in other boreal climate regions: snow melt fed spring floods are predicted to disappear in southern parts of the boreal zone, which would result in considerable loss of riparian habitat. Our study emphasizes the importance of long‐term ecological field experiments given that plant communities often respond slowly and in a nonlinear fashion to external pressures.     

Rapid genetic identification of local provenance seed collection zones for ecological restoration and biodiversity conservation

The ecological restoration of native plant communities requires the collection of large amounts of seed. Use of non-local provenance seed can have detrimental consequences for the success of restoration if there is a home-site advantage, and for nature conservation through the erosion of natural patterns of population genetic structuring and/or genetic swamping (and extirpation) of locally significant genotypes. As part of an ongoing project to genetically delineate local provenance seed collection zones for species within a large urban bushland remnant of high conservation value, we assessed population genetic differentiation in two widespread coastal leguminous species, Acacia rostellifera and A. cochlearis (Fabaceae), commonly used in restoration programmes in SW Australia. Using amplified fragment length polymorphism (AFLP), we found very high levels of genetic differentiation among populations, with an analysis of molecular variance (AMOVA) showing more than 50% of the total genetic variance to be partitioned among populations (Φ_ST=0.58 and 0.51 for A. rostellifera and A. cochlearis, respectively), and marked non-overlap of almost all potential seed source populations from the local population in ordinations. Our results suggest extremely restricted natural dispersal among populations, possibly due to a combination of low seed set, seed dispersal by ants, clonality, a linear distribution of naturally fragmented populations and possibly low outcrossing rates. We suggest a narrow seed collection zone should be applied to these species for the conservation of genetic diversity and natural patterns of population genetic structure, and we highlight the value and importance of provenance evaluation to ecological restoration.     

Scenario-based assessment of future land use change on butterfly species distributions

Species distribution models (SDMs) are increasingly used to predict environmentally induced range shifts of habitats of plant and animal species. Consequently SDMs are valuable tools for scientifically based conservation decisions. The aims of this paper are (1) to identify important drivers of butterfly species persistence or extinction, and (2) to analyse the responses of endangered butterfly species of dry grasslands and wetlands to likely future landscape changes in Switzerland. Future land use was represented by four scenarios describing: (1) ongoing land use changes as observed at the end of the last century; (2) a liberalisation of the agricultural markets; (3) a slightly lowered agricultural production; and (4) a strongly lowered agricultural production. Two model approaches have been applied. The first (logistic regression with principal components) explains what environmental variables have significant impact on species presence (and absence). The second (predictive SDM) is used to project species distribution under current and likely future land uses. The results of the explanatory analyses reveal that four principal components related to urbanisation, abandonment of open land and intensive agricultural practices as well as two climate parameters are primary drivers of species occurrence (decline). The scenario analyses show that lowered agricultural production is likely to favour dry grassland species due to an increase of non-intensively used land, open canopy forests, and overgrown areas. In the liberalisation scenario dry grassland species show a decrease in abundance due to a strong increase of forested patches. Wetland butterfly species would decrease under all four scenarios as their habitats become overgrown.     

Pyrosequencing of prey DNA in faeces of carnivorous land snails to facilitate ecological restoration and relocation programmes

Identifying and understanding predator diets is of high importance in biological conservation. This is particularly true for the introduction, establishment and maintenance of predator populations in newly created or modified ecological communities, such as translocation sites or restored habitats. Conservation status of predators may not permit captive feeding trials or intrusive gut-content methods, so non-intrusive diet assessment is required, such as faecal analysis. However, prey such as earthworms leave no morphological clues suitable for accurately discriminating between species consumed through visual faecal analysis. This study uses non-intrusive molecular methods on earthworm DNA extracted from the faeces of the carnivorous land snail Powelliphanta patrickensis to identify its earthworm diet and any seasonal trends. Data from 454-pyrosequencing revealed earthworm DNA in all samples (n = 60). Sequences were compared to a DNA library created from published and unpublished studies of New Zealand’s endemic earthworms and online databases. Unidentified earthworm sequences were clustered into molecular operational taxonomic units (MOTUs). Twenty-six MOTUs were identified, 17 of which matched the library, whereas nine did not. Similarity indices indicate that there were seasonal differences (P < 0.05) in the earthworm communities represented in the summer and the winter diets. This study highlights the importance of utilising the vast body of data generated by pyrosequencing to investigate potential temporal diet shifts in protected species. The method described here is widely applicable to a wide range of predatory species of conservation interest and can further inform habitat restoration and relocation programmes to optimize the long-term survival of the target species.     

Mechanical effects on endothelial cell morphology: In vitro assessment

Summary Endothelial cells are subjected to fluid mechanical forces which accompany blood flow. These cells become elongated and orient their long axes parallel to the direction of shear stress when the cultured cells are subjected to flow in an in vitro circulatory system. When the substrate is compliant and cyclically deformed, to simulate effects of pressure in the vasculature, the cells elongate an orient perpendicular to the axis of deformation. Cell shape changes are reflected in the alignment of microtubule networks. The systems described provide tools for assessing the individual roles of shear stress, pressure, and mechanical strain on vascular cell structure and function. This work was partially supported by grants HL 17437, HL 18072, and HL 23016 from the National Institutes of Health, Bethesda, MD, and grant C-938 from the Robert A. Welch Foundation.     

Hydrology and history: land use changes and ecological responses in an urban wetland

The impacts of changing land use on hydrology and dominant plant species from 1850–1990 were investigated in a palustrine wetland in southern Wisconsin, USA. Aerial photographs, historic maps and water levels of the area were used to determine changes in land use, wetland vegetation, and groundwater and surface flows over time. Piezometers and water table wells were monitored weekly for two years. Vegetation was quantified in four one-square meter quadrats at each water level measurement site. Linear regression models and multivariate ordinations were used to relate wetland plant species to hydrologic, chemical and spatial variables. The current hydrologic budget of the wetland was dominated by precipitation and evapotranspiration, although overland flow into the wetland from the subwatershed has increased twenty-fold since 1850. Water level stabilization in the adjacent Yahara River, creek channelization, and groundwater pumping have decreased inputs of groundwater and spring-fed surface water, and increased retention of precipitation. Typha spp. and Phalaris arundinacea L. have increased in the wetland, while Carex spp. have decreased. Phalaris arundinacea was found most often in the driest sites, and the sites with the greatest range of water levels. Typha spp. dominated in several hydrologic settings, indicating that water depth was not the only factor controlling its distribution. The distributions of dominant plant species in the wetland were most closely correlated with site elevation and average water levels, with some weaker correlations with vertical groundwater inflows and specific conductance.     

Life Cycle Impact assessment of land use based on the hemeroby concept

The impact category ‘land use’ describes in the Life Cycle Assessment (LCA) methodology the environmental impacts of occupying, reshaping and managing land for human purposes. Land use can either be the long-term use of land (e.g. for arable farming) or changing the type of land use (e.g. from natural to urban area). The impact category ‘land use’ comprises those environmental consequences, which impact the environment due to the land use itself, for instance through the reduction of landscape elements, the planting of monocultures or artificial vegetation, or the sealing of surfaces. Important environmental consequences of land use are the decreasing availability of habitats and the decreasing diversity of wildlife species. The assessment of the environmental impacts of land use within LCA studies is the objective of this paper. Land use leads to a degradation of the naturalness of the area utilised. In this respect the naturalness of any area can be defined as the sum of land actually not influenced by humans and the remaining naturalness of land under use. To determine the remaining naturalness of land under use, this study suggests applying the Hemeroby concept. “Hemeroby is a measure for the human influence on ecosystems” (Kowarik 1999). The Hemeroby level of an area describes the intensity of land use and can therefore be used to characterise different types of land use. Characterization factors are proposed, which allow calculating the degradation of the naturalness of an area due to a specific type of land use. Since the resource ‘nature/naturalness’ is on a larger geographical scale by far not homogeneous, the assessment of land use needs to be regionalised. Therefore, the impact category ‘land use’ has been subdivided into the impact sub-categories ‘land use in European biogeographic regions’. Following the general LCA framework, normalization values for the impact sub-categories are calculated in order to facilitate the evaluation of the characterization results with regard to their share in a reference value. Weighting factors, which enable an aggregation of the results of the different land use sub-categories and make them comparable to other impact categories (e.g. climate change or acidification) are suggested based on the assumption that the current land use pattern in the European biogeographic regions is acceptable.     

Coherence of phytoplankton and attached diatom-based ecological status assessment in Lake Balaton

Coherence between ecological status assessment by phytoplankton and attached diatoms was analyzed in the littoral zone of Lake Balaton. Sampling of periphytic diatoms, phytoplankton, and water were carried out at ten different littoral sites in the northern and southern shores of the lake for a year. Phytoplankton species were sorted into functional groups and ecological status was assessed by means of the phytoplankton assemblage Q index. The index TDIL was calculated using quantitative attached diatom data. Significant differences were found between the ecological assessments based on phytoplankton and phytobenthos metrics, both seasonally and spatially. The Q index indicated ecological states varying from bad to good, while the average of diatom indices varied from moderate to high conditions. The Q index provided more realistic ecological status of Lake Balaton, compared with trophic status based on TP values, especially in the summer period. Differences in the response-time indication of phytoplankton and attached diatoms suggest that lack of coherence should also be expected between the responses of other BQEs.     

Hydrology and history: land use changes and ecological responses in an urban wetland

The impacts of changing land use on hydrology and dominant plant species from 1850–1990 were investigated in a palustrine wetland in southern Wisconsin, USA. Aerial photographs, historic maps and water levels of the area were used to determine changes in land use, wetland vegetation, and groundwater and surface flows over time. Piezometers and water table wells were monitored weekly for two years. Vegetation was quantified in four one-square meter quadrats at each water level measurement site. Linear regression models and multivariate ordinations were used to relate wetland plant species to hydrologic, chemical and spatial variables. The current hydrologic budget of the wetland was dominated by precipitation and evapotranspiration, although overland flow into the wetland from the subwatershed has increased twenty-fold since 1850. Water level stabilization in the adjacent Yahara River, creek channelization, and groundwater pumping have decreased inputs of groundwater and spring-fed surface water, and increased retention of precipitation. Typha spp. and Phalaris arundinacea L. have increased in the wetland, while Carex spp. have decreased. Phalaris arundinacea was found most often in the driest sites, and the sites with the greatest range of water levels. Typha spp. dominated in several hydrologic settings, indicating that water depth was not the only factor controlling its distribution. The distributions of dominant plant species in the wetland were most closely correlated with site elevation and average water levels, with some weaker correlations with vertical groundwater inflows and specific conductance.