首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
This study evaluates the prospects for restoration of the Cirsio-Molinietum orchietosum by sod cutting of an eutrophicated Cirsio-Molinietum stand and of a former agricultural grassland and an alder cart, respectively. Sod cutting of the former agricultural grassland and of the alder cart sufficed to restore this plant community, whereas sod cutting of the eutrophicated Cirsio-Molinietum was not successful. The unsuccessful restoration of the eutrophicated Cirsio-Molinietum might be due to prolonged inundation resulting from the sod cutting, causing anaerobic conditions under which no nitrification takes place. The chemical composition of the deep groundwater supplying the site changed from base-rich and SO42−-poor to base-rich and SO42−-rich. This change in chemical composition of the deep groundwater, discharging in the study area, might cause a higher nutrient availability in the root zone, and therefore, negatively influence the prospects for the restoration of the Cirsio-Molinietum. Furthermore, successful restoration of the Cirsio-Molinietum requires (1) water tables close to the soil surface during at least six months and (2) discharging base-rich groundwater in the root zone.  相似文献   

2.
Question: Which are the success and failure of restoration measures, particularly sod‐cutting and hydrological measures, in small wetlands on mineral soils in The Netherlands. Location: Twente, in the eastern part of The Netherlands. Methods: Success or failure of restoration measures has been assessed by comparing experimental plots with that in reference plots for (1) species richness, (2) re‐establishment of endangered species and (3) species composition, including life forms and Red List species. In total 119 samples were taken in 42 permanent plots in fen meadows, small‐sedge marshes, wet heathlands, and soft‐water pools. Topsoil samples were analysed for pH, Ca, Mg, Na, K and Cation Exchange Capacity. Gradient analysis was carried out by means of Canonical Correspondence Analysis. Results: Sod‐cutting, in combination with re‐wetting measures (infilling of ditches and drains), led to restoration of communities of soft‐water pools and small sedge marshes within five years. This rapid recovery is probably related to the presence of persistent seed banks of the component species of these communities. Complete restoration of fen meadows took longer (10–15 yr). Apparently, many species of fen meadows have short‐lived seed banks. Sod‐cutting of a degraded wet heathland and a soft‐water pool was only successful temporarily, probably as a consequence of low water tables. Conclusions: To prevent depletion of (persistent) soil seed banks, sod‐cutting in nutrient‐poor wetlands is not recommended in areas where the groundwater regime and the base status of the soil can not be restored to levels required by plant communities of wet heathlands.  相似文献   

3.
Temperate heaths have an unfavorable conservation status in most European biogeographical regions. Increasing nitrogen levels promote competitive grass species such as Molinia caerulea, which is a main threat to heathland conservation in Europe. This article investigates the long‐term influence of sod cutting and the resulting changes in soil properties on the heath composition, integrity, and structure. In 15 nature reserves across the northern half of Belgium, we used (1) a large number of plots (203); (2) a broad range of sod cut depths (2–40 cm), and (3) a temporal dimension that describes how long the effects of sod cutting persist (census up to 19 years after sod cutting). Multivariate analyses were used in order to explore the influence of sod cut depth and time after sod cutting on the soil and vegetation properties. There was a positive relationship between sod cut depth and soil pH and water level, and a negative relationship with Al3+, NH4+, and total organic matter (TOM). However, only a limited number of typical (target) species appeared after sod cutting, and then only weakly. Most of the time they remained a minor component of the restored vegetation. Moreover, M. caerulea reappeared and its cover significantly increased during the years following sod cutting. Although we were able to show that sod cut depth has a differential effect on soil properties and vegetation recovery, it also appeared that sod cutting does not restore wet heaths in the long term when applied in regions with high nitrogen deposition.  相似文献   

4.
Abstract. The population dynamics and reproductive strategies of two rare wet heathland species, Gentiana pneumonanthe and Rhynchospora, were studied in experimental permanent plots in a wet heathland near Bremen, NW Germany, to assess how effective sod cutting and mowing are in promoting these species. In one experiment, small plots (0.25 m2 - 4 m2) were sod-cut or mown; in the second, one large plot 30 mx 50m) was sod-cut. The development of the vegetation and the number of shoots of the two target species were recorded annually. Sod cutting lead to the highest shoot numbers of Gentiana in the long run, whilst mowing was more effective at the beginning of the experiment. Seedlings and adult shoots slowly became more and more abundant after sod cutting. In contrast, Rhynchospora soon formed closed stands after sod-cutting, first through seed germination and then through fast clonal growth of the established individuals. Moist soil or short inundations promoted the germination and seedling establishment of Gentiana, whereas drought negatively affected seedling recruitment. Long periods of inundation severely reduced the population at first, but high numbers of seedlings were found in the following growing season. For the disturbance-dependent Gentiana and Rhynchospora, the availability of gaps within the vegetation is of crucial importance. To promote existing populations, we suggest small-scale sod cuttings which create gaps without disturbing existing flowering individuals too much. For degenerated stands of wet heathland we recommend large-scale sod cutting to activate the seed bank. Additionally, seed introduction may be helpful to encourage the development of a wet heathland with characteristic floristic composition.  相似文献   

5.
Over the last two centuries wet heathlands and associated habitats, such as poor fens and bogs, have suffered extensive fragmentation. Recently, large-scale projects aim to restore these rare habitats throughout Europe. To evaluate post-restoration trajectories of wet heathlands, suitable monitoring tools are urgently needed. Here, we investigated whether spider communities are useful tools for evaluating the restoration success of wet heathlands. Ordination revealed that dissimilarity in spider communities between patches of different age classes resulted mainly from vegetation cover and soil moisture. By using a functional trait-approach, we tested if the time since restoration affects trait distribution of spiders in wet heathlands. Typical wet heathland spider species were less common with increasing vegetation encroachment and lower water content. New patches were inhabited by summer active, eurytopic (non-heathland) spiders, while more typical heathland species were found in middle-aged and old patches. Our results suggest that time-related changes in vegetation structure and moistness of restored wet heathlands are clearly reflected by spider communities. Although mobile spiders quickly recolonize the restored heathlands, it takes time for typical heathland spiders to settle. Restoration measures should prevent the negative effects of a vegetation encroachment and a high density of forested edges and should rehabilitate the hydrological cycle in order to preserve rare heathland spiders. We discuss that accounting for responses of spiders provides additional information to guide wet heathlands restoration.  相似文献   

6.
Questions: What are the effects of raised water levels on wet grassland plant communities and dynamics? To what extent do time since raised water levels, vegetation management and water regime influence community composition? Location: Pevensey Levels, southeast England, UK. Methods: Plant communities and hydrology were monitored during 2001‐03 within 23 wet grassland meadows and pastures where water levels had been raised for nature conservation at different times over 21 years. Community variations were examined using species abundance and ecological traits. Results: Water regime, measured as duration of flooding, groundwater level and soil moisture was significantly related to plant community variation. Communities were divided into grasslands where inundation was shallow (≤8 cm) and relatively short (≤3 months) and sites where deeper flooding was prolonged (≥5 months), supporting a variety of wetland vegetation. With increasing wetness, sites were characterised by more bare ground and wetland plants such as sedges, helophytes and hydrophytes, and species with a stress‐tolerating competitive strategy. All sites showed considerable annual dynamics, especially those with substantially raised water levels. There were no significant relationships between time since water levels were raised and plant community composition. Grassland management exerted a limited influence upon vegetation compared to water regime. Conclusions: Grassland plant communities are responsive to raised water levels and have potential for a rapid transition to wetland vegetation, irrespective of grazing or cutting management. Creation or restoration of wet grasslands by (re)wetting is feasible but challenging due to the high dynamism of wetland plant communities and the need for substantially raised water levels and prolonged flooding to produce significant community changes.  相似文献   

7.
Abstract. Fen meadows (Cirsio dissecti‐Molinietum) are seriously threatened by desiccation, acidification and eutro‐phication. In The Netherlands several projects were launched to restore damaged fen meadows. This review describes how successes and failures of these restoration projects depend on hydrological systems. Six hydrological systems have been distinguished, which all provide the site conditions required by this community. Nowadays, the best developed fen meadows are found in the higher Pleistocene landscape of The Netherlands, where they depend on base‐rich groundwater discharging from local or large groundwater systems. Fen meadows of the lower Holocene landscape usually occur in man‐made surface water systems. Almost all stands have been severely deteriorated. Restoration of fen meadows in the Pleistocene landscape is promising when the hydrology is only slightly disturbed or when hydrological measures are taken in combination with sod cutting. Restoration prospects of fen meadows in the Holocene landscape are low. Until now a complete regeneration of Cirsio‐Molinietum meadows has not been realized. Restoration measures failed to restore high pH values in the top soil. It is hypothesized that viable seeds of many target species lack in the soil seed bank. In addition, the dispersal capacities of these species seem to be limited.  相似文献   

8.
Current restoration measures of degraded, acidified heathland ecosystems have not always been successful in the Netherlands. Positive effects of a restored hydrology are often counteracted by acidification of the soil and the local groundwater system. Liming of the heathlands in the catchment of moorland pools might contribute to the restoration of both habitats. Experimental catchment liming was carried out in two degraded Dutch heathlands, with doses varying between 2 and 6 tons/ha. Catchment liming resulted in increased pH and base cation concentrations in the highest elevated limed parts, as well as in the lower situated, nonlimed heath areas and moorland pools. Generally, catchment liming created suitable conditions for the return of heathland target species, and the positive effects lasted for at least 6 years. The response of the heathland vegetation to the liming has, however, been slow because only a small number of endangered plant species increased in abundance. In contrast, four Red List soft‐water macrophytes strongly increased in abundance in the moorland pool. Our results show that, even with the slow return of Red List plant species, catchment liming can be a successful management tool for the restoration of the acidified heathland landscape.  相似文献   

9.
At the beginning of the 20th century, many montane heathlands were abandoned and became subject to natural succession or afforestation by humans. Thus, the formerly large montane heathlands slowly degraded into small and isolated patches. In this study, we evaluate the influence of restoration measures on leafhopper (Auchenorrhyncha) assemblages of montane heathland ecosystems in Central Europe. Our analyses comprised three different site types that were adjacent to each other: (1) montane heathlands, (2) restoration sites, and (3) control sites. Leafhoppers showed a clear response to montane heathland restoration. Thus, after 4–5 years since implementation of restoration measurements restoration sites were characterized by the highest species richness. However, detailed analyses of leafhopper diversity, species composition, and environmental parameters on the three site types revealed that restoration sites were rather similar to control sites and significantly differing from montane heathlands. We conclude that leafhoppers are excellent bioindicators for restoration measurements because they reflected environmental differences between the three site types. Restoration measurements might only be a useful instrument to promote typical montane heathland leafhopper communities in the long run. Colonization by leafhoppers is, however, dependent on many different factors such as leafhopper mobility, vegetation structure, microclimate, and the establishment of ericaceous dwarf shrubs. Practitioners should establish a management regime (grazing and sod‐cutting) that creates a mosaic of different habitat structures and increases typical heathland vegetation, thus, favoring the colonization of typical heathland leafhoppers.  相似文献   

10.
Restoration of brook valley meadows in the Netherlands   总被引:5,自引:1,他引:4  
Grootjans  A.P.  Bakker  J.P.  Jansen  A.J.M.  Kemmers  R.H. 《Hydrobiologia》2002,478(1-3):149-170
Until recently, restoration measures in Dutch brook valley meadows consisted of re-introducing traditional management techniques, such as mowing without fertilisation and low-intensity grazing. In the Netherlands, additional measures, such as rewetting and sod cutting, are now carried out on a large scale to combat negative influences of drainage and acidifying influences by atmospheric deposition. An analysis of successful and unsuccessful projects shows that restoration of brook valley meadows is most successful if traditional management techniques are applied in recently abandoned fields that had not been drained or fertilised. Large-scale topsoil removal in former agricultural fields that had been used intensively for several decades is often unsuccessful since seed banks are depleted, while hydrological conditions and seed dispersal mechanisms are sub-optimal. In areas with an organic topsoil, long-term drainage had often led to irreversible changes in chemical and physical properties of the soil. Successful sites were all characterised by a regular discharge of calcareous groundwater provided by local or regional hydrological systems, and, where not very long ago, populations of target species existed. On mineral soils, in particular, sod removal in established nature reserves was a successful measure to increase the number of endangered fen meadow species. It is argued that attempts to restore species-rich meadows should be avoided on former agricultural fields, where pedological processes have led to almost irreversible changes in the soil profile and where soil seed banks have been completely depleted. From a soil conservation point of view, such areas should be exploited as eutrophic wetlands that are regularly flooded.  相似文献   

11.
Floating fens are species‐rich succession stages in fen areas in the Netherlands. Many of these fens are deteriorating due to acidification; Sphagnum species and Polytrichum commune build 10–25 cm thick moss carpets, and the species diversity decreases. Earlier experiments in wet ecosystems indicate that successful restoration of circum‐neutral and mesotrophic conditions requires a combination of hydrological measures and sod removal. In an acidified fen recharged by rainwater in the nature reserve Ilperveld (The Netherlands), a ditch/trench system was dug for the purpose of creating a run‐off channel for acid rainwater in wet periods and to enable circum‐neutral surface water to enter the fen in dry periods. Moreover, the sod was removed in part of the fen. Ditch/trench creation or sod cutting had no effect individually, but a combination of the two measures led to a change in the abiotic conditions (higher pH and Ca), and in turn to an increase of species‐richness and the reestablishment of a number of characteristic species. Reestablishment of rare vascular plant species and characteristic bryophytes might be a long‐term process because of incomplete recovery of site conditions and constraints in seed dispersal.  相似文献   

12.
Question: Why do similar fen meadow communities occur in different landscapes? How does the hydrological system sustain base‐rich fen mires and fen meadows? Location: Interdunal wetlands and heathland pools in The Netherlands, percolation mires in Germany, Poland, and Siberia, and calcareous spring fens in the High Tatra, Slovakia. Methods: This review presents an overview of the hydrological conditions of fen mires and fen meadows that are highly valued in nature conservation due to their high biodiversity and the occurrence of many Red List species. Fen types covered in this review include: (1) small hydrological systems in young calcareous dune areas, and (2) small hydrological systems in decalcified old cover sand areas in The Netherlands; (3) large hydrological systems in river valleys in Central‐Europe and western‐Siberia, and (4) large hydrological systems of small calcareous spring fens with active precipitation of travertine in mountain areas of Slovakia. Results: Different landscape types can sustain similar nutrient poor and base‐rich habitats required by endangered fen meadow species. The hydrological systems of these landscapes are very different in size, but their ground water flow pattern is remarkably similar. Paleoecological research showed that travertine forming fen vegetation types persisted in German lowland percolation mires from 6000 to 3000 BP. Similar vegetation types can still be found in small mountain mires in the Slovak Republic. Small pools in such mires form a cascade of surface water bodies that stimulate travertine formation in various ways. Travertine deposition prevents acidification of the mire and sustains populations of basiphilous species that elsewhere in Europe are highly endangered. Conclusion: Very different hydrological landscape settings can maintain a regular flow of groundwater through the top soil generating similar base‐rich site conditions. This is why some fen species occur in very different landscape types, ranging from mineral interdunal wetlands to mountain mires.  相似文献   

13.
The heaths of Lygra, western Norway, were investigated, and 19 communities at the association level were distinguished. Distinct ecotypes of Ranunculus acris and Poa humilis and microspecies of Euphrasia were restricted to the grass heaths. No distinct ecotypes were found in the Calluna -dominated vegetation. It is suggested that the regular burning, which has been part of the management of the area, has activated the seed bank of the ericaceous heath, and thus maintained genetic diversity and slowed down ecotype differentiation. The grass heaths, with no combustible material, have been unaffected in this way. Permanent plots in the two dominant heath types, dry heath (Vaccinio-Callunetum) and wet heath (Ericetum tetralicis) were followed over six years and the data analysed using a modification of Jaccard's index, allowing for species abundances.  相似文献   

14.
Restoration of coastal dune slacks in the Netherlands   总被引:6,自引:1,他引:5  
Grootjans  A.P.  Geelen  H.W.T.  Jansen  A.J.M.  Lammerts  E.J. 《Hydrobiologia》2002,478(1-3):181-203
In order to stop the continuous decline of typical dune slack communities along the Dutch coast, restoration projects have been carried out since 1952. Restoration measures consisted of re-introducing traditional management techniques in dune slacks, such as mowing, grazing and sod removal, or constructing artificial dune slacks to compensate for lost biodiversity elsewhere. An analysis of successful and unsuccessful projects showed that constructing new dune slacks was not very successful for maintaining new populations of endangered dune slack species, since such projects were often carried out in areas where seed banks were depleted, while hydrological conditions and seed dispersal mechanisms were sub-optimal. The construction of sand dikes to prevent sea intrusion in large beach plains was, unintentionally, a temporary success for the establishment of many Red List species, although such measures often disrupted natural dune slack formation. Successful sites were all characterised by a regular discharge of calcareous groundwater provided by local or regional hydrological systems, where not very long ago populations of typical dune slack plants were present. Under such conditions, sod removal was a successful measure to create pioneer stages which were relatively stable, due to a very slow accumulation of organic matter in the topsoil. It is argued that new and more flexible coastal defence strategies can provide new opportunities for natural and relatively stable pioneer stages of dune slack formation, suitable for the long term preservation of endangered dune slack species.  相似文献   

15.
In areas with intensive land use, such as the Netherlands, habitat fragmentation and loss of habitat quality due to eutrophication and drainage are major threats to the preservation of species‐rich communities of heathland and acid grassland. Restoration of such nutrient‐poor habitats may be carried out by removing the topsoil from ex‐arable land, in order to lower the nutrient levels. However, the establishment of target plant communities is known to be fragmentary. The current study shows that this also applies to butterflies. Ten years after topsoil removal in eight study areas, on average, only 3.5 of 10 characteristic heathland species were recorded on the sites. Species that did colonize had a significantly lower density than in the source populations. Our study indicates that although isolation effects were limiting colonization, poor habitat quality was the main limiting factor, mainly due to lack of host plants, hydrological conditions, and, to a lesser extent, lack of nectar plants and excessive residual nutrient levels. An experiment with the introduction of cut heather in one study area showed a significantly higher abundance of both target and nontarget butterflies in manipulated sites than in control sites. It can be concluded that habitat restoration by topsoil removal can be successful for butterflies of especially wet heathland habitats, provided that source populations are at close range and care is taken that complete plant communities are restored.  相似文献   

16.
Saltwater intrusion and inundation can affect soil microbial activity, which regulates the carbon (C) balance in mangroves and helps to determine if these coastal forests can keep pace with sea level rise (SLR). This study evaluated the effects of increased salinity (+15 ppt), increased inundation (?8 cm), and their combination, on soil organic C loss from a mangrove peat soil (Everglades, Florida, USA) under simulated tides. Soil respiration (CO2 flux), methane (CH4) flux, dissolved organic carbon (DOC) production, and porewater nutrient concentrations were quantified. Soil respiration was the major pathway of soil organic C loss (94–98%) and was approximately 90% higher in the control water level than the inundated treatment under elevated salinity. Respiration rate increased with water temperature, but depended upon salinity and tidal range. CH4 flux was minimal, while porewater DOC increased with a concomitant, significant decline in soil bulk density under increased inundation. Porewater ammonium increased (73%) with inundation and soluble reactive phosphorus increased (32%) with salinity. Overall, the decline in soil organic C mineralization from combined saltwater intrusion and prolonged inundation was not significant, but results suggest SLR could increase this soil’s susceptibility to peat collapse and accelerate nutrient and DOC export to adjacent Florida Bay.  相似文献   

17.
The effects of sod cutting, a common restoration measure to remove excess nutrients from grass-dominated heathlands, on nitrification were studied in dry and wet Dutch heathlands and in incubation experiments. In the field, soil ammonium and nitrate concentrations were measured after treatment by sod cutting, with or without additional liming. Potential net nitrification was measured by incubating soil samples of all treatments with extra ammonium in a climate chamber at pH 6. Potential net nitrification of heaths dominated by Molinia caerulea was significantly higher than that of dwarf-shrub dominated heaths. Sod cutting of the former areas significantly decreased potential net nitrification, whereas in the latter areas no differences were found. Liming of sod-cut soils greatly increased potential net nitrification and the accumulation of ammonium in the soil up to toxic concentrations could be prevented. Our results show that the combination of sod cutting and liming would create suitable soil conditions for the germination and establishment of endangered plant species of dry and wet heathlands. The success of restoration projects of these areas can thus be increased.  相似文献   

18.
漓江水陆交错带不同淹没区植物多样性与土壤特征   总被引:1,自引:0,他引:1  
李扬  王冬梅  信忠保  王晶  任远  李青山 《生态学报》2015,35(15):5121-5130
针对旅游区水陆交错带出现植被退化、砾石裸露导致景观观赏度降低的问题,以广西桂林市大圩古镇水陆交错带为研究区域,按照水陆交错带淹没程度将其划分不同淹没区,并在详细调查基础上研究了各淹没区植被指标与土壤理化特征分布特征。结果表明:研究区内水陆交错带物种组成以一年生草本植物为主,物种多样性在各个不同淹没区基本呈现为先增后减的趋势,具体为轻度淹没区中度淹没区重度淹没区微度淹没区;随着水文作用的减弱,土壤砂粒含量呈现逐渐减小的趋势,粉粒和黏粒含量呈现逐渐增加趋势,土壤容重、土壤有机质含量和土壤全磷含量呈现先减后增的趋势;全氮含量呈现先增后减趋势,全钾含量在各淹没区差异不明显;研究表明大圩古镇水陆交错带土壤理化性质与植被多样性强烈地受以水位为主导的水文过程的影响与控制。扁蓄可以作为一种指示水淹时间的物种;此外,大圩古镇水陆交错带除受水文作用影响较大外,高强度旅游干扰也是重要的因素之一,植被恢复工作应兼顾生态和旅游,提升大圩古镇景观游憩度。  相似文献   

19.
Question: In fen meadows with Junco‐Molinion plant communities, falling groundwater levels may not lead to a boosted above‐ground biomass production if limitation of nutrients persists. Instead, depending on drainage intensity and micro‐topography, acidification may trigger a shift into drier and more nutrient‐poor plant communities. Location: Nature reserve, central Netherlands, 5 m a.s.l. Methods: Long‐term study (1988‐1997) in a fen meadow along a gradient in drainage intensity at different scales. Results: Above‐ground biomass increased only slightly over ten years, despite a lower summer groundwater table. The accountable factors were probably a limited availability of nutrients (K in the higher well‐drained plots, P in the intermediate plots and N in the lower hardly drained plots), plus removal of hay. Junco‐Molinion species increased in dry sites and Parvo‐caricetea species increased in wet sites, presumably primarily because of soil acidification occurring when rainwater becomes more influential than base‐rich groundwater. The extent of the shift in species composition depends primarily on the drainage intensity and secondarily on microtopography. Local hydrological measures have largely failed to restore wetter and more basic‐rich conditions. Conclusions: Acidification and nutrient removal, leaching and immobilization resulted in the succession towards Junco‐Molinion at the cost of Calthion palustris elements. Lower in the gradient this change was reduced by the presence of buffered groundwater in slightly drained sites. To conserve the typical plant communities of the Junco‐Molinion to Calthion gradient in the long term, further acidification must be prevented, for example by inundation with base‐rich surface water.  相似文献   

20.
In northeastern Illinois, restored wetlands are used to improve water quality in streams degraded by agriculture and urban development. Using freshwater wetlands to reduce nitrogen loading to lakes and rivers is well documented; however, there are fewer studies addressing their use to remove phosphorous. In 1998, a systematic water quality monitoring project was begun at Prairie Wolf Slough Wetland Demonstration Project, a restored palustrine emergent marsh wetland located on an abandoned farm field north of Chicago. The wetland drains 98 ha of mixed land uses into the Chicago River. Our objectives were to assess spatial and temporal variations in total suspended solids, soluble reactive and total phosphorous concentrations, and mass loadings and compute a mass balance and retention efficiency for these constituents. Water sampling was conducted from 1998 to 2003. In 2004, soil samples were collected from the marsh and an adjacent abandoned farm site and analyzed for soil test (Bray) phosphorus. The marsh effectively traps suspended solids but acts as a source of soluble reactive and total phosphorous to the river both during the growing and nongrowing seasons. Net export of phosphorous from the wetland was likely due to mobilization of orthophosphate as a result of anoxic conditions produced during inundation events. Often little consideration is given to the link between soil and water quality when locating restoration sites. Our study adds to a growing body of literature that clearly demonstrates the need for both soil and water quality assessments in wetland restoration planning, design, and monitoring.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号