Aquatic microinvertebrate abundance and species diversity in peat bogs of Tierra del Fuego (Argentina)

Peat bogs are regarded as extreme environments due to their low pH and low nutrient concentration, and thus hold a unique biota adapted to these particular conditions. The island of Tierra del Fuego encompasses the southernmost extensive peat bog area in the world, and is therefore particularly interesting from a biogeographical viewpoint. Within the same peat bog, different environment types can be identified: clear ponds, vegetated ponds and Sphagnum patches. In this study we compare the abundance, richness and species diversity of microinvertebrates (Copepoda, Cladocera and Rotifera) in these three types of environments from two peat bogs (Andorra and Rancho Hambre). Out of the 29 taxa recorded, 19 were common to both peat bogs, including four cladocerans endemic to Southern Patagonia and three rotifers endemic to Fuegian peat bogs. The rotifers were the dominant group in all environment types from Rancho Hambre, while in Andorra the Sphagnum moss was dominated by copepods, particularly harpacticoids. The results revealed that the environment type rather than peat bog was the key factor at explaining differences in species richness and diversity among microinvertebrate communities. This study highlights the importance of Sphagnum moss as a low diversity extreme environment which supports highly endemic species.     

Hounsfield Units ranges in CT-scans of bog bodies and mummies

Mummification processes, either artificial or natural, preserve the tissues from postmortem decay, but change them from their original state. In this study we provided the first comprehensive set of Hounsfield Unit (HU) ranges specific for tissues mummified under different environmental conditions (peat bog, cold-dry and hot-dry environment). We also analyzed the impact of different museal preservation techniques on the HU ranges, as e.g. in the Tollund Man and Grauballe Man, two bog bodies from Denmark. The HU results for mummies were compared with HU results from forensic cases, cremated and inhumated ancient human skeletal remains, and fossil animal bones. Knowledge of the typical HU range for the different tissues in mummies may help to avoid misinterpretation of increased or reduced radiodensity as evidence of paleopathological conditions. Finally, we demonstrate the practical benefit of using our re-defined HU ranges by showing the improved results of 3D visualization from automatic segmentation in an Inca mummy from Mount Llullaillaco.     

Microclimatic buffering and resource‐based habitat in a glacial relict butterfly: significance for conservation under climate change

In contrast to several organisms that have already shown range shifts to the north as a response to climate change, southern populations of relict species are trapped in isolated altitudinal habitats. Therefore, there is a growing interest to better understand their habitat use, with particular attention to the thermal aspects and associated significance for their habitat management. We address this issue by a study of larval habitat use relative to vegetation structure and microclimate in a glacial relict butterfly of peat bog ecosystems, using a functional, resource‐based habitat approach. We analysed caterpillar presence and density relative to vegetation composition (reflecting gradients of humidity, temperature, and natural succession of the peat bog) and to the availability and quality of thermal refuges for caterpillars (i.e., structures provided by Sphagnum hummocks). We also tested caterpillar survival rates under different temperature and humidity treatments. We found that (1) Boloria aquilonaris was a specialist butterfly of early successional stages with very humid zones of peat bog, (2) the lack of Sphagnum hummocks reduced larval habitat suitability, and hence the population density, and (3) a reduction of the thermal buffering ability of Sphagnum hummocks was observed in less humid, degraded parts, or late‐successional stages of peat bog. A larval rearing experiment showed a significant impact of temperature on caterpillar survival; survival being higher at lower temperature. Our field and laboratory results support the idea that the thermal environment exploited by caterpillars should be considered as a functional resource and included in a population‐specific habitat definition. Appropriate management of the peat bog habitat of this glacial relict species should not exclusively focus on the larval and adult feeding resources, but also on the quality of thermal refuges provided by Sphagnum hummocks in humid zones of the peat bog, especially in the current critical context of climate warming.     

Associations of Chironomidae (Diptera) of shallow,acid, humic lakes and bog pools in Atlantic Canada,and a comparison with an earlier paleoecological investigation

The composition of benthos in a series of 29 lake and peat pool sites is examined especially in relation to a successional gradient. The results indicate a sharp distinction between the fauna of peat pools and lakes. Chironomus, Psectrocladius, Monopsectrocladius, and Zalutschia are characteristic of bog lakes at the latter stages of their evolution and peat pools. Procladius and Tanytarsus dominate in most lakes. Between weakly acidic and strongly acidic lakes a sharp boundary exists for many other components of the benthos. Chaoborus occurs in strongly acidic lakes. Amphipoda, and Ephemeroptera are limited to weakly acidic or circum-neutral waters.A comparison of the results of this investigation with a parallel paleoecological study is made.     

Succession changes in diversity and assemblages composition of planthoppers and leafhoppers in natural ancient peat bogs in Belarus

Succession has a strong influence on species diversity and composition of terrestrial ecosystems. Peat bogs are among them. They have a large area in Belarus compared to other Central European countries. While in several studies have analyzed the effects of succession on vegetation in peat bog ecosystems, the response of peatland insects to succession has not been investigated yet. To address this issue were sampled Auchenorrhyncha abundance and environmental parameters on the ancient and one of the largest natural peat bog along a successional gradient from the margin to the bog dome. The results provide evidence that succession of peat bogs has influence on planthoppers and leafhoppers abundance, diversity and species composition. Along the successional gradient from younger towards older successional stages an increase abundance of specialized peat bog species, chamebionts, oligophagous and monophagous was observed. On the contrary, the younger stages of natural peat bog succession offer favorable conditions to eurytopic, polyphagous and chortobiont planthoppers and leafhoppers. The highest abundance and species richness of Auchenorrhyncha were in the lagg zone followed by early stages of natural peat bog succession. The highest diversity was in the middle stages of succession. A determinant of Auchenorrhyncha diversity was the cover of ericaceous dwarf shrubs. Linear models shrub cover and number of plants species had a positive effect on planthoppers and leafhoppers diversity and a negative effect on their abundance. Amount of ericaceous dwarf shrubs within the peat bog could be as a measure of heterogeneity.     

Hydrogenotrophic methanogenesis by moderately acid-tolerant methanogens of a methane-emitting acidic peat

The emission of methane (1.3 mmol of CH(4) m(-2) day(-1)), precursors of methanogenesis, and the methanogenic microorganisms of acidic bog peat (pH 4.4) from a moderately reduced forest site were investigated by in situ measurements, microcosm incubations, and cultivation methods, respectively. Bog peat produced CH(4) (0.4 to 1.7 micro mol g [dry wt] of soil(-1) day(-1)) under anoxic conditions. At in situ pH, supplemental H(2)-CO(2), ethanol, and 1-propanol all increased CH(4) production rates while formate, acetate, propionate, and butyrate inhibited the production of CH(4); methanol had no effect. H(2)-dependent acetogenesis occurred in H(2)-CO(2)-supplemented bog peat only after extended incubation periods. Nonsupplemented bog peat initially produced small amounts of H(2) that were subsequently consumed. The accumulation of H(2) was stimulated by ethanol and 1-propanol or by inhibiting methanogenesis with bromoethanesulfonate, and the consumption of ethanol was inhibited by large amounts of H(2); these results collectively indicated that ethanol- or 1-propanol-utilizing bacteria were trophically associated with H(2)-utilizing methanogens. A total of 10(9) anaerobes and 10(7) hydrogenotrophic methanogens per g (dry weight) of bog peat were enumerated by cultivation techniques. A stable methanogenic enrichment was obtained with an acidic, H(2)-CO(2)-supplemented, fatty acid-enriched defined medium. CH(4) production rates by the enrichment were similar at pH 4.5 and 6.5, and acetate inhibited methanogenesis at pH 4.5 but not at pH 6.5. A total of 27 different archaeal 16S rRNA gene sequences indicative of Methanobacteriaceae, Methanomicrobiales, and Methanosarcinaceae were retrieved from the highest CH(4)-positive serial dilutions of bog peat and methanogenic enrichments. A total of 10 bacterial 16S rRNA gene sequences were also retrieved from the same dilutions and enrichments and were indicative of bacteria that might be responsible for the production of H(2) that could be used by hydrogenotrophic methanogens. These results indicated that in this acidic bog peat, (i) H(2) is an important substrate for acid-tolerant methanogens, (ii) interspecies hydrogen transfer is involved in the degradation of organic carbon, (iii) the accumulation of protonated volatile fatty acids inhibits methanogenesis, and (iv) methanogenesis might be due to the activities of methanogens that are phylogenetic members of the Methanobacteriaceae, Methanomicrobiales, and Methanosarcinaceae.     

How Sphagnum bogs down other plants

Recent research on the organo-chemical composition of Sphagnum and on the fate of its litter has further clarified how this plant builds acidic, nutrient-poor, cold and anoxic peat bogs. The bog environment helps Sphagnum to outcompete other plants for light. Its morphology, anatomy, physiology and composition make it an effective ecosystem engineer and at the same time benefit the plant in the short term. This may have facilitated the evolution of the genus.     

Modeling Northern Peatland Decomposition and Peat Accumulation

To test the hypothesis that long-term peat accumulation is related to contemporary carbon flux dynamics, we present the Peat Decomposition Model (PDM), a new model of long-term peat accumulation. Decomposition rates of the deeper peat are directly related to observable decomposition rates of fresh vegetation litter. Plant root effects (subsurface oxygenation and fresh litter inputs) are included. PDM considers two vegetation types, vascular and nonvascular, with different decomposition rates and aboveground and belowground litter input rates. We used PDM to investigate the sensitivities of peat accumulation in bogs and fens to productivity, root:shoot ratio, tissue decomposability, root and water table depths, and climate. Warmer and wetter conditions are more conducive to peat accumulation. Bogs are more sensitive than fens to climate conditions. Cooler and drier conditions lead to the lowest peat accumulation when productivity is more temperature sensitive than decomposition rates. We also compare peat age–depth profiles to field data. With a very general parameterization, PDM fen and bog age–depth profiles were similar to data from the the most recent 5000 years at three bog cores and a fen core in eastern Canada, but they overestimated accumulation at three other bog cores in that region. The model cannot reliably predict the amount of fen peat remaining from the first few millennia of a peatland's development. This discrepancy may relate to nonanalogue, early postglacial climatic and nutrient conditions for rich-fen peat accumulation and to the fate of this fen peat material, which is overlain by a bog as the peatland evolves, a common hydroseral succession in northern peatlands. Because PDM sensitivity tests point to these possible factors, we conclude that the static model represents a framework that shows a consistent relationship between contemporary productivity and fresh-tissue decomposition rates and observed long-term peat accumulation. Received 19 June 2000; accepted 24 January 2001.     

Vertical profiles of methanogenesis and methanogens in two contrasting acidic peatlands in central New York State, USA

Northern acidic peatlands are important sources of atmospheric methane, yet the methanogens in them are poorly characterized. We examined methanogenic activities and methanogen populations at different depths in two peatlands, McLean bog (MB) and Chicago bog (CB). Both have acidic (pH 3.5-4.5) peat soils, but the pH of the deeper layers of CB is near-neutral, reflecting its previous existence as a neutral-pH fen. Acetotrophic and hydrogenotrophic methanogenesis could be stimulated in upper samples from both bogs, and phylotypes of methanogens using H2/CO2 (Methanomicrobiales) or acetate (Methanosarcinales) were identified in 16S rRNA gene clone libraries and by terminal restriction fragment length polymorphism (T-RFLP) analyses using a novel primer/restriction enzyme set that we developed. Particularly dominant in the upper layers was a clade in the Methanomicrobiales, called E2 here and the R10 or fen group elsewhere, estimated by quantitative polymerase chain reaction to be present at approximately 10(8) cells per gram of dry peat. Methanogenic activity was considerably lower in deeper samples from both bogs. The methanogen populations detected by T-RFLP in deeper portions of MB were mainly E2 and the uncultured euryarchaeal rice cluster (RC)-II group, whereas populations in the less acidic CB deep layers were considerably different, and included a Methanomicrobiales clade we call E1-E1', as well as RC-I, RC-II, marine benthic group D, and a new cluster that we call the subaqueous cluster. E2 was barely detectable in the deeper samples from CB, further evidence for the associations of most organisms in this group with acidic habitats.     

Plant and Soil Nitrogen in an Ombrotrophic Peatland,Southern Canada

Ecosystems - We examined the concentration of nitrogen (N) and δ15N in vegetation and peat in the Mer Bleue bog, Ontario, Canada. Compared with other ecosystems, N concentration in bog plant...     

Associations of diatoms in the surficial sediments of lakes and peat pools in Atlantic Canada

The distribution of diatom frustules in the surficial sediments of lakes and ombrotrophic peat pools in Atlantic Canada are examined especially in relation to pH and bog lake succession. Sedimentary diatom associations for peat pools, strongly acidic lakes, and weakly acidic lakes are characterized. These associations and the derived diatom-pH calibration functions will facilitate improved paleoecological interpretation of natural ontogenetic pathways and assessments of recent anthropogenic impacts.     

Persistent versus transient tree encroachment of temperate peat bogs: effects of climate warming and drought events

Peatlands store approximately 30% of global soil carbon, most in moss‐dominated bogs. Future climatic changes, such as changes in precipitation patterns and warming, are expected to affect peat bog vegetation composition and thereby its long‐term carbon sequestration capacity. Theoretical work suggests that an episode of rapid environmental change is more likely to trigger transitions to alternative ecosystem states than a gradual, but equally large, change in conditions. We used a dynamic vegetation model to explore the impacts of drought events and increased temperature on vegetation composition of temperate peat bogs. We analyzed the consequences of six patterns of summer drought events combined with five temperature scenarios to test whether an open peat bog dominated by moss (Sphagnum) could shift to a tree‐dominated state. Unexpectedly, neither a gradual decrease in the amount of summer precipitation nor the occurrence of a number of extremely dry summers in a row could shift the moss‐dominated peat bog permanently into a tree‐dominated peat bog. The increase in tree biomass during drought events was unable to trigger positive feedbacks that keep the ecosystem in a tree‐dominated state after a return to previous ‘normal’ rainfall conditions. In contrast, temperature increases from 1 °C onward already shifted peat bogs into tree‐dominated ecosystems. In our simulations, drought events facilitated tree establishment, but temperature determined how much tree biomass could develop. Our results suggest that under current climatic conditions, peat bog vegetation is rather resilient to drought events, but very sensitive to temperature increases, indicating that future warming is likely to trigger persistent vegetation shifts.     

利用雨养泥炭沼泽及湖泊沉积物重建多氯联苯污染时空变化趋势

为了重建不同历史时期多氯联苯(PCBs)的沉降速率以研究其污染的时空变化趋势,本研究分析了PCBs在泥炭芯和湖泊沉积柱芯中浓度和沉降速率的变化规律,并评估了泥炭芯和湖泊沉积柱芯用于PCBs沉降变化研究的适用性.对采集柱芯进行定年分析发现,泥炭沼泽可以很好地记录PCBs历史沉降变化,并且泥炭中的PCBs没有出现降解情况,...     

A comparison of restoration techniques to accelerate recovery of litter decomposition and microbial activity in an experimental peat bog restoration trial

Restoration of mined Restionaceae-dominated peat bogs in northern New Zealand is currently initiated by establishing native vegetation cover to minimise erosion of the remaining peat. The relative effects of various restoration techniques on litter decomposition and microbial activity within experimental litter bags were investigated in a restoration trial established on a mined peat surface. Decomposition and microbial activity of litter were compared between four different restoration treatments: direct transfer of intact habitat ‘islands’; the addition of processed peat with seed; the addition of processed peat with no seed; and recently mined peat surface (a ‘do nothing’ restoration option), with the four treatments replicated at each of five distances from an undisturbed peat bog. Treatments were compared with an undisturbed peat bog (control). Litter decomposition and associated microbial respiration rates were significantly higher in the undisturbed peat bog sites than in any of the restoration treatments, but the technique used to restore mined peatlands did have a significant effect on these ecosystem process rates. Results suggest that ecosystem processes such as decomposition and microbial community activity recover faster with restoration techniques such as direct transfer of intact habitat islands, than with other techniques such as simple seed addition. However, even after 12 months, litter decomposition and microbial activity in restored habitats were still far from reaching the levels recorded in the undisturbed peat bog. In addition, there was a strong relationship between the effort (and cost) applied to plant community restoration treatments and the rate of decomposition and microbial community activity.     

Ecological Succession of a Relict Central European Peat Bog and Variability of Its Insect Biodiversity

The isolated habitat of the ervené Blato bog (South Bohemia, Czech Republic) and its relict insect fauna have been the subject of long-term monitoring. The species composition and abundance of Lepidoptera (light traps) and Coleoptera (pitfall traps) were monitored for 4 years (1994–1997) simultaneously on two sites – in the edaphic climax pine forest and in wetland successional habitats. The method of statistical evaluation by RDA and CCA ordination, representing the habitat preference of species of Coleoptera (Carabidae only) and Lepidoptera (all nocturnal phototactic taxa) between the edaphic climax forest and succession stages, was used. All categories of the peatland taxa (tyrphobiontic, tyrphophilous and tyrphoneutral species) were analysed. Ten highly stenotopic tyrphobiontic species and 23 tyrphophilous species of Lepidoptera (out of 487) were most characteristic of the bog habitat. Only two tyrphophilous carabid species (out of 20) were characteristic of the bog. The most important relict species (tyrphobionts) of Lepidoptera are most diverse and abundant within the successional habitats and in the open wet forest. The relict fauna of the closed climax pine forest is much less diverse and composed mostly of abundant tyrphophilous and tyrphoneutral forest species. Preservation or restoration of sufficiently constant hydrological conditions, which prevents formation of the closed forest, is the basic management for habitat conservation of all relict tyrphobiontic species of the ervené Blato bog and similar peat land habitat islands. The peat bog is a unified complex system of specific diverse and relict taxa. The most specific taxa are tyrphobiontic Lepidoptera, but a number of other vulnerable tyrphophilous and tyrphoneutral insects are associated with the peat bog as well.     

Fungal and Bacterial Activity in Northern Peatlands

Selective inhibition of substrate-induced respiration with antibiotics cycloheximide and streptomycin sulphate provided insight into eukaryotic versus prokaryotic activities in surface peat soil of three Canadian peatlands. Prokaryotic and eukaryotic communities in peatlands are important in the net sequestration of atmospheric carbon dioxide and therefore play a unique role in global carbon cycling. Selective inhibition techniques were generally successful, with a maximum non-target inhibition of only 17%. Assuming that eukaryotic and prokaryotic activities were dominated by fungi and bacteria respectively, across 3 ecologically and hydrologically diverse and spatially dispersed peatlands, we demonstrated bacterial dominance in a bog and a poor fen both with acidic and primarily Sphagnum derived peat soil and in a near pH neutral wetter rich fen with sedge peat (fungal to bacterial activity ratio = 0.31 to 0.68). These results differ in that in other acidic environments, such as conifer forest soils, fungal to bacterial activity ratios are mostly greater than 1 indicative of fungal dominance.     

Spatial Distribution of Ground Beetles (Coleoptera: Carabidae) and Moths (Lepidoptera) in the Mrtvý Luh Bog, Šumava Mts (Central Europe): A Test of Habitat Island Community

Spatial distribution of ground beetles and moths in the isolated Central European Mrtvy luh bog was analyzed. The most stenotopic tyrphobiontic species (relicts restricted to the peat bog) of ground beetles (Coleoptera: Carabidae) and moths (Lepidoptera) are distributed according to a distinct ecological gradient between the bog margin (lagg) and the bog centre. The degree of habitat preference between the bog margin and centre is taxonomically specific and significant. A list of stenotopic species of high conservation value is given. Several tyrphobiontic species occur in the treeless bog centre only. The tyrphophilous and tyrphoneutral species are distributed in the peat bog mostly randomly, some of such species prefer bog margins. The migratory highly opportunistic moths from habitats outside the bog usually cross the treeless centre. Most of the ubiquitous tyrphoneutral and migratory moths represent the faunal component, which is a very temporary phenomenon only, not associated with the peat bog permanently. The conservation of insect biodiversity associated with isolated peat bogs depends on complete preservation of the edaphic ecological conditions of the fragile paleorefugial habitat island and its spatial structure.     

The effects of aperiodic desiccation on the diversity of benthic desmid assemblages in a lowland peat bog

The lowland minerotrophic “Swamp” peat bog, located in the Czech Republic, is one of the most important European sites of desmidiacean diversity. The hydrological regime of the bog is driven by the water level of a nearby ancient manmade pond. Therefore, the bog experiences severe aperiodic drying events related to the pond draining. In this study, we investigated the drought-related response of the benthic desmid assemblages of the bog. The samples were taken bimonthly from 12th May 2008 to 19th May 2010, including the 8-month drying out period between October 2008 and June 2009. In addition to the species frequency data, morphometric methods were used to analyse the disparity, morphological turnover and surface-to-volume (S:V) ratios of Desmidiales. The drying event influenced the species composition, biovolume and S:V ratio data of the more species-rich pool, but its influence was less conspicuous in the species-poor acidic site. Accordingly, the species-rich site had generally higher species or morphological turnover between successive samples. The indicators based on the morphometric data were generally more sensitive than the species data. Therefore, we propose that the biovolume, S:V ratios or disparity measures of desmidiacean assemblages might be of benefit for future studies of peat bog microphytobenthos. Desmid assemblages at both sites recovered rapidly following the re-wetting of the bog, and they attained the pre-disturbance diversity, species composition and disparity values. We conclude that the drying event of the bog did not irreversibly influence its valuable desmid assemblages.     

Assessing butterfly diversity and their response to habitat condition in pristine peat bogs in Belarus

Peat bogs are valuable ecosystems because they support regional and local hydrological conditions, and store carbon and other greenhouse gases. Nevertheless, their area in Europe is extremely reduced due to human activities. As a result, the number of studies on biodiversity and the environmental factors affecting the distribution of insects, including butterflies, in large intact peatlands is limited. Such studies provide an important baseline for the subsequent analysis of changes during climate warming and for the assessment of succession in degraded peatlands. The results of such research have shown how butterfly assemblages react to local peat bog habitat conditions and contribute new information on the relations of consumers and the very specific environment of peat bogs. The presented research targets the relationship between characteristics of butterfly assemblages and key environmental variables in intact peat bog habitats. A total of 1427 individuals belonging to 23 butterfly species were recorded. In this study, I found that butterfly abundance, diversity and species composition varied significantly among three main habitat types, namely lagg zones, pine bogs and open bogs, although these habitats did not differ in species richness. The highest abundance was in the pine bogs which are characterized by higher plant community structural complexity and, as a result, higher butterfly food resources. The results confirmed positive responses of species richness and abundance of butterflies to nectariferous flower cover. On the other hand, open, sunny, but windy sites on the peat bogs contribute to a decrease of abundance.     

Late Holocene vegetation history and human activity shown by pollen analysis of Novienki peat bog (Kargaly region,Orenburg Oblast,Russia)

The vegetation history of the Kargaly region has been reconstructed on the basis of pollen analysis of archaeological sediments and one peat bog, the only one found during some years of surveying this area. This latter, Novienky peat bog, located in the steppe transition zone, offers an interesting cultural and natural sequence. Palynological analysis reveals several palaeoecological phases from 4300 b.p. (Bronze Age) to the 18th–19th centuries a.d. (Russian period). Metallurgical activities in Kargaly caused deforestation from the Bronze Age onwards that mainly affected the distribution of birch forests in the region. The palaeoclimatic interpretation of the Novienki pollen diagram is based on the observed changes in the pollen curves of Picea (spruce), Pinus (pine), Abies (silver fir) and Betula (birch). These arboreal taxa are regarded as main climate indicators. The chronology is established on a ¹⁴C-dated pollen profile from the lowest peat layer as well as on the regional pollen sequences and archaeological stratigraphies.