Browsing by Subject "STREAMS"

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  • Strona, Giovanni; Fattorini, Simone; Fiasca, Barbara; Di Lorenzo, Tiziana; Di Cicco, Mattia; Lorenzetti, Walter; Boccacci, Francesco; Galassi, Diana M. P. (2019)
    We introduce a suite of software tools aimed at investigating multiple bio-ecological facets of aquatic Groundwater Dependent Ecosystems (GDEs). The suite focuses on: (1) threats posed by pollutants to GDE invertebrates (Ecological Risk, ER); (2) threats posed by hydrological and hydromorphological alterations on the subsurface zone of lotic systems and groundwater-fed springs (Hydrological-Hydromorphological Risk, HHR); and (3) the conservation priority of GDE communities (Groundwater Biodiversity Concern index, GBC). The ER is assessed by comparing tolerance limits of invertebrate species to specific pollutants with the maximum observed concentration of the same pollutants at the target site(s). Comparison is based on an original, comprehensive dataset including the most updated information on tolerance to 116 pollutants for 474 freshwater invertebrate species. The HHR is assessed by accounting for the main direct and indirect effects on both the hyporheic zone of lotic systems and groundwater-fed springs, and by scoring each impact according to the potential effect on subsurface invertebrates. Finally, the GBC index is computed on the basis of the taxonomical composition of a target community, and allows the evaluation of its conservation priority in comparison to others.
  • Manninen, Noora Johanna; Soinne, Helena Susanna; Lemola, Riitta; Hoikkala, Laura Kristiina; Turtola, Eila (2018)
    Dissolved organic carbon (DOC) load in discharges from cultivated soils may have negative impacts on surface waters. The magnitude of the load may vary according to soil properties or agricultural management practices. This study quantifies the DOC load of cultivated mineral soils and investigates whether the load is affected by agricultural practices. Discharge volumes and concentrations of DOC and dissolved organic nitrogen (DON) were continually measured at three sites from surface runoff and artificial subsurface drainage or from combined total discharge over a two-year period (2012-2014). Two experimental sites in South-West Finland had clayey soils (with soil carbon contents of 2.7-5.9% in the topmost soil layer), and the third site in West-Central Finland had sandy soil (soil carbon contents of 4.3-6.2%). Permanent grassland, organic manure application, mineral fertilization, and conventional ploughing or no-till activities were studied. Furthermore, the biodegradable DOC pool of surface runoff and subsurface drainage water from no-till and ploughed fields was estimated in a 2-month incubation experiment with natural bacterial communities collected from the Baltic Sea seawater. The annual DOC and DON loads were affected by discharge volume and seasonal weather conditions. The loads varied between 25-52 kg ha(-1) and 0.8-3.2 kg ha(-1), respectively, and were comparable to those from boreal forests with similar soil types. The DOC load increased with increasing topsoil carbon content at all sites. There were slightly higher DOC concentrations and DOC load from permanent grassland, but otherwise we could not distinguish any clear management-induced differences in the total DOC loads. While only 6-17% of the DOC in discharge water was biologically degraded during the 2-month incubation, the proportion of biodegradable (labile) DOC in surface runoff appeared to increase when soil was ploughed compared to no-till. (c) 2017 Elsevier B.V. All rights reserved.
  • Group Author (2019)
    River ecosystems receive and process vast quantities of terrestrial organic carbon, the fate of which depends strongly on microbial activity. Variation in and controls of processing rates, however, are poorly characterized at the global scale. In response, we used a peer-sourced research network and a highly standardized carbon processing assay to conduct a global-scale field experiment in greater than 1000 river and riparian sites. We found that Earth's biomes have distinct carbon processing signatures. Slow processing is evident across latitudes, whereas rapid rates are restricted to lower latitudes. Both the mean rate and variability decline with latitude, suggesting temperature constraints toward the poles and greater roles for other environmental drivers (e.g., nutrient loading) toward the equator. These results and data set the stage for unprecedented "next-generation biomonitoring" by establishing baselines to help quantify environmental impacts to the functioning of ecosystems at a global scale.
  • Kilpua, E. K. J.; Hietala, H.; Koskinen, H. E. J.; Fontaine, D.; Turc, L. (2013)
  • Kilpua, Emilia K. J.; Fontaine, Dominique; Good, Simon W.; Ala-Lahti, Matti; Osmane, Adnane; Palmerio, Erika; Yordanova, Emiliya; Moissard, Clement; Hadid, Lina Z.; Janvier, Miho (2020)
    In this work, we investigate magnetic field fluctuations in three coronal mass ejection (CME)-driven sheath regions at 1 AU, with their speeds ranging from slow to fast. The data set we use consists primarily of high-resolution (0.092 s) magnetic field measurements from the Wind spacecraft. We analyse magnetic field fluctuation amplitudes, compressibility, and spectral properties of fluctuations. We also analyse intermittency using various approaches; we apply the partial variance of increments (PVIs) method, investigate probability distribution functions of fluctuations, including their skewness and kurtosis, and perform a structure function analysis. Our analysis is conducted separately for three different subregions within the sheath and one in the solar wind ahead of it, each 1 h in duration. We find that, for all cases, the transition from the solar wind ahead to the sheath generates new fluctuations, and the intermittency and compressibility increase, while the region closest to the ejecta leading edge resembled the solar wind ahead. The spectral indices exhibit large variability in different parts of the sheath but are typically steeper than Kolmogorov's in the inertial range. The structure function analysis produced generally the best fit with the extended p model, suggesting that turbulence is not fully developed in CME sheaths near Earth's orbit. Both Kraichnan-Iroshinikov and Kolmogorov's forms yielded high intermittency but different spectral slopes, thus questioning how well these models can describe turbulence in sheaths. At the smallest timescales investigated, the spectral indices indicate shallower than expected slopes in the dissipation range (between 2 and 2 :5), suggesting that, in CME-driven sheaths at 1 AU, the energy cascade from larger to smaller scales could still be ongoing through the ion scale. Many turbulent properties of sheaths (e.g. spectral indices and compressibility) resemble those of the slow wind rather than the fast. They are also partly similar to properties reported in the terrestrial magnetosheath, in particular regarding their intermittency, compressibility, and absence of Kolmogorov's type turbulence. Our study also reveals that turbulent properties can vary considerably within the sheath. This was particularly the case for the fast sheath behind the strong and quasi-parallel shock, including a small, coherent structure embedded close to its midpoint. Our results support the view of the complex formation of the sheath and different physical mechanisms playing a role in generating fluctuations in them.
  • Hakkinen, Suvi; Ovaska, Noora; Rinne, Teemu (2015)
    The relationship between stimulus-dependent and task-dependent activations in human auditory cortex (AC) during pitch and location processing is not well understood. In the present functional magnetic resonance imaging study, we investigated the processing of task-irrelevant and task-relevant pitch and location during discrimination, n-back, and visual tasks. We tested three hypotheses: (1) According to prevailing auditory models, stimulus-dependent processing of pitch and location should be associated with enhanced activations in distinct areas of the anterior and posterior superior temporal gyrus (STG), respectively. (2) Based on our previous studies, task-dependent activation patterns during discrimination and n-back tasks should be similar when these tasks are performed on sounds varying in pitch or location. (3) Previous studies in humans and animals suggest that pitch and location tasks should enhance activations especially in those areas that also show activation enhancements associated with stimulus-dependent pitch and location processing, respectively. Consistent with our hypotheses, we found stimulus dependent sensitivity to pitch and location in anterolateral STG and anterior planum temporale (PT), respectively, in line with the view that these features are processed in separate parallel pathways. Further, task-dependent activations during discrimination and n-back tasks were associated with enhanced activations in anterior/posterior STG and posterior STG/inferior parietal lobule (IPL) irrespective of stimulus features. However, direct comparisons between pitch and location tasks performed on identical sounds revealed no significant activation differences. These results suggest that activations during pitch and location tasks are not strongly affected by enhanced stimulus dependent activations to pitch or location. We also found that activations in PT were strongly modulated by task requirements and that areas in the inferior parietal lobule (IPL) showed task-dependent activation modulations, but no systematic activations to pitch or location. Based on these results, we argue that activations during pitch and location tasks cannot be explained by enhanced stimulus specific processing alone, but rather that activations in human AC depend in a complex manner on the requirements of the task at hand.
  • Rinne, Teemu; Ala-Salomaki, Heidi; Stecker, G. Christopher; Pätynen, Jukka; Lokki, Tapio (2014)
  • Denfeld, Blaize A.; Kortelainen, Pirkko; Rantakari, Miitta; Sobek, Sebastian; Weyhenmeyer, Gesa A. (2016)
    Northern lakes are ice-covered for considerable portions of the year, where carbon dioxide (CO2) can accumulate below ice, subsequently leading to high CO2 emissions at ice-melt. Current knowledge on the regional control and variability of below ice partial pressure of carbon dioxide (pCO(2)) is lacking, creating a gap in our understanding of how ice cover dynamics affect the CO2 accumulation below ice and therefore CO2 emissions from inland waters during the ice-melt period. To narrow this gap, we identified the drivers of below ice pCO(2) variation across 506 Swedish and Finnish lakes using water chemistry, lake morphometry, catchment characteristics, lake position, and climate variables. We found that lake depth and trophic status were the most important variables explaining variations in below ice pCO(2) across the 506 lakes(.) Together, lake morphometry and water chemistry explained 53% of the site-to-site variation in below ice pCO(2). Regional climate (including ice cover duration) and latitude only explained 7% of the variation in below ice pCO(2). Thus, our results suggest that on a regional scale a shortening of the ice cover period on lakes may not directly affect the accumulation of CO2 below ice but rather indirectly through increased mobility of nutrients and carbon loading to lakes. Thus, given that climate-induced changes are most evident in northern ecosystems, adequately predicting the consequences of a changing climate on future CO2 emission estimates from northern lakes involves monitoring changes not only to ice cover but also to changes in the trophic status of lakes.
  • Olden, Anna; Peura, Maiju; Saine, Sonja; Kotiaho, Janne S.; Halme, Panu (2019)
    Riparian forests have cool and humid microclimates, and one aim of leaving forested buffer strips between clear-cut areas and streams is to conserve these microclimatic conditions. We used an experimental study set up of 35 streamside sites to study the impacts of buffer strip width (15 or 30 m) and selective logging within the buffer strips on summer-time air temperature, relative air humidity and canopy openness 12 years after logging. The buffer strip treatments were compared to unlogged control sites. We found that 15-meter buffer strips with or without selective logging and 30-meter buffer strips with selective logging were insufficient in maintaining temperature, relative humidity and canopy openness at similar levels than they were in control sites. In contrast, 30-meter buffer strips differed only little from control sites, although they did have significantly lower mean air humidity. Microclimatic changes were increased by southern or southwestern aspect of the clear-cut, and by logging on the opposite side of the stream. We also tested how the cover of three indicator mosses (Hylocomium splendens, Pseudobqum cinclidioides and Polytrichum commune) had changed (from pre-logging to 12 years post-logging) in relation to post-logging air temperature, relative air humidity and canopy openness. We found that each of the species responded to at least one of these physical conditions. Air humidity was the most significant variable for explaining changes in the cover of the indicator moss species, suggesting that the changes in this microclimatic component has biological impacts. We conclude that to preserve riparian microclimatic conditions and species dependent on those, buffer strips should exceed 30 m in width, and not be selectively logged. Wider buffer strips are required if the clear-cut is towards south or southwest, or if the two sides of the stream are logged at the same time or during subsequent years.
  • Schiesari, Luis; Matias, Miguel G.; Prado, Paulo Inacio; Leibold, Mathew A.; Albert, Cecile H.; Howeth, Jennifer G.; Leroux, Shawn J.; Pardini, Renata; Siqueira, Tadeu; Brancalion, Pedro H. S.; Cabeza, Mar; Coutinho, Renato Mendes; Felizola Diniz-Filho, Jose Alexandre; Fournier, Bertrand; Lahr, Daniel J. G.; Lewinsohn, Thomas M.; Martins, Ayana; Morsello, Carla; Peres-Neto, Pedro R.; Pillar, Valerio D.; Vazquez, Diego P. (2019)
    The complexity of ecological systems is a major challenge for practitioners and decision-makers who work to avoid, mitigate and manage environmental change. Here, we illustrate how metaecology - the study of spatial interdependencies among ecological systems through fluxes of organisms, energy, and matter - can enhance understanding and improve managing environmental change at multiple spatial scales. We present several case studies illustrating how the framework has leveraged decision-making in conservation, restoration and risk management. Nevertheless, an explicit incorporation of metaecology is still uncommon in the applied ecology literature, and in action guidelines addressing environmental change. This is unfortunate because the many facets of environmental change can be framed as modifying spatial context, connectedness and dominant regulating processes - the defining features of metaecological systems. Narrowing the gap between theory and practice will require incorporating system-specific realism in otherwise predominantly conceptual studies, as well as deliberately studying scenarios of environmental change. (C) 2019 Associacao Brasileira de Ciencia Ecologica e Conservacao. Published by Elsevier Editora Ltda.