Carbon availability in soils of thermo-erosional valleys – a case study from a valley on Herschel Island, West Canadian Arctic

Permafrost is a perennially frozen ground often occurring in periglacial environments. Due to its frozen state, organic carbon accumulates in the soils. By temperature rise and thaw of the active layer, these stocks become vulnerable to microbial decomposition. To predict the future of organic carbon in the Arctic, it is necessary to expand the knowledge on its spatial distribution across arctic environments. This study examined the spatial distribution of organic carbon and its availability within a valley, which is subjected to thermo-erosion on Herschel Island, Yukon Territory. By analyses of soil samples variations in soil organic carbon, total nitrogen and the carbon-to-nitrogen ratio (C/N) were investigated. Ecological units, hillslope position and distance to shore helped to identify spatial differences between sites. The analyses showed that highest values for soil organic carbon, total nitrogen and C/N occurred on uplands, followed closely of the values in the valley bed. On slopes the values of soil organic carbon, total nitrogen and C/N were lower. Further, differences of the soil organic carbon, total nitrogen and C/N stocks occurred across the valley locations with distance to the shore. Upstream the soil organic carbon, total nitrogen and C/N stocks were higher to those downstream. Sites on slopes and downstream are characterized by continuous surface disturbances due to permafrost degradation, thermo-erosion and hillslope processes. This study could demonstrate that even in local scales organic carbon stocks and its availability differs spatially depending on environmental parameters

Spatial variability shapes microbial communities of permafrost soils and their reaction to warming

Climate change threatens the Earth’s biggest terrestrial organic carbon reservoir: permafrost soils. With climate warming, frozen soil organic matter may thaw and become available for microbial decomposition and subsequent greenhouse gas emissions. Permafrost soils are extremely heterogenous within the soil profile and between landforms. This heterogeneity in environmental conditions, carbon content and soil organic matter composition, potentially leads to different microbial communities with different responses to warming. The aim of the present study is to (1) elucidate these differences in microbial community compositions and (2) investigate how these communities react to warming. We performed short-term warming experiments with permafrost soil organic matter from northwestern Canada. We compared two sites characterized by different glacial histories (Laurentide Ice Sheet cover during LGM and without glaciation), three landscape types (low-center, flat-center, high-center polygons) and four different soil horizons (organic topsoil layer, mineral topsoil layer, cryoturbated soil layer, and the upper permanently frozen soil layer). We incubated aliquots of all soil samples at 4 °C and at 14 °C for 8 weeks and analyzed microbial community compositions (amplicon sequencing of 16S rRNA gene and ITS1 region) before and after the incubation, comparing them to microbial growth, microbial respiration, microbial biomass and soil organic matter composition. We found distinct bacterial, archaeal and fungal communities for soils of different glaciation history, polygon types and for different soil layers. Communities of low-center polygons differ from high-center and flat-center polygons in bacterial, archaeal and fungal community compositions, while communities of organic soil layers are significantly different from all other horizons. Interestingly, permanently frozen soil layers differ from all other horizons in bacterial and archaeal, but not fungal community composition. The 8-week incubations led to minor shifts in bacterial and archaeal community composition between initial soils and those subjected to 14 °C warming. We also found a strong warming effect on the community compositions in some of the extreme habitats: microbial community compositions of (i) the upper permanently frozen layer and of (ii) low-center polygons differ significantly for incubations at 4 °C and 14 °C. Yet, the lack of a community change in horizons of the active layer suggests that microbes are adapted to fluctuating temperatures due to seasonal thaw events. Our results suggest that warming responses of permafrost soil organic matter, if not frozen or water-saturated, may be predictable by current models. Process changes induced by short-term warming can be rather attributed to changes in microbial physiology than community composition. This work is part of the EU H2020 project “Nunataryuk”

Microbial growth in a warming Arctic: Exploring controls and temperature responses in permafrost soils

Permafrost soils are particularly vulnerable to climate warming. With ~1,500&amp;#160;Gt Carbon&amp;#160;(C), they store a significant proportion of global soil C. Organic matter that was frozen and thus unavailable for microbial decomposition for millennia, is now thawing. How much of this permafrost C is decomposed will be determined by microbial activities and the partitioning of assimilated C to microbial growth (potential C stabilization) or microbial respiration (C loss). Our current knowledge on the controls of microbial growth and respiration in permafrost soils is, however, limited. The objective of this study was to analyze microbial growth and respiration in permafrost soils and to explore soil organic matter composition, microbial community composition and various soil parameters as potential drivers. We collected 81 soil samples from four soil layers (organic, mineral, cryoturbated, permafrost) and three lowland tundra polygon types (low-center, flat-center, high-center) in Arctic Canada. We used pyrolysis-GC-MS fingerprinting to characterize soil organic matter composition and amplicon sequencing (16S, ITS1) to identify archaeal, bacterial, and fungal community composition. Temperature responses (Q10) were analyzed in an 8-week laboratory incubation experiment, subjecting soil aliquots to 4 &amp;#176;C and 14 &amp;#176;C. Microbial growth was determined by 18O-H2O-incorporation into DNA and microbial respiration by gas analysis. Soil organic matter composition differed between soil layers along a gradient of degradation and C content. Organic matter complexity and diversity decreased with the level of decomposition. We found distinct soil organic matter composition for each polygon type, including all soil layers, suggesting different decomposition pathways, induced by differences in vegetation and soil water regime. Anoxic conditions in low-center polygons resulted in more archaea and distinct fungal communities. Microbial community composition differed among all soil layers, with particularly more fungi in organic soils. Microbial mass-specific growth and respiration differed among polygons and soil layers, and both increased with warming. Overall, temperature responses (Q10) were higher for respiration than for growth, implying that microbes are less efficient in using C for growth. Linear mixed effect models revealed that soil organic matter composition and microbial community composition were good predictors for mass-specific growth at field and warmed conditions. Mass-specific respiration was best explained by microbial community composition. Our predictors, however, did not explain the temperature responses. Our results indicate that under warming, microbes allocated more C to respiration, leading to increased greenhouse gas emissions per unit of carbon taken up. We found these results while including all soil layers and polygon types, suggesting these responses to be representative for lowland Arctic ecosystems. Moreover, we could show that organic matter composition and microbial community composition are good predictors for microbial growth and respiration, thus deserving more attention in future studies. This study is part of the EU H2020 project &amp;#8220;Nunataryuk&amp;#8221;.</jats:p

Strategies, processes, outcomes, and costs of implementing experience sampling-based monitoring in routine mental health care in four European countries:study protocol for the IMMERSE effectiveness-implementation study

BACKGROUND: Recent years have seen a growing interest in the use of digital tools for delivering person-centred mental health care. Experience Sampling Methodology (ESM), a structured diary technique for capturing moment-to-moment variation in experience and behaviour in service users' daily life, reflects a particularly promising avenue for implementing a person-centred approach. While there is evidence on the effectiveness of ESM-based monitoring, uptake in routine mental health care remains limited. The overarching aim of this hybrid effectiveness-implementation study is to investigate, in detail, reach, effectiveness, adoption, implementation, and maintenance as well as contextual factors, processes, and costs of implementing ESM-based monitoring, reporting, and feedback into routine mental health care in four European countries (i.e., Belgium, Germany, Scotland, Slovakia).METHODS: In this hybrid effectiveness-implementation study, a parallel-group, assessor-blind, multi-centre cluster randomized controlled trial (cRCT) will be conducted, combined with a process and economic evaluation. In the cRCT, 24 clinical units (as the cluster and unit of randomization) at eight sites in four European countries will be randomly allocated using an unbalanced 2:1 ratio to one of two conditions: (a) the experimental condition, in which participants receive a Digital Mobile Mental Health intervention (DMMH) and other implementation strategies in addition to treatment as usual (TAU) or (b) the control condition, in which service users are provided with TAU. Outcome data in service users and clinicians will be collected at four time points: at baseline (t0), 2-month post-baseline (t1), 6-month post-baseline (t2), and 12-month post-baseline (t3). The primary outcome will be patient-reported service engagement assessed with the service attachment questionnaire at 2-month post-baseline. The process and economic evaluation will provide in-depth insights into in-vivo context-mechanism-outcome configurations and economic costs of the DMMH and other implementation strategies in routine care, respectively.DISCUSSION: If this trial provides evidence on reach, effectiveness, adoption, implementation and maintenance of implementing ESM-based monitoring, reporting, and feedback, it will form the basis for establishing its public health impact and has significant potential to bridge the research-to-practice gap and contribute to swifter ecological translation of digital innovations to real-world delivery in routine mental health care.TRIAL REGISTRATION: ISRCTN15109760 (ISRCTN registry, date: 03/08/2022).</p

Modelling human choices: MADeM and decision‑making

Research supported by FAPESP 2015/50122-0 and DFG-GRTK 1740/2. RP and AR are also part of the Research, Innovation and Dissemination Center for Neuromathematics FAPESP grant (2013/07699-0). RP is supported by a FAPESP scholarship (2013/25667-8). ACR is partially supported by a CNPq fellowship (grant 306251/2014-0)

Raster land cover product derived from TerraSAR-X imagery for the Komakuk Beach study site on the Beaufort Coast, Canada

The dataset contains a high-resolution (5m) land cover classification product for the Komakuk Beach study site located on the Beaufort Coast, Canada. Land cover types were classified using a Random Forest classifier with predictors derived from the Kennaugh elements K0 and K1 of seven dual-polarimetric HH/HV TerraSAR-X images acquired between July and December 2019. Land cover in-situ data were collected in August 2019 and upscaled to image objects (314 to 4766 m2) using segmentation of a WorldView-3 image and ArcticDEM elevation data. The SAR pixel values within these objects were used as reference data for the land cover classification. This dataset was produced to examine the potential of the Kennaugh Element Framework applied on dual-pol SAR data for Arctic tundra land cover classification

Arctic Tundra Land Cover Classification on the Beaufort Coast using the Kennaugh Element Framework on Dual-Polarimetric TerraSAR-X Imagery

Arctic tundra landscapes are highly complex and are rapidly changing due to the warming climate. Datasets which document the spatial and temporal variability of the landscape are needed to monitor the rapid changes. Synthetic Aperture Radar (SAR) imagery is specifically suitable for monitoring the Arctic, as SAR, unlike optical remote sensing, can provide time series regardless of weather and illumination conditions. This study examines the seasonal backscatter mechanisms in Arctic tundra environments and their potential for land cover classification purposes using a time series of HH/HV TerraSAR-X imagery. A Random Forest classification was applied on multi-temporal backscatter intensity and Kennaugh matrix element data. The backscatter analysis revealed clear differences in the polarimetric response of water, soil and vegetation, while backscatter signal variations within different vegetation classes were more nuanced. The RF models show that the land cover classes can be distinguished with 92.4% accuracy using the Kennaugh element data, compared to 57.7% accuracy for backscatter intensity data. The accuracy was improved by adding texture measures to the predictor datasets, but the spatial resolution was reduced. TerraSAR-X acquisitions from the summer as well as from the autumn and winter seasons were important for the classification. The results of this study demonstrate that the Kennaugh elements derived from dual-polarized X-band imagery are a powerful tool for Arctic tundra land cover mapping

High resolution mapping shows differences in soil carbon and nitrogen stocks in areas of varying landscape history in Canadian lowland tundra

Soil organic carbon (SOC) in Arctic coastal polygonal tundra is vulnerable to climate change, especially in soils with occurrence of large amounts of ground ice. Pan-arctic studies of mapping SOC exist, yet they fail to describe the high spatial variability of SOC storage in permafrost landscapes. An important factor is the landscape history which determines landform development and consequently the spatial variability of SOC. Our aim was to map SOC stocks, and which environmental variables that determine SOC, in two adjacent coastal areas along Canadian Beaufort Sea coast with different glacial history. We used the machine learning technique random forest and environmental variables to map the spatial distribution of SOC stocks down to 1 m depth at a spatial resolution of 2 m for depth increments of 0–5, 5–15, 15–30, 30–60 and 60–100 cm.The results show that the two study areas had large differences in SOC stocks in the depth 60–100 cm due to high amounts of ground ice in one of the study areas. There are also differences in variable importance of the explanatory variables between the two areas. The area low in ground ice content had with 66.6 kg C/m−2 more stored SOC than the area rich in ground ice content with 40.0 kg C/m−2. However, this SOC stock could be potentially more vulnerable to climate change if ground ice melts and the ground subsides. The average N stock of the area low in ground ice is 3.77 kg m−2 and of the area rich in ground ice is 3.83 kg m−2.These findings support that there is a strong correlation between ground ice and SOC, with less SOC in ice-rich layers on a small scale. In addition to small scale studies of SOC mapping, detailed maps of ground ice content and distribution are needed for a validation of large-scale quantifications of SOC stocks and transferability of models

How do microorganisms from permafrost soils respond to short-term warming?

Arctic ecosystems outpace the global rate of temperature increases and are exceptionally susceptible to global warming. Concerns are raising that CO2 and CH4 released from thawing permafrost upon warming may induce a positive feedback to climate change. This is based on the assumption, that microbial activity increases with warming and does not acclimate over time. However, we lack a mechanistic understanding of carbon and nutrient fluxes including their spatial control in the very heterogeneous Arctic landscape. The objective of this study therefore was to elucidate the microbial controls over soil organic matter decomposition in different horizons of the active layer and upper permafrost. We investigated different landscape units (high-centre polygons, low-centre polygons and flat polygon tundra) in two small catchments that differ in glacial history, at the Yukon coast, Northwestern Canada. In total, 81 soil samples were subjected to short-term (eight weeks) incubation experiments at controlled temperature (4 °C and 14 °C) and moisture conditions. Heterotrophic respiration was assessed weekly, whereas physiological parameters of soil microbes and their temperature response (Q10) were determined at the end of the incubation period. Microbial growth was estimated by measuring the incorporation of 18O from labelled water into DNA and used to calculate microbial carbon use efficiencies (CUE). Microbial biomass was determined via chloroform fumigation extraction. Potential activities of extracellular enzymes involved in C, N, P and S cycling were measured using microplate fluorimetric assays. Cumulative heterotrophic respiration of investigated soil layers followed the pattern organic layers > upper frozen permafrost > cryoturbated material > mineral layers in both catchments. Microbial respiration responded strongly in all soils to warming in all soils, but the observed response was highest for organic layers and cryoturbated material at the beginning and end of the experiment. Average Q10 values at the beginning of the experiment varied between 1.7 to 4.3 with differences between horizons but converged towards Q10 values between 2.0min to 2.9max after eight weeks of incubation. Even though microbial biomass C did not change with warming, microbial mass specific growth was enhanced in organic, cryoturbated and permafrost soils. Overall, warming resulted in a 65% reduced CUE in organic horizons. Our results show no indication for physiological acclimatization of permafrost soil microbes when subjected to 8-weeks of experimental warming. Given that the duration of the season in which most horizons are unfrozen is rarely longer than 2 months, our results do not support an acclimation of microbial activity under natural conditions. Instead, our data supports the current view of a high potential for prolonged carbon losses from tundra soils with warming by enhanced microbial activity. This work is part of the EU H2020 project “Nunataryuk”

Subjecting permafrost microorganisms to short-term warming

Arctic environments are a prime example for ecosystems facing manifold vast and rapid changes in the wake of climate change, outpacing the global rate of temperature increases. The risk of thawing permafrost soils raises concerns about a positive feedback process being mediated by increased microbial activity that does not acclimate over time freeing greenhouse gases. However, the mechanistic understanding of the controls on microbial carbon cycling upon warming is still vague. In the following study we investigate microbial growth and soil organic matter decomposition in different soil horizons of the active layer and upper permafrost, covering different polygonal landscape units in two small catchments at the Canadian Yukon Coast. 81 soil samples were subjected to a short-term warming experiment under controlled temperature (4 °C and 14 °C) and moisture conditions. Microbial respiration was measured weekly whereas microbial biomass and physiological parameters were determined at the end of the incubation period and used to assess temperature responses. Microbial growth was estimated by measuring the incorporation of 18O from labelled water into DNA and used to calculate CUE. Microbial biomass was determined via chloroform fumigation. Potential activities of extracellular enzymes were measured using microplate fluorometric assays. Microbial biomass carbon was not affected by warming except for permafrost layers where it either increased or decreased depending on the examined catchment. Microbial respiration strongly responded to warming following the pattern organic layers > upper frozen permafrost > cryoturbated material > mineral layers. Mass specific growth and extracellular enzymatic activities were also enhanced with short-term warming in all soil horizons. This led to rather variable CUE being unaffected in mineral and cryoturbated layers whereas we could observe a minor reduction in organic and permafrost layers where the response of respiration outpaced the one of microbial growth. Our results are not indicative for any physiological acclimatization of permafrost microbes when subjected to 8 weeks of experimental warming and hence support the current concern for potential prolonged carbon losses from warming tundra soils. This work is part of the EU H2020 project “Nunataryuk”