Bog Ecosystems Research Articles

Chronic atmospheric reactive N deposition has breached the N sink capacity of a northern ombrotrophic peatbog increasing the gaseous and fluvial N losses

Peatlands play an important role in modulating the climate, mainly through sequestration of carbon dioxide into peat carbon, which depends on the availability of reactive nitrogen (Nr) to mosses. Atmospheric Nr deposition in the UK has been above the critical load for functional and structural changes to peatland mosses, thus threatening to accelerate their succession by vascular plants and increasing the possibility of Nr export to downstream ecosystems. The N balance of peatlands has received comparatively little attention, mainly due to the difficulty in measuring gaseous N losses as well as the Nr inputs due to biological nitrogen fixation (BNF). In this study we have estimated the mean annual N balance of an ombrotrophic bog (Migneint, North Wales) by measuring in situ N2 + N2O gaseous fluxes and also BNF in peat and mosses. Fluvial N export was monitored through a continuous record of DON flux, while atmospheric N deposition was modelled on a 5 × 5 km grid. The mean annual N mass balance was slightly positive (0.7 ± 4.1 kg N ha−1 y−1) and varied interannually indicating the fragile status of this bog ecosystem that has reached N saturation and is prone to becoming a net N source. Gaseous N losses were a major N output term accounting for 70% of the N inputs, mainly in the form of the inert N2 gas, thus providing partial mitigation to the adverse effects of chronic Nr enrichment. BNF was suppressed by 69%, compared to rates in pristine bogs, but was still active, contributing ~2% of the N inputs. The long-term peat N storage rate (8.4 ± 0.8 kg N ha−1 y−1) cannot be met by the measured N mass balance, showing that the bog catchment is losing more N than it can store due its saturated status.

Mapping the Groundwater Level and Soil Moisture of a Montane Peat Bog Using UAV Monitoring and Machine Learning

One of the best preconditions for the sufficient monitoring of peat bog ecosystems is the collection, processing, and analysis of unique spatial data to understand peat bog dynamics. Over two seasons, we sampled groundwater level (GWL) and soil moisture (SM) ground truth data at two diverse locations at the Rokytka Peat bog within the Sumava Mountains, Czechia. These data served as reference data and were modeled with a suite of potential variables derived from digital surface models (DSMs) and RGB, multispectral, and thermal orthoimages reflecting topomorphometry, vegetation, and surface temperature information generated from drone mapping. We used 34 predictors to feed the random forest (RF) algorithm. The predictor selection, hyperparameter tuning, and performance assessment were performed with the target-oriented leave-location-out (LLO) spatial cross-validation (CV) strategy combined with forward feature selection (FFS) to avoid overfitting and to predict on unknown locations. The spatial CV performance statistics showed low (R2 = 0.12) to high (R2 = 0.78) model predictions. The predictor importance was used for model interpretation, where temperature had strong impact on GWL and SM, and we found significant contributions of other predictors, such as Normalized Difference Vegetation Index (NDVI), Normalized Difference Index (NDI), Enhanced Red-Green-Blue Vegetation Index (ERGBVE), Shape Index (SHP), Green Leaf Index (GLI), Brightness Index (BI), Coloration Index (CI), Redness Index (RI), Primary Colours Hue Index (HI), Overall Hue Index (HUE), SAGA Wetness Index (TWI), Plan Curvature (PlnCurv), Topographic Position Index (TPI), and Vector Ruggedness Measure (VRM). Additionally, we estimated the area of applicability (AOA) by presenting maps where the prediction model yielded high-quality results and where predictions were highly uncertain because machine learning (ML) models make predictions far beyond sampling locations without sampling data with no knowledge about these environments. The AOA method is well suited and unique for planning and decision-making about the best sampling strategy, most notably with limited data.

Новый подход к оценке площади поверхности хвои пихты сибирской

Новый подход к оценке площади поверхности хвои пихты сибирской

Пигментный состав Sphagnum fuscum заболоченных территорий в условиях техногенного воздействия

Oligotrophic bogs prevail among wetlands in the mainland of the North of Russia. The study of the moss cover response to the increase in anthropogenic load makes it possible to reveal a shift in the ecological balance of bog ecosystems. The goаl of the research is to reveal changes in the pigment apparatus of the moss cover under drainage, road construction and mining operation as in the case of the Arkhangelsk region. Sphagnum fuscum (Schimp.) H. Klinggr. was used as the main object for studying the pigment composition of the photosynthetic apparatus. A change in the pigment composition during the drainage of bogs was found when comparing the pigments of S. fuscum moss on the undisturbed Ilas bog massif and the drained bog massif “Ovechye”; the content of carotenoids decreases and the content of chlorophyll a increases. The influence of the traffic load was studied in an open wetland of the Mezen district, where there is no tree-shrub layer. Succession of dominant species is observed in the moss-lichen layer of the bog in the immediate vicinity of the road (34 m); the projective cover of sphagnum mosses decreases to less than 10 %, and brie mosses emerge as dominants. The content of all analyzed pigments in moss samples increases with the distance from unpaved roads, especially the content of chlorophylls (>5 times at a distance of 100 m and more). As an example of the anthropogenic impact of a mining enter prise, we used terricones of the Lomonosov Mining and Processing Plant, PJSC Severalmaz, from which aeolian transport of dust particles of rocks containing saponite occurs. Near the pollution source, the content of total moss pigments is noticeably lower than in the area protected by a forest belt. A decrease in the proportion of chlorophylls a and b with a slight increase in the content of carotenoids was found in the pigment complex. The changes are due to the transfer of saponite; a clay mineral that actively absorbs water. The increased moisture provides favorable conditions for the moss vegetation, which mitigates the negative effect of pollutants on the pigment apparatus of plants. Overall, pigments content change represents plants adaptation to the adverse impacts and anthropogenic pressing.

Modeling the temperature and humidity conditions of mineral soils in an active layer model taking into account in depth changes in the thermodynamic properties of the soil

The thermal regimes of peat and mineral soils differ significantly. Peat soils are characterized by the presence of a surface peat horizon, which is replaced by organogenic rock. The total thickness of the peat layer can reach several meters. The peat strata is a complex organomineral system with specific properties: high water content and porosity, the content of a large amount of little decomposed organic. For the correct modeling of this type of soil, a transition was made from the approach of modeling heat and moisture transfer in a porous medium with averaged thermodynamic characteristics (porosity, density, hydraulic conductivity …), to modeling heat and moisture transfer for each of the identified soil types with individual properties. In addition, in the modified model, all constants describing the thermodynamic properties of the soil are functions of depth. This made it possible to model soils with a complex soil profile, for example, bog ecosystems (peat deposit and a layer of mineral soil under it). To calculate the thermophysical characteristics of soils, the measured volumetric content of organic matter, mineral particles of different sizes, and soil porosity at all depths were used. Calculations based on the model of the active layer showed that within the framework of the approach used it is possible to correctly reproduce heat and moisture transfer in both mineral and organic soils without adding any runoff-related parameterizations, but using relevant thermophysical characteristics of the soil.

Plant resistome profiling in evolutionary old bog vegetation provides new clues to understand emergence of multi-resistance

The expanding antibiotic resistance crisis calls for a more in depth understanding of the importance of antimicrobial resistance genes (ARGs) in pristine environments. We, therefore, studied the microbiome associated with Sphagnum moss forming the main vegetation in undomesticated, evolutionary old bog ecosystems. In our complementary analysis of culture collections, metagenomic data and a fosmid library from different geographic sites in Europe, we identified a low abundant but highly diverse pool of resistance determinants, which targets an unexpectedly broad range of 29 antibiotics including natural and synthetic compounds. This derives both, from the extraordinarily high abundance of efflux pumps (up to 96%), and the unexpectedly versatile set of ARGs underlying all major resistance mechanisms. Multi-resistance was frequently observed among bacterial isolates, e.g. in Serratia, Rouxiella, Pandoraea, Paraburkholderia and Pseudomonas. In a search for novel ARGs, we identified the new class A β-lactamase Mm3. The native Sphagnum resistome comprising a highly diversified and partially novel set of ARGs contributes to the bog ecosystem´s plasticity. Our results reinforce the ecological link between natural and clinically relevant resistomes and thereby shed light onto this link from the aspect of pristine plants. Moreover, they underline that diverse resistomes are an intrinsic characteristic of plant-associated microbial communities, they naturally harbour many resistances including genes with potential clinical relevance.

Nutrient addition increases rotifer abundance and diversity in a temperate bog

Rotifers are among the smallest metazoan animals living in lakes, ponds, rivers and in interstitial water within Sphagnum mats. When in sufficient numbers they are capable of regenerating large amounts of nitrogen (N) as NO3 and NH4 and phosphorus (P) as PO4; all of these nutrients are immediately available to bog plants. The ecological role of rotifers in bog ecosystems has been recognized at both local and global scales, but the effect of N and P addition on rotifers in bogs remains unknown. Here we present data on the influence of N and P addition on rotifers at a temperate Canadian bog dominated by Sphagnum mosses. We found that rotifer species abundance and diversity were significantly higher in surficial pore water after long-term exposure to increased N and P addition than in the control. A change in plant species distribution and increased rotifer abundance may partly explain the faster decomposition rates, jeopardizing the carbon sink capacity of bogs.

Alkaline air: changing perspectives on nitrogen and air pollution in an ammonia-rich world.

Ammonia and ammonium have received less attention than other forms of air pollution, with limited progress in controlling emissions at UK, European and global scales. By contrast, these compounds have been of significant past interest to science and society, the recollection of which can inform future strategies. Sal ammoniac (nūshādir, nao sha) is found to have been extremely valuable in long-distance trade (ca AD 600–1150) from Egypt and China, where 6–8 kg N could purchase a human life, while air pollution associated with nūshādir collection was attributed to this nitrogen form. Ammonia was one of the keys to alchemy—seen as an early experimental mesocosm to understand the world—and later became of interest as ‘alkaline air’ within the eighteenth century development of pneumatic chemistry. The same economic, chemical and environmental properties are found to make ammonia and ammonium of huge relevance today. Successful control of acidifying SO2 and NOx emissions leaves atmospheric NH3 in excess in many areas, contributing to particulate matter (PM2.5) formation, while leading to a new significance of alkaline air, with adverse impacts on natural ecosystems. Investigations of epiphytic lichens and bog ecosystems show how the alkalinity effect of NH3 may explain its having three to five times the adverse effect of ammonium and nitrate, respectively. It is concluded that future air pollution policy should no longer neglect ammonia. Progress is likely to be mobilized by emphasizing the lost economic value of global N emissions ($200 billion yr−1), as part of developing the circular economy for sustainable nitrogen management.This article is part of a discussion meeting issue ‘Air quality, past present and future’.

Reconstruction of Bacterial Metagenome-Assembled Genome Sequences from Alpine Bog Vegetation.

Bacteria are essential constituents of bog ecosystems. Here, we report 44 bacterial genome sequences reconstructed from metagenomes sampled across 12 plant species representing Alpine bog vegetation. This resource will facilitate further exploration of the genetic potential of these bacteria and allow researchers to refine their ecological roles in association with their plant hosts.

УСЛОВИЯ ТРАНСФОРМАЦИИ КОММУНАЛЬНО-БЫТОВЫХ СТОЧНЫХ ВОД В БОЛОТНЫХ ЭКОСИСТЕМАХ (НА ПРИМЕРЕ ОБСКОГО БОЛОТА, ЗАПАДНАЯ СИБИРЬ)

Актуальность. Проблема охраны и использования болот является весьма актуальной во всем мире, в том числе в Западной Сибири, на территории которой добывается значительная часть углеводородного сырья в Российской Федерации, что сопровождается изменением окружающей среды, в том числе и болотных экосистем. В свою очередь, это определяет необходимость разработки методологии и технологий природоохранных мероприятий на болотах, подвергающихся антропогенному воздействию. В рамках такой методологии требуется достоверная оценка изменений состояния болотной экосистемы под влиянием поступления веществ антропогенного происхождения. Цель: анализ и обоснование условий трансформации коммунально-бытовых сточных вод в низинном болоте на примере типичного для Западной Сибири евтрофного Обского болота. Методы. Химический и микробиологический составы вод и торфов исследовались в Проблемной научно-исследовательской лаборатории гидрогеохимии (ТПУ), зарегистрированной в Системе аналитических лабораторий Госстандарта России. Для проведения полного химического анализа использовались традиционные методы. Микробиологический анализ производили после отбора проб, как правило, в течение суток. Доставка проб в лабораторию осуществлялась в сумке-холодильнике. Для выявления микроорганизмов использовали жидкие и твердые элективные питательные среды. Микрокомпонентный состав определялся при помощи масс-спектрометрического метода с индуктивно-связанной плазмой (ICP-MS). Структурно-групповой состав растворенных органических веществ изучался методом хромато-масс-спектрометрии в лаборатории разработки месторождений нефти и газа (ТПУ). Для изучения гидрогеохимических процессов применялись статистические методы и математическое моделирование. Результаты и выводы. Установлено, что болотные воды относительно ПДК характеризуются повышенными содержаниями органических веществ, продуктов их трансформации, а также некоторых химических элементов, с которыми органические вещества способны образовывать комплексы. Среди растворенных органических соединений в болотных водах доминируют сложные эфиры, карбоновые кислоты, которые способствуют не только накоплению некоторых элементов (Ni, Ba) в водах, но и развитию микроорганизмов. Показано, что накопление веществ, поступающих с коммунально-бытовыми сточными водами с. Мельниково, происходит в основном на границе деятельного и инертного горизонтов торфяной залежи. Показано, что сброс коммунально-бытовых сточных вод в болото (с. Мельниково) не приводит к существенному изменению химического состава болотных вод, а антропогенное воздействие лимитируется микробиологическими и геохимическими условиями в болоте. На основе полученных данных предложено скорректировать природоохранные мероприятия, ограничивающие рост заболоченности территорий за счет увеличения лесных угодий вследствие осушительных мелиораций и дополнительного внесения соединений азота и кальция, входящих в состав сточных вод жилищно-коммунального хозяйства и нефтегазодобывающего комплекса.

Mercury exposure in songbird communities within Sphagnum bog and upland forest ecosystems in the Adirondack Park (New York, USA).

Mercury (Hg) is a potent neurotoxin that biomagnifies within both aquatic and terrestrial food webs resulting in adverse physiological and reproductive effects on impacted wildlife populations, including songbird communities. Due to reducing conditions, wetland ecosystems promote the formation of methylmercury. Regional studies have documented elevated blood mercury concentrations in songbird species within these habitat types. The overall goal of this research was to examine spatial and seasonal patterns of Hg exposure for targeted songbird species within Sphagnum bog wetland systems and compare these patterns with adjacent upland forests in the Adirondack Park of New York State. Project sampling was conducted at study plots within four Sphagnum bog and associated upland forest sites from May - August during the 2008, 2009, and 2011 field seasons. The overall results documented: (1) blood Hg concentrations were elevated in songbird species inhabiting Sphagnum bog habitats as compared to nearby upland forest species; (2) target species within each habitat type exhibited consistent species-level patterns in blood Hg concentrations at each study site; and (3) no seasonal change in blood Hg concentrations within Sphagnum bog habitats was documented, but an increasing, followed by a decreasing seasonal pattern in mercury exposure was detected for upland forest species. Habitat type was demonstrated to influence avian Hg exposure levels. Moreover, Sphagnum bog ecosystems may be contributing to elevated Hg concentrations in biota within the surrounding environment. Seasonal patterns for blood Hg concentrations were found to vary between habitat type and are likely related to a combination of variables including habitat-driven Hg concentrations in prey items, seasonal dietary shifts, and annual molting cycles. This project emphasizes the importance of prioritizing future research efforts within identified high Hg habitat types, specifically wetland systems, to better characterize associated avian exposure levels, estimate the spatial extent of wetland systems on the surrounding environment, and identify locations of potential biological hotspots across the Adirondack Park.

МОДЕЛИРОВАНИЕ СЕЗОННОГО ХОДА УГЛЕРОДНОГО ОБМЕНА В БОЛОТНЫХ ЭКОСИСТЕМАХ

The paper summarizes the results of expeditionary studies to study biological productivity, carbon dioxide fluxes in the bog ecosystems of the Central Taiga of Western Siberia. The paper summarizes the results of expeditionary studies to study biological productivity, carbon dioxide fluxes in the bog ecosystems of the Central Taiga of Western Siberia. Measurements of carbon dioxide fluxes were carried out from July 7 to July 14, 2019 at six observation sites located on the territory of typical wetland ecosystems of eutrophic, mesotrophic and oligotrophic types, taking into account the diversity of microlandscapes. Automatic measurements of the CO2 fluxes were carried out using the Licor LI-8100A soil respiration system. To extend the obtained observation data to other periods and to calculate the annual carbon balance of the ecosystem, a net ecosystem exchange (NEE) model was proposed, and the net fluxes of greenhouse gases for the growing season were calculated. The model uses air temperature and incoming photosynthetically active radiation as explanatory factors for gross primary production and ecosystem respiration. The model was calibrated in accordance with field measurements of carbon dioxide fluxes. For each observation site, six parameters were determined: two parameters for the photosynthesis model, two parameters for the respiration model and two for the biomass growth model. As a result of calculations for the period from May to October 2019, time series of fluxes of carbon dioxide absorption by vegetation during photosynthesis, CO2 release during ecosystem respiration, and the resulting flux – net ecosystem exchange were obtained. In the annual course, an increase in the intensity of photosynthesis during the daytime is associated with both the annual course of solar radiation and the accumulation of plant biomass. It was found that the net ecosystem exchange varies more strongly than its components. The NEE for ecosystems without vegetation is always positive. NEE is negative for the hollow and the open transit mesotrophic fen on any day of the growing season. Other ecosystems show both positive and negative daily mean fluxes. Wetland ecosystems with large biomass storages have significant fluxes (more than 1500 g CO2 / m2 ) associated with photosynthesis, but they also have a large expenditure component of carbon exchange (750–2200 g / m2 ). As a result, it was found that the greatest total absorption of carbon dioxide is observed in the mesotrophic sedge- menyanthes fen (1062 g / m2 ) and in the low ryam, taking into account the tree layer (603 g / m2 ). Other wetlands accumulate 244–466 g / m2 from the atmosphere during the growing season.

CONCENTRATION OF BIOGENIC TRACE ELEMENTS (Zn, Co, Cr), ALKALINE (Rb, Cs), ALKALINE-EARTH (Sr, Ba) METALS AND LANTHANUM IN THE EUTROPHIC PEAT BOG ECOSYSTEM

Peats and marsh waters of the peat bog eutrophic ecosystem (Tomsk region) for the content of trace elements have been studied. The peat deposit is composed of lowland peats of grass type predominantly. The deposit average depth is about 3 meters. Samples of several observation points, which differ in botanical composition and hydrothermal conditions of occurrence were analyzed. The concentration of biogenic (Zn, Co, Cr), alkaline (Rb, Cs), alkaline earth (Sr, Ba) and rare earth (Hf, La) metals in peat and marsh waters has been determined by the method of neutron activation analysis. It was shown that the amount of various elements in peat is determined by regional characteristics and botanical composition. From comparative elements concentration analysis, it has been found that concentration of metals varies identically depending on the depth of the peat bog, which indicates typical conditions for the accumulation of these elements. As a result of the research was founded high content of the Ba and Sr in peats of all observation points. It has been established that the peat of native section 3 is enriched with all studied metals Zn, Cr, Sr, Ba in comparison with peats of the first and the second observation points. Besides, under the conditions of this ecosystem cobalt, rubidium and lanthanum were accumulated in peats. The average concentration of trace elements in the studied peat bog ecosystem is comparable to the average values of this region. We have found that samples of marsh water are enriched with the biogenic zinc. Among rare metals, such elements as strontium and barium are the most abundant in marsh water, what correlates with the largest content of Zn, Sr and Ba in the studied peats. Light Rb and Sr ions transfer from peat to swamp waters in greater amount than heavier Cs and Ba ions. Strontium enters and migrates intensively to the swamp waters of all three observation points.

Ecotypic differentiation, hybridization and clonality facilitate the persistence of a cold-adapted sedge in European bogs

AbstractRecent research has shown that many cold-adapted species survived the last glacial maximum (LGM) in northern refugia. Whether this evolutionary history has had consequences for their genetic diversity and adaptive potential remains unknown. We sampled 14 populations of Carex limosa, a sedge specialized to bog ecosystems, along a latitudinal gradient from its Scandinavian core to the southern lowland range-margin in Germany. Using microsatellite and experimental common-garden data, we evaluated the impacts of global climate change along this gradient and assessed the conservation status of the southern marginal populations. Microsatellite data revealed two highly distinct genetic groups and hybrid individuals. In our common-garden experiment, the two groups showed divergent responses to increased nitrogen/phosphorus (N/P) availability, suggesting ecotypic differentiation. Each group formed genetically uniform populations at both northern and southern sampling areas. Mixed populations occurred throughout our sampling area, an area that was entirely glaciated during the LGM. The fragmented distribution implies allopatric divergence at geographically separated refugia that putatively differed in N/P availability. Molecular data and an observed low hybrid fecundity indicate the importance of clonal reproduction for hybrid populations. At the southern range-margin, however, all populations showed effects of clonality, lowered fecundity and low competitiveness, suggesting abiotic and biotic constraints to population persistence.

Verification of the INM RAS-MSU land surface scheme using temperature and moisture measurements in peat and mineral soils

Detailed monitoring of soil temperature provides a unique experimental material for studying the complex processes of heat transfer from the surface layer of the atmosphere to the soil. According to air temperature monitoring data, within each of the key areas there are no significant differences between the data of the observation sites. According to annual (2011-2018) observations of soil temperature, it has been found that the microclimatic properties of bog ecosystems clearly manifest themselves in the characteristics of daily and annual variations of soil temperature. The thickness of the seasonally frozen layer at all sites is 20-60 cm, and maximum freezing of the peat layer is reached in February-March. There is evidence of degradation of the seasonally frozen layer that occurs both from above and from below. It has been found that similar bog ecosystems in different bog massifs may have significantly different temperature regimes. The peat stratum of northern bogs may be both warmer (in winter) and colder (in summer), in comparison with some bogs located 520 km to the south and 860 km to the west.

Transformation of Arctic ecosystems under impact of open-pit extraction of mineral resources

The article considers the influence of open-pit mining of diamonds on the state of Arctic ecosystems outside of the zone of the direct impact of the enterprise. To assess changes in natural complexes, a retrospective analysis was carried out on the basis of the data from social surveys of the local population using adapted methodological approaches and comparing descriptions of the biodiversity of aquatic macrophytes made in 1969-1970 and 2018. The comprehensive studies of peat soils and the laboratory modeling of the flow of the saponite into the watercourse were carried out, in order to understand the possible ways of the impact of diamond mining on natural complexes. The shallowing of the river, the change in the nature of soils in the lower reaches of the river, the crowding out a number of native species of aquatic plants by invasive macrophytes were educed. It is shown that saponite interacts with components of bog ecosystems, changes its physicochemical properties and forms intermolecular associates with dissolved organic matter. This contributes to the transport of mineral particles over long distances, to its accumulation in bottom sediments, and to the prolonged desorption, which creates favorable conditions for the introduction of invasive species.

Temperature regimes of drained and natural peatlands in arid and water-logged years

The results of a study of temperature regimes of oligotrophic bog ecosystems in the south taiga zone of Western Siberia in 2011-2018 are presented. Soil temperature regimes are studied using an atmospheric-soil measuring complex at several depths from the surface to 320 cm. Waterlogged (excessive moisture) and arid years are determined by calculating the aridity index of Ped (S). The years with most severe hydrothermal conditions over the past 10 years have been found to be 2012 and 2018. In 2012, a drought is observed from April to July, with extreme aridity in June (S = 4.07), and a severe drought in July (S = 3.42). It has been found that the native treed bog in a wet year warms up much more than in a dry year. On average, the temperature values are higher by 1.5°C for all depths. On average, the drained bog is colder than the natural one at depths up to 80 cm by 4.0°C, and at depths of 120 to 240 cm by 2.5°C. The maximum temperature differences of the native bog during the warm period of a waterlogged (excessive moisture) year are 8.0°C (at a depth of 60 cm) and, at depths from 80 to 240 cm they are reduced from 5.0 to 2.5°C. The maximum differences of the native bog in the waterlogged (excessive moisture) 2018 and dry 2012 in the warm period at a depth of 60 cm are 8.0-9.0°C, and from 80 to 240 cm they are reduced from 6.0 to 1.5°C.

Peatland degradation: The relationship between raised bog hydrology and normalized difference vegetation index

AbstractPeatlands are recognized as important landscape elements and their disturbance, followed by the loss of their ecohydrological functions, leads to falling water tables and degradation. Sometimes, the shortage of hydrological monitoring data impedes the detection of degrading peatland areas. The application of cost‐effective remote sensing methods for assessment of humidity conditions permits monitoring of a large area and longer periods of time. Therefore, in this study, we assessed the links between hydrological parameters and the normalized difference vegetation index (NDVI) as well as identifying spatio‐temporal patterns in the condition of raised bog vegetation, according to NDVI, in the Čepkeliai raised bog, a semipristine peatland in south‐eastern Lithuania. Time series of NDVI (2000–2018) were obtained from the moderate resolution imaging spectroradiometer and compared with field measurements. A strong positive correlation between NDVI and water table depth was found. Moderate (for the whole raised bog) and strong (for control subbasin) positive correlations between NDVIavg and annual minimum flow over 30 and 7 days were found. This confirms that NDVI could be treated as an appropriate indicator, showing the degradation processes of the raised bog ecosystem and could be applied in its management. Analysis of the interannual NDVIavg variation confirmed the prevalence of stable favourable conditions during the growing season with a slight decrease in NDVImax over last 4 years. Meanwhile, analysis of spatial NDVI variation revealed obvious spatial patterns where possible degradation processes tend to appear.

DNA metabarcoding reveals modern and past eukaryotic communities in a high-mountain peat bog system

Peat bogs located in high mountains are suitable places to study local environmental responses to climate variability. These ecosystems host a large number of eukaryotes with diverse taxonomic and functional diversity. We carried out a metabarcoding study using universal 18S and COI markers to explore the composition of past and present eukaryotic communities of a Pyrenean peat bog ecosystem. We assessed the molecular biodiversity of four different moss micro-habitats along a flood gradient in the lentic Bassa Nera system (Central Pyrenees). Five samples collected from different sediment depths at the same study site were also analysed, to test the suitability of these universal markers for studying paleoecological communities recovered from ancient DNA and to compare the detected DNA sequences to those obtained from the modern community. We also compared the information provided by the sedimentary DNA to the reconstruction from environmental proxies such as pollen and macro-remains from the same record. We successfully amplified ancient DNA with both universal markers from all sediment samples, including the deepest one (~ 10,000 years old). Most of the metabarcoding reads obtained from sediment samples, however, were assigned to living edaphic organisms and only a small fraction of those reads was considered to be derived from paleoecological communities. Inferences from ancient sedimentary DNA were complementary to the reconstruction based on pollen and macro-remains, and the combined records reveal more detailed information. This molecular study yielded promising findings regarding the diversity of modern eukaryotic peat bog communities. Nevertheless, even though information about past communities could be retrieved from sediment samples, preferential amplification of DNA from living communities is a caveat for the use of universal metabarcoding markers in paleoecology.

Cushion bogs are stronger carbon dioxide net sinks than moss-dominated bogs as revealed by eddy covariance measurements on Tierra del Fuego, Argentina

Abstract. The near-pristine bog ecosystems of Tierra del Fuego in southernmost Patagonia have so far not been studied in terms of their current carbon dioxide (CO2) sink strength. CO2 flux data from Southern Hemisphere peatlands are scarce in general. In this study, we present CO2 net ecosystem exchange (NEE) fluxes from two Fuegian bog ecosystems with contrasting vegetation communities. One site is located in a glaciogenic valley and developed as a peat moss-dominated raised bog, and the other site is a vascular plant-dominated cushion bog located at the coast of the Beagle Channel. We measured NEE fluxes with two identical eddy covariance (EC) setups at both sites for more than 2 years. With the EC method, we were able to observe NEE fluxes on an ecosystem level and at high temporal resolution. Using a mechanistic modeling approach, we estimated daily NEE models to gap fill and partition the half-hourly net CO2 fluxes into components related to photosynthetic uptake (gross primary production, GPP) and to total ecosystem respiration (TER). We found a larger relative variability of annual NEE sums between both years at the moss-dominated site. A warm and dry first year led to comparably high TER sums. Photosynthesis was also promoted by warmer conditions but less strongly than TER with respect to absolute and relative GPP changes. The annual NEE carbon (C) uptake was more than 3 times smaller in the warm year. Close to the sea at the cushion bog site, the mean temperature difference between both observed years was less pronounced, and TER stayed on similar levels. A higher amount of available radiation in the second observed year led to an increase in GPP (5 %) and NEE (35 %) C uptake. The average annual NEE-C uptake of the cushion bog (-122±76 gm-2a-1, n=2) was more than 4 times larger than the average uptake of the moss-dominated bog (-27±28 gm-2a-1, n=2).