1,720,983 research outputs found
Interannual and seasonal variability in carbon dioxide and methane fluxes of a pine peat bog in the Eastern Alps, Austria
No full textIntact peat bogs are carbon dioxide (CO2) sinks and methane (CH4) sources. Facing drought and drainage, they may turn into CO2 sources and decreased CH4 sources. Information on the CO2 and CH4 exchange of alpine peat bogs in Central Europe has been missing so far. Here, we present data from two years of CO2 and CH4 exchange between an alpine low-shrub pine bog in the Eastern Alps and the atmosphere using the eddy covariance method. The annual net CO2 ecosystem exchange of the peatland differs substantially between the two measurement years, with -24 ± 13 g C m−2 yr−1 for the drought affected first year and -84 ± 13 g C m−2 yr−1 for the more humid second year. We found ecosystem respiration (Reco) to depend on variations in soil temperature and soil moisture, and gross primary production (GPP) to be strongly linked to net radiation and daylength. The summer drought in 2015 shifted the peatland from a C sink to a C source, as increases in Reco clearly exceeded enhanced GPP. Annual CH4 emission was 4.40 ± 2.40 g C m−2 yr−1 during the drought-affected year and 5.24 ± 2.57 g C m−2 yr−1 during the wetter year. Summer CH4 fluxes contribute 44% to the annual balance, followed by autumn (27%), spring (20%) and winter season fluxes (9%). CH4 fluxes most strongly depend on soil temperatures, soil moisture effects increase at smaller time-scales. Annual CH4 emissions are low compared to other temperate bogs, which most likely is the result of the ongoing degradation, indicated by a shift in vegetation composition. Net flux of both greenhouse gases was positive in the first year (+75 g CO2-eq m−2) and negative in the second year (−110 g CO2-eq m−2). Our results indicate that drought events and seasonal and interannual variations in temperature and precipitation strongly affect the C cycle of alpine peat bogs
Quantifying post-fire effects and recovery in a disturbed landscape: Quesenbank fire, Harz National Park
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Topographic indices and ERA5-Land data to describe soil moisture variability in a Central European beech forest
Full text linkStudy region: Temperate beech forest in central Germany’s low mountain range Study focus: Soil moisture is essential for ecosystem functioning, influencing hydrological, biological, and biogeochemical processes. It regulates water, energy, and carbon cycles, supporting ecosystem organization, biodiversity, and vegetation resilience. However, climate change and human activities increasingly disrupt soil moisture dynamics, altering spatio-temporal variability due to altered precipitation, rising temperatures, and droughts, making prediction attempts a challenge. This study examines a temperate beech forest in central Germany’s low mountain range, aiming to: (1) analyse spatio-temporal variations in soil moisture and temperature, (2) assess correlations with topographic indices across seasons, and (3) validate ERA5-Land retrievals. We employed 62 automatic sensors and manual measurements at 236 sites within a 900 × 600 m area. Field data were merged with ERA5-Land reanalysis and topographic indices, including depth-to-water and topographic position indices, to assess their performance in predicting soil water content spatial patterns. New hydrological insights for the region: Temporal variation exceeded spatial variation by 3.60–3.68 times. While soil moisture was associated with mesorelief (topographic position index), the correlation was weak. Flow accumulation-based indices were ineffective in capturing spatial soil moisture variation and failed to model spatio-temporal variability. This suggests that model results need to be reconsidered, and suitable indices developed. Insights from this study contribute to improving soil–vegetation–atmosphere models and support sustainable forest management in a changing climate
Carbon flux, energy balance and vegetation change of a recently restored forest peatland in the Solling mountains, Germany
No full textRestoration of afforested peatland: immediate effects on peatland-atmosphere carbon and water exchanges
No full textIn contrast to pristine peatlands, drained peatlands have been identified as hotspots of greenhouse gas (GHG) emissions. Projections suggest that, due to severe human impacts, peatlands worldwide will shift from a global net GHG sink to a source in the near future, causing positive radiative forcing. Peatlands are also a relevant climate factor in Germany, accounting for ~7.2 % of the annual GHG emissions. Thus, restoration of peatlands constitutes an effective nature-based climate change mitigation measure. Accordingly, as a society, we need to ask ourselves whether we should restore afforested peatlands on a large scale to mitigate climate change. To allow for more careful consideration and to identify the measures providing the most effective changes in each ecosystem, the benefits of restoration must be contrasted with the initial investments and future losses when the land is taken out of economic production. Thus, a deep understanding of the effects of forest peatland restoration and its underlying processes across ecosystems and time scales is essential.
Here we present a dataset of two years of eddy covariance-derived carbon dioxide, methane and water vapour fluxes of a clear-cut forest peatland during early stages of restoration in the Solling mountains, Lower Saxony. We found large amounts of carbon to be released from the peatland to the atmosphere. This is due to extraordinarily high ecosystem respiration but low gross primary production rates and minimal methane emissions. Calculations of GHG fluxes are complemented by UAV flights, geophysical measurements and soil analyses to disentangle the spatio-temporal variability of influencing factors. We relate results of repeated electrical resistivity tomography to soil properties and discuss the effects of their spatial heterogeneity on gas fluxes. True colour orthophotos obtained from repeated UAV flights have been successfully used to delimit vegetation units and changes in plant composition with ongoing plant succession. Thermal images are used to assess fine-scale differences in soil moisture based on variations in heat capacity of different matter and to evaluate their potential to model and upscale spatio-temporal trends of thermal characteristics and ecosystem respiration in unprecedented detail. Finally, we evaluate underlying factors of GHG fluxes, discuss implications of restoration measures and outline potential future developments
Soil moisture modeling with ERA5-Land retrievals, topographic indices, and in situ measurements and its use for predicting ruts
No full textOpen-Access-Publikationsfonds 202
Recent changes in rainfall patterns alter precipitation partitioning in European beech forest
No full textAbstract Climate change models suggest increasing rain variability in Europe with hypothesized cascading effects on ecosystems. However, model results are inconsistent, coarse and lack empirical data. Here, we used a 6.5-year dataset of gross precipitation, throughfall, and plant litter deposition from a beech forest in central Germany to show how water that reaches the Critical Zone is driven by shifting rainfall characteristics and canopy structure. Rain event duration declined distinctly over the observation period, while rain intensity and event frequency increased. These changes caused the throughfall fraction to decrease by 5.75% per year and spatial throughfall variability to rise exponentially. This study provides empirical evidence that precipitation intensification strongly impacts the spatio-temporal distribution of net precipitation in beech forests. This may progressively decouple hydrological links in Europe’s most dominant forest stands, potentially resulting in changing water and element fluxes, weathering, and soil processes.Ministry of Science and Culture of Lower Saxon
Decreasing nutrient concentrations in soils and trees with increasing elevation across a treeline ecotone in Rolwaling Himal, Nepal
No full textAt a global scale, tree growth in alpine treeline ecotones is limited by low temperatures. At a local scale, however, tree growth at its upper limit depends on multiple interactions of influencing factors and mechanisms. The aim of our research was to understand local scale effects of soil properties and nutrient cycling on tree growth limitation, and their interactions with other abiotic and biotic factors in a near-natural Himalayan treeline ecotone. Soil samples of different soil horizons, litter, decomposition layers, and foliage samples of standing biomass were collected in four altitudinal zones along three slopes, and were analysed for exchangeable cations and nutrient concentrations, respectively. Additionally, soil and air temperature, soil moisture, precipitation, and tree physiognomy patterns were evaluated. Both soil nutrients and foliar macronutrient concentrations of nitrogen (N), magnesium (Mg), potassium (K), and foliar phosphorus (P) decrease significantly with elevation. Foliar manganese (Mn) concentrations, by contrast, are extraordinarily high at high elevation sites. Potential constraining factors on tree growth were identified using multivariate statistical approaches. We propose that tree growth, treeline position and vegetation composition are affected by nutrient limitation, which in turn, is governed by low soil temperatures and influenced by soil moisture conditions
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