Bog Forest Research Articles

Vertical Distribution of Mites (Acari) in a “Miniature Forest” of Sphagnum Mosses in a Forest Bog in Western Norway

The Sphagnum habitat is a ”miniature forest” to the mites, of which the layers offer different microenvironmental conditions. We studied the vertical distribution of the Oribatida, Mesostigmata, and Prostigmata groups in four layers (0–5 cm, 5–10 cm, 10–15 cm, and 15–20 cm) of a forest bog on Neshalvøya, Norway, to improve the knowledge of the ecology of these mites. The sampled bog was grazed by farm animals; thus, another aim was to investigate the vertical distribution of the oribatid species, which are intermediate hosts of tapeworms. The selected study site is known for its valuable yet increasingly endangered nature, so our aim was also to contribute to the knowledge on its diversity. We collected Sphagnum samples in four replicates and extracted them in the laboratory in modified Berlese funnels. In total, 16.880 mites were studied, including 16.384 Oribatida, 466 Mesostigmata, and 30 Prostigmata. The total abundance of mites, the Oribatida and Mesostigmata groups, was the highest in the upper layer of Sphagnum and decreased with depth, while the abundance of the Prostigmata did not follow any pattern. Among the Oribatida, at deeper layers, significant declines in abundance were observed in adults, but not in juveniles. Most oribatid species, e.g., Nothrus pratensis, preferred the upper layer of Sphagnum, whereas some preferred deeper layers. For example, Suctobelbella acutidens and Carabodes femoralis preferred the 5–10 cm layer, Quadroppia maritalis the 10–15 cm layer, and Ceratozetes gracilis and Eulohmannia ribagai preferred the deepest layer of Sphagnum. Adults and juveniles of the same species showed a preference for the same layer. In total, 62 species of the Oribatida were recorded, including 11 species that are known to be intermediate hosts of tapeworms. Most of them occurred in the upper layer of Sphagnum. Over 20% of the species were found exclusively in deeper layers, so sampling these layers is important for a better evaluation of the mites’ diversity. Studying the vertical distribution of the mites in bogs helps us to understand their ecology, including their role as intermediate hosts of tapeworms, as well as their diversity.

Peatland restoration pathways to mitigate greenhouse gas emissions and retain peat carbon

Peatlands play a crucial role in the global carbon (C) cycle, making their restoration a key strategy for mitigating greenhouse gas (GHG) emissions and retaining C. This study analyses the most common restoration pathways employed in boreal and temperate peatlands, potentially applicable in tropical peat swamp forests. Our analysis focuses on the GHG emissions and C retention potential of the restoration measures. To assess the C stock change in restored (rewetted) peatlands and afforested peatlands with continuous drainage, we adopt a conceptual approach that considers short-term C capture (GHG exchange between the atmosphere and the peatland ecosystem) and long-term C sequestration in peat. The primary criterion of our conceptual model is the capacity of restoration measures to capture C and reduce GHG emissions. Our findings indicate that carbon dioxide (CO2) is the most influential part of long-term climate impact of restored peatlands, whereas moderate methane (CH4) emissions and low N2O fluxes are relatively unimportant. However, lateral losses of dissolved and particulate C in water can account up to a half of the total C stock change. Among the restored peatland types, Sphagnum paludiculture showed the highest CO2 capture, followed by shallow lakes and reed/grass paludiculture. Shallow lakeshore vegetation in restored peatlands can reduce CO2 emissions and sequester C but still emit CH4, particularly during the first 20 years after restoration. Our conceptual modelling approach reveals that over a 300-year period, under stable climate conditions, drained bog forests can lose up to 50% of initial C content. In managed (regularly harvested) and continuously drained peatland forests, C accumulation in biomass and litter input does not compensate C losses from peat. In contrast, rewetted unmanaged peatland forests are turning into a persistent C sink. The modelling results emphasized the importance of long-term C balance analysis which considers soil C accumulation, moving beyond the short-term C cycling between vegetation and the atmosphere.

Carbon Dioxide and Methane Distribution in Peat Deposits of an Oligotrophic Forest Bog and Their Emission in Western Siberia

Carbon Dioxide and Methane Distribution in Peat Deposits of an Oligotrophic Forest Bog and Their Emission in Western Siberia

Fires in Raised Bog: Their Influence and Changes to Geochemical Elements in Peat Layers

Fires in forested raised bogs occur both as a result of natural processes and as a result of human activity. Although there is a generally accepted opinion that their impact on ecosystems is significant, there is still a lack of scientifically reliable research on how individual components of damaged ecosystems change and recover under the influence of fires. The purpose of our study was to assess whether and how these fires affect the chemical composition of the peat layers. This study is based on a geochemical analysis of surface peat layers in areas after a controlled fire and in adjacent areas which were untouched by the fire in a raised bog of Čepkeliai. This study showed a low concentration of potentially toxic elements in the peat layers. In this respect, it is clear that there is no risk of environmental contamination in this natural raised bog. Furthermore, the research revealed other important insights on the combination of potentially toxic elements that can be used as a tracer for the identification of fire events that occurred in the past. Multiple analyses on various combinations of potentially toxic elements revealed the optimal combination (Cu-Zr-Pb-Se-Fe) for distinguishing between the burnt and non-burnt areas. Based on the results of our research, it can be stated that the low-temperature, controlled burning of the peat layers of raised bog forests can be successfully carried out to achieve the environmental and ecological goals of forest management.

First results of estimating possible habitat-forming role of forest reindeer in forest-wetland complexes of central Russian Plain (on example of adaptation enclosure of Kerzhensky Stare Nature Reserve)

The relevance of the study is determined by a high conservation value of activities on the reintroduction of forest reindeer (Rangifer tarandus tarandus) listed in the Red Data Book of Russia, in the territory of the Kerzhensky State Nature Reserve (Nizhny Novgorod Region). The paper aims to estimate the first results of studying the environmental-forming role of the forest reindeer in the forest bog complexes of the reserve (using the example of an adaptation enclosure). Our purpose is to assess the location character of reindeer trails in forest and bog habitats, the extent of grazing pressure on the vegetation in summer; to assess changes in the number of plants consumed by reindeer mainly in summer; to assess the foraging activity of reindeer in winter under condition of snow cover; to analyze possible consequences of reindeer impact on ecosystems. To solve these problems, vegetation mapping was carried out in the territory of an adaptation enclosure before the animals were placed there, reindeer trails were mapped to identify the features of their distribution throughout the enclosure, and the reindeer impact on ecosystems was estimated. It is shown that due to the environment-forming activity of the reindeer, the biological diversity of bog ecosystems increases, possible stagnation in forest succession are eliminated, and the fire hazard in lichen pine forests decreases.

Seasonally and Spatially Variable Organic Matter Contributions From Watershed, Marine Macrophyte, and Pelagic Sources to the Northeast Pacific Coastal Ocean Margin

Globally, coastal waters are considered biogeochemical hotspots because they receive, transform, and integrate materials and waters from both land and the open ocean. Extending from northern California to southeast Alaska, the Northeast Pacific Coastal Temperate Rainforest (NPCTR) region is no exception to this, and hosts a diversity of watershed types (old-growth rainforest, bog forest, glaciers), and tidal (sheltered, exposed) and pelagic marine (deep fjord, shallow estuary, well-mixed channel) environments. With large freshwater fluxes to the coastal ocean, cross-ecosystem connectivity in the NPCTR is expected to be high, but seasonally variable, with pulses in runoff from rainfall, snowmelt and glacial melt, and primary production associated with changes in ocean upwelling and incident light. However, the relative contribution of each ecosystem to surface ocean organic matter pools over time and space remains poorly constrained, despite their importance for the structure and function of coastal marine ecosystems. Here, we use a four-year dataset of particulate organic matter (POM) chemical composition (δ13C, δ15N, C:N ratio) to quantify the relative contributions of watershed materials via riverine inputs, marine phytoplankton, and macrophytes (macroalgae and seagrass) to surface waters (0-10 m) at 11 stations representing fjord, shallow non-fjord estuary, sheltered channel and well-mixed coastal environments at the heart of the NPCTR in British Columbia, Canada. Watershed, marine phytoplankton, and macrophyte contributions to surficial POM ranged between 5-78%, 22-88%, and 0.1-18%, respectively, and varied by season and station. Watershed inputs were the primary source of POM across all stations in winter and were important throughout the year within the fjord. Marine phytoplankton were the principal source of POM in spring and at all stations outside of the fjord through summer and autumn, while macrophyte contributions were greatest in summer. These results demonstrated high, but seasonally and spatially variable, connectivity between ecosystems that are often considered in isolation of one another and highlight the need to consider coastal waters as integrated land-ocean meta-ecosystems. Future work should investigate how heterogeneity in POM sources determines its fate in coastal ecosystems,and the relative importance of different basal organic matter sources for the marine food web.

Effect of the depositional environment on the formation of tar-rich coal: A case study in the northeastern Ordos Basin, China

Tar yield, as a basic evaluation index of tar-rich coal, is unclear to be affected by the depositional environment. In this work, the vertical variations in tar yield, macerals, and major/trace elements were investigated for highly volatile bituminous coal in the Ordos Basin, China, to analyse the effect of the depositional environment on the tar-rich coal distribution. The results show that the tar yield more than 7% (tar-rich coal) accounts for 70% in this formation, which formed in a depositional environment with a stable supply of terrestrial sediments, a warm and humid climate, and weakly reducing to reducing conditions. For the coal facies, all samples were distributed into two groups of coal facies, with the first group containing limnic, dry forest swamp, wet forest swamp and another group contains bog, forest bog. Moreover, limnic and bog with less woody tissue and a higher water table contribute to the higher tar yield of coal. Correspondingly, the vitrinite content and the gelation index (GI) were positively correlated with tar yield, and the tissue preservation index (TPI) and vegetation index (VI) were negatively correlated with tar yield. The inorganic composition, the ash yield, which is mainly composed of SiO2 and Al2O3, reduced the tar yield. CaO and MgO in small proportions promote the tar yield of coal due to catalytic effects. The relationship between tar yield and the parameters Sr/Ba, Sr/Cu, Cu/Zn, (Cu + Mo)/Zn, U/Th, Ni/Co, δU, Ce/La, δCe, and δEu are also discussed here. It was concluded that the paleoclimate had little effect on the tar yield, while the paleoreduction conditions had an obvious influence on the tar yield. The depositional environment with higher reduction and lower salinity conditions was conducive to the increase in tar yield of coal. This work aims to accurately identify and predict tar-rich coal based on its depositional environment, which provides guidance for its exploration and development.

High Blood Parasite Infection Rate and Low Fitness Suggest That Forest Water Bodies Comprise Ecological Traps for Pied Flycatchers

Blood parasites are considered to have strong negative effects on host fitness. Negative fitness consequences may be associated with proximity to areas where blood parasite vectors reproduce. This study tested for relationships between haemosporidian infection prevalence, parasitemia, and fitness parameters of breeding Pied Flycatchers (Ficedula hypoleuca) at different distances from forest water bodies. Prevalence and parasitemias (the intensity of infection) of haemosporidians and vector abundance generally decreased with increasing distance from forest lakes, streams, and bogs. Fledgling numbers were lower, and their condition was worse in the vicinity of water bodies, compared with those located one kilometer away from lakes and streams. At the beginning of the breeding season, adult body mass was not related to distance to the nearest water body, whereas at the end of the breeding season body mass was significantly lower closer to water bodies. Forest areas around water bodies may represent ecological traps for Pied Flycatchers. Installing nest boxes in the vicinity of forest water bodies creates unintended ecological traps that may have conservation implications.

Spontaneous regeneration of Collembola assemblages in a raised bog after human-induced disturbance

Peatlands in anthropogenically transformed landscapes play an important role in biodiversity conservation. Most Baltic raised bogs have been completely destroyed by drainage and peat extraction. Collembolan and plant assemblages from an old peat mine (post-excavation pits and dykes overgrown by pine trees) were compared to those of intact ombrotrophic raised bog habitats (open bog and bog-pine forest) 70 years after excavation cessation. The plant cover and collembolan structure in regenerating pits were similar to those of the assemblages in natural open raised bogs. Rare tyrphobiont and tyrphofilous Collembola species occurred in both habitats. The assemblages in open bog habitats differed significantly from those in natural pine bog forest and dykes overgrown by pine trees. The assemblages of the natural open raised bog and pine bog forest were the most diverse and included numerous highly specialized Collembola species. The assemblages occurring on wooded dykes were significantly different from those at other peatland sites and were more similar to those of upland pine forests. The analysis of environmental factors (determined by moss Ellenberg numbers) showed that moisture was the most important factor affecting Collembola occurrence in natural and disturbed habitats. The occurrence of moss species also had a significant influence on the species composition of the collembolan assemblages. Our study revealed that seventy years of spontaneous ecosystem regeneration after peat excavation have led to habitat restoration for peat bog mesofauna. These results have important implications for conservation and restoration planning in disturbed peatlands.

Cognettia sphagnetorum (Vejdovský, 1878) (Annelida, Clitellata, Enchytraeidae) in North America, confirmed with molecular support

Cognettia sphagnetorum (Vejdovský, 1878), a common inhabitant of forest soils and bogs in northern Europe, is a model organism in soil biology. We report the first documented occurrence of C. sphagnetorum in North America, based on DNA sequencing from a Sphagnum bog in western Washington, USA. Sequences were identical to that of worms from Sweden and the Czech Republic.

Old‐growth forest structure in a low‐productivity hypermaritime rainforest in coastal British Columbia, Canada

AbstractDendrochronological analyses were conducted across a gradient of productivity and soil drainage quality characterizing four vegetation types in a low‐productivity hypermaritime (perhumid) temperate rainforest on the Central Coast of British Columbia, Canada. We examined the structure, composition, and stand dynamics of trees growing in 400 m2 plots located in blanket bog, bog woodland, bog forest, and zonal forest vegetation types. We sampled over 2500 trees and 1500 seedlings and saplings and our dendrochronological reconstruction of six tree species revealed establishment ages extending to 660 A.D. (1350 yr). All forest plots contained numerous old trees (>250 yr) and the zonal forest and bog forest vegetation types contained significantly taller trees and also had the greatest amount of suppressed, shade‐tolerant tree species. The bog woodland vegetation type contained more seedlings and saplings than the other three vegetation types combined. The bog forest vegetation type had the highest density of dead standing trees (~530 per hectare). Blanket bogs contained an open structure with very few old trees (>250 yr). Significant differences in the ages of trees existed between forested vegetation types and the more open blanket bog vegetation type. Several trees exceeded 1000 yr in age and were situated in lower‐productivity bog forest and bog woodland sites. We found no evidence of widespread tree cohort establishment, indicating that small‐scale disturbances such as individual tree mortality and gap‐forming dynamics are likely the most frequent disturbance in the study area.

Conflicting portrayals of remaining old growth: the British Columbia case

Old growth is disappearing globally, with implications for biodiversity, forest resilience, and carbon storage; yet uncertainty remains about how much exists, partly because assessments stratify ecosystems differently, sometimes obscuring relevant patterns. This paper compares portrayals of British Columbia’s (BC) old-growth forest stratified in two ways: by biogeoclimatic variant, as per policy, and by relative site productivity. Our analyses confirm provincial government claims that about a quarter of BC’s forests are old growth but find that most of this area has low realized productivity, including subalpine and bog forests, and that less than 1% is highly productive old growth, growing large trees. Within biogeoclimatic variant, nearly half of high-productivity forest landscapes have less than 1% of the expected area of old forest. Low-productivity ecosystems are over-represented in protected forest. We suggest that the experiment of managing old growth solely by biogeoclimatic variant has failed and that current forest policy, in combination with timber harvesting priorities, does not maintain representative ecosystems, counter to the intent of both policy and international conventions. Stratifying old growth by relative productivity within biogeoclimatic variant seems an appropriate method to portray ecosystem representation, potentially increasing the probability of maintaining ecosystem resilience.

Tree species and microhabitat affect forest bog spider fauna

Peat bogs are among the most threatened habitats in Central Europe. They are characterized by stagnant water with low pH and lower nutrient content compared to the surrounding habitats. The flora and fauna of peat bogs comprised of many habitat specialist and rare species. We explored the differences in spider fauna of European spruce and Scots pine forests. Furthermore, we assessed the effect of microhabitat diversity in the bog forests of the Poiana Stampei peat bog complex, Bucovina, Romania. We collected numerous rare and cold-adapted species. .We found a strong effect of forest type, presumably due to the different microclimatic conditions of the forests. European spruce forests had lower species richness of ground-dwelling fauna than Scots pine forests; however, we found contradictory results for vegetation-dwelling species richness. Hummocks had a more positive effect on the ground-dwelling spiders of Scots pine than in European spruce forests, presumably due to the more open structure of sphagnum hummocks than ground level. However, this effect was negative for vegetation dwellers. The cold-adapted species with restricted ranges are vulnerable to climate change, and bogs may serve as important micro-refugia for them. Central European bogs are isolated and highly threatened by anthropogenic activities, such as drainage, peat extraction, and eutrophication. The deterioration habitat quality of peat bogs will result in a significant loss in the regional species pool of the Carpathians.

Historic and recent occurrences of Kievan nettle (Urtica kioviensis Rogow.) in Hungary

This paper presents occurrence data of Urtica kioviensis Rogow. in Hungary from the 20th century till today, based on a survey of six Hungarian public herbaria and the literature. Altogether 84 herbarium sheets from 9 counties, 83 literature records mentioned from 12 counties, and 57 flora mapping data were encountered. Based on these, we updated the distribution map of the species in Hungary. We found that the typical habitats of U. kioviensis in Hungary include marginal zones of bog forests, reeds, and old small watercourses. We report two newly discovered locations of the species in the Hanság area. Near Fehértó, in a peat-forming reed bordering a lake, approximately 150 plants were found, while in the vicinity of Dör, in a former open pit sand mine, approximately 300 plants were observed. The habitat at Dör is secondary, the current vegetation must be the result of progressive succession processes that started after the abandonment of sand mining. The integrity of Hungarian habitats has been threatened in recent decades by increasingly frequent climatic anomalies (mainly water shortages due to the lack of precipitation for long periods) and anthropogenic factors (fragmentation of biotopes, organic/inorganic substances washing into groundwater), which may cause a decrease in the number of plants. As a significant part of the distribution area of the species is located in Hungary, the protection of its populations and habitats is also of key importance.

Об инвазиях орнитохорных кустарников на особо охраняемых природных территориях Санкт-Петербурга и Ленинградской области

The research deals with recent invasions of bird-dispersed shrubs in specially protected natural reservations of St.Petersburg and Leningrad Region. The results of bird-dispersed woody species inventory in 5 partial nature reserves and nature sanctuaries of the area (See Fig. 1), based upon the extensive phytocoenological research data of 2014-2018, are given (See Table 1). Out of the adventive shrub species listed, the two most aggressive invaders were chosen according to their constancy and abundance in natural forest communities. These are Lonicera nigra in Komarovskiy Bereg [Komarovo Coast] Nature Sanctuary and Amelanchier spicata in Lisinskiy [Lisino] Partial Nature Reserve. For this purpose, distributions of these species are traced along with different forest types they invade, paying attention to species constancy and projective cover in different layers of forest communities (See Tables 2 and 4). Values of intralandscape species activeness, based upon the proper relevé sets, were also calculated for both aboriginal and adventitious plant species from different community types in each study area (See Tables 3 and 5). Lonicera nigra has never been detected as an invader before. It is presumably dispersed by robins, thrushes, and warblers, also by means of barochory and secondary hydrochory. The latter is proved by the occurrence of the oldest shrubs in riverine Norway spruce and Scots pine forests on the Littorine terrace of the Gulf of Finland within Komarovo Coast Nature Sanctuary. The results of secondary bird dispersal of this species are observed in sorrel spruce forests where the untypical low shrub layer is being formed (See Fig. 2). These plants are remote form brooks or drainage channels (See Table 2). L. nigra acts as one of the most active species in the sanctuary forest coenofloras studied (See Table 3). Nevertheless, floristic composition of these forest communities remains yet unchanged in its main features. The invasion of L. nigra in the sanctuary area was first mentioned in literature by NN Tzvelev in 2000 but it took place much earlier, as the ancestral plant specimens were likely to grow in a transplant nursery near the present-day sanctuary north-eastern border in the early XX-th century. According to Komarov Botanical Institute Herbarium (LE) data, the secondary area of L. nigra in Russia is restricted to several findings in the Karelian Isthmus. Amelanchier spicata, the June berry, listed among the most aggressive plant invaders in European Russia, is dispersed by thrushes along roads in forests and then invades sorrel and horsetail-peatmoss spruce and pine forests on southern-boreal watersheds in Lisino Reserve, often as a gap-filling species. It is less common and abundant in secondary birch and aspen forests. In contrast to Lonicera nigra, it is infrequent and never abundant in riverine forests (See Table 4), the fact probably explained by difference in prevailing bird distributor species. A. spicata is never found in feathermoss pine forests on fluvial-glacial sand as well as in dwarfshrub-peatmoss pine bog forests. The invasion of this species in the reserve area probably took place after 1984-1987 when the species was not registered in forest communities of the area according to the author’s personal observations. In 2017, the activeness of A. spicata is low in all the forest types it inhabits, being compared to that of the dominant aboriginal species (See Table 5). As follows from the correlation analysis results, no one of the discussed invaders affects the projective cover of any of the native plant species in both protected areas significantly. Speaking of Amelanchier spicata, it is in fact far less aggressive than in the more southern areas of Central and Southern Russia where the species transforms forest communities actively and affects aboriginal field- and ground-layer plants negatively, even as far as to the extinction of some of the latter, as it is well-known from the literature on the subject. We are just at the beginning of the invasion process in the forests of the Russian North-West yet. The invasion of both species studied is likely to be connected with the climate change processes. The research reveals that a neglected adventive species, persisting long within a given area, may also suddenly become an aggressive invader (the case of Lonicera nigra). The invasion of adventive shrubs into the paludified forest communities, including those of the boreal peatmoss spruce forests which served as etalons of floristic stability quite recently, is also alarming.

The hydraulic conductivity of peat with respect to scaling, botanical composition, and greenhouse gas transport: Mini-aquifer tests from the Red Lake Peatland, Minnesota

Hydraulic conductivity (K) is a key but problematic parameter in groundwater models particularly those that simulate flow in weak, readily deformable media, such as peat deposits. As a result, K represents a critical source of error in models that couple hydrological processes with the carbon balance of peatlands, a globally important source for greenhouse gases. We therefore conducted mini-aquifer tests on two mesoscale bog landforms within the large 1300 km2 Red Lake Peatland of northern Minnesota. These tests offer the dual advantage of determining the fine-scale distribution of K within a large (>900 m3) model domain. In addition, the stress created by a 24 h pumping operation should be capable of mobilizing pools of biogenic gases thoughout a deep peat deposit. The pumping results were monitored by 24 to 38 wells in order to calibrate a 3D finite-volume groundwater model with the aid of PEST (Parameter Estimation Analysis). High K values were determined at a Bog Forest (10−5 to 10−6 m s−1) and Bog Lawn (10−3 to 10−4 m s−1) sites, throughout their deep (>4 m) peat profiles. These tests also detected vertically continuous zones of unexpectedly high or low K values in contrast to the horizontal bedding planes and increasing degree of decomposition with depth. The vertical K zones are suggestive of three different modes of bubble transport that either locally dilate or partially block the peat pores. In addition, the tests provided new insights on a conceptual model linking K to the development of all large (>20 km2) forested bog complexes in mid-continental boreal North America.

Shrub influences on seedling performance when restoring the slow‐growing conifer Pilgerodendron uviferum in southern bog forests

Forest restoration is most efficient if it can take advantage of facilitative interactions between established vegetation and planted trees. However, positive and negative interactions have been identified in a number of plant communities. After centuries of anthropogenic fires, forest recovery has been extremely slow in southern bog forests previously dominated by the slow‐growing and vulnerable conifer Pilgerodendron uviferum on Chiloé Island, Chile. Today, the landscape is dominated by secondary shrublands with scattered patches of Sphagnum moss and limited natural tree regeneration. We hypothesized that the retention of secondary shrubs facilitates the early performance of P. uviferum restoration plantings by providing better microsite conditions. To test this hypothesis, we compared the response of seedlings planted on sites prepared at two levels of intervention: after shrubs had been removed or where shrubs were retained. Shrub retention showed a nurse‐plant effect on P. uviferum seedlings 4 years after planting, which resulted in reduced physiological stress (measured as Fv/Fm) for seedlings, as well as reduced browsing. Consequently, the seedlings growing in areas with shrub retention had larger height increment and higher vitality than those in areas where shrubs had been removed. Thus, the more open micro‐site conditions created by shrub removal resulted in generally poorer seedling performance, although seedling mortality—which was low overall (approximately 2–4%)—showed no significant difference between the two levels of intervention. These findings have direct implications for the restoration of slow‐growing conifers that can tolerate extreme wet conditions in highly degraded forests.

Succession of Tree Species on Drained Bogs in ‘Brzozowe Bagno koło Czaplinka’ Nature Reserve, NW Poland

Succession of woody species on bogs is a process limited by high groundwater table. In the case of drainage, this limiting factor becomes suppressed and succession may accelerate. The aim of the study was to assess the development of tree stands on a raised bog influenced by drainage and wild fire and to assess the dynamics of woody species encroachment. The study was conducted in the ‘Brzozowe Bagno kolo Czaplinka’ nature reserve in NW Poland, where the originally unforested peat bog was influenced by peat harvesting, drainage and fire over 100 years. The diameter at breast height of tree species and natural regeneration were assessed. Six types of tree stands were distinguished: open bog, bog forest with Pinus sylvestris, early-, mid- and late-successional bog forest with Betula pubescens and pioneer forest with Populus tremula, which occurred in the post-fire sites. After ca 100 years of human activity on an unforested peat bog, dense forest emerged on almost all of the study area. Drainage and wildfire influenced tree stand structure. The course of succession most probably goes from open bog to pine bog forest and early-, mid- and late-successional birch forests. Regeneration of B. pubescens is a crucial phase of woody species succession, because this species creates suitable conditions for growth of late-successional species.

Seasonal and ecohydrological regulation of active microbial populations involved in DOC, CO2, and CH4 fluxes in temperate rainforest soil

The Pacific coastal temperate rainforest (PCTR) is a global hot-spot for carbon cycling and export. Yet the influence of microorganisms on carbon cycling processes in PCTR soil is poorly characterized. We developed and tested a conceptual model of seasonal microbial carbon cycling in PCTR soil through integration of geochemistry, micro-meteorology, and eukaryotic and prokaryotic ribosomal amplicon (rRNA) sequencing from 216 soil DNA and RNA libraries. Soil moisture and pH increased during the wet season, with significant correlation to net CO2 flux in peat bog and net CH4 flux in bog forest soil. Fungal succession in these sites was characterized by the apparent turnover of Archaeorhizomycetes phylotypes accounting for 41% of ITS libraries. Anaerobic prokaryotes, including Syntrophobacteraceae and Methanomicrobia increased in rRNA libraries during the wet season. Putatively active populations of these phylotypes and their biogeochemical marker genes for sulfate and CH4 cycling, respectively, were positively correlated following rRNA and metatranscriptomic network analysis. The latter phylotype was positively correlated to CH4 fluxes (r = 0.46, p < 0.0001). Phylotype functional assignments were supported by metatranscriptomic analysis. We propose that active microbial populations respond primarily to changes in hydrology, pH, and nutrient availability. The increased microbial carbon export observed over winter may have ramifications for climate–soil feedbacks in the PCTR.

Persistent carbon sink at a boreal drained bog forest

Abstract. Drainage of peatlands is expected to turn these ecosystems into carbon sources to the atmosphere. We measured carbon dynamics of a drained forested peatland in southern Finland over 4 years, including one with severe drought during growing season. Net ecosystem exchange (NEE) of carbon dioxide (CO2) was measured with the eddy covariance method from a mast above the forest. Soil and forest floor CO2 and methane (CH4) fluxes were measured from the strips and from ditches with closed chambers. Biomass and litter production were sampled, and soil subsidence was measured by repeated levellings of the soil surface. The drained peatland ecosystem was a strong sink of carbon dioxide in all studied years. Soil CO2 balance was estimated by subtracting the carbon sink of the growing tree stand from NEE, and it showed that the soil itself was a carbon sink as well. A drought period in one summer significantly decreased the sink through decreased gross primary production. Drought also decreased ecosystem respiration. The site was a small sink for CH4, even when emissions from ditches were taken into account. Despite the continuous carbon sink, peat surface subsided slightly during the 10-year measurement period, which was probably mainly due to compaction of peat. It is concluded that even 50 years after drainage this peatland site acted as a soil C sink due to relatively small changes in the water table and in plant community structure compared to similar undrained sites, and the significantly increased tree stand growth and litter production. Although the site is currently a soil C sink, simulation studies with process models are needed to test whether such sites could remain C sinks when managed for forestry over several tree-stand rotations.