Dune Slacks Research Articles

Ecology and trophic links of macroinvertebrates in a dune slack of a Mediterranean coastal ecosystem (Grosseto, Italy)

Along a Tyrrhenian coastal ecosystem the macroinvertebrates of a dune slack were studied to assess food webs, guilds and the possible links with other beach compartments. Environmental monitoring was conducted for an entire year through beach profiling, collection of the vegetation, of substrate samples and of the chemico-physical parameters of the ground water. Macroinvertebrates were assessed seasonally with two line transects of pitfall traps whereas monthly captures were carried out for coleopterans only. Zonations were also calculated to subdivide dune slack residents from non-residents. The plant and invertebrate specie were then grouped using Hierarchical Cluster analysis. Canonical Correspondence Analysis was instead used to evaluate the effect of the environmental parameters of the dune slack on the vegetation structure and macroinvertebrate composition. To evaluate the relative contribution of the different food sources to the diets of the macroinvertebrates a Bayesian stable isotope mixing model was employed. The study clearly showed that the inhabiting dune slack fauna was subdivided in two main guilds of non-predator and predator species and that slacks could be used all year round by resident species adopting particular behaviours or avoiding interspecific competition by modulating their spatial and temporal strategies. Furthermore slacks were exploited as nursery grounds for immature stages of specific species and in other cases as important feeding areas for predators. These findings indicated that macroinvertebrates exploited beach compartments according to the different stages of their life-cycle and that the integrity of the entire beach ecosystem is a key factor to promote a high biodiversity in a sandy beach-dune ecosystem.

From overexploitation to sustainable use, an overview of 160 years of water extraction in the Amsterdam dunes, the Netherlands

Dune slacks are low-lying, nutrient-poor, species-rich, inter-dunal, seasonally flooded wetlands, are amongst the most threatened habitats in the Dutch coastal dunes. Since 1853 Waternet has been extracting groundwater from the coastal dunes southwest of Haarlem to produce its drinking water. Dune slacks largely disappeared due to the desiccation caused by this water abstraction, over more than a century biodiversity declined as a consequence. Increased societal concern pushed habitat restoration high on the political agenda by the end of the 1980s. It was agreed to do what is possible to restore original dune slacks without endangering the water supply. Far reaching interventions in the dune water system were foreseen to achieve this mutual goal. To allow reliable decision making, the entire hydrological history of the drinking water production in the Amsterdam Dunes since 1853 and its ecological consequences were evaluated over a 10-year study period. The main tool was a 3D groundwater model constructed using all information gathered to date and calibrated using the long-term monitoring data available and widely extended for the purpose, to which ecological modeling was added and calibrated with the available long-term and extended vegetational inventories. These scientific tools were used to assess proposed interventions to be decided upon, which aimed at finding a new balance between groundwater extraction and nature restoration. In 1996 and 2007 large-scale measures were taken, which include filling in of recovery canals, mowing, grazing and sod-cutting to support the native plant communities of wet dune slack habitats. Results of these measures in terms of the restoration of natural hydrological conditions are shown together with the first results for the recovery of wet slacks vegetation that resulted from the combined hydrological and ecological restoration measures that were taken since 1995.

Diversity and classification of tall humid herb grasslands (Molinio‐Holoschoenion) in Western Mediterranean Europe

AbstractQuestionsWhat is the community diversity of tall, humid herb grasslands in Western Mediterranean Europe? What are the diagnostic species of the Molinio‐Holoschoenion alliance? What underlying ecological patterns influence their diversity?LocationWestern Mediterranean Europe (France, Portugal and Spain).MethodsWe compiled a vegetation plot database of Molinio‐Holoschoenion plant communities. The initial data set of 1056 plots was filtered according to physiognomic and floristic criteria, and geographically stratified. We used hierarchical agglomerative classification and semi‐supervised classification techniques based on the k‐means algorithm as a combination of methods to define vegetation types. A DCA analysis was performed to assess the main ecological drivers of diversity in the Molinio‐Holoschoenion community.ResultsSeventeen vegetation types were defined, which can be classified in the following major vegetation groups: (1) tall humid grasslands on base‐poor and sandy soils; (2) Scirpoides holoschoenus grasslands on base‐rich soils; and (3) eastern Iberian and southwestern French Schoenus nigricans and/or Molinia caerulea grasslands. The water‐logging gradient was recognized as a major underlying pattern influencing the diversity and distribution of Molinio‐Holoschoenion, and at a second level, the soil factor.ConclusionsWe suggest a revision of the concept of the Molinio‐Holoschoenion alliance to be considered for the interpretation of habitat type 6420 of the European Habitats Directive, which should include Mediterranean wet dune slacks and tall, humid inland grasslands. This vegetation type is largely distributed on the eastern Iberian Peninsula, where base‐rich soils are predominant and Scirpoides holoschoenus grasslands comprise the main floristic composition of the alliance.

Window of opportunity of Liparis loeselii populations during vegetation succession on the Wadden Sea islands

The present study aims at assessing the life span of populations of the orchid L. loeselii during successional in dune slacks on the Wadden Sea islands. An inventory of Liparis loeselii populations was carried out on 6 islands, while the population structure was assessed in more detail on the island of Texel. The occurrence of the orchid was related to soil factors and hydrological conditions. Groundwater levels were measured in a dune area with natural dune slack formation. The groundwater composition was analyses and the freshwater lenses were modelled. Various scenarios were investigated, including sea level rise and sand nourishment. The window of opportunity for L. loeselii to colonize a new slack is relatively narrow. Under favorable management, the population can survive c. 20 years. Soil pH was positively correlated with the occurrence of L. loeselii populations, while a high organic matter content was negatively correlated. Sites with large populations of L. loeselii, were situated in young dune slacks, that functioned as flow-through lakes and has top soilsinfluenced by anoxic calcareous groundwater. Modelling showed that the freshwater lens would decrease due to sea level rise, while artificial sand nourishment could counteract this effect. The populations of the Hors area on Texel, the Netherlands, can survive for several decades due to continuous formation of new slacks. Discharge of calcareous groundwater is essential to keep the pH on a high level. The hydrological systems that supply dune slack with groundwater are relatively small and are vulnerable for changes in sea level rise.

Past and future of the EU-habitat directive species Liparis loeselii in relation to landscape and habitat dynamics in SW-Texel, the Netherlands

Dune slacks are important habitats, with many endangered plant species. A series of eleven dune slacks of 1–42years old was studied in SW-Texel, the Netherlands, with the EU-habitat directive species Liparis loeselii present in all except the youngest and oldest. Analysis of aerial photographs revealed that new slacks are currently formed every 4–5years. In each slack, topsoil and vegetation data were collected in 2010 and 2014–2015. During succession, vegetation changed from brackish pioneer stages to dune slacks with L. loeselii and Parnassia palustris and ultimately grassland species. Differences between dune slacks and sampling periods were mostly significant. Herb cover and soil C increased with slack age, and over the five year study period, while bare sand, bulk density and pH decreased. The annual pH-decrease was 0.055 and 0.075 for pH-H2O and pH-KCl respectively, and annual C-increase 0.16% and 35gm−2. Liparis loeselii was only present between pHH2O 5.8–7.5 and pHKCl 5.6–7.6, and only occurred at C-content below 4.3%. In lime-poor dunes, environmental conditions thus become unsuitable approximately 34years after the start of succession. In the dune slacks, Liparis loeselii established within 6years, showed peak values after 11–16years, and declined until conditions became unsuitable. Rejuvenation may occur after large storms with fresh sand deposits. However, even with further succession, the present populations are not endangered and probably last until 2040. With new dune slacks every 5years, L. loeselii occurs in approximately eight different dune slacks at the same time, ensuring viable populations also in the future. This shows that adverse effects of succession can be counteracted by dynamics on local and landscape scale.

Small changes in water levels and groundwater nutrients alter nitrogen and carbon processing in dune slack soils

Dune slacks are biodiverse seasonal wetlands which experience considerable fluctuation in water table depth. They are under threat from eutrophication and lowered water tables due to climate change and water abstraction. The biological effects caused by the interactions of these pressures are poorly understood, particularly on soil processes. We used a mesocosm experiment and laboratory assays to study the impact of lowered water tables, groundwater nitrogen contamination, and their synergistic effects on soil microbial processes and greenhouse gas emissions. This study showed that just a 10 cm decrease in water table depth led to a reduction in denitrification and to a corresponding increase in soil nitrogen content. Meanwhile N2O emissions occurred for longer durations within dune slack soils subject to higher concentrations of groundwater nitrogen contamination. The results from extracellular enzyme assays suggest that decomposition rates increase within drier soils shown by the increase in β-glucosidase activity, with further sensitivity to groundwater nitrogen contamination shown by the increase in phenol oxidase activity. Dune slack soils with a 10 cm lower water table had significantly lower CH4 emissions, nearly 5 times lower in the drier soils. Our findings demonstrate that dune slacks are sensitive to both small changes in groundwater levels and to groundwater nitrogen contamination. The biological impacts from lowered water tables are likely to be intensified where there is also groundwater nitrogen contamination.

Differences in mycorrhizal communities between Epipactis palustris, E. helleborine and its presumed sister species E. neerlandica.

In orchid species that have populations occurring in strongly contrasting habitats, mycorrhizal divergence and other habitat-specific adaptations may lead to the formation of reproductively isolated taxa and ultimately to species formation. However, little is known about the mycorrhizal communities associated with recently diverged sister taxa that occupy different habitats. In this study, 454 amplicon pyrosequencing was used to investigate mycorrhizal communities associating with Epipactis helleborine in its typical forest habitat and with its presumed sister species E. neerlandica that almost exclusively occurs in coastal dune habitats. Samples of the phylogenetically more distant E. palustris, which co-occurred with E. neerlandica, were also included to investigate the role of habitat-specific conditions on mycorrhizal communities. A total of 105 operational taxonomic units (OTUs) of putative orchid mycorrhizal fungi were observed in the three studied species. The majority of these fungi were endophytic fungi of Helotiales and ectomycorrhizal fungi belonging to Thelephoraceae, Sebacinaceae and Inocybaceae. In addition, a large number of other ectomycorrhizal taxa were detected, including Cortinarius, Cenococcum, Tuber, Geopora, Wilcoxina, Meliniomyces, Hebeloma, Tricholoma, Russula and Peziza Mycorrhizal communities differed significantly between the three species, but differences were most pronounced between the forest species (E. helleborine) and the two dune slack species (E. neerlandica and E. palustris). The results clearly showed that recently diverged orchid species that occupy different habitats were characterized by significantly different mycorrhizal communities and call for more detailed experiments that aim at elucidating the contribution of habitat-specific adaptations in general and mycorrhizal divergence in particular to the process of speciation in orchids.

DINÁMICA DEL CARBONO Y NITRÓGENO DEL SUELO EN ECOSISTEMAS DE LA COSTA TROPICAL SECA, EN LA MANCHA (CICOLMA), VERACRUZ, MÉXICO

<p>This study was carried out at the La Mancha Coastal Research Center (CICOLMA) in tropical semi-deciduous forest, secondary forest and two locations in coastal dune scrub (crest and slack). The aim was to study the carbon and organic nitrogen dynamics of the soil to quantify organic matter mineralization and nitrogen supply. In the laboratory, soil samples were incubated at 25 °C for 97 days and over this time 10 samples were analyzed to monitor the soil’s carbon (CO<sub>2</sub>-C) and nitrogen ( , ) dynamics. The results reveal that mean cumulative organic carbon content was: dune slack (2.70 mg g<sup>-1</sup>) > secondary forest (2.0 mg g<sup>-1</sup>) > semi-deciduous forest (1.9 mg g<sup>-1</sup>) > dune crest (1.2 mg g<sup>-1</sup>). A comparison of the means using Tukey’s test (α = 0.05) detected differences only between the dune slack and the crest. Mean cumulative inorganic nitrogen content was: secondary forest (1284 mg kg<sup>-1</sup>) > dune slack (1140 mg kg<sup>-1</sup>) > semi-deciduous forest (1021 mg kg<sup>-1</sup>) > dune crest (302 mg kg<sup>-1</sup>), with significant differences only between the dune crest and the other treatments. In general, organic matter mineralization was higher in the dune slack and nitrogen supply was higher in the secondary forest. We conclude that organic matter mineralization and nitrogen supply are depending on the type of ecosystem and soil properties.</p>

Spatial structure and species composition of soil seed banks in moving sand dune systems of northeast China

Soil seed banks can provide a mechanistic for understanding the recruitment dynamics and can inform conservation management of ecosystems. To investigate the contribution of soil seed banks to vegetation restoration in moving sand dune systems, we compared seed structure and species similarity between soil seed banks and standing vegetation among moving sand dunes, ecotones and dune slacks in northeast China. Average seed density in dune slacks was greater than in ecotones or moving sand dunes. Seed density in the soil layer of 0–10 cm was greater than at 10–20 cm both in the moving sand dunes and the ecotones, but seed densities were similar at depths of 10–20 and 20–30 cm in moving sand dunes. Moreover, the spatial autocorrelation of seed density on moving sand dunes was weak but was strong on the ecotones and dune slacks. The species in the soil seed bank of moving sand dune systems were nearly all annuals, and the low similarity was mainly due to the lack of perennial species that were common in standing vegetation. Consequently, vegetation restoration cannot mainly rely on the soil seed banks in the moving sand dunes and more attention should be paid to protection of the dune slacks because they are the main source of seed disperse and seedling recruitment in moving sand dune systems.

The impact of 36 years of grazing management on soil nitrogen (N) supply rate and Salix repens N status and internal cycling in dune slacks

To determine the impact of long-term rabbit and sheep grazing on Salix repens N status (green and abscised leaf N content and C:N ratio), internal N dynamics and soil N supply rate in dune slacks. Herbivore exclosures were erected in dune slacks at Ainsdale Sand Dunes NNR, creating three grazing treatments: rabbit grazing; rabbits excluded for 36 years; rabbit grazing followed by sheep and rabbit grazing for 18 years. Soil N supply rate was analysed using ion exchange membranes; leaf N dynamics of S. repens were measured over one summer. Soil N supply rate was higher in ungrazed plots. There was no difference in green leaf NMASS or C:N ratio between treatments, but N dynamics differed. Adding sheep to existing rabbit grazing reduced S. repens N resorption efficiency (REFF) from 67 to 37 %; excluding rabbits had no impact. Litter NMASS was lower and C:N ratio higher in ungrazed plots. Grazing can impact significantly on leaf N resorption, but this impact depends on the grazing regime.

Combining field observations and laboratory experiments to assess the ecological preferences ofTanymastix stagnalis(L., 1758) (Crustacea, Branchiopoda) in Mediterranean temporary ponds

AbstractMalladas de El Saler is a mosaic of dune slacks scattered along a coastal sand bar in the Mediterranean region. Active populations of the fairy shrimpT. stagnalisare exclusively present in one of these ponds. We combined field observations and laboratory experiments to find the ecological requirements ofT. stagnalisthat determine this habitat exclusiveness and the possibility of future establishment in nearby ponds. Conductivity revealed as a determinant ecological constraint. In the field, the species was restricted to conductivity levels below 1.28 mS cm−1and in experimental microcosms, hatchability, survival and reproductive potential were detrimental from 2.9 mS cm−1. The observation of life history characteristics from the experimental individuals confirmed the importance of the unpredictable character of Mediterranean temporary ponds in shaping life history strategies, as they hatched early, matured rapidly and produced a high number of cysts. We discuss the essential steps during colonization that may explain the presence or absence in our ponds, and revealed a harsh future for the species if the current conditions of habitat deterioration persist. We suggest several conservation measures, including a cyst bank storage or/and adult translocations to nearby suitable ponds. These measures will ensure (1) the preservation of genetic diversity and (2) healthy metapopulation dynamics with recolonization rates compensating for local extinctions.

Proposal for new EU habitats associated with coastal dune fields of the Macaronesian region. A case study in the Canary Islands (Spain)

The aim of this work is to identify habitats of European interest for the existing dunes in the Canaries, in order to provide data for their proper management. Dune systems considered were the following: aeolian sedimentary systems that cover both most of the island of La Graciosa and also the dune fields of Maspalomas (Gran Canaria) and Corralejo (Fuerteventura). The methodology consisted of overlapping layers of habitats and vegetation by using geographic information systems, so the correspondence between habitat and plant community are analyzed. The results indicate that dune habitats in the Canary Islands have not been well defined. The habitat “2110 embryonic shifting dunes” is associated with several situations incompatible with their biotic and abiotic characteristics. Meanwhile, habitat “2130 fixed dunes with herbaceous vegetation (grey dunes)” is linked, among others, to the phytosociological association Traganetum moquinii. However, embryonic dune formation in the Canaries is mainly done by this community, which is inconsistent with its inclusion in the grey dunes habitat. The proposed habitats of European interest associated with dunes in the Canaries are the following: Coastal shifting dunes with Traganum moquinii, dunes with Tamarix canariensis, Macaronesian aeolian sand sheets and humid dune slacks. It is also suggested the need for a comprehensive study of dune habitats existing in the Canaries and Macaronesia, covering the whole of aeolian sedimentary systems, performing a proper identification, characterization and detailed mapping of these habitats, based on both the existing vegetation and also on the associated landforms and geomorphic processes.

Using chemical, microbial and fluorescence techniques to understand contaminant sources and pathways to wetlands in a conservation site

Nutrients and faecal contaminants can enter wetland systems in a number of ways, with both biological and potentially human-health implications. In this study we used a combination of inorganic chemistry, dissolved organic matter (DOM) fluorescence and Escherichia coli and total coliform (TC) count techniques to study the sources and multiple pathways of contamination affecting a designated sand dune site of international conservation importance, surrounded by agricultural land. Analysis of stream samples, groundwater and dune slack wetlands revealed multiple input pathways. These included riverbank seepage, runoff events and percolation of nutrients from adjacent pasture into the groundwater, as well as some on-site sources. The combined techniques showed that off-site nutrient inputs into the sand dune system were primarily from fertilisers, revealed by high nitrate concentrations, and relatively low tryptophan-like fulvic-like ratios <0.4Ramanunits (R.U.). The E. coli and TC counts recorded across the site confirm a relatively minor source of bacterial and nutrient inputs from on-site grazers. Attenuation of the nutrient concentrations in streams, in groundwater and in run-off inputs occurs within the site, restoring healthier groundwater nutrient concentrations showing that contaminant filtration by the sand dunes provides a valuable ecosystem service. However, previous studies show that this input of nutrients has a clear adverse ecological impact.

In this issue

P R O C E E D I N G S O F T H E R O Y A L I R I S H A C A D E M Y In this issue Bruce Osborne Developing status tests for selected Irish groundwater-dependent terrestrial ecosystem (GWDTE) types as part of groundwater body status assessment under the EU Water Framework Directive Sarah Kimberley and Catherine Coxon Are Ireland’s reintroduced Pinus sylvestris forests floristically analogous to their native counterparts in oceanic north-west Europe? Jenni R. Roche, Fraser J.G. Mitchell, Stephen Waldren and Jørn E. Bjørndalen Population status and factors affecting the productivity of peregrine falcon Falco peregrinus in County Wicklow, Ireland, 2008–2012 Brian J. Burke, Damian Clarke,Ann Fitzpatrick,Tim Carnus and Barry J. McMahon Short Communication: Behaviour of sea lamprey (Petromyzon marinus L.) at man-made obstacles during upriver spawning migration: use of telemetry to assess efficacy of weir modifications for improved passage Seán M. Rooney, Glen Wightman, Ruairi Ó’Conchúir and James J. King Short Communication: Historical change in the European eel population in the Foyle estuary, Northern Ireland J. Barry, K.J. Bodles, P. Boylan and C.E.Adams www.ria.ie ISSN 0791-7945 i 83 97 115 125 137 CONTENTS BIOLOGY ENVIRONMENT and VOLUME 115B Issue 2 (2015) V OL . 115B Scots pine (Pinus sylvestris)© CanStock Photo Inc. B I O L O G Y A N D E N V I RO N M E N T VOLUME 115B Issue 2 (2015) BIOLOGY ENVIRONMENT and RA I N O . 2 (2015) P RO C E E D I N G S O F T H E R OYA L I R I S H A C A D E M Y to print_Layout 1 15/10/2015 11:58 Page 1 IN THIS ISSUE Bruce Osborne Groundwater status Although the sustainable management of water resources is covered through the EU Water Framework directive this does not just cover surface waters, as is often commonly assumed, but also encompasses wetlands and groundwater. Less attention is focused, however, on groundwater reserves, even though much of the water on land is actually derived from groundwater sources. In Ireland 20%25% of our drinking water may come from groundwater sources so contamination of this source could result in significant health issues as well as impacting on the natural biota. This ‘hidden resource’ and its interaction with surface waters have, however, received much needed attention in recent years. Specific measures are also now in place that explicitly cover the prevention and control of groundwater pollution. Significant challenges exist, however, in assessing any deleterious effects on groundwater systems, particularly groundwaterdependent terrestrial ecosystems, such as wetlands, as Kimberley and Coxon, in this issue, indicate. In their paper they report on an assessment of eleven groundwater-dependent ecosystems, including springs, mires, bogs, turloughs, machair and dune slacks, using ecohydrological models and available data. Their objectives included developing an improved understanding of the hydrology of groundwaters but, perhaps more importantly, determining nutrient threshold values that could be used to assess the trophic status of these systems. Unfortunately, because of the paucity of experimental data, accurate assessments of nitrate and phosphate, nutrients that are key factors in determining water quality and trophic status, were not possible. Clearly, a more comprehensive set of experimental data is required before the status of groundwater sources can be predicted with any accuracy. Introduced but no alien impacts? The Scots pine, Pinus sylvestris, is one of our oldest living trees, with one specimen in Finnish Lapland recently dated at 764 years of age. It is also one of the most widespread, and Scots pine has a remarkable ability to tolerate a range of environmental conditions. Based on pollen analyses, it is evident that significant parts of Ireland were formerly covered by this species, and there has been a continuing discussion about whether some of the existing populations are native or have been introduced. Some populations actually look very similar to native populations elsewhere but the consensus is that they have all been re-introduced, as have many populations in the UK, The Netherlands and Denmark, perhaps around 140 years ago. But...

In this issue

P R O C E E D I N G S O F T H E R O Y A L I R I S H A C A D E M Y In this issue Bruce Osborne Developing status tests for selected Irish groundwater-dependent terrestrial ecosystem (GWDTE) types as part of groundwater body status assessment under the EU Water Framework Directive Sarah Kimberley and Catherine Coxon Are Ireland’s reintroduced Pinus sylvestris forests floristically analogous to their native counterparts in oceanic north-west Europe? Jenni R. Roche, Fraser J.G. Mitchell, Stephen Waldren and Jørn E. Bjørndalen Population status and factors affecting the productivity of peregrine falcon Falco peregrinus in County Wicklow, Ireland, 2008–2012 Brian J. Burke, Damian Clarke,Ann Fitzpatrick,Tim Carnus and Barry J. McMahon Short Communication: Behaviour of sea lamprey (Petromyzon marinus L.) at man-made obstacles during upriver spawning migration: use of telemetry to assess efficacy of weir modifications for improved passage Seán M. Rooney, Glen Wightman, Ruairi Ó’Conchúir and James J. King Short Communication: Historical change in the European eel population in the Foyle estuary, Northern Ireland J. Barry, K.J. Bodles, P. Boylan and C.E.Adams www.ria.ie ISSN 0791-7945 i 83 97 115 125 137 CONTENTS BIOLOGY ENVIRONMENT and VOLUME 115B Issue 2 (2015) V OL . 115B Scots pine (Pinus sylvestris)© CanStock Photo Inc. B I O L O G Y A N D E N V I RO N M E N T VOLUME 115B Issue 2 (2015) BIOLOGY ENVIRONMENT and RA I N O . 2 (2015) P RO C E E D I N G S O F T H E R OYA L I R I S H A C A D E M Y to print_Layout 1 15/10/2015 11:58 Page 1 IN THIS ISSUE Bruce Osborne Groundwater status Although the sustainable management of water resources is covered through the EU Water Framework directive this does not just cover surface waters, as is often commonly assumed, but also encompasses wetlands and groundwater. Less attention is focused, however, on groundwater reserves, even though much of the water on land is actually derived from groundwater sources. In Ireland 20%25% of our drinking water may come from groundwater sources so contamination of this source could result in significant health issues as well as impacting on the natural biota. This ‘hidden resource’ and its interaction with surface waters have, however, received much needed attention in recent years. Specific measures are also now in place that explicitly cover the prevention and control of groundwater pollution. Significant challenges exist, however, in assessing any deleterious effects on groundwater systems, particularly groundwaterdependent terrestrial ecosystems, such as wetlands, as Kimberley and Coxon, in this issue, indicate. In their paper they report on an assessment of eleven groundwater-dependent ecosystems, including springs, mires, bogs, turloughs, machair and dune slacks, using ecohydrological models and available data. Their objectives included developing an improved understanding of the hydrology of groundwaters but, perhaps more importantly, determining nutrient threshold values that could be used to assess the trophic status of these systems. Unfortunately, because of the paucity of experimental data, accurate assessments of nitrate and phosphate, nutrients that are key factors in determining water quality and trophic status, were not possible. Clearly, a more comprehensive set of experimental data is required before the status of groundwater sources can be predicted with any accuracy. Introduced but no alien impacts? The Scots pine, Pinus sylvestris, is one of our oldest living trees, with one specimen in Finnish Lapland recently dated at 764 years of age. It is also one of the most widespread, and Scots pine has a remarkable ability to tolerate a range of environmental conditions. Based on pollen analyses, it is evident that significant parts of Ireland were formerly covered by this species, and there has been a continuing discussion about whether some of the existing populations are native or have been introduced. Some populations actually look very similar to native populations elsewhere but the consensus is that they have all been re-introduced, as have many populations in the UK, The Netherlands and Denmark, perhaps around 140 years ago. But...

Which is the contribution to the carbon sequestration of the forest ecosystems in the Castelporziano Reserve? Evidences from an integrated study on humus and vegetation

Soil is a major carbon sink or source on terrestrial ecosystems. Despite their great importance, humus forms, which constitute the small portion above the soil, have been often neglected in local studies and in international research projects. In the present work we evaluated the organic carbon stocked in the different humus forms in a Mediterranean lowland forest, to highlight the carbon concentration in different vegetation types, particularly between evergreen and deciduous woodlands. Results showed that the carbon stock stored in the organic and organo-mineral horizons of humus and soil, expressed in Tons/Ha, had a wide range for each vegetation type, reflecting the high diversity of the forest vegetation and the variability within each type. The vegetation with the highest value of carbon stock despite its small extension was represented by humid woodlands dominated by Fraxinus oxycarpa, a relic forest type occurring in the dune slacks within the study area, which gives, therefore, an important contribution to the climate warming reduction. We demonstrated as the humus forms play a role in the carbon sequestration in a forest ecosystem; therefore, it may be important to add the evaluation of carbon stock when carbon concentration is evaluated for the soil and above and plants below ground biomass.

Interstadial inland dune slacks in south-west Slovakia: a multi-proxy vegetation and landscape reconstruction

Palaeoecological studies spanning back to the Bølling/Allerød (GI-1) Interstadial of the Late Glacial in the whole Western Carpathians and adjacent lowlands are extremely scarce. To improve our knowledge about the landscape structure and diversity of wetland habitats, we analysed two palaeoecological interstadial sequences of pollen and macrofossils (bryophytes, vascular plants and molluscs) from the sandy landscape of the Borská lowland (southwest Slovakia). The deposits differed between the two sequences analysed, consisting predominantly of lacustrine chalk or brown-moss sedge fen peat, respectively. The results showed that, during wetter and warmer conditions during the Interstadial, open large dunes had been stabilised by pine woodlands admixed by birch. Contrary to the Podunajská lowland, which is situated eastwards towards the centre of the Pannonian Plain, broadleaf thermophilous trees such as Ulmus, Quercus and Tilia were almost absent in the study region, which suggests an importance of the bedrock for Late-Glacial forest vegetation. Salix, Alnus and Betula nana scrubs were probably scattered across wetlands. Active dunes were occupied by Hippophaë rhamnoides and steppe vegetation with grasses, Artemisia and Helianthemum. Low abundance of Chenopodiaceae pollen suggests that the sandy bedrock was probably unfavourable for the development of salt-rich habitats. Wetland habitats were diverse and abundant in the inter-dune space, partly resembling recent coastal dune slack vegetation or alluvial salty grasslands in continental central Asia. The wetland habitats comprised aquatic habitats with Myriophyllum, Potamogeton filiformis, P. pectinatus, P. pussilus, Sparganium minimum and planktonic algae (Pediastrum and Botryococcus), strongly continental calcareous-fens with Blysmus rufus and Triglochin maritima, boreocontinental brown-moss sedge fen fens with Drepanocladus trifarius, Carex lasiocarpa, Menyanthes trifoliata and Scorpidium scorpioides) and reed beds with Cicuta virosa, Phragmites and Schoenoplectus tabernaemontani. Remains of these unique wetland mosaics have recently disappeared because of human activities including peat extraction and dune stabilisation by pine plantations, which have transformed the modern landscape.

Inferring population and metapopulation dynamics of Liparis loeselii from single-census and inventory data

To conserve endangered species, information is needed on (meta)population responses to habitat quality and management. As possibilities for long-term studies are generally limited, it is important to obtain as much information as possible in a single field season.We obtained such single-census data for the orchid Liparis loeselii, a European Habitat Directive species. Stage structures of 15 Dutch dune and fen populations were related to vegetation structure, environmental indicators, and management. Botanical inventory records from 1930 to 2003 were used to infer population life spans.Cluster analysis did not reveal successional stage structure types. Dense populations with high recruitment mainly occurred in open, young-successional vegetation with high soil pH. High soil humidity and acidification negatively affected orchid densities. Early mowing was preferable over late mowing in dune slacks, because the latter reduced juvenile densities. The predominant population life span was three to eight years, and similar for dune slacks and fens. Longer life spans were occasionally observed at mown sites with influx of base-rich water.Our results suggest high metapopulation dynamics. Long-term metapopulation viability requires the formation of new habitat by dune slack formation in dunes and peat removal in fens. Population persistence can be prolonged to some extent by mowing, extensive grazing, or sod removal if natural habitat formation is impossible. Our study demonstrates that useful information on (meta)population ecology and viability can be obtained in a single field season.

Biological Flora of the British Isles: Epipactis palustris

Summary This account presents information on all aspects of the biology of Epipactis palustris (L.) Crantz that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characteristics, herbivores and disease, history, and conservation. Epipactis palustris is native to Britain, being widely distributed throughout England and Wales, but is less common in the north. Although absent from most of Scotland, it occurs as far north as Perthshire. It is widely distributed in Ireland. The species extends throughout most of Europe, occurring as far east as Mongolia and the north of Turkey, but it is absent from the southern Mediterranean region. Epipactis palustris grows mainly in full sunlight, rarely under shade, and on calcareous, but nutrient‐poor, moist to wet substrates. It favours flushed or seasonally inundated areas in which the intensity of competition from other vegetation is low. It is most commonly found in wet dune slacks, calcareous fens and on peat, but it also occurs on sandy substrates overlying heavy clay or loamy soils. Occasionally, it can also be found near the top of slopes in chalk downland. Epipactis palustris multiplies both by vegetative propagation and sexual reproduction. Vegetative propagation involves the production of regularly branched rhizomes. It flowers in Britain from the end of June until the beginning of September. The flowers produce nectar, which is often colonized by bacteria and to a lesser extent by yeasts. The species is pollinated by a wide range of insects, including honeybees, flies, wasps, beetles, bumblebees and ants, but is also capable of limited spontaneous autogamy. The most efficient pollinators are small bees and solitary wasps. Fruit production is generally high (&gt;80% of the flowers produce capsules). Epipactis palustris is vulnerable to changes in soil water level and to substrate nutrient enrichment. It has suffered a strong decline in its distribution range in Britain, with most losses of local populations occurring before 1930. Habitat destruction and drainage of marshes and fens appear to be the most common causes for the decline of the species. Restoration of old wet dune slacks by topsoil removal and addition of hay from neighbouring vegetation has been successful in encouraging colonization and establishment of populations of the species within a few years. Cessation of draining of mires may also promote the long‐term survival of populations of the species.

Effects of habitat and landscape characteristics on the arthropod assemblages (Araneae, Orthoptera, Heteroptera) of sand grassland remnants in Southern Hungary

For adequate conservation planning, ecologists need to understand the driving factors of the species richness and composition patterns of arthropod assemblages. The present study scrutinizes how the vegetation, the surrounding matrix and the process of fragmentation affects the diversity and the composition of arthropod assemblages in dune slack meadow remnants of an agricultural landscape in southern Hungary. Spiders, orthopterans and true bugs were sampled with sweep netting in a total of 25 sand steppe, mesotrophic wet meadow and alkaline meadow patches. Our general findings showed that the structure and species composition of arthropod assemblages depended primarily on the vegetation type. From among the size and shape of the patches, their extent of isolation and the types of the surrounding landscapes only the latter one could be shown to have a significant effect, though this was also restricted to the group of spiders. Therefore, the structure and composition of spider assemblages may be used as indicators for the adjacent agricultural activities. Unlike its effect on species composition, the effect of vegetation type was not consistent on the species richness of the arthropod assemblages and functional groups. The influence of vegetation type was greater on the species richness of herbivores (specialist and generalist true bugs and grasshoppers) than on that of the carnivores (spiders, bush crickets and carnivorous true bugs). Based on the fact that neither patch size nor the extent of isolation, i.e. the measures of fragmentation, influenced the species richness of the majority of the arthropod groups significantly, we conclude that fragmentation was not the main threat for the studied arthropod fauna. Furthermore, the present study calls attention to the limited efficiency of Island Biogeography Theory in the case of relatively large, traditionally managed grasslands embedded in extensive agricultural landscapes, like the general landscape pattern of the Great Hungarian Plain.