Browsing by Subject "kasvit"

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  • Nummi, Petri (Ministry of the Environment, 2001)
    The Finnish Environment 466
  • Väisänen, Eero; Kellomäki, Seppo; Hari, Pertti (Suomen metsätieteellinen seura, 1977)
  • Bergström, Irina (Finnish Environment Institute, 2011)
    Monographs of the Boreal Environment Research 38
    The carbon dioxide (CO2) and methane (CH4) fluxes from aquatic sediments have recently received considerable interest because of the role of these gases in enhancing climate warming. CO2 is the main end product of aerobic respiration and CH4 is produced in large amounts under anaerobic conditions. Shallow, vegetated sediments are an important source of both gases. CH4 may be transported via rhizomes and aerenchymal tissues of aquatic plants from the sediment to the atmosphere, thus avoiding oxidation in the aerated sediment surface and water column. Temperature is known to be a key factor affecting benthic CO2 and CH4 flux rates, but the interplay between other factors that may affect the fluxes from sediments is still poorly known. In order to study the spatial and temporal variability of carbon gas fluxes in boreal aquatic sediments, the area-based CO2 production rates in lake and brackish water sediments and CH4 emissions in vegetated lake littorals were measured in this work. The effects of temperature, sediment quality, plant species, zoobenthos and seasonal variation on flux rates were also estimated. The range of CO2 production rates measured in the field was 0.1–12.0 mg C m–2 h–1 and that of CH4 emission rates 0–14.3 mg C m–2 h–1. When incubated at elevated temperatures (up to 30 °C) in the laboratory, the CO2 production rates increased up to 70 mg C m–2 h–1. Temperature explained 70–94% of the temporal variation in the CO2 production in lake sites and 51% in a brackish water site. In the lake mesocosm, temperature explained 50–90% of the variation of CH4 emission. By contrast, CH4 oxidation rate was not dependent on temperature. The CH4 fluxes through the plants of six emergent and floating-leaved plant species were studied in the field (temperature range 20.4–24.9 °C). Stands of the emergent macrophyte Phragmites australis emitted the largest amounts of CH4 (mean emission 13.9 ± 4.0 (SD) mg C m-2 h–1), the mean emission rate being correlated with mean net primary production (NPP) and mean solar radiation. In the stands of floating-leaved Nuphar lutea the mean CH4 efflux (0.5 ± 0.1 (SD) mg C m–2 h–1) was negatively correlated with mean fetch and positively with percentage cover of leaves on the water surface. On a regional level, stands of the emergents P. australis and Equisetum fluviatile emitted 32% more CH4 than natural open peatland during the growing season, although their areal coverage in the study region was only 41% of that of peatland area. Climate warming will presumably increase the carbon gas emission from vegetated littorals. The model-based estimated increase of CO2 production rate in June was 29% and for CH4 emissions as much as 65% for the time interval of 110 years from 1961–1990 to 2071–2100. The results indicate that carbon gas fluxes from aquatic sediments, especially from vegetated littorals, are significant at the landscape level. They are linked to temperature but also to several other interacting factors such as e.g. water and bottom quality and ecosystem composition. Detailed investigation of the overall links between the causes and effects is urgently needed in order to understand and predict the changes caused by warming climate.
  • Iversen, L.L.; Winkel, A.; Baastrup-Spohr, L.; Hinke, A.B.; Alahuhta, J.; Baattrup-Pedersen, A.; Birk, S.; Brodersen, P.; Chambers, P. A.; Ecke, F; Feldmann, T.; Gebler, D.; Heino, J.; Jespersen, T. S.; Moe, S. J.; Riis, T.; Sass, L.; Vestergaard, O.; Maberly, S. C.; Sand-Jensen, K.; Pedersen, O. (American Association for the Advancement of Science, 2019)
    Science Vol. 366, Issue 6467, pp. 878-881
    Unlike in land plants, photosynthesis in many aquatic plants relies on bicarbonate in addition to carbon dioxide (CO2) to compensate for the low diffusivity and potential depletion of CO2 in water. Concentrations of bicarbonate and CO2 vary greatly with catchment geology. In this study, we investigate whether there is a link between these concentrations and the frequency of freshwater plants possessing the bicarbonate use trait. We show, globally, that the frequency of plant species with this trait increases with bicarbonate concentration. Regionally, however, the frequency of bicarbonate use is reduced at sites where the CO2 concentration is substantially above the air equilibrium, consistent with this trait being an adaptation to carbon limitation. Future anthropogenic changes of bicarbonate and CO2 concentrations may alter the species compositions of freshwater plant communities.
  • Niittynen, Pekka; Heikkinen, Risto K.; Luoto, Miska (2020)
    Proceedings of the National Academy of Sciences of the United States of America 117: 35, 21480-21487
    The Arctic is one of the least human-impacted parts of the world, but, in turn, tundra biome is facing the most rapid climate change on Earth. These perturbations may cause major reshuffling of Arctic species compositions and functional trait profiles and diversity, thereby affecting ecosystem processes of the whole tundra region. Earlier research has detected important drivers of the change in plant functional traits under warming climate, but studies on one key factor, snow cover, are almost totally lacking. Here we integrate plot-scale vegetation data with detailed climate and snow information using machine learning methods to model the responsiveness of tundra communities to different scenarios of warming and snow cover duration. Our results show that decreasing snow cover, together with warming temperatures, can substantially modify biotic communities and their trait compositions, with future plant communities projected to be occupied by taller plants with larger leaves and faster resource acquisition strategies. As another finding, we show that, while the local functional diversity may increase, simultaneous biotic homogenization across tundra communities is likely to occur. The manifestation of climate warming on tundra vegetation is highly dependent on the evolution of snow conditions. Given this, realistic assessments of future ecosystem functioning require acknowledging the role of snow in tundra vegetation models.
  • Backman, A. L.; Cleve-Euler, Astrid (Suomen metsätieteellinen seura, 1922)
  • Lindholm, Tapio; Heikkilä, Raimo; Kuznetsov, Oleg (International Mire Conservation Group and International Peatland Society, 2019)
    Mires and Peat 24 (2019), 12, 1–18
    In this article we compile wartime botanical information about mires in Olonets region (Russian Karelia) and compare it with new data collected as part of the Finnish-Russian cooperation in mire research. We also describe the historical background of both the local economy and the visits of Finnish botanists, which date back to the days of the Grand Duchy of Finland and the Russian Empire but were most active during the Second World War. For Finnish mire research, these excursions have allowed important comparisons between the mostly degraded rich fens of southern Finland and largely pristine examples in Olonets region. In the 2000s, 176 vascular plant and 53 moss species, corresponding to 40–50 % of the Karelian mire flora, have been recorded in this area; more than 20 different mire plant communities (associations) have been identified; and one site has been confirmed as the oldest studied mire in East Fennoscandia (12,700 years). The understanding arising from this research is especially important for nature conservation work in the Republic of Karelia.
  • Laine, Anna M.; Lindholm, Tapio; Nilsson, Mats; Kutznetsov, Oleg; Jassey, Vincent E. J.; Tuittila, Eeva-Stiina (John Wiley & Sons Ltd, 2021)
    Journal of Ecology 109, 4 (2021), 1774–1789
    1. Most of the carbon accumulated into peatlands is derived from Sphagnum mosses. During peatland development, the relative share of vascular plants and Sphagnum mosses in the plant community changes, which impacts ecosystem functions. Little is known on the successional development of functional plant traits or functional diversity in peatlands, although this could be a key for understanding the mechanisms behind peatland resistance to climate change. Here we aim to assess how functionality of successive plant communities change along the autogenic peatland development and the associated environmental gradients, namely peat thickness and pH, and to determine whether trait trade-offs during peatland succession are analogous between vascular plant and moss communities. 2. We collected plant community and trait data on successional peatland gradients from post-glacial rebound areas in coastal Finland, Sweden and Russia, altogether from 47 peatlands. This allowed us to analyse the changes in community-weighted mean trait values and functional diversity (diversity of traits) during peatland development. 3. Our results show comparative trait trade-offs from acquisitive species to conservative species in both vascular plant and Sphagnum moss communities during peatland development. However, mosses had higher resistance to environmental change than vascular plant communities. This was seen in the larger proportion of intraspecific trait variation than species turnover in moss traits, while the proportions were opposite for vascular plants. Similarly, the functional diversity of Sphagnum communities increased during the peatland development, while the opposite occurred for vascular plants. Most of the measured traits showed a phylogenetic signal. More so, the species common to old successional stages, namely Ericacae and Sphagna from subgroup Acutifolia were detected as most similar to their phylogenetic neighbours. 4. Synthesis. During peatland development, vegetation succession leads to the dominance of conservative plant species accustomed to high stress. At the same time, the autogenic succession and ecological engineering of Sphagna leads to higher functional diversity and intraspecific variability, which together indicate higher resistance towards environmental perturbations.
  • Pykälä, Juha (Elsevier, 2019)
    Global Ecology and Conservation 18 (2019), e00610
    Why populations of threatened species disappear is among the key questions in conservation biology. However, very few local and regional studies have attempted to quantify the importance of the various causes. In this investigation, the status of the populations of threatened vascular plants, bryophytes and lichens found between the years 1860–1979 in a national biodiversity hot spot in SW Finland was studied during the years 1990–2008. Of the populations, 82% had disappeared and 18% were re-discovered. The disappearance rate of populations differed between habitats: exceeding 80% in most habitat types whilst being lowest on rock outcrops (58%). Complete destruction of all locally suitable habitats was the main reason for the disappearance of the populations (73%) concerned. Habitat deterioration (including partial habitat loss) was identified as the reason for the disappearance for 22% of the populations. Only for 5% of the populations could it not be revealed whether habitat quality had changed or not, but deterioration of habitat quality or habitat loss is possible even in these cases. For none of the disappeared populations was no change in habitat quality verified. In most cases, habitat loss and deterioration were caused by agriculture or forestry. These results support the conclusion that vascular plant, bryophyte and lichen populations in the boreal landscape have disappeared directly because their habitats have disappeared, declined in size or deteriorated due to forestry, agriculture, construction, mining and pollution. More subtle changes in habitat quality, fragmentation, problems related to small population size per se and other reasons may have contributed to only a few disappearances of local populations. The disappearance rate was similar between the study groups, but the relative importance of reasons for disappearance was different. The results emphasize the importance of habitat protection for threatened vascular plants, bryophytes and lichens.
  • Kittamaa, Sanna; Ryttäri, Terhi; Ajosenpää, Terhi; Aapala, Kaisu; Hallman, Erkki; Lehesvirta, Timo; Tukia, Harri (Suomen ympäristökeskus, 2009)
    Suomen ympäristö 25/2009
    Harjumetsien paahdeympäristöt ja niillä elävä erikoistunut ja uhanalaistunut eliölajisto ovat viimeisten vuosikymmenten aikana vähentyneet suuresti muun muassa metsäpalojen loppumisen ja yleisen rehevöitymiskehityksen vuoksi. Harjumetsien paahdeympäristöjen nykytila ja hoito 2006 - 2008 -hankkeessa koottiin kattava harjumetsien metsätaloutta ja suojelua edustava yhteistyöverkosto, johon kuuluivat SYKEn luontoasiantuntijoiden lisäksi Metsätalouden kehittämiskeskus Tapio, 10 metsäkeskusta (2008), Metsähallituksen metsätalous ja luontopalvelut, UPM-Kymmene sekä Helsingin yliopisto. Hankkeessa etsittiin jäljellä olevia, hoitotoimin parannettavia paahde­ympäristöjä ja käynnistettiin niillä sekä hoitotoimia että erilaisia koejärjestelyjä, joiden avulla hoitojen onnistumista voidaan arvioida. Hankkeen aikana inventoitiin yhteensä noin 30 000 hehtaaria harjumetsää, joista suurin osa sijaitsee Natura 2000 -alueilla. Löydettyjen, hoitokohteiksi soveltuvien paahdekohteiden yhteispinta-ala on noin 120 hehtaaria. SYKEn tutkijoiden inventoimalta 14 200 hehtaarin alueelta löydettiin noin 1,7 hehtaaria luonnontilaista tai lähes luonnontilaista paahdekohdetta. Tämä on vain noin 3 % löydetystä 52 hehtaarin paahde­alasta. Täten lähes kaikki inventoinneissa löydetyt kohteet olivat enemmän tai vähemmän umpeenkasvaneita ja niiden tilaa on perusteltua parantaa hoitotoimin. Tulosten perusteella paahdeympäristöjen hoito pystytään toteuttamaan myös kustannustehokkaasti normaalien metsänhoitotoimien ohessa eikä se välttämättä ole ristiriidassa metsätalouden tavoitteiden tai esimerkiksi maisemansuojelun kanssa. Työ on saanut myös sekä maanomistajien että suuren yleisön tuen. Yhteistyöverkosto on ollut aktiivisesti keskusteleva ja se on onnistunut luomaan innostuneen ja kannustavan ilmapiirin ja yhteisön, jonka yhteisenä tavoitteena on ollut ja tulee jatkossakin olemaan uhanalaistuneen harjulajiston pelastaminen.
  • García‐Girón, Jorge; Lindholm, Marja; Heino, Jani; Toivonen, Heikki; Alahuhta, Janne (Wiley, 2022)
    Limnology and Oceanography
    Community ecology has had a strong focus on single snapshots of species compositional variation in time. However, environmental change often occurs slowly at relatively broad spatio-temporal scales, which requires historically explicit assessments of long-term metacommunity dynamics, such as the order of species arrival during community assembly (i.e., priority effects), a theme that merits further empirical quantification. In this study, we applied the Bayesian inference scheme of Hierarchical Modeling of Species Communities together with information on functional traits and evolutionary dependencies to efficiently explore the question of how ecological communities are organized in space and time. To do this, we used a comprehensive time-series dataset from boreal lake plants and adopted the perspective that more sound conclusions on metacommunity dynamics can be gained from studies that consider a historically integrative approach over long timeframes. Our findings revealed that historical contingency via priority effects can profoundly shape community assembly under the influence of environmental change across decades (here, from the 1940s to the 2010s). Similarly, our results supported the existence of both positive and negative species-to-species associations in lake plants, suggesting that functional divergence can switch the inhibition–facilitation balance at the metacommunity level. Perhaps more importantly, this proof-of-concept study supports the notion that community ecology should include a historical perspective and suggests that ignoring priority effects may risk our ability to identify the true magnitude of change in present-day biotic communities.
  • Cockayne, L. (Suomen metsätieteellinen seura, 1929)
  • Aarnio, Pirkko (University of Helsinki, 1992)
  • Tammela, Päivi (University of Helsinki, 1997)
  • Ikonen, Liisa (Helsingin yliopisto, 2019)
    Tutkin tässä pro gradu -tutkielmassani eräiden suomalaisten ruohovartisten kasvilajien ja biohiilen vaikutuksia huleveden määrään ja laatuun. Tutkimuksessa järjestettiin koekasteluita, joiden avulla oli tarkoitus selvittää kasvilajien kykyä vähentää huleveden määrää ja poistaa siitä ravinteita sekä biohiilen vaikutusta huleveden määrään ja laatuun. Kasvillisuuden ja biohiilen vaikutusta on tutkittu aikaisemminkin, mutta erityisesti tiettyihin kasvilajeihin liittyviä tutkimuksia ei ole tehty Suomessa. Tutkimus on osa Luonnonvarakeskuksen Hulevesialueiden kasvit ja kasvualustat (HuleKas) -projektia. Kaupungistuminen lisää talojen, parkkipaikkojen ja teiden rakentamista. Tämä kasvattaa läpäisemättömien pintojen määrää, ja se puolestaan estää veden imeytymisen maan läpi. Kaupungeissa ongelma on ratkaistu rakentamalla hulevesiviemäriverkostoja, mutta erityisesti muuttuva ilmasto lisää sateiden ja sitä kautta huleveden määrää. Rankkasateilla kaupunkien hulevesiviemärit osoittautuvat usein riittämättömiksi. Lisäksi hulevesi huuhtoo epäpuhtaudet kaduilta, ja hulevesi onkin todettu yhdeksi tärkeimmistä hajakuormituksen aiheuttajista. Nyttemmin on kehitetty perinteisten sadevettä pois johtavien viemäriverkostojen rinnalle ekologisempia ja kestävämpiä ratkaisuja. Hulevesi pyritään käsittelemään sen syntysijoilla, ja tähän voidaan päästä rakentamalla erilaisia hulevesirakenteita, kuten hulevesipainanteet tai sadepuutarhat. Hulevesirakenteiden tärkeimmät osat ovat kasvualusta ja kasvillisuus. Hyvällä kasvualustavalinnalla voidaan pidättää mm. fosforin yhdisteitä ja kuparia, kun taas nitraatin pidättyminen vaatii rakennetta peittävää kasvillisuutta ja hapettomia olosuhteita. Kasvillisuuden avulla voidaan myös hidastaa huippuvirtaamia, pidättää kiintoainesta ja poistaa metalleja ja ravinteita hulevedestä. Myös kasvualustan mikrobeilla on tärkeä merkitys ravinteiden sitojina. Tutkimusasetelmani oli astiakoe. Astioihin oli istutettu seitsemää suomalaista luonnon kasvilajia, nurmea ja kontrollina toimivat kasvittomat astiat. Osaan astioista oli lisätty biohiiltä. Tutkimusjakson aikana järjestettiin kolme koekastelua, joissa liuoslannoitteilla lisättyä tekohulevettä kaadettiin jokaiseen astiaan sama määrä. Tämän jälkeen kirjattiin ylös tietyin aikavälein, paljonko vettä astiasta on valunut ulos. Tutkielman aineisto koostuu kahdesta osasta. Ensimmäinen osa muodostuu koekasteluiden valuntatiedoista ja kolmas osa koekasteluiden vesinäytteiden laboratorioanalyyseistä. Parhaita kokonaistypenpidättäjiä olivat viiltosara, jänönsara, korpikaisla, luhtakastikka ja rantatyräkki. Kokonaisfosforin pidätyksessä puolestaan erottuivat viiltosara, korpikaisla, ja rantatyräkki. Kaikki kasvikäsittelyt alensivat tekohuleveden kokonaisfosforin konsentraatiota. Biohiili paransi kaikkien edellä mainittujen kasvilajien ravinteenpidätyskykyä. Myös mikrobitoiminnan merkitys ravinteiden sidonnassa on tärkeä. Eniten vettä koekastelussa käyttivät viiltosara, luhtakastikka sekä jänönsara. Jänönsaran suorituskyky on kiistanalainen johtuen epätasaisesta kastelusta kolmannen jakson aikana. Jaksojen aikaisessa veden käytössä tehokkaina veden käyttäjinä nousevat esiin viiltosara, jänönsara, korpikaisla, luhtakastikka ja rantatyräkki. Kaikki kasvikäsittelyt tuottivat vähemmän valuntaa, kuin kontrolli. Biohiilen avulla voidaan hidastaa valunnan alkamista ja kertymistä.
  • Blomqvist, Soile (University of Helsinki, 1993)