Article

Calcium and iron as key drivers of brown moss composition through differential effects on phosphorus availability

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  • Altenburg & Wymenga ecological research
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Abstract

Brown moss-dominated rich fens are characterized by minerotrophic conditions, in which calcium (Ca) and iron (Fe) concentrations show large variations. We examined the relative importance of Ca and Fe in relation to the occurrence of three typical brown moss species: Scorpidium scorpioides, Scorpidium cossonii, and Hamatocaulis vernicosus. Peat chemistry was examined in 24 stands of brown moss-dominated rich fens: 12 in the Netherlands and 12 in central Sweden. Ca and Fe turned out to be important drivers of brown moss composition. Fens dominated by Scorpidium scorpioides or Scorpidium cossonii were characterized by high pore water Ca-concentrations and total soil Ca-contents, but low P-availability. In these Ca-rich, but Fe-poor fens, foliar N:P ratios of vascular vegetation exceeded 20 g g⁻¹, indicating phosphorus (P)-limitation due to Ca-P precipitation or low P-sorption capacity due to low Fe-levels. In contrast, fens dominated by Hamatocaulis vernicosus were characterized by high pore water Fe-concentrations and total soil Fe-contents, but also relatively high P-availability. N:P ratios in these fens were below 13.5 g g⁻¹, indicating potential nitrogen (N)-limitation. We conclude that the relative roles of Ca and Fe, as related to the geohydrological conditions present, strongly determine the brown moss composition in rich fens through their differential effects on plant P-availability.

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... Calcium and iron ions can additionally influence the availability of phosphorus and nitrogen and thus determine which of these elements will become a factor limiting primary productivity. Mettrop et al. (2018) found correlations between a high content of calcium and limitation by phosphorus deficit and between a high iron content and limitation by nitrogen deficit (see also below). ...
... As it was already mentioned, it seems that iron is an element the abundance of which can strongly modify species composition or ecological processes within alkaline fens. Since this element can occur in two oxidation states, dependent upon redox potential, and ferric and ferrous salts differ in solubility, iron strongly influences the above-described factors determining phosphorus and nitrogen availability ( Mettrop et al. 2018) and thus the fertility of alkaline fens, especially under conditions of unstable water supply. First of all, oxidized iron exposed to even a short drought episode can be a source of electrons for aerobic microorganisms even after water level rise and can accelerate the decomposition of organic matter (including peat). ...
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Review of knowledge on alkaline fens (7230 habitats) in Poland. Enflish translation of the book originally pritned in Polish language. Contains: characteristic of the habitat type, ecohydrological considerations, ecosystem ecology, ecosystem services, diversity of plant cover in Poland, related fauna, resources and conservation staus in Poland on the European Union background, details of current distribution and diversity in Poland, analysis of inclusion to protected areas system, conservation experience, monitoring methods, results and experiences.
... Jony wapnia i żelaza mogą dodatkowo wpływać na dostępność fosforu i azotu, decydując który z tych pierwiastków stanie się limitujący. Mettrop et al. (2018) znaleźli korelacje między wysoką zawartością wapnia a limitacją produkcji pierwotnej niedoborem fosforu, oraz wysoką zawartością żelaza a limitacją niedoborem azotu (por. też dalej). ...
... Wydaje się, że jeszcze jednym pierwiastkiem, którego zasobność może silnie modyfikować skład gatunkowy czy procesy ekologiczne w obrębie torfowisk alkalicznych jest żelazo. Ze względu na występowanie tego pierwiastka w dwóch formach utlenienia, w zależności od potencjału redoks i równocześnie różnej rozpuszczalności soli żelaza dwu-i trójwartościowego, pierwiastek ten silnie wpływa na opisane powyżej uwarunkowania dostępności fosforu i azotu (Mettrop et al. 2018), a tym samym żyzność torfowisk alkalicznych, szczególnie w warunkach niestabilnego uwodnienia. Po pierwsze, utlenione żelazo, nawet w wyniku krótkiego epizodu suszy, może stanowić źródło elektronów dla mikroorganizmów tlenowych (nawet po podniesieniu się poziomu wody) i umożliwiać im szybki rozkład materii organicznej (w tym samego torfu). ...
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Przegląd wiedzy o torfowiskach alkalicznych (siedlisko przyrodnicze 7230). Charakterystyka, ekohydrologia, budowa i stratygrafia, chemiczne uwarunkowania rozwoju roślinności. Zróżnicowanie roślinności, aktualne ujęcia fitosocjologiczne. Fauna (w szczególności bezkręgowce). Regionalne zróżnicowanie w Polsce i najważniejsze obiekty. Ujęcie w sieci obszarów chronionych, potrzebne uzupełnienia; sposoby i skuteczność ochrony. Usługi ekosystemów. Metody monitoringu stosowane w Polsce i ich krytyczna analiza.
... Hedenäs and Hamatocaulis vernicosus (Mitt.) Hedenäs, which are characteristic for mesotrophic fens, and occur over a range of Ca-rich to Fe-rich habitats (Mettrop et al. 2018). In central Sweden, all fens were characterized by groundwater seepage areas, but Ca-rich fens were found in areas with limestone and marl parent materials, while Fe-rich fens were found in areas with granitic glacial deposits. ...
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Aim To further unravel P availability in mineral-rich fens, and test whether high Fe in the soil would lead to low P availability to the vegetation. Methods Mesotrophic fens were selected over gradients in Ca and Fe in central Sweden and the Netherlands, to study characteristics of vegetation, pore water and peat soil, including inorganic and organic forms of P, Fe and Al. Results Soil Fe was more important than region or soil Ca, and P availability to the vegetation increased from Fe-poor to Fe-rich fens. Contrary to expectations, precipitation of iron phosphates played a minor role in Fe-rich fens. Fe-rich fens were P-rich for three reasons: (1) high P sorption capacity, (2) relatively weak sorption to Fe-OM complexes and (3) high amounts of sorbed organic P, which probably consists of labile P. Also, nonmycorrhizal wetland plants probably especially take up weakly sorbed (organic) P. However, high P did not lead to high biomass or low plant diversity. Fe-rich fens were limited by other nutrients, and high P may help protect the vegetation against Fe-toxicity. Conclusions Fe-poor fens are P-poor, irrespective of Ca, and Fe-rich fens P-rich even under mesotrophic conditions. However, high P itself does not endanger Fe-rich fens.
... Manukjanová et al. 2014), declined less and some of them are still frequent in calcium-rich fens (e.g. C. giganteum and H. vernicosus). Hamatocaulis vernicosus can further benefit from the recent increase in phosphorus concentration (Hájek et al. 2014, Vicherová et al. 2015, Mettrop et al. 2018 if competition with fast-growing species of moss and vascular plants is reduced by mowing (Štechová & Kučera 2007). ...
Article
Modern databases containing large amounts of botanical data are a promising source of new results based on large data analyses. We used a new database of plant macrofossils of the Czech and Slovak Republics to compare the recent distributions of putative relict species of fen bryophytes with their past distributions since the late glacial. All the species studied occur in lateglacial sediments, but mostly in regions where they are recently recorded (19–21st centuries). There are specific regions rich in putative relict species of fen bryophytes both in late glacial / early Holocene times and recently. In some cases the target species were, however, found outside the recent distribution range where environmental conditions are no longer suitable for their occurrence. We further found that the total number of the glacial and early-Holocene records greatly exceeds the total number of records for the middle Holocene, when succession to woodlands or bogs resulted in a reduction in species of bryophytes that are specific to open rich fens. The observed patterns may imply a relict status of the target species. We especially documented a substantial decline in the abundance of species requiring a high and stable water level (Drepanocladus trifarius, Meesia triquetra and Scorpidium scorpioides), both throughout the Holocene and during the most recent transformations of the landscape. In contrast, those species that tolerate transient decreases in water level persisted into recent times at more localities (Calliergon giganteum, Hamatocaulis vernicosus, Paludella squarrosa). Macrofossil data cannot, however, provide a quantitative analysis of the distribution of a species, because the number of recent data usually greatly exceeds the number of fossil records. The reason is that the area sampled in palaeoecological research is very small as it is time-consuming and expensive; cores or excavations usually are of only a few square centimetres. Despite this shortcoming, macrofossil data are an important, but not the only, source of evidence for the identification of the relict status of a species.
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Die Literaturzusammenstellung erhebt keinen Anspruch auf Vollständigkeit. Sie berücksichtigt überwiegend Publikationen aus dem Jahr 2018 und beinhaltet hauptsächlich bryologische Fachbücher und Fachartikel zu Studien und Fundberichten über Moose in Mitteleuropa. Ausnahmsweise sind auch außereuropäische Arbeiten aufgelistet, die aufgrund der behandelten Arten oder Methoden eine starke Relevanz für Mitteleuropa haben. Für aktuelle Veröffentlichungen mit Fokus auf Taxonomie und Systematik sei auf den Beitrag "Taxonomische und nomenkla-torische Neuerungen-Moose, Vierte Folge" von Markus K. Meier in diesem Heft verwiesen. Für Hinweise auf entsprechende Publikationen für die dritte Folge dieser Serie sind wir dankbar.
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1. Water levels in areas with intensive agriculture have often been strictly controlled for decades. Recently, more natural fluctuating water levels have been propagated to improve the ecological quality of wetlands in these areas. This study investigated the effects of water levels on protected base-rich mesotrophic fens during winter and summer. 2. We used a mesocosm approach to simulate water level fluctuations under winter and summer conditions (light and temperature) to test the effects of water level on the biogeochemistry and vegetation of two highly endangered fen types with the brownmosses Scorpidium scorpioides and Hamatocaulis vernicosus as dominant mosses. 3. Both species showed decreased photosynthetic capacity at lower water levels. These levels also resulted in decreased alkalinity due to oxidation processes in the moss layer. High water levels led to increased pH and alkalinity, due to reduction processes and infiltration of baserich water. 4. For the P-limited S. scorpioides mesocosms, high water levels did not lead to P mobilization or to significant changes in biomass production, P uptake and N:P ratios. However, for the mesocosms with H. vernicosus, where P limitation was not obvious, high water levels did result in P mobilization and increased P availability due to iron reduction. The lower P mobilization for S. scorpioides appeared to be related to lower total soil P content and higher Fe:P and Ca:P ratios. Although high water levels resulted in the accumulation of ammonium under winter conditions, this did not happen under summer conditions, making ammonium toxicity unlikely. 5. Synthesis and applications. Our results suggest that low water levels could hamper protected brownmosses in rich fens, especially during the summer. In contrast, inundations may have a positive effect on rich fens by increasing the alkalinity. However, inundations may lead to eutrophication due to internal P mobilization in soils with a high total P content and low Fe:P ratio. Therefore, we recommend that soils with high total P content and low Fe:P ratios should not be flooded.
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Hamatocaulis vernicosus, a rare moss species, was monitored in 33 fens in the Czech Republic for five to six years. Population size, vitality and trends of population development were recorded. Water chemistry, water level fluctuation, vegetation type and cover, as well as mowing regime were assessed and the effect of these potential predictors on the species populations was examined. Populations of H. vernicosus were affected mainly by the density of vascular plants, the species thrived best in habitats with sparse herb and abundant “brown moss” cover. Other important factors included water table fluctuation and water concentration of iron. Populations were more vital and prospered better in sites with a stable water table and more iron-rich conditions. Dependence of population parameters on other measured characteristics of water chemistry was not detected.
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. Nitrogen, phosphorus and potassium were supplied to some Belgian fens of varying nutrient status and productivity. Plant growth in the lowest productive fen with a species-rich Caricion davallianae vegetation was strongly P-limited. N was ineffective when applied alone, but increased the effect of P-addition when applied together. Summer biomass and plant nutrient concentrations were monitored for four years, and showed partial recovery of nutrient limitation. In a more productive fen dominated by Carex lasiocarpa and in a fen meadow, nutrient limitation was less strong. N limited growth in the productive fen, and N and K were co-limiting in the fen meadow. The P-concentration in the productive fen vegetation showed a marked increase after P-fertilization, but it did not result in higher standing crop. The significance of P-limitation for the conservation of species rich low productive fens is discussed. P-limitation may be an essential feature in the conservation of low productive rich fens: because it is less mobile in the landscape than N and/or because it is an intrinsic property of this vegetation type. Plant nutrient concentrations and N:P-ratios may be used as an indication for the presence and type of nutrient limitation in the vegetation. We found N:P-ratios of 23 to 31 for a P-limited site and 8 to 15 in N-limited sites. This was in agreement with critical values from the literature: N:P > ca. 20 for P-limitation and N:P < 14 for N-limitation. Thus, this technique appears valid in the vegetation types that were studied here.
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(1) Relationships between vegetation composition and nutrient and major ion concentrations in groundwater and peat were examined in 58 stands of fen vegetation in the Biebrza mire, Poland. The 58 stands included rich fens with a large standing biomass, rich fens with lower standing biomass and poor fens. (2) The highly productive rich fen (i.e. rich fen with large standing biomass) receives moderately eutrophic river water. The rheophilous part of the mire that is not, or only occasionally flooded contains gradients from quite productive rich fens to less productive rich fens and poor fens. In this part of the gradient, occasional river flooding appeared to be an important source of K and was probably responsible for the presence of quite productive rich fen vegetation. (3) Upward seepage of calcium-rich and phosphate-poor groundwater keeps phosphate concentration low in the superficial mire water and the peat from the lower productive rich fen. Phosphate concentration is higher in the mire water and the peat from the poor fen which is fed by downward-flowing rainwater. (4) Nitrogen concentration in mire water and peat is only poorly correlated with species composition and vegetation structure.
Article
1. Nutrient limitation (mostly N or P) is a driving force in ecosystem development. Current techniques to determine the nature of nutrient limitation use laborious fertilization experiments. 2. It was hypothesized that the N:P ratio of the vegetation directly indicates the nature of nutrient limitation on a community level (N vs. P limitation). This hypothesis was tested by reviewing data on fertilization studies in a variety of European freshwater wetland ecosystems (bogs, fens, wet heathlands, dune slacks, wet grasslands). In a subset of the data (dune slacks) between-site intraspecific variation and within-site interspecific variation in nutrient content and N:P ratio was studied in five plant species. 3. A review of 40 fertilization studies reveals that an N:P ratio >16 indicates P limitation on a community level, while an N:P ratio
Article
asterisk inside a circle sign In Dutch fens, subjected to high nitrogen (N) deposition, Scorpidium and other brown mosses have declined markedly. A concurrent strong increase of Sphagnum and Polytrichum has promoted acidification. We measured nitrate (NO3-) and ammonium (IMH4+) availability in Dutch fens. We also tested preference for either N form of Scorpidium scorpioides, Sphagnum squarrosum and Polytrichum commune. asterisk inside a circle sign Ion exchange membranes were installed in the field. In a hydroponic experiment, plants were grown on 100 μM (reflecting concentrations in Dutch precipitation since 1980), provided as NO3-, NH4NO3, or NH 4+. asterisk inside a circle sign NH4+ availability in Sphagnum and Polytrichum stands and NH 4+:NO3- ratio in Sphagnum stands were higher than in brown moss stands. In the experiment, Scorpidium performed best on NO3-. NH4NO3 tended to decrease its growth, whereas NH4+ was very toxic. N treatment did not significantly affect growth of Sphagnum and Polytrichum. Tissue pH and nutrient concentrations confirmed the growth patterns and indicated that Scorpidium was most sensitive to NH4+ stress. asterisk inside a circle sign We conclude that high NH4+ inputs pose a serious threat to the brown moss flora of rich fens.
Article
1 The historical development of mire ecology and terminology is reviewed in relation to evolving concepts and perceptions, and the diverse schools and traditions of vegetation and habitat description and research. 2 Most ecological and floristic variation within north-west European mire vegetation is accounted for by three ecological gradients: the acid base-poor vs. neutral, base- and bicarbonate-rich gradient; the gradient in fertility related to availability of the limiting nutrient elements N and P; and the water level gradient. Effects of salinity and the spring–flush–fen gradients are of more local significance, usually easily recognized. Land use is an important additional factor. 3 The mineral-soil-water limit between ombrotrophic and minerotrophically influenced sites is not sharp, and cannot be related to consistent differences in either vegetation or water chemistry. It should be abandoned as a general main division within mires. 4 The most important natural division is between ‘bog’, with pH generally < 5.0, low Ca2+, and Cl– and SO42– as the main inorganic anions, typically dominated by sphagna, ericoids and calcifuge Cyperaceae, and ‘fen’, with pH generally > 6.0, high Ca2+ and HCO3–, vegetation rich in dicotyledonous herbs and ‘brown mosses’. This division is reflected in a bimodal distribution of pH. 5 The terms oligotrophic, mesotrophic and eutrophic should refer only to nutrient richness (fertility, mainly N and P), not to base richness (metallic cations and pH). 6 It is recommended that ‘mire’ should embrace both wetlands on peat and related communities on mineral soils, that ‘bog’ (unqualified) should encompass both ombrotrophic and weakly minerotrophic mires, including ‘bog woodland’, and that ‘fen’ should be restricted to base-rich mires but include both herbaceous and wooded vegetation (‘fen carr’). 7 Definitions are given for a range of broadly defined categories that should cover most vegetation types commonly encountered. The relation of these to British national vegetation classification types and to major units in European phytosociology is outlined.
Article
It is demanded currently in public discussions to rewet peatlands and re-establish their function as nutrient sinks. But due to high phosphorus (P) concentrations in the pore water of rewetted peatlands (40–420 μM) it is hypothesized that they can act as a surplus P source for adjacent surface waters and consequently support the eutrophication of such waters. Our detailed investigations of processes at the redox interface in four fens with different geochemical character show the dependence of P retention from the chemistry of the pore water. The precipitation of Fe(III) oxyhydroxide led to high retention of phosphorus and other substances such as DOC and sulphate in the eutrophic fens. When molar Fe/P ratios were larger than about 3 the initially high P concentrations in the anaerobic pore water (20–210 μM) decreased to concentrations below 1 μM under aerobic conditions. Thus, after rewetting high pore water concentrations of P do not automatically result in an increased P load to adjacent surface waters compared to pre-rewetting conditions. An enhanced P export to adjacent surface waters from eutrophic fens can be expected when the Fe/P ratio is smaller than 3 in the anaerobic pore water. In our investigations of natural, oligotrophic to mesotrophic fens the precipitation of Fe(III) oxyhydroxide was inhibited by the formation of stable dissolved Fe ∼ humic complexes. P retention in these fens was only related to the DOC concentrations at the redox interface, so that lower DOC concentrations concurred with higher P retention. The P equilibrium concentrations in an aerobic environment can be higher than that of eutrophic fens with Fe/P ratios larger than about 3 in the anaerobic pore water.
Article
Genus level phylogenetic patterns within a monophyletic group of wetland mosses consisting ofTomentypnum, Hamatocaulis, Scorpidium, Conardia, Calliergon, Warnstorfia, Straminergon, andLoeskypnum (Amblystegiaceae) are cladistically analysed, usingPalustriella and partlyCratoneuron as outgroups. The ingroup consists of two clades, one withTomentypnum, Hamatocaulis andScorpidium, the other with the other ingroup genera. The second clade gets completely resolved only with the inclusion of habitat data. The adaptation to relatively dry wetland habitats probably evolved in the ancestor ofStraminergon andLoeskypnum, the species ofCalliergon andWarnstorfia, which are more ancestral, growing in wetter habitats. The more primitive taxa of the ingroup, as well asPalustriella species, occur in relatively mineral-rich habitats and adaptations to poorer habitats occurred several times in the two clades.
Article
A single solution reagent is described for the determination of phosphorus in sea water. It consists of an acidified solution of ammonium molybdate containing ascorbic acid and a small amount of antimony. This reagent reacts rapidly with phosphate ion yielding a blue-purple compound which contains antimony and phosphorus in a 1:1 atomic ratio. The complex is very stable and obeys Beer's law up to a phosphate concentration of at least 2 μg/ml.The sensitivity of the procedure is comparable with that of the stannous chloride method. The salt error is less than 1 %.RésuméUne méthode spectrophotométrique est décrite pour le dosage du phosphate dans l'eau de mer, an moyen de molybdate d'ammonium, en présence d'acide ascorbique et d'antimoinc. Il se forme rapidement un composé violet bleu, renfermant antimoine et phosphore dans un rapport atomique de 1:1.ZusammenfassungBeschreibung einer Methode zur Bestimmung von Phosphat in Mecrwasser mit Hilfe von Ammoniummolybdat in Gegenwart von Ascorbinsäure und Antimon. Der gebildete blau-violette Komplex wird spektrophotometrisch gemessen.
Article
The use of nutrient concentrations in plant biomass as easily measured indicators of nutrient availability and limitation has been the subject of a controversial debate. In particular, it has been questioned whether nutrient concentrations are mainly species' traits or mainly determined by nutrient availability, and whether plant species have similar or different relative nutrient requirements. This review examines how nitrogen and phosphorus concentration and the N:P ratio in wetland plants vary among species and sites, and how they are related to nutrient availability and limitation. We analyse data from field studies in European non-forested wetlands, from fertilisation experiments in these communities and from growth experiments with wetland plants. Overall, the P concentration was more variable than the N concentration, while variation in N:P ratios was intermediate. Field data showed that the N concentration varies more among species than among sites, whereas the N:P ratio varies more among sites than among species, and the P concentration varies similarly among both. Similar patterns of variation were found in fertilisation experiments and in growth experiments under controlled nutrient supply. Nutrient concentrations and N:P ratios in the vegetation were poorly correlated with various measures of nutrient availability in soil, but they clearly responded to fertilisation in the field and to nutrient supply in growth experiments. In these experiments, biomass N:P ratios ranged from 3 to 40 and primarily reflected the relative availabilities of N and P, although N:P ratios of plants grown at the same nutrient supply could vary three-fold among species. The effects of fertilisation with N or P on the biomass production of wetland vegetation were well related to the N:P ratios of the vegetation in unfertilised plots, but not to N or P concentrations, which supports the idea that N:P ratios, rather than N or P concentrations, indicate the type of nutrient limitation. However, other limiting or stressing factors may influence N:P ratios, and the responses of individual plant species to fertilisation cannot be predicted from their N:P ratios. Therefore, N:P ratios should only be used to assess which nutrient limits the biomass production at the vegetation level and only when factors other than N or P are unlikely to be limiting.
Article
Mire terminology, subdivision and gradient structure have been subjected to an intense debate intensified in the last years. The conception of Wheeler and Proctor (J. Ecol. 88, 187–203), which divides mires into bogs, having pH<5.5, and fens, having pH>5.5, becomes generally accepted despite a certain critique from the Scandinavian perspective and despite the fact that few contributions to the debate have come from central and southern Europe and from other than botanical disciplines. In this paper, we demonstrated that the bog-fen boundary is clearly determinable not by pH, but by a set of nutrient-requiring species that avoid truly ombrotrophic conditions in central Europe. We therefore defined fens as groundwater-fed wetlands that host low productive nutrient-limited vegetation dominated by Cyperaceae and bryophytes. The fertility gradient within fens, another controversial point in the ongoing debate, is easily distinguishable using both plant and animal data, but it appears primarily within calcium-richer fens. We suggest defining fen grasslands by the high abundance of nutrient-requiring grasses and forbs rather than purely by fen origin and management. Concerning pH/calcium gradient, there is large variation in plant, mollusc, algal, fungal and testacean assemblages within fens with a pH>5.5 in central Europe even though some authors named all mires having such pH ‘(rich) fens’. This clear and extended poor–rich (pH/calcium) gradient in floristical data is independent of the fertility gradient. Conductivity (approximating water mineral richness) contributes significantly to the pH in explaining the vegetation variation. Vegetation composition accounts for a larger amount of the variation in algal, molluscan, testacean and fungal assemblages than even long-term measured environmental data. The chemical limit of the occurrence of any Sphagnum species, even the calcitolerant ones, is the most important and easily recognised natural boundary between major functional fen types, although it varies among regions and hydrological situations. We therefore believe that fen classification based exclusively on floristic data is necessary to avoid circular argumentation and provides the best basis for the characterization of habitats. We propose to subdivide fens into five standard vegetation types with defined boundaries: poor fens (Sphagno recurvi-Caricion canescentis), moderately rich fens (Caricion fuscae), rich fens (Sphagno warnstorfii-Tomenthypnion), extremely rich fens and calcareous fens (both corresponding to Caricion davallianae). Calcareous fens were neglected during the ongoing debate due to its relative scarcity in some traditionally explored regions. Its ecological boundary is the point at which calcium carbonate starts to precipitate, which is connected with marked change in plant and animal species composition. The ecological differentiation of all proposed fen types was tested using a data set from two different regions (Carpathians and Bulgaria). Both conductivity and pH differ significantly between pairs of vegetation types. All proposed fen types also markedly differ in molluscan assemblages.
Article
Rich fen bryophytes used to occur widely in The Netherlands some decades ago in dune slacks, pleistocene valley mires and large holocene peatland areas. Scorpidium scorpioides (Hedw.) Limpr., S. cossoni. (Schimp.) Hedenäs and S. revolvens (Anon.) Rubers have disappeared completely at most localities and been replaced by Sphagnum species or more eutrophic fen species such as Calliergonella cuspidata (Hedw.) Loeske. Apart from natural succession from fen to bog, anthropogenic acidification and eutrophication are thought to be responsible for the changes in the bryophyte layer of rich fens. The importance of hydrology in determining the rate of changes is stressed.
Article
An HCl/HNO3/HF PTFE bomb dissolution technique using microwave heating was tested on several environmental and biological materials. Nearly 25 elements in the dissolved samples were determined mainly by inductively coupled plasma—atomic emission spectrometry or graphite furnace atomic absorption spectrometry. Results of the analysis of several hundred samples are discussed.
Article
Groundwater samples collected near a secondary-sewage infiltration site on Cape Cod, Massachusetts were examined for colloidal materials (10–1000 nm). In two wells the water contained a population of monodisperse 100-nm particles, detected using laser-light scattering and autocorrelation data processing. SEM and SEM-EDAX analysis of these colloidal materials collected on ultrafilters confirmed the laser light scattering result and revealed that these microparticles consisyed of primarily iron and phosphorus in a 1.86 Fe to 1.0 P stoichiometric ratio. Chemical analyses of the water samples, together with equilibrium solubility calculations, strongly suggest that the ion-activity product should exceed the solubility product of a 100-nm diameter predominantly vivianite-type (Fe3(PO4)2 · 8H2O) colloidal phase. In light of our results, we conclude that these microparticles were formed by sewage-derived phosphate combining with ferrous iron released from the aquifer solids, and that these colloids may be moving in the groundwater flow. Such a subsurface transport process could have major implications regarding the movement of particle-reactive pollutants traditionally viewed as non-mobile in groundwater.
Article
We evaluated whether the kind of nutrient limitation (N, P, or K) may affect species richness–productivity patterns and subsequently may explain variation in species richness and in richness of threatened species. We present a data set from previous studies in wetlands in Poland, Belgium, and The Netherlands and examine species richness–productivity patterns for vascular plants in all 150 sites together as well as for N-, P-, and Klimited sites separately. The kind of nutrient limitation was assessed by N:P, N:K, and K: P ratios in the vegetation. Critical values for these ratios were derived from a literature review of fertilization experiments. The kind of nutrient limitation influenced species richness– productivity patterns in our 150 sites through large differences in productivity. P (co)- limitation occurred only at low productivity, K (co)-limitation up to intermediate productivity, and N limitation along the entire productivity gradient. There was a decreasing trend in species richness with increasing productivity for K (co)-limited sites, whereas for both the N-limited sites and P (co)-limited sites a sort of ‘‘filled hump-shaped curve’’ was observed. The species richness–productivity relationship for threatened species was restricted to a much narrower productivity range than that for all species. Richness of threatened species was higher in P (co)-limited sites than in N-limited sites, suggesting that increased P availabilities in wetlands may be particularly important in causing disappearance of threatened species in western Europe. The role of nutrient limitation in species richness– productivity relationships not only reveals mechanisms that may explain variation in species richness and occurrence of threatened species, but it also may be important for nature management practice.
Article
Anaerobic soils released more phosphate to soil solutions low in soluble phosphate and sorbed more phosphate from soil solutions high in soluble phosphate than did aerobic soils. The difference in behavior of phosphate under aerobic and anaerobic conditions is attributed to the change brought about in ferric oxyhydroxide by soil reduction. The probably greater surface area of the gel-like reduced ferrous compounds in an anaerobic soil results in more soil phosphate being solubilized where solution phosphate is low and more solution phosphate being sorbed where solution phosphate is high.
  • Olde Venterink
  • H G M Wassen
  • M J Verkroost
  • A W M De Ruiter
Olde Venterink, H.G.M., Wassen, M.J., Verkroost, A.W.M. & de Ruiter, P.C. 2003. Species richness-productivity patterns differ between N-, P-, and K-limited wetlands. Ecology, 84: 2191-9.
Soil testing and plant analysis
  • Segoe
Segoe, ed. Soil testing and plant analysis. 3rd edn. Madison, WI: Soil Science Society of American Book Series, pp. 141-72.
  • Westerman R.L.