Lowland tundra plant stoichiometry is somewhat resilient decades following fire despite substantial and sustained shifts in community structure

The Arctic is experiencing the greatest increase in average surface temperature globally, which is projected to amplify wildfire frequency and severity. Wildfire alters the biogeochemical characteristics of arctic ecosystems. However, the extent of these changes over time-particularly with regard to plant stoichiometries relative to community structure-is not well documented. Four years after the Yukon-Kuskokwim Delta, Alaska, experienced its largest fire season, aboveground plant and lichen biomass was harvested across a gradient of burn history: unburned ("reference"), 2015 burn ("recent burn"), and 1972 burn ("historic burn") to assess the resilience of tundra plant communities to fire disturbance. Fire reduced aboveground biomass in the recent burn; early recovery was characterized by evergreen shrub and graminoid dominance. In the historic burn, aboveground biomass approached reference conditions despite a sustained reduction of lichen biomass. Although total plant and lichen carbon (C) and nitrogen (N) were reduced immediately following fire, N stocks recovered to a greater degree-reducing community-level C:N. Notably, at the species level, N enrichment was observed only in the recent burn. Yet, community restructuring persisted for decades following fire, reflecting a sustained reduction in N-poor lichens relative to more N-rich vascular plant species

Nivel de conocimiento y actitudes sobre tamizaje neonatal en las madres de los recién nacidos de la Clínica Monteluz – Lima, 2023

El presente estudio tuvo como objetivo establecer la relación entre el nivel de conocimiento y las actitudes sobre tamizaje neonatal en las madres de los recién nacidos de la Clínica Monteluz – Lima en el 2023. La metodología fue de enfoque cuantitativo, básico, diseño no experimental, tipo descriptivo correlacional de corte transversal. La población censal estuvo conformada por 140 madres. Para la recolección de los datos se aplicó como técnica la encuesta y como instrumento un cuestionario. Los resultados obtenidos en relación al nivel de conocimiento mostraron que el 57.2% de las madres tuvieron nivel medio; en la dimensión prueba de tamizaje se halló que el 67.9% obtuvo conocimiento medio; así como también en la dimensión procedimiento el 65% tuvo un conocimiento medio. Respecto a las actitudes de las madres sobre el tamizaje neonatal fueron regulares en un 52.1%. Se concluyó que no existe relación significativa entre el nivel de conocimiento y las actitudes sobre tamizaje neonatal (p=0.741) en las madres de los recién nacidos de la Clínica Monteluz – Lima en el 2023.The objective of this study was to establish the relationship between the level of knowledge and attitudes about neonatal screening in the mothers of newborns at the Monteluz Clinic - Lima in 2023. The methodology was quantitative, basic, non-experimental in design. cross-sectional correlational descriptive type. The census population was made up of 140 mothers. For data collection, a survey was applied as a technique and a questionnaire as an instrument. The results obtained in relation to the level of knowledge showed that 57.2% of the mothers had a medium level; In the screening test dimension, it was found that 67.9% obtained average knowledge; As well as in the procedure dimension, 65% had average knowledge. Regarding mothers' attitudes about neonatal screening, 52.1% were regular. It was concluded that there is no significant relationship between the level of knowledge and attitudes about neonatal screening (p=0.741) in the mothers of newborns at the Monteluz Clinic - Lima in 2023

Textstrukturen und weibliche Subjektivität in Texten von Leslie Kaplan

Zu Beginn der 80er Jahre macht sich in Frankreich eine innovative Prosaliteratur bemerkbar, die sich sowohl von der vorangegangenen theorieorientierten Avantgarde als auch vom konventionellen Roman unterscheidet. Die Autorin Leslie Kaplan hat diese von der Literaturkritik provisorisch als autre roman bezeichnete Strömung maßgeblich mitgeprägt. Ihre frühen Texte stehen mit ihrer experimentellen, nicht-narrativen Form noch deutlich unter dem Einfluss der theoriefreudigen 70er Jahre. Allmählich vollzieht sie jedoch die für die innovative Literatur der 80er als charakteristisch geltende \u27Rückkehr zum Erzählen\u27. Die Arbeit beschäftigt sich mit der Frage, welche Impulse Leslie Kaplan aus den feministischen Debatten der 70er Jahre bezieht. Untersucht werden die literaturästhetischen Erklärungen der Autorin, sowie die drei frühen Texte L\u27excès-l\u27usine (1982), Le criminel (1985) und Le Pont de Brooklyn (1987). Mit ihrem literarischen Programm eines \u27Schreibens ohne Machtausübung\u27 knüpft Kaplan implizit an die Diskussionen und Erkenntnisse der feministischen Kritik an, so eine These der Arbeit. Die literarischen Texte Kaplans kreisen um den Entwurf weiblicher Subjektivität, was ebenfalls ein zentrales Thema der Neuen Frauenliteratur war. Weibliche Subjektivität ist in den drei Texten als Offenheit entworfen. In L\u27excès-l\u27usine ist Offenheit noch negativ konstruiert als eine schmerzhafte Selbstauflösung, in Le criminel als ein Schwanken zwischen lustvoller Selbstentgrenzung und bedrohlichem Selbstverlust und in Le Pont de Brooklyn schließlich uneingeschränkt positiv als Aufgeschlossenheit und Fähigkeit, sich selbst in Frage zu stellen. Die Konstruktion einer nicht-hierarchischen Erzählstruktur erscheint dabei als Voraussetzung für den Entwurf von freien, selbstbestimmten weiblichen Figuren

Summer methane ebullition from a headwater catchment in Northeastern Siberia

Streams and rivers are active processors of terrestrial carbon and significant sources of carbon dioxide (CO2) and methane (CH4) to the atmosphere. Recent studies suggest that ebullition may represent a sizable yet overlooked component of the total CH4 flux from these systems; however, there are no published CH4 ebullition estimates for streams or rivers in subarctic or arctic biomes, regions that store vast quantities of vulnerable, old organic carbon in permafrost soils. We quantified CH4 ebullition from headwater streams in a small arctic watershed in Northeastern Siberia. Ebullitive emissions were 0.64 mmol m-2 d-1, which is lower than the global average but approximately 2 times greater than the pan-arctic diffusive CH4 flux estimate reported in a recent synthesis of global freshwater CH4 emissions. The high CO2:CH4 of sediment bubbles (0.52) suggests that methane emissions may currently be constrained by resource competition between methanogens and microbes using more efficient metabolic strategies. Furthermore, the magnitude and frequency of ebullition events were greater as temperatures increased, suggesting that ebullition from streams could become a more prominent component of the regional CH4 flux in a warmer future

Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire: an expert assessment

As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release will be offset by increased production of Arctic and boreal biomass; however, the lack of robust estimates of net carbon balance increases the risk of further overshooting international emissions targets. Precise empirical or model-based assessments of the critical factors driving carbon balance are unlikely in the near future, so to address this gap, we present estimates from 98 permafrost-region experts of the response of biomass, wildfire, and hydrologic carbon flux to climate change. Results suggest that contrary to model projections, total permafrost-region biomass could decrease due to water stress and disturbance, factors that are not adequately incorporated in current models. Assessments indicate that end-of-the-century organic carbon release from Arctic rivers and collapsing coastlines could increase by 75% while carbon loss via burning could increase four-fold. Experts identified water balance, shifts in vegetation community, and permafrost degradation as the key sources of uncertainty in predicting future system response. In combination with previous findings, results suggest the permafrost region will become a carbon source to the atmosphere by 2100 regardless of warming scenario but that 65%–85% of permafrost carbon release can still be avoided if human emissions are actively reduced

Permafrost and Climate Change: Carbon Cycle Feedbacks From the Warming Arctic

Rapid Arctic environmental change affects the entire Earth system as thawing permafrost ecosystems release greenhouse gases to the atmosphere. Understanding how much permafrost carbon will be released, over what time frame, and what the relative emissions of carbon dioxide and methane will be is key for understanding the impact on global climate. In addition, the response of vegetation in a warming climate has the potential to offset at least some of the accelerating feedback to the climate from permafrost carbon. Temperature, organic carbon, and ground ice are key regulators for determining the impact of permafrost ecosystems on the global carbon cycle. Together, these encompass services of permafrost relevant to global society as well as to the people living in the region and help to determine the landscape-level response of this region to a changing climate

Using radon to quantify groundwater discharge and methane fluxes to a shallow, tundra lake on the Yukon-Kuskokwim Delta, Alaska

Northern lakes are a source of greenhouse gases to the atmosphere and contribute substantially to the global carbon budget. However, the sources of methane (CH4) to northern lakes are poorly constrained limiting our ability to the assess impacts of future Arctic change. Here we present measurements of the natural groundwater tracer, radon, and CH4 in a shallow lake on the Yukon-Kuskokwim Delta, AK and quantify groundwater discharge rates and fluxes of groundwater-derived CH4. We found that groundwater was significantly enriched (2000%) in radon and CH4 relative to lake water. Using a mass balance approach, we calculated average groundwater fluxes of 1.2 ± 0.6 and 4.3 ± 2.0 cm day−1, respectively as conservative and upper limit estimates. Groundwater CH4 fluxes were 7—24 mmol m−2 day−1 and significantly exceeded diffusive air–water CH4 fluxes (1.3–2.3 mmol m−2 day−1) from the lake to the atmosphere, suggesting that groundwater is an important source of CH4 to Arctic lakes and may drive observed CH4 emissions. Isotopic signatures of CH4 were depleted in groundwaters, consistent with microbial production. Higher methane concentrations in groundwater compared to other high latitude lakes were likely the source of the comparatively higher CH4 diffusive fluxes, as compared to those reported previously in high latitude lakes. These findings indicate that deltaic lakes across warmer permafrost regions may act as important hotspots for CH4 release across Arctic landscapes

Burned area and carbon emissions across northwestern boreal North America from 2001-2019

Fire is the dominant disturbance agent in Alaskan and Canadian boreal ecosystems and releases large amounts of carbon into the atmosphere. Burned area and carbon emissions have been increasing with climate change, which have the potential to alter the carbon balance and shift the region from a historic sink to a source. It is therefore critically important to track the spatiotemporal changes in burned area and fire carbon emissions over time. Here we developed a new burned-area detection algorithm between 2001-2019 across Alaska and Canada at 500 m (meters) resolution that utilizes finer-scale 30 m Landsat imagery to account for land cover unsuitable for burning. This method strictly balances omission and commission errors at 500 m to derive accurate landscape- and regional-scale burned-area estimates. Using this new burned-area product, we developed statistical models to predict burn depth and carbon combustion for the same period within the NASA Arctic-Boreal Vulnerability Experiment (ABoVE) core and extended domain. Statistical models were constrained using a database of field observations across the domain and were related to a variety of response variables including remotely sensed indicators of fire severity, fire weather indices, local climate, soils, and topographic indicators. The burn depth and aboveground combustion models performed best, with poorer performance for belowground combustion. We estimate 2.37×106 ha (2.37 Mha) burned annually between 2001-2019 over the ABoVE domain (2.87 Mha across all of Alaska and Canada), emitting 79.3 ± 27.96 Tg (±1 standard deviation) of carbon (C) per year, with a mean combustion rate of 3.13 ± 1.17 kg C m-2. Mean combustion and burn depth displayed a general gradient of higher severity in the northwestern portion of the domain to lower severity in the south and east. We also found larger-fire years and later-season burning were generally associated with greater mean combustion. Our estimates are generally consistent with previous efforts to quantify burned area, fire carbon emissions, and their drivers in regions within boreal North America; however, we generally estimate higher burned area and carbon emissions due to our use of Landsat imagery, greater availability of field observations, and improvements in modeling. The burned area and combustion datasets described here (the ABoVE Fire Emissions Database, or ABoVE-FED) can be used for local- to continental-scale applications of boreal fire science