Browsing by Subject "hiili"

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  • Nikinmaa, Eero (The Society of Forestry in Finland - The Finnish Forest Research Institute, 1992)
  • Vihanninjoki, Vesa (Finnish Environment Institute, 2014)
    Reports of the Finnish Environment Institute 41/2014
    Due to the Arctic climate change and the related diminishing of Arctic sea ice cover, the general conditions for Arctic shipping are changing. The retreat of Arctic sea ice opens up new routes for maritime transportation, both trans-Arctic passages and new alternatives within the Arctic region. Hence the amount of Arctic shipping is presumed to increase. Despite the observed development, the sailing conditions in the Arctic waters will remain challenging. Thus particular attention will be required also in the future with regard to crew, fleet and other infrastructural issues. In addition to other apparent challenges and risks, the increase in Arctic shipping will lead to an increased amount of emissions. The increased emissions may have considerable and unpredictable influences to the particularly sensitive Arctic environment. With regard to emission species, especially black carbon is presumed to have climatic sig-nificance within the Arctic context. Black carbon absorbs solar radiation very effectively, and when deposited to snow or sea ice cover, it may notably alter the radiative equilibrium of the Arctic region. The increased Arctic marine activities produce black carbon emissions, whose climate impacts are assessed in this report.
  • Böttcher, Kristin; Paunu, Ville-Veikko; Kupiainen, Kaarle; Zhizhin, Mikhail; Matveev, Alexey; Savolahti, Mikko; Savolahti, Mikko; Klimont, Zbigniew; Väätäinen, Sampsa; Lamberg, Heikki; Karvosenoja, Niko (Elsevier, 2021)
    Atmospheric Environment 254 (2021), 118390
    Gas flaring in the oil and gas industry has been identified as an important source of anthropogenic black carbon (BC) affecting the climate, particularly in the Arctic. Our study provides spatially-explicit estimates of BC emissions from flaring in Russia utilising state-of-the-art methodology for determining the emission factors. We utilised satellite time series of the flared gas volume from Visible Infrared Imaging Radiometer Suite (VIIRS) for the period 2012 to 2017, supplemented with information on the gas and oil field type. BC emissions at flaring locations were calculated based on field type-specific emission factors, taking into account different gas compositions in each field type. We estimate that the average annual BC emissions from flaring in Russia were 68.3 Gg/year, with the largest proportion stemming from oil fields (82%). We observed a decrease in the yearly emissions during the period 2012 to 2017 with regional differences in the trend. Our results highlight the importance of detailed information on gas composition and the stage of oil and gas separation of the flared gas to reduce uncertainties in the BC emission estimates.
  • Luoma, Antti (Helsingin yliopisto, 2018)
    Plantation forestry has increased dramatically in Uruguay during the past 25 years. Thus, planted forests have an increasing importance in providing other ecosystem services in addition to wood provision in landscape scale. Forest sector company UPM owns more than 250 000 hectares of Eucalyptus plantations in Uruguay. UPM seeks to enhance their systems to measure and monitor ecosystem services, to better understand sustainable provision of ecosystem services in their plantation landscapes, and to mitigate negative and maximize positive impacts. Benefits of monitoring and incorporating ecosystem services at management level include strengthened decision-making and communication, license to operate in long-term and better corporate image. Four ecosystem services were selected for analysis based on their relevance in UPM’s corporate strategy: wood provision, climate regulation, water provision and biodiversity maintenance. Provision of the ecosystem services were estimated quantitatively and compared to a pasture land baseline. Provision of ecosystem services was also linked to product level, tonne of pulp, when applicable. Data for the analysis was partly provided by UPM and partly by literature meta-analysis. Climate benefit of converting pasture to Eucalyptus is 8–31 MgC/ha or 29–115 MgCO2/ha depending on species and rotation number. Planting 40% of a micro water-shed with Eucalyptus reduces water streamflow approximately by 20–27%, while reducing streamflow of peak rainfall months by up to 40%, potentially alleviating floods. Pastures in UPM’s landscapes are well connected, but provided little core habitats. Native riparian forests are fragmented and maintain biodiversity poorly. Suggestions for future monitoring and measuring are presented. This thesis works as a waypoint for future studies of holistic ecosystem services provision in UPM assets.
  • Mattsson, Tuija (Finnish Environment Institute, 2010)
    Monographs of the Boreal Environment Research 36
    The terrestrial export of dissolved organic matter (DOM) is associated with climate, vegetation and land use, and thus is under the influence of climatic variability and human interference with terrestrial ecosystems, their soils and hydrological cycles. The present study provides an assessment of spatial variation of DOM concentrations and export, and interactions between DOM, catchment characteristics, land use and climatic factors in boreal catchments. The influence of catchment characteristics, land use and climatic drivers on the concentrations and export of total organic carbon (TOC), total organic nitrogen (TON) and dissolved organic phosphorus (DOP) was estimated using stream water quality, forest inventory and climatic data from 42 Finnish pristine forested headwater catchments, and water quality monitoring, GIS land use, forest inventory and climatic data from the 36 main Finnish rivers (and their sub-catchments) flowing to the Baltic Sea. Moreover, the export of DOM in relation to land use along a European climatic gradient was studied using river water quality and land use data from four European areas. Additionally, the role of organic and minerogenic acidity in controlling pH levels in Finnish rivers and pristine streams was studied by measuring organic anion, sulphate (SO4) and base cation (Ca, Mg, K and Na) concentrations. In all study catchments, TOC was a major fraction of DOM, with much lower proportions of TON and DOP. Moreover, most of TOC and TON was in a dissolved form. The correlation between TOC and TON concentrations was strong and TOC concentrations explained 78% of the variation in TON concentrations in pristine headwater streams. In a subgroup of 20 headwater catchments with similar climatic conditions and low N deposition in eastern Finland, the proportion of peatlands in the catchment and the proportion of Norway spruce (Picea abies Karsten) of the tree stand had the strongest correlation with the TOC and TON concentrations and export. In Finnish river basins, TOC export increased with the increasing proportion of peatland in the catchment, whereas TON export increased with increasing extent of agricultural land. The highest DOP concentrations and export were recorded in river basins with a high extent of agricultural land and urban areas, reflecting the influence of human impact on DOP loads. However, the most important predictor for TOC, TON and DOP export in Finnish rivers was the proportion of upstream lakes in the catchment. The higher the upstream lake percentage, the lower the export, indicating organic matter retention in lakes. Molar TOC:TON ratio decreased from headwater catchments covered by forests and peatlands to the large river basins with mixed land use, emphasising the effect of the land use gradient on the stoichiometry of rivers. This study also demonstrated that the land use of the catchments is related to both organic and minerogenic acidity in rivers and pristine headwater streams. Organic anion dominated in rivers and streams situated in northern Finland, reflecting the higher extent of peatlands in these areas, whereas SO4 dominated in southern Finland and on western coastal areas, where the extent of fertile areas, agricultural land, urban areas, acid sulphate soils, and sulphate deposition is highest. High TOC concentrations decreased pH values in the stream and river water, whereas no correlation between SO4 concentrations and pH was observed. This underlines the importance of organic acids in controlling pH levels in Finnish pristine headwater streams and main rivers. High SO4 concentrations were associated with high base cation concentrations and fertile areas, which buffered the effects of SO4 on pH.
  • Jaale, Marko (Helsingfors universitet, 2007)
    Saaristomeren pinnanalaisen ravintoverkon rakennetta sekä ravinteiden alkuperää ja kulkeutumista tutkittiin hiilen ja typen pysyviä isotooppeja hyväksi käyttäen. Tutkimuksen kohteena olivat suspendoitunut partikkeliaines (SPM), sedimentin pintakerros, pohjaeläimet, kalat ja makrolevät. Näytteitä otettiin toukokuussa, kesäkuussa ja lokakuussa. Ravinnelähteiden arvioinnin ohella tutkittiin voiko sisäsaariston kalankasvatuksen vaikutusta määritellä analysoimalla kalanrehupellettejä. Lisäksi arvioitiin joidenkin lajikohtaisten tai lajien välisten ominaisuuksien erojen vaikutusta (esimerkiksi eläimen koko ja kudosten C:N –suhde rasvapitoisuuden kuvaajana) δ-arvojen määräytymiseen. Myös joitain tarkennuksia tehtiin lajien ravinnonkäyttöluokituksiin. Sisäsaaristossa toukokuussa pian lumien sulamisen aiheuttaman kasvaneen jokivirtaaman jälkeen SPM:stä havaittiin korkeita δ13C- ja δ15N-arvoja (keskimäärin -16 ‰ ja 9 ‰, vastaavasti). Ulkosaariston asemilta saatiin paljon alempia arvoja (-24 ‰ ja 4 ‰, vastaavasti). Sisäsaaristossakin arvot laskivat kesäkuuhun mennessä (-26 ‰ ja 5 ‰, vastaavasti) ollen kuitenkin hieman korkeampia kuin samaan aikaan tutkituilla ulommilla välisaariston asemilla. Kasviplanktonin lajistokoostumusta tutkittiin touko- ja kesäkuussa, mutta suuria eroja ei ajankohtien välillä havaittu. Lokakuussa sateisen loppukesän jälkeen δ13C oli tasainen (-23 ‰ - -24 ‰) koko tutkimusalueella, mutta δ15N oli taas huomattavasti korkeampi sisäsaaristossa (8 ‰) kuin ulkosaaristossa (4 ‰). Päinvastoin kuin yleensä tutkimuksissa on esitetty, tässä tutkimuksessa korkeat δ13C ja/tai δ15N-arvot kuvannevat lisääntynyttä jokien tuomaa terrestristä alkuperää olevaa ravinnekuormaa. Lisäksi kauden aikana suuresti vaihtelevat, mutta silti voimakkaasti korreloivat δ13C ja δ15N indikoivat hiilen ja typen olevan pääosin samaista alkuperää. Kirjallisuudessa ravinnepulssien yhtäaikaisesti korkeat δ13C ja δ15N katsotaan alkuperältään ihmis- tai eläinperäisiksi ja yleensä liitetään karjanlannan käyttöön lannoitteena. Tätä ei kuitenkaan voitu Saaristomerellä osoittaa, koska terrestrisiä ravinnelähteitä ei tutkittu. Kuitenkin muista tunnetuista SPM:n δ-arvoja voimakkaasti muokkaavista tekijöistä voitiin poissulkea ravinnerajoitteisuudesta johtuva fraktionaation muutos sekä synteettisten lannoitteiden käyttö ja kalankasvatus ravinnelähteinä. Pintasedimentistä saatiin paljon tasaisempia δ13C- ja δ15N-arvoja kaikilla näytteenotoilla (keskimäärin -24 ‰ ja 4 ‰, vastaavasti), jotka kuvannevat sedimentoituvan aineksen pitkäaikaisia keskiarvoja. Havaittavissa oli hienoinen laskeva suuntaus kohti ulompia asemia ja monista pohjan lähellä tai sedimentissä elävistä eläimistä saatiin samaan tapaan laskevia arvoja. SPM:n vaihtelevat ja eläinten δ-arvot korreloivat heikosti lukuunottamatta joitakin suspensionsyöjiä (Balanus improvisus ja Mytilus edulis). δ13C ja C:N korreloivat negatiivisesti joillakin lajeilla (Macoma balthica, Monoporeia affinis ja Mytilus edulis), joka johtunee muuttuvasta rasvojen osuudesta kudoksissa. Ainakin näiden lajien käyttöön ravinnelähteiden arvioinnissa kannattaa suhtautua varauksella. Makrolevien δ15N oli n. 4 ‰ korkeampi sisäsaaristossa kuin ulommilla asemilla, joka myöskin heijastanee jokien tuoman terrestristä alkuperää olevien ravinteiden vaikutusta. Fucus vesiculosus, tutkimuksen ainut varsinainen monivuotinen levä, sai 6 ‰ korkeampia δ13C-arvoja kuin muut levät keskimäärin. Gammarus sp:n Idothea baltican δ15N seurasi makrolevien δ15N:n vaihtelua, mutta δ13C:n perusteella arvioituna ne suosivat rehevöitymisen seurauksena runsastuvia rihmaleviä sisäsaaristossa, kun taas F. vesiculosus näytti kasvattavan tärkeyttä ravintona ulkosaaristossa. Hiilen ja typen pysyvät isotoopit osoittautuivat tehokkaiksi työkaluiksi ravinteiden lähteiden ja kulkeutumisen tarkasteluissa erityisesti sisäsaaristossa, vaikkakin joitakin lajikohtaisia piirteitä on otettava huomioon ja joidenkin biologisten prosessien, kuten denitrifikaation osuus fraktionaation aiheuttajana pitäisi määrittää ennen kuin luotettavia arvioita ravinnelähteistä voidaan tehdä.
  • Kärppä, Mai (Helsingin yliopisto, 2020)
    Arctic peatlands are globally extensive and long-lasting storages of carbon and are therefore important ecosystems controlling global carbon cycling. Changes in climate affect peatlands’ ability to accumulate carbon through changes in hydrology and water table level, vegetation, soil temperature and permafrost thaw. As climate warming is projected mostly to northern and arctic regions, it may change the peatlands’ capacity to sequester and release carbon as carbon dioxide and methane. In this Master’s Thesis I studied how the past climate changes are reflected in carbon accumulation rates over the past millennia. Known climate anomalies, such as the Medieval Climate Anomaly, Little Ice Age and the last rapid warming starting from 1980, and their impact on average long-term apparent rate of carbon accumulation were studied from the peat proxies. 15 peat cores were collected from northern subarctic Swedish Lapland and from North-East European Russia. Cores were collected from the active peat layer above permafrost that is known to be sensitive to climate warming. Cores were dated with radiocarbon (14C) and lead (210Pb) methods and peat properties and accumulation patterns were calculated for one centimeter thick subsamples based on chronologies. The Little Ice Age and the last rapid warming affected the carbon accumulation rate considerably whereas for Medieval Climate Anomaly period the peat records did not show very distinctive response. During the Little Ice Age the carbon accumulation rates were low (median 10,5 g m-2v-1) but during the post-Little Ice Age and especially during the last warm decades after 1980 carbon accumulation rates have been high (median 48,5 g m-2v-1). Medieval Climate Anomaly had only a minor positive effect on accumulation rates. On average, the long-term apparent rate of carbon accumulation during the past millennia was 43,3 g m-2v-1 which is distinctly higher than the previously studied rate of 22,9 g m-2v-1 for northern peatlands (p-value 0,0003). Based on results it can be concluded that warm climate periods accelerated the carbon accumulation rate whereas during cold periods accumulation decelerated. Warm climate prolongs the growth period and accelerates the decomposition of peat; cold climate shortens the period of plant growth and thickens the permafrost layer in peatlands, respectively. However, peat layers that are formed after the Little Ice Age are incompletely decomposed which amplifies the carbon accumulation rate partly. Nevertheless, permafrost thawing has been shown to increase accumulation rates, as well. Studying past carbon accumulation rates helps to understand the peatland and carbon cycling dynamics better. Even though accumulation rates reveal a lot about carbon sequestration capabilities of peat, it does not indicate whether a peatland has been a carbon sink or a source.
  • Salminen, Eero-Matti (Helsingfors universitet, 2012)
    The purpose of this study was to examine the integrated climatic impacts of forestry and the use fibre-based packaging materials. The responsible use of forest resources plays an integral role in mitigating climate change. Forests offer three generic mitigation strategies; conservation, sequestration and substitution. By conserving carbon reservoirs, increasing the carbon sequestration in the forest or substituting fossil fuel intensive materials and energy, it is possible to lower the amount of carbon in the atmosphere through the use of forest resources. The Finnish forest industry consumed some 78 million m3 of wood in 2009, while total of 2.4 million tons of different packaging materials were consumed that same year in Finland. Nearly half of the domestically consumed packaging materials were wood-based. Globally the world packaging material market is valued worth annually some €400 billion, of which the fibre-based packaging materials account for 40 %. The methodology and the theoretical framework of this study are based on a stand-level, steady-state analysis of forestry and wood yields. The forest stand data used for this study were obtained from Metla, and consisted of 14 forest stands located in Southern and Central Finland. The forest growth and wood yields were first optimized with the help of Stand Management Assistant software, and then simulated in Motti for forest carbon pools. The basic idea was to examine the climatic impacts of fibre-based packaging material production and consumption through different forest management and end-use scenarios. Economically optimal forest management practices were chosen as the baseline (1) for the study. In the alternative scenarios, the amount of fibre-based packaging material on the market decreased from the baseline. The reduced pulpwood demand (RPD) scenario (2) follows economically optimal management practices under reduced pulpwood price conditions, while the sawlog scenario (3) also changed the product mix from packaging to sawnwood products. The energy scenario (4) examines the impacts of pulpwood demand shift from packaging to energy use. The final scenario follows the silvicultural guidelines developed by the Forestry Development Centre Tapio (5). The baseline forest and forest product carbon pools and the avoided emissions from wood use were compared to those under alternative forest management regimes and end-use scenarios. The comparison of the climatic impacts between scenarios gave an insight into the sustainability of fibre-based packaging materials, and the impacts of decreased material supply and substitution. The results show that the use of wood for fibre-based packaging purposes is favorable, when considering climate change mitigation aspects of forestry and wood use. Fibre-based packaging materials efficiently displace fossil carbon emissions by substituting more energy intensive materials, and they delay biogenic carbon re-emissions to the atmosphere for several months up to years. The RPD and the sawlog scenarios both fared well in the scenario comparison. These scenarios produced relatively more sawnwood, which can displace high amounts of emissions and has high carbon storing potential due to the long lifecycle. The results indicate the possibility that win-win scenarios exist by shifting production from pulpwood to sawlogs; on some of the stands in the RPD and sawlog scenarios, both carbon pools and avoided emissions increased from the baseline simultaneously. On the opposite, the shift from packaging material to energy use caused the carbon pools and the avoided emissions to diminish from the baseline. Hence the use of virgin fibres for energy purposes, rather than forest industry feedstock biomass, should be critically judged if optional to each other. Managing the stands according to the silvicultural guidelines developed by the Forestry Development Centre Tapio provided the least climatic benefits, showing considerably lower carbon pools and avoided emissions. This seems interesting and worth noting, as the guidelines are the current basis for the forest management practices in Finland.
  • Arppe, Laura (University of Helsinki, 2009)
    Publications of the Department of Geology. D.
  • Launonen, Erno (Helsingin yliopisto, 2015)
    Because of European unions goals, direction of Finnish energy politics has been the increase of renewable energy. Stump harvesting has been in focus, because it is thought to be carbon neutral. Using stumps for energy has increased through the 2000s. It is better to harvest stumps than tree crowns, for they contain a lot of nutrients in the needles. On the other hand leaving stumps on the site will let them slowly decompose, and as they also collect nutrients they can decrease leaching. This study aimed to determine the long term effects of stump harvesting on soil disturbance and carbon and nitrogen storage. Study areas are in central Finland, where in 2013 there had been 9-13 years since stump harvesting. Soil surface disturbance was estimated both visually and with the point frequency method based on soil samples. For determination of soil carbon and nitrogen content there was a systematic line-assessment, where the soil samples were taken and divided to full 5cm layers that were dried and sieved. Carbon and nitrogen content and soil pH was analysed. Statistical analysis was made with variance analysis. Soil pH was between 4,2 and 5. At Honkola and Haukilahti in the stump harvesting areas the share of undisturbed soil surface was between 59-65% and where there was no stump harvesting this share was significantly larger, between 70-77%. The share of mounds was 18-23% in stump harvesting areas and where there was no stump harvesting 13-17%. Pits accounted for 15-17% in stump harvesting areas and where there was no stump harvesting 6-14%. The point frequency determination at one meter intervals was the best practical method for estimating soil surface disturbance.
  • Mickwitz, Per; Seppälä, Jyri; Kauppi, Lea; Hildén, Mikael (Suomen ympäristökeskus, 2014)
    SYKE Policy Briefs
  • Jokinen, Henri (Helsingin yliopisto, 2019)
    Dead wood includes everything between small branches and large trunks. Dead wood is created by abiotic and biotic factors like wind, lightning, competition and diseases. The amount of dead wood in Finland varies significantly between managed and natural forests. Approximately 50 % of the biomass of dead wood is carbon and thus dead wood is a notable carbon storage. Carbon may remain in dead wood for decades after the tree death. The amount of nitrogen in dead wood is small and it increases when the decay process proceeds. The aim of this study was to research the amount and quality of dead wood near the SMEAR II -station. The study also examined how the amount of carbon and nitrogen in dead wood varies between tree species and decay classes. Dead wood measurements were done at the ICOS-plots (24 pcs.) near the SMEAR II -station. At every plot there was a measurement area of 60 m2 where every piece of dead wood at the diameter of 2 cm or more was measured. Only dead wood inside the measurement area was measured. The length and top and down diameters of downed dead wood were measured. In case of standing dead wood the length and diameter at breast height were measured. The height and top diameter of stumps were measured as well. The decay class and appearance of dead wood were determined according to national forest inventory´s criteria. Based on the measurements the amount of dead wood at the plots and the whole area was calculated. Dead wood samples were taken from the plots. The samples were dried, milled and their carbon and nitrogen concentrations were analysed. The study revealed that the amount of dead wood in the study area is larger than in managed forests on average. Downed dead wood was the most common dead wood type while standing dead wood was the rarest type. The number of stumps was quite large. The most common species were Scots pine, Norway spruce and birch. The amount of dead wood varied significantly between the plots. The concentration of carbon in dead wood was on average 49 % and there were no differences between tree species and decay classes. The concentration of nitrogen was on average 0,8 % which is relatively high compared to other studies, and the concentration increased with increased decaying. There was a significant variation on nitrogen concentration between decay classes but not between tree species. This study supports other studies´ results that dead wood has an important role on carbon and nitrogen cycling in the forest.
  • Kramarenko, Dmitri (Helsingfors universitet, 2012)
    In the carbon cycle carbon is sequestrated from the atmosphere through photosynthesis in vegetation, returned into soils as litter and released into atmosphere in decomposition as carbon dioxide. In the boreal zone a large proportion of the organic carbon is bound into soil. The aim of this study was to find out how the amount of soil organic carbon (SOC) has changed in Finnish forests in last 20 years by comparing results of empirical measurements from two projects (1986-1995 and 2006). The purpose of the study was also to analyze how well the field measurements of SOC collected in two consecutive periods of time are suitable for characterization of changes in the SOC stock. The effect of soil structure, vegetation type and climatic factors on possible SOC changes were also studied. The average size of SOC stock (organic layer + mineral layer 0-40cm) in Finnish forests is 5.65 kg C m-2. About one third of SOC is in the organic layer (2.10 kg C m-2) and the rest of it is in the mineral soil (3.56 kg C m-2 ). Higher amount of SOC stock in the organic layer has been determined on plots with thicker organic layer, poor drainage and the presence of peat mosses. Higher amount of SOC in the mineral layer has been measured on plots which have a more southerly location, lower stoniness and high proportion of fine textures. Coefficients of determination in General Linear Models were between 23-61%. The average annual change of SOC (organic layer + mineral layer 0-40 cm) is +33.9 g C m-2a-1. Change in the organic layer has been +11.4 g C m-2a-1 and in the mineral soil +22.5 g C m-2a-1. The accumulation of organic carbon into the organic layer is positively correlated with the thickness of the organic layer, the southern location, pine dominance in tree layer and the age of the trees, while in the mineral soil higher carbon accumulation occurs in less stony soils and in more southern locations. Coefficients of determination in General Linear Models describing the change in SOC were low, between 11-14%. The largest positive or negative changes in SOC are in plots where the depth of the organic layer measured in two successive measurements was very different. Also, the differences in the measurements of SOC were large if the plots were drained, divided to two different sections or plots were excessively moist. Climate change and higher temperature will probably affect soil carbon sequestration positively, forecasted by using the results of the south-north gradient in which more carbon was accumulated into the soils of southern Finland. Soil monitoring research should be developed by using precise sampling methods and establishing permanent instructions for field work in order to avoid additional sources of error and to minimize variation.
  • Bergroth, F.G. (J. Simeliuksen perillisten kirjapaino, 1885)
    Suomen metsäyhdistyksen kirjasia;3
  • Lippu, Jukka (The Finnish Society of Forest Science and The Finnish Forest Research Institute, 1994)
    Changes in dry matter partitioning, 14C-incorporation, and sink 14C-activity of 1.5-year-old Scots pine (Pinus sylvestris L.) seedlings grown in growth chamber conditions were studied during a 91-day experiment. On five sampling dates, seedlings were labeled with 14CO2, and whole-plant allocation patterns were determined. Intensively growing shoots modified the dry matter partitioning: during shoot growth the proportion of roots decreased but after that it increased. Based on their large proportion of dry matter, the needles (excluding current needles) were the strongest sink of carbon containing 40% of the incorporated 14C. Despite their small initial sink size, the elongating shoots (current main shoot + current branch) and their needles were the second strongest sink (30–40% of the total 14C) which reflects their high physiological activity. The proportion of 14C in the current year’s main shoot increased during shoot growth but decreased as the growth began to decline after 70 days. 10–20% of the total assimilated 14C was translocated to the roots. Laterals above 2nd order were the strongest sink in the root system, containing twice as much 14C as the other roots together. Alternation between shoot and root growth can be seen clearly: carbon allocation to roots was relatively high before and after the period of intensive shoot growth. Changes in root sink strength resulted primarily from changes in root sink activity rather than sink size.
  • Salmi, Jouko (University of Helsinki, 1987)
  • Immonen, Peter (Helsingin yliopisto, 2020)
    Maaperän fysikaaliset, kemialliset ja biologiset ominaisuudet tarjoavat lukuisia ekosysteemipalveluja, joista erityisesti haitallisten yhdisteiden, mukaan lukien hiilidioksidin, sidonta on saanut paljon huomiota ilmastonmuutosta hillitsevän potentiaalinsa tähden. Orgaanisten ja epäorgaanisten yhdisteiden varastointi on tärkeää etenkin kaupungeissa, jotka kuuluvat suurimpiin kasvihuonekaasujen päästölähteisiin. Kaupunkien vihermaat kuuluvat tehokkaimpiin sitojiin runsaiden orgaanisen aineen varantojensa ansiosta, minkä lisäksi ne tuottavat useita muita paikallisia ekosysteemipalveluja sekä toimivat virkistysalueina. Vihermaat vähenevät kuitenkin jatkuvan rakentamisen vuoksi, kun niitä peitetään esimerkiksi asfaltilla ja mukulakivillä, minkä seurauksena myös pinnoitetun kaupunkimaaperän merkitystä on alettu tutkia. Selvitysten mukaan pinnoitettu maa on hiili- ja typpivarannoiltaan selkeästi pinnoittamattomia vihermaita niukempi, mikä johtuu fyysisen esteen rajoittavasta vaikutuksesta kaasujenvaihtoon ja veden läpäisyyn. Lisäksi hiilen (C) ja typen (N) sidonnassa ja ravinnekierrossa olennainen pintamaa poistetaan ja korvataan C:n ja N:n osalta niukemmalla rakennusmaalla. On tärkeää selvittää, kuinka nämä muutokset vaikuttavat kaupunkimaaperän kykyyn sitoa ilmakehän hiiltä ja haitallisia yhdisteitä ja ylläpitää ainekiertoja. Tutkimuksessani tarkastelin pinnoitetun kaupunkimaan ominaisuuksia Helsingissä, sillä Suomen kaltaisilla kylmillä alueilla tutkimukseen perustuvaa tietoa ei käytännössä ole. Tätä varten keräsin maanäytteen 11 katutyöojasta kahdelta eri syvyydeltä rakennusmaasta. Näytteistä mitattiin kokonaishiili ja –typpi, hiilen ja typen suhdeluku (C/N), orgaanisen aineen määrä, kosteusprosentti, pH, maahengitys ja tiheys (engl. bulk density). Vertailin maan ominaisuuksia syvyyksien, pinnoitetun ja pinnoittamattoman maan sekä kylmien ja lämpimämpien alueiden välillä, minkä lisäksi laskin tulosten perusteella pinnoitetun ja pinnoittamattoman maan C- ja N-varastot Helsingin keskustassa sekä pinnoitteen osuuden maa-alasta. Aikaisempien tutkimusten perusteella laadin 3 hypoteesia: 1) Pinnoitetun maan C- ja N-pitoisuudet ovat selkeästi pienempiä pinnoittamattomaan maahan nähden. 2) Pinnoitetussa maassa C- ja N-pitoisuuksien erot kahden syvyyden välillä ovat tasaisemmat kuin pinnoittamattomassa maassa, sillä C- ja N-rikas pintamaa on vaihdettu niukempaan rakennusmaahan ja pinnoite estää karikkeen tuomaa C:tä ja N:ä kulkeutumasta ja keskittymästä pintamaahan. 3) Kylmillä alueilla pinnoitteen aiheuttama C- ja N-hävikki on suurempi kuin lämpimämmillä alueilla paksumman rakennusmaakerroksen vuoksi. Odotusten mukaisesti 1) pinnoitetun maan C- ja N-pitoisuudet olivat pienemmät kuin pinnoittamattomassa maassa, 2) pinnoitetun maan C- ja N-pitoisuudet pysyivät tasaisina eri syvyyksillä verrattuna pinnoittamattomaan maahan ja 3) Helsingin C- ja N-hävikki on suurempi verrattuna aiempiin tutkimustuloksiin lämpimämmistä maista. Kaikkien kolmen tarkastelukohdan tulokset ovat yhdistettävissä maanvaihdon ja pinnoituksen aiheuttamiin muutoksiin. Muidenkin muuttujien tulokset vastasivat kirjallisuuden luomia ennakkokäsityksiä. Helsingin C- ja N-varastot ovat myös huomattavasti pienentyneet pinnoitteen lisäännyttyä, mikä heikentää kaupungistuneiden alueiden ekosysteemipalvelupotentiaalia. Tulokset vahvistavat oletuksia pinnoitteen tuomista muutoksista maaperän sitomiskykyyn sekä yleisesti että verrattaessa kylmiä ja lämpimämpiä alueita keskenään.
  • Karjalainen, Timo; Kellomäki, Seppo; Pussinen, Ari (The Finnish Society of Forest Science and The Finnish Forest Research Institute, 1994)
    The amount of carbon (C) stored in wood products manufactured in Finland was calculated with the help of a model using wood harvesting statistics, product flows and lifespans in order to study how much C could be set aside from the atmospheric C cycle outside the forest ecosystem. The calculations showed that on the average 9.9 Tg C/a was in harvested timber in 1986–1991 in Finland. C emissions of timber harvest and transport were 0.1 Tg C/a. In production processes about one third of the C bound in timber was released into the atmosphere, but two thirds was still bound in products. After 50 and 100 years, more than 40% and 33% of the C initially in products was either in products still in use or disposed to landfills. The wood product C storage was most sensitive to landfill decay rate and to the burning of abandoned products for energy, but not to the same extent to the length of the lifespan of products.
  • Rantakari, Miitta (Finnish Environment Institute, 2010)
    Monographs of the Boreal Environment Research 35
    Lakes are an important component of ecosystem carbon cycle through both organic carbon sequestration and carbon dioxide and methane emissions, although they cover only a small fraction of the Earth’s surface area. Lake sediments are considered to be one of the rather permanent sinks of carbon in boreal regions and furthermore, freshwater ecosystems process large amounts of carbon originating from terrestrial sources. These carbon fluxes are highly uncertain especially in the changing climate.The present study provides a large-scale view on carbon sources and fluxes in boreal lakes situated in different landscapes. We present carbon concentrations in water, pools in lake sediments, and carbon gas (CO2 and CH4) fluxes from lakes. The study is based on spatially extensive and randomly selected Nordic Lake Survey (NLS) database with 874 lakes. The large database allows the identification of the various factors (lake size, climate, and catchment land use) determining lake water carbon concentrations, pools and gas fluxes in different types of lakes along a latitudinal gradient from 60oN to 69oN.Lakes in different landscapes vary in their carbon quantity and quality. Carbon (C) content (total organic and inorganic carbon) in lakes is highest in agriculture and peatland dominated areas. In peatland rich areas organic carbon dominated in lakes but in agricultural areas both organic and inorganic C concentrations were high. Total inorganic carbon in the lake water was strongly dependent on the bedrock and soil quality in the catchment, especially in areas where human influence in the catchment is low. In inhabited areas both agriculture and habitation in the catchment increase lake TIC concentrations, since in the disturbed soils both weathering and leaching are presumably more efficient than in pristine areas.TOC concentrations in lakes were related to either catchment sources, mainly peatlands, or to retention in the upper watercourses. Retention as a regulator of the TOC concentrations dominated in southern Finland, whereas the peatland sources were important in northern Finland. The homogeneous land use in the north and the restricted catchment sources of TOC contribute to the close relationship between peatlands and the TOC concentrations in the northern lakes. In southern Finland the more favorable climate for degradation and the multiple sources of TOC in the mixed land use highlight the importance of retention.Carbon processing was intensive in the small lakes. Both CO2 emission and the Holocene C pool in sediments per square meter of the lake area were highest in the smallest lakes. However, because the total area of the small lakes on the areal level is limited, the large lakes are important units in C processing in the landscape. Both CO2 and CH4 concentrations and emissions were high in eutrophic lakes. High availability of nutrients and the fresh organic matter enhance degradation in these lakes. Eutrophic lakes are often small and shallow, enabling high contact between the water column and the sediment. At the landscape level, the lakes in agricultural areas are often eutrophic due to fertile soils and fertilization of the catchments, and therefore they also showed the highest CO2 and CH4 concentrations. Export from the catchments and in-lake degradation were suggested to be equally important sources of CO2 and CH4 in fall when the lake water column was intensively mixed and the transport of substances from the catchment was high due to the rainy season. In the stagnant periods, especially in the winter, in-lake degradation as a gas source was highlighted due to minimal mixing and limited transport of C from the catchment.The strong relationship between the annual CO2 level of lakes and the annual precipitation suggests that climate change can have a major impact on C cycling in the catchments. Increase in precipitation enhances DOC export from the catchments and leads to increasing greenhouse gas emissions from lakes. The total annual CO2 emission from Finnish lakes was estimated to be 1400 Gg C a-1. The total lake sediment C pool in Finland was estimated to be 0.62 Pg, giving an annual sink in Finnish lakes of 65 Gg C a-1.