The Finnish Environment Institute - Publications archive


The Finnish Environment Institute (SYKE) is both a research institute, and a centre for environmental expertise. SYKE's research focuses on changes in the environment, and seeks ways to control these changes. The repository contains publications of SYKE as well as the offices preceding it such as the National Board of Waters, The National Board of Waters and the Environment and the Finnish Institute of Marine Research. The repository consists of articles, professional and scientific series and monographs.  Further information: ;

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  • Humalisto, Niko; Valve, Helena; Åkerman, Maria (Taylor & Francis, 2021)
    Environmental Politics, 30:5, 833-853
    The circular economy (CE) is currently generating considerable expectations. The concept describes an aspired future but does not provide clear guidance for policy-making. As policy outcomes often rest on initiatives generated in a bottom-up fashion, our attention must be directed to the ways policies are made accessible and interesting to those who might take the initiative. We claim that on-line publicity plays a key role in this. Our findings from a hyperlink analysis focusing on a government funding call for nutrient recycling in Finland show how multiple versions of the policy topic unfold online, as emergent hyperlink clusters prioritize specific agents, material circuits, and policy visions over others. The topic becomes connected with activities and agendas to create path dependencies and to strengthen existing divisions rather than to advocate change. Thus, we argue that CE policy design must recognize the way policy is shaped through online publicity creation.
  • Kuprijanov, Ivan; Väli, Germo; Sharov, Andrey; Berezina, Nadezhda; Liblik, Taav; Lips, Urmas; Kolesova, Natalja; Mannio, Jaakko; Lips, Inga; Junttila, Ville (Macmillan, 2021)
    Marine Pollution Bulletin, 170 (2021), 112642
    Contamination by hazardous substances is one of the main environmental problems in the eastern Gulf of Finland, Baltic Sea. A trilateral effort to sample and analyse heavy metals (HMs), polycyclic aromatic hydrocarbons (PAHs), and organotins from bottom sediments in 2019–2020 were conducted along with harvesting historical data in Russian, Estonian and Finnish waters. We suggest that the input of organotins still occurs along the ship traffic routes. The tributyltin content exceeded the established quality criteria up to more than 300 times. High contamination by PAHs found near the ports, most likely originate from incomplete fuel incineration processes. The Neva River Estuary and Luga Bay might potentially suffer from severe cadmium contamination. The high ecological risk attributed to the HMs was detected at deep offshore areas. The simulated accumulation pattern qualitatively agrees with field observations of HMs in sediments, demonstrating the potential of numerical tools to tackle the hazardous substances problems.
  • Finér, Leena; Lepistö, Ahti; Karlsson, Kristian; Räike, Antti; Härkönen, Laura; Huttunen, Markus; Joensuu, Samuli; Kortelainen, Pirkko; Mattsson, Tuija; Piirainen, Sirpa; Sallantaus, Tapani; Sarkkola, Sakari; Tattari, Sirkka; Ukonmaanaho, Liisa (Elsevier, 2021)
    Science of The Total Environment 762 (2021), 144098
    More reliable assessments of nutrient export to surface waters and the Baltic Sea are required to achieve good ecological status of all water bodies. Previous nutrient export estimates have recently been questioned since they did not include the long-term impacts of drainage for forestry. We made new estimates of the total nitrogen (N), total phosphorus (P) and total organic carbon (TOC) export from forests to surface waters at different spatial scales in Finland. This was done by formulating statistical equations between streamwater concentrations and climate, soil, forest management and runoff variables and spatial data on catchment characteristics. The equations were based on a large, long-term runoff and streamwater quality dataset, which was collected from 28 pristine and 61 managed boreal forest catchments located around Finland. We found that the concentrations increased with temperature sum (TS), i.e. from north to south. Nitrogen, P and TOC concentrations increased with the proportion of drained areas in the catchment; those of N and TOC also increased with the proportion of peatlands. In contrast, with the increasing concentrations of N and TOC with time, P concentrations showed a decreasing trend over the last few decades. According to our estimates, altogether 47,300 Mg of N, 1780 Mg of P and 1814 Gg of TOC is transported from forest areas to surface waters in Finland. Forest management contributes 17% of the N export, 35% of the P export and 12% of the TOC export. Our new forest management export estimates for N and P are more than two times higher than the old estimates used by the environment authorities. The differences may be explained by the long-term impact of forest drainage. The spatial results indicate that peatland forests are hotspots for N, P and TOC export, especially in the river basins draining to the Gulf of Bothnia.
  • Häkkinen, Tarja; Tarpio, Jyrki (Suomen ympäristökeskus, 2021)
    Suomen ympäristökeskuksen raportteja 46/2021
    Rakennuksen elinkaariominaisuudet mahdollistavat rakennuksen tai sen osien vaihtoehtoisia käyttötapoja tai pitkäkestoista käyttöä. Tässä työssä rakennusten elinkaariominaisuudet jäsenneltiin seuraavasti: A. Monikäyttöinen rakennus (tiloilla useita käyttäjiä päivittäin). B. Monikäyttötilasarja (tilat sellaisenaan mahdollistavat käyttötarkoituksen muutoksia tulevaisuudessa). C. Sisäisesti muunneltava rakennus. D. Laajennettavissa oleva rakennus. E. Supistettavissa oleva rakennus. F. Siirrettävissä oleva rakennus (myös runko siirtyy). G. Uuteen käyttöön purettavissa oleva rakennus (rakennusosat hyödynnettävissä). H. Hyvin pitkän käyttöiän rakennus. Rakennusten elinkaariominaisuuksiin kuuluu useita osatekijöitä, joita on erikseen käsitelty monissa rakennusten arviointiin kehitetyissä menetelmissä. Säädösohjauksen näkökulmasta yhteinen ymmärrys keskeisestä terminologiasta on tärkeä, ja siksi raportissa esitetään katsaus terminologiaan ja ehdotus keskeisistä termeistä ja niiden määritelmistä. Elinkaariominaisuudet voivat edistää resurssitehokkuutta ja vähähiilistä rakentamista. Ne voivat myös lisätä käyttäjien hyvinvointia tarjoamalla ratkaisuja, jotka vastaavat paremmin käyttäjien erilaisia tarpeita. Ehdotuksessa uudeksi kaavoitus- ja rakennuslaiksi (KRL) sanotaan, että rakentamisen on hillittävä ilmastonmuutosta perustumalla elinkaariominaisuuksiltaan kestäviin ratkaisuihin. Tulevien säädösten laadinnan kannalta on tarpeen ymmärtää eri elinkaariominaisuuksien vaikutuspotentiaalia sekä ilmasto- että muiden ympäristö- ja resurssivaikutuksien suhteen. Raportti taustoittaa tätä kuvaamalla periaatteellisia vaikutuksia. KRL-ehdotuksessa sanotaan myös, että ympäristöministeriön asetuksella voidaan antaa tarkempia säännöksiä eräistä elinkaariominaisuuksista. Osana tulevan säädöstyön taustoitusta raportissa esitetään rakentamisen asiantuntijoiden haastatteluihin ja kirjoittajien näkemyksiin pohjautuvia ehdotuksia elinkaariominaisuuksien ohjaamisesta. Työn yksi keskeinen johtopäätös on, että elinkaariominaisuuksien ohjausta hankaloittaa niihin liittyvien käytännön suunnittelu- ja arviointimenetelmien puute. Ohjaaminen tulisikin aloittaa informatiivisen ohjaamisen keinoin kehittämällä eri elinkaariominaisuuksien suunnittelumenetelmiä, kriteeristöä ja arviointimenetelmiä hyödyntämällä laajaa olemassa olevaa tutkimustietoa.
  • Bhattacharjee, Joy; Marttila, Hannu; Haghighi, Ali Torabi; Saarimaa, Miia; Tolvanen, Anne; Lepistö, Ahti; Futter, Martyn N.; Kløve, Bjørn (American Society of Civil Engineers, 2021)
    Journal of Irrigation and Drainage Engineering, 147(4), 04021006
    Spatiotemporal information on historical peatland drainage is needed to relate past land use to observed changes in catchment hydrology. Comprehensive knowledge of historical development of peatland management is largely unknown at the catchment scale. Aerial photos and light detection and ranging (LIDAR) data enlarge the possibilities for identifying past peatland drainage patterns. Here, our objectives are (1) to develop techniques for semiautomatically mapping the location of ditch networks in peat-dominated catchments using aerial photos and LIDAR data, and (2) to generate time series of drainage networks. Our approaches provide open-access techniques to systematically map ditches in peat-dominated catchments through time. We focused on the algorithm in such a way that we can identify the ditch networks from raw aerial images and LIDAR data based on the modification of multiple filters and number of threshold values. Such data are needed to relate spatiotemporal drainage patterns to observed changes in many northern rivers. We demonstrate our approach using data from the Simojoki River catchment (3,160  km2) in northern Finland. The catchment is dominated by forests and peatlands that were almost all drained after 1960. For two representative locations in cultivated peatland (downstream) and peatland forest (upstream) areas of the catchment; we found total ditch length density (km/km2), estimated from aerial images and LIDAR data based on our proposed algorithm, to have varied from 2% to 50% compared with the monitored ditch length available from the National Land survey of Finland (NLSF) in 2018. A different pattern of source variation in ditch network density was observed for whole-catchment estimates and for the available drained-peatland database from Natural Resources Institute Finland (LUKE). Despite such differences, no significant differences were found using the nonparametric Mann-Whitney U test with a 0.05 significance level based on the samples of pixel-identified ditches between (1) aerial images and NLSF vector files and (2) LIDAR data and NLSF vector files.
  • Mykrä, Heikki; Kuoppala, Minna; Nykänen, Vesa; Tolonen, Katri; Turunen, Jarno; Vilmi, Annika; Karjalainen, Satu Maaria (Elsevier, 2021)
    Journal of Environmental Management 278, Part 2 (2021), 111532
    Mining has changed landscapes locally in northern Fennoscandia and there is an increasing pressure for exploitation of the remaining mineral deposits of the region. Mineral deposits, even if unmined, can strongly influence stream water chemistry, stream biological communities and the ability of organisms to tolerate stressors. Using data sampled from six mining areas with three active (gold and chrome), two closed (gold) and one planned mine (phosphate), we examined how mineral deposits and mining influence water chemistry and diatom and macroinvertebrate communities in subarctic streams in Finnish Lapland. We supplemented the data by additional samples compiled from databases and further assessed how variation in background geological conditions influences bioassessments of the impacts arising from mining. We found that water specific conductivity was elevated in our study streams draining through catchments with a high mineral potential. Mining effects were mainly seen as increased concentration of nitrogen. Influence of mineral deposits was detected in composition of diatom and macroinvertebrate communities, but communities in streams in areas with a high mineral potential were as diverse as those in streams in areas with a low mineral potential. Mining impacts were better detected for diatoms using a reference condition based on sites with a high than low mineral potential, while for macroinvertebrates, the responses were generally less evident, likely because of only minor effects of mining on water chemistry. Community composition and frequencies of occurrence of macroinvertebrate taxa were, however, highly similar between mine-influenced streams and reference streams with a high potential for minerals indicating that the communities are strongly structured by the natural influence of mineral deposits. Incorporating geochemistry into the reference condition would likely improve bioassessments of both taxonomic groups. Replicated monitoring in potentially impacted sites and reference sites would be the most efficient framework for detecting environmental impacts in streams draining through mineral-rich catchments.
  • Ukkonen, Aino; Sahimaa, Olli (Elsevier, 2021)
    Waste Management 135 (2021), 372-380
    Municipal solid waste is associated with different systemic challenges, such as climate change, resource scarcity, and ocean plastic pollution. European countries are striving towards more circular material use and the European Commission has advocated the use of economic incentives to boost recycling. The pay-as-you-throw (PAYT) scheme is an economic instrument that applies the ‘polluter pays’ principle by charging for waste according to the actual amount of generated waste. Volume-based PAYT fees have shown to be potentially less effective in waste prevention and recycling than weight-based fees. This paper illustrates how waste management operators can price residual waste with weight-based fees that encourage recycling, are fair with respect to service levels, and cover the current income for municipal waste operators. The result, obtained by forming equations satisfying the above conditions, is a model with a linear, discrete price function, where the price of the residual waste generated by the citizen is a function of the service level. This model encourages efficient source separation through internal subsidies, wherein a citizen can decrease the price of household waste by 32% if they increase the sorting efficiency from a default of 40% to 80% efficiency. The application of the model was illustrated in a case example. The model developed in this study can be used to implement weight-based PAYT schemes locally, thereby supporting the formulation of waste management systems that facilitate waste reduction and recycling.
  • Saarikoski, Heli; Mustajoki, Jyri (Elsevier, 2021)
    Ecological Economics 183 (2021), 106955
    Deliberative valuation of ecosystem services is expected to capture the diversity of values related to ecosystem services and to facilitate learning and reconsideration of previously held preferences and positions. This paper reports on a study of a deliberative non-monetary valuation process that was designed to address the value of peatland ecosystem services in Southern Finland. Three parallel citizen panels were organised in order to consider the relative merits of energy peat extraction and peatland protection and to assign value to peatland ecosystem services. The results suggest that increased understanding of peatlands' role in carbon storage, together with reflection on the underlying value positions, led the panellists to adopt a more critical view of energy peat use. All three panels came independently to the same conclusion that peat extraction should be gradually phased out and replaced with renewable energy production. The results also sustain the hypothesis that deliberative settings evoke citizen preferences as the arguments used in the discussions were predominantly public spirited, referring to the common good instead of individual interests. We discuss the outcomes and factors that influenced the deliberations and make recommendations for effective deliberative designs.
  • Uurasjärvi, Emilia; Sainio, Erika; Setälä, Outi; Lehtiniemi, Maiju; Koistinen, Arto (Elsevier, 2021)
    Environmental Pollution 288 (2021), 117780
    Despite the ubiquitousness of microplastics, knowledge on the exposure of freshwater fish to microplastics is still limited. Moreover, no standard methods are available for analyzing microplastics, and the quality of methods used for the quantification of ingested microplastics in fish should be improved. In this study, we studied microplastic ingestion of common wild freshwater fish species, perch (Perca fluviatilis) and vendace (Coregonus albula). Further, our aim was to develop and validate imaging Fourier-transform infrared spectroscopic method for the quantification of ingested microplastics. For this purpose, enzymatically digested samples were measured with focal plane array (FPA) based infrared microscope. Data was analyzed with siMPle software, which provides counts, mass estimations, sizes, and materials for the measured particles. Method validation was conducted with ten procedural blanks and recovery tests, resulting in 75% and 77% recovery rates for pretreatment and infrared imaging, respectively. Pretreatment caused contamination principally by small <100 μm microplastics. The results showed that 17% of perch and 25% of vendace had ingested plastic. Most of the fish contained little or no plastics, while some individuals contained high numbers of small particles or alternatively few large particles. Perch from one sampling site out of five had ingested microplastics, but vendace from all sampling sites had ingested microplastics. The microplastics found from fish were mostly small: 81% had particle size between 20 and 100 μm, and most of them were polyethylene, polypropylene, and polyethylene terephthalate. In conclusion, the implemented method revealed low numbers of ingested microplastics on average but needs further development for routine monitoring of small microplastics.
  • Ghosh, Bipashyee; Kivimaa, Paula; Ramirez, Matias; Schot, Johan; Torrens, Jonas (Oxford University Press, 2021)
    Science and Public Policy, 48, 5, October 2021, 739–756
    The impending climate emergency, the Paris agreement and Sustainable Development Goals demand significant transformations in economies and societies. Science funders, innovation agencies, and scholars have explored new rationales and processes for policymaking, such as transformative innovation policy (TIP). Here, we address the question of how to orient the efforts of science, technology, and innovation policy actors to enable transformations. We build on sustainability transitions research and a 4-year co-creation journey of the TIP Consortium to present twelve transformative outcomes that can guide public policy agencies in evaluating and reformulating their projects, programmes, and policies. We illustrate the transformative outcomes in two empirical cases: transitions towards mobility-as-a-service in the Finnish transport system and the emergence of speciality coffee in Colombia. We argue that the twelve transformative outcomes can guide public policy agents to fundamentally transform their ways of thinking and operation in advancing transformative change.
  • Tiitu, Maija; Viinikka, Arto; Ojanen, Maria; Saarikoski, Heli (Elsevier, 2021)
    Environmental Science & Policy 126 (2021), 177-188
    Worldwide urbanisation emphasises the importance of planning for cities that sustain and promote the well-being of their residents. The planning of a living environment that supports well-being requires both intersectoral cooperation between policy sectors and interaction between researchers and practitioners. With 12 case studies (of 11 Finnish municipalities and one city region), we provide a description of a knowledge co-production process originating from the use of a new planning-support tool called StrateGIS that can be used for discovering built-environment indicators for integrated planning for well-being. Based on spatial multi-criteria analysis, we also investigate how the tool fostered intersectoral discussion among practitioners during the process. Practitioner knowledge was merged with scientific knowledge at different stages of the process: in structuring the value tree, in setting the objectives, in selecting the criteria and in defining the spatial representation for each criterion. Intersectoral discussion during the process was seen as fruitful and relatively easy despite the different types of expertise present in the workshops. Based on our results, the local experts specialised in spatial data have an intermediary role between practitioners since they can build understanding of how data is translated into spatial information when using a spatial planning-support tool.
  • Pitkänen, Timo P.; Sirro, Laura; Häme, Lauri; Häme, Tuomas; Törmä, Markus; Kangas, Annika (ScienceDirect, 2020)
    International Journal of Applied Earth Observation and Geoinformation 86 (2020)
    The majority of the boreal forests in Finland are regularly thinned or clear-cut, and these actions are regulated by the Forest Act. To generate a near-real time tool for monitoring management actions, an automatic change detection modelling chain was developed using Sentinel-2 satellite images. In this paper, we focus mainly on the error evaluation of this automatized workflow to understand and mitigate incorrect change detections. Validation material related to clear-cut, thinned and unchanged areas was collected by visual evaluation of VHR images, which provided a feasible and relatively accurate way of evaluating forest characteristics without a need for prohibitively expensive fieldwork. This validation data was then compared to model predictions classified in similar change categories. The results indicate that clear-cuts can be distinguished very reliably, but thinned stands exhibit more variation. For thinned stands, coverage of broadleaved trees and detections from certain single dates were found to correlate with the success of the modelling results. In our understanding, this relates mainly to image quality regarding haziness and translucent clouds. However, if the growing season is short and cloudiness frequent, there is a clear trade-off between the availability of good-quality images and their preferred annual span. Gaining optimal results therefore depends both on the targeted change types, and the requirements of the mapping frequency.
  • Taipale, Sami J.; Kuoppamäki, Kirsi; Strandberg, Ursula; Peltomaa, Elina; Vuorio, Kristiina (SpringerLink, 2020)
    Hydrobiologia 847 21 (2020)
    Food quality is one of the key factors influencing zooplankton population dynamics. Eutrophication drives phytoplankton communities toward the dominance of cyanobacteria, which means a decrease in the availability of sterols and long-chain polyunsaturated fatty acids (EPA and DHA). The effects of different restoration measures on the nutritional quality of the phytoplankton community and subsequent impacts on zooplankton biomass have rarely been considered. We analyzed the nutritional quality of phytoplankton in the eutrophic Lake Vesijärvi in southern Finland over a 37-year period, and studied the impacts of two restoration measures, biomanipulation and hypolimnetic aeration, on the abundance of high-quality phytoplankton. We found that biomanipulation had a positive impact on the abundance of taxa synthesizing sterols, EPA, and DHA and, concurrently, on the biomass of the keystone species Daphnia. In contrast, hypolimnetic aeration did not result in such a beneficial outcome, manifested as a decrease in the abundance of Daphnia and frequent phytoplankton blooms dominated by cyanobacteria suggesting reduction in the nutritional quality of food for Daphnia. Our analysis shows that the determination of the nutritional value of algae and the contribution of essential fatty acids and sterols is an effective method to evaluate the success of various restoration measures.
  • Tiitu, Maija; Naess, Petter; Ristimäki, Mika (Taylor & Francis, 2021)
    European Planning Studies, 29:6, 1092-1112
    Situated in northern Europe, the capital regions of Helsinki, and Oslo have many similar premises concerning urban development. However, the structure of the two regions differs by many measures. We explore the differences in urban density and its development in the both regions and the policy instruments that have affected them. Differences are identified by comparing the population densities of urban settlements and the mean distances from residents and workplaces to the city centres of Oslo and Helsinki using GIS methodology and existing literature. In the Oslo region, the population density shifted from a decreasing trend to an increasing one in the late 1980s. In contrast, the Helsinki region only started to densify in the 2010s. Also, the mean distance of residents and workplaces from the city centre is farther in Helsinki. The long period of low-density housing development and the creation of jobs outside centres in Helsinki is related to weaker political steering towards a compact urban form. In Oslo, regulations such as a greenbelt policy but also physical factors, led to densification relatively early. Lagging in densification policies, Helsinki could learn from the experiences of steering land use and mobility in Oslo, which would need additional research.
  • Jiang, Xiaoming; Pan, Baozhu; Jiang, Wanxiang; Hou, Yiming; Yang, Haiqiang; Zhu, Penghui; Heino, Jani (Elsevier, 2021)
    Ecological Indicators 124 (2021), 107407
    There is a growing recognition that examining patterns of ecological communities and their underlying determinants is not only feasible based on taxonomic data, but also functional and phylogenetic approaches. This is because these additional facets can enhance the understanding of the relative contribution of multiple processes in shaping biodiversity. However, few studies have focused on multifaceted beta diversities in lotic macroinvertebrates, especially when considering driving factors operating at multiple spatial scales. Here, we examined the spatial patterns of multi-faceted (i.e., taxonomic, functional and phylogenetic) beta diversity and their components (i.e., turnover and nestedness) of macroinvertebrates in 50 sites in 10 streams situated in the north and south slope of the Qinling Mountains, the geographical dividing line of Northern and Southern China. We found that the streams draining the north slope showed significantly lower values of beta diversity based on all three facets than the streams draining the south slope. Such north-to-south increases of beta diversity were caused by the distinct climatic and local environmental conditions between the sides of the mountain range. Moreover, spatial variables generally played the most important role in structuring all facets and components of beta diversity, followed by local environmental and climatic variables, whereas catchment variables were less important. Despite the similar results of relative contribution of explanatory variables on each beta diversity facet, the details of community-environment relationships (e.g., important explanatory variables and explanatory power) were distinct among different diversity facets and their components. In conclusion, measuring functional and phylogenetic beta diversity provides complementary information to traditional taxonomic approach. Therefore, an integrative approach embracing multiple facets of diversity can better reveal the mechanisms shaping biodiversity, which is essential in assessing and valuing aquatic ecosystems for biodiversity management and conservation.
  • Grant, Danielle M.; Brodnicke, Ole Bjørn; Evankow, Ann M.; Ferreira, André O.; Fontes, João T.; Hansen, Aslak Kappel; Jensen, Mads Reinholdt; Kalaycı, Tuğba Ergül; Leeper, Alexandra; Patil, Shalaka Kiran; Prati, Sebastian; Reunamo, Anna; Roberts, Aradhana J.; Shigdel, Rajesh; Tyukosova, Valentina; Bendiksby, Mika; Blaalid, Rakel; Costa, Filipe O.; Hollingsworth, Peter M.; Stur, Elisabeth; Ekrem, Torbjørn (MDPI, 2021)
    Diversity 2021, 13(7), 313
    Over the last two decades, the use of DNA barcodes has transformed our ability to identify and assess life on our planet. Both strengths and weaknesses of the method have been exemplified through thousands of peer-reviewed scientific articles. Given the novel sequencing approaches, currently capable of generating millions of reads at low cost, we reflect on the questions: What will the future bring for DNA barcoding? Will identification of species using short, standardized fragments of DNA stand the test of time? We present reflected opinions of early career biodiversity researchers in the form of a SWOT analysis and discuss answers to these questions.
  • Schoenefeld, Jonas J.; Schulze, Kai; Hildén, Mikael; Jordan, Andrew J. (Taylor & Francis, 2021)
    The International Spectator, 56:3, 24-40
    To achieve its ambitious climate targets, the European Union (EU) must adopt new policies, increase the impact of existing policies and/or remove dysfunctional ones. The EU has developed an elaborate system to monitor national policy mixes in order to support these challenging requirements. Data that member states have reported to the EU over the last ten years reveal that the average expected per-policy-instrument emission reduction has declined, while national policy mixes have remained generally stable over time. This is strikingly discordant with the EU’s ambitious commitment to become carbon neutral by 2050 (‘net zero’).
  • Wologo, Ethan; Shakil, Sarah; Zolkos, Scott; Textor, Sadie; Ewing, Stephanie; Klassen, Jane; Spencer, Robert G. M.; Podgorski, David C.; Tank, Suzanne E. T.; Baker, Michelle A.; O'Donnell, Jonathan A.; Wickland, Kimberly P.; Foks, Sydney S. W.; Zarnetske, Jay P.; Lee-Cullin, Joseph; Liu, Futing; Yang, Yuanhe; Kortelainen, Pirkko; Kolehmainen, Jaana; Dean, Joshua F.; Vonk, Jorien E.; Holmes, Robert M.; Pinay, Gilles; Powell, Michaela M.; Howe, Jansen; Frei, Rebecca J.; Bratsman, Samuel P.; Abbott, Benjamin W. (American Geophysical Union, 2021)
    Global Biogeochemical Cycles 35 (1), e2020GB006719
    Permafrost degradation is delivering bioavailable dissolved organic matter (DOM) and inorganic nutrients to surface water networks. While these permafrost subsidies represent a small portion of total fluvial DOM and nutrient fluxes, they could influence food webs and net ecosystem carbon balance via priming or nutrient effects that destabilize background DOM. We investigated how addition of biolabile carbon (acetate) and inorganic nutrients (nitrogen and phosphorus) affected DOM decomposition with 28-day incubations. We incubated late-summer stream water from 23 locations nested in seven northern or high-altitude regions in Asia, Europe, and North America. DOM loss ranged from 3% to 52%, showing a variety of longitudinal patterns within stream networks. DOM optical properties varied widely, but DOM showed compositional similarity based on Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) analysis. Addition of acetate and nutrients decreased bulk DOM mineralization (i.e., negative priming), with more negative effects on biodegradable DOM but neutral or positive effects on stable DOM. Unexpectedly, acetate and nutrients triggered breakdown of colored DOM (CDOM), with median decreases of 1.6% in the control and 22% in the amended treatment. Additionally, the uptake of added acetate was strongly limited by nutrient availability across sites. These findings suggest that biolabile DOM and nutrients released from degrading permafrost may decrease background DOM mineralization but alter stoichiometry and light conditions in receiving waterbodies. We conclude that priming and nutrient effects are coupled in northern aquatic ecosystems and that quantifying two-way interactions between DOM properties and environmental conditions could resolve conflicting observations about the drivers of DOM in permafrost zone waterways.
  • Ge, Yihao; Meng, Xingliang; Heino, Jani; García‐Girón, Jorge; Liu, Yang; Li, Zhengfei; Xie, Zhicai (Ecological Society of America, 2021)
    Ecosphere 12 (7), e03675
    Deterministic and stochastic processes are two major factors shaping community dynamics, but their relative importance remains unknown for many aquatic systems, including those in the high-elevation Qinghai–Tibet Plateau. Here, we explored the causes of multidimensional beta diversity patterns (i.e., taxonomic, functional, and phylogenetic) of a macroinvertebrate metacommunity in this large aquatic system by using multiple approaches (i.e., null models, phylogenetic signal testing, and ordination-based approaches). To obtain insights into community assembly mechanisms, we also analyzed beta diversity in two deconstructed sub-metacommunities (e.g., different tributaries and the main lake body). We found that most functional traits showed significant phylogenetic signals, indicating that the functional traits were profoundly influenced by evolutionary history. The null models showed randomness of functional and phylogenetic beta diversities for the whole basin and its tributaries, confirming the importance of stochasticity over deterministic processes in controlling community structure. However, both phylogenetic and functional community structures were clustered in the Qinghai Lake, probably reflecting the importance of environmental filtering. Ordination-based approaches also revealed that both environmental factors and spatial processes accounted for variation in taxonomic, functional, and phylogenetic beta diversity. More specifically, environmental filtering was more important than spatial processes for the functional dimension, but the opposite was true for the taxonomic and phylogenetic dimensions. The paleogeographic history of the Qinghai Lake basin may have contributed substantially to the prevalence of stochastic processes. Overall, this study provides a better understanding of ecological patterns and assembly mechanisms of macroinvertebrate communities across this poorly known high-elevation aquatic system that is highly sensitive to climate warming.
  • Chumachenko, Kateryna; Raitoharju, Jenni; Iosifidis, Alexandros; Gabbouj, Moncef (Elsevier, 2021)
    Pattern Recognition 111, (2021), 107660
    In this paper, we propose a speed-up approach for subclass discriminant analysis and formulate a novel efficient multi-view solution to it. The speed-up approach is developed based on graph embedding and spectral regression approaches that involve eigendecomposition of the corresponding Laplacian matrix and regression to its eigenvectors. We show that by exploiting the structure of the between-class Laplacian matrix, the eigendecomposition step can be substituted with a much faster process. Furthermore, we formulate a novel criterion for multi-view subclass discriminant analysis and show that an efficient solution to it can be obtained in a similar manner to the single-view case. We evaluate the proposed methods on nine single-view and nine multi-view datasets and compare them with related existing approaches. Experimental results show that the proposed solutions achieve competitive performance, often outperforming the existing methods. At the same time, they significantly decrease the training time.

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