Sari Juutinen

Sari Juutinen
University of Eastern Finland | UEF · Department of Geographical and Historical Studies

PhD

About

69
Publications
14,361
Reads
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2,409
Citations
Additional affiliations
September 2015 - present
University of Helsinki
Position
  • Researcher
October 2007 - April 2010
Mount Holyoke College
Position
  • PostDoc Position

Publications

Publications (69)
Article
Full-text available
Arctic tundra is facing unprecedented warming, resulting in shifts in the vegetation, thaw regimes, and potentially in the ecosystem–atmosphere exchange of carbon (C). However, the estimates of regional carbon dioxide (CO2) and methane (CH4) budgets are highly uncertain. We measured CO2 and CH4 fluxes, vegetation composition and leaf area index (LA...
Preprint
The subarctic landscape consists of a mosaic of forest, peatland and aquatic ecosystems and their ecotones. The carbon (C) exchange between ecosystems and the atmosphere through carbon dioxide (CO2) and methane (CH4) fluxes varies spatially and temporally among these ecosystems. Our study area in Kaamanen in northern Finland covering 7 km2 of borea...
Preprint
Arctic tundra is facing unprecedented warming, resulting in shifts in the vegetation, thaw regimes, and potentially in the ecosystem-atmosphere exchange of carbon (C). The estimates of regional carbon dioxide (CO2) and methane (CH4) budgets, however, are highly uncertain. We measured CO2 and CH4 fluxes, vegetation composition and leaf area index (L...
Article
Full-text available
Methane emissions from boreal and arctic wetlands, lakes, and rivers are expected to increase in response to warming and associated permafrost thaw. However, the lack of appropriate land cover datasets for scaling field-measured methane emissions to circumpolar scales has contributed to a large uncertainty for our understanding of present-day and f...
Preprint
Full-text available
Methane emissions from boreal and arctic wetlands, lakes, and rivers are expected to increase in response to warming and associated permafrost thaw. However, the lack of appropriate land cover datasets for scaling field-measured methane emissions to circumpolar scales has contributed to a large uncertainty for our understanding of present-day and f...
Article
Full-text available
A Correction to this paper has been published: https://doi.org/10.1038/s41558-021-00991-1.
Article
Full-text available
The patterned microtopography of subarctic mires generates a variety of environmental conditions, and carbon dioxide (CO2) and methane (CH4) dynamics vary spatially among different plant community types (PCTs). We studied the CO2 and CH4 exchange between a subarctic fen and the atmosphere at Kaamanen in northern Finland based on flux chamber and ed...
Article
Full-text available
The carbon balance of peatlands is predicted to shift from a sink to a source this century. However, peatland ecosystems are still omitted from the main Earth system models that are used for future climate change projections, and they are not considered in integrated assessment models that are used in impact and mitigation studies. By using evidenc...
Article
High latitude peatlands act as globally important carbon (C) sinks and are in constant interaction with the atmosphere. Their C storage formed during the Holocene. In the course of time, the aggregate effect of the C fluxes on radiative forcing (RF) typically changes from warming to cooling, but the timing of this shift varies among different peatl...
Preprint
Full-text available
The patterned microtopography of subarctic mires generates a variety of environmental conditions, and carbon dioxide (CO2) and methane (CH4) dynamics vary spatially among different plant community types. We studied the CO2 and CH4 exchange between a subarctic fen and the atmosphere at Kaamanen in northern Finland based on flux chamber and eddy cova...
Article
Full-text available
There is fine-scale spatial heterogeneity in key vegetation properties including leaf-area index (LAI) and biomass in treeless northern peatlands, and hyperspectral drone data with high spatial and spectral resolution could detect the spatial patterns with high accuracy. However, the advantage of hyperspectral drone data has not been tested in a mu...
Article
Rotifers are among the smallest metazoan animals living in lakes, ponds, rivers and in interstitial water within Sphagnum mats. When in sufficient numbers they are capable of regenerating large amounts of nitrogen (N) as NO3 and NH4 and phosphorus (P) as PO4; all of these nutrients are immediately available to bog plants. The ecological role of rot...
Article
Full-text available
Lakes account for about 10% of the boreal landscape and are responsible for approximately 30% of biogenic methane emissions that have been found to increase under changing climate. However, the quantification of this climate-sensitive methane source is fraught with large uncertainty under warming climate conditions. Only a few studies have addresse...
Article
Full-text available
Within northern peatlands, landscape elements such as vegetation and topography are spatially heterogenic from ultra‐high (centimeter level) to coarse scale. In addition to within‐site spatial heterogeneity, there is evident between‐site heterogeneity, but there is a lack of studies assessing whether different combinations of remotely sensed featur...
Article
Full-text available
Estimates of regional and global freshwater N2O emissions have remained inaccurate due to scarce data and complexity of the multiple processes driving N2O fluxes the focus predominantly being on summer time measurements from emission hot spots, agricultural streams. Here we present four‐season data of N2O concentrations in the water columns of rand...
Article
How to map floristic variation in a patterned fen in an ecologically meaningfully way? Can plant communities be delineated with species data generalized into plant functional types? What are the benefits and drawbacks of the two selected remote‐sensing approaches in mapping vegetation patterns, namely: (a) regression models of floristically defined...
Article
Remote sensing based biomass estimates in Arctic areas are usually produced using coarse spatial resolution satellite imagery, which is incapable of capturing the fragmented nature of tundra vegetation communities. We mapped aboveground biomass using field sampling and very high spatial resolution (VHSR) satellite images (QuickBird, WorldView-2 and...
Article
Full-text available
Arctic tundra ecosystems will play a key role in future climate change due to intensifying permafrost thawing, plant growth and ecosystem carbon exchange, but monitoring these changes may be challenging due to the heterogeneity of Arctic landscapes. We examined spatial variation and linkages of soil and plant attributes in a site of Siberian Arctic...
Article
Full-text available
Peatlands cover a large area in Canada and globally (12% and 3% of the landmass, respectively). These ecosystems play an important role in climate regulation through the sequestration of carbon dioxide from, and the release of methane to, the atmosphere. Monitoring approaches, required to understand the response of peatlands to climate change at la...
Article
Full-text available
Peatlands are globally significant sources of atmospheric methane (CH4). While several studies have examined the effects of nutrient addition on CH4dynamics, there are few long-term peatland fertilization experiments, which are needed to understand the aggregated effects of nutrient deposition on ecosystem functioning. We investigated responses of...
Article
Full-text available
Arctic tundra ecosystems will have a key role in future climate change due to intensifying permafrost thawing, plant growth and ecosystem carbon exchange, but monitoring these changes may be challenging due to the heterogeneity of Arctic landscapes. We examined spatial variation and linkages of soil and plant attributes in a site of Siberian Arctic...
Article
Full-text available
Wetlands are one of the most significant natural sources of methane (CH4) to the atmosphere. They emit CH4 because decomposition of soil organic matter in waterlogged anoxic conditions produces CH4, in addition to carbon dioxide (CO2). Production of CH4 and how much of it escapes to the atmosphere depend on a multitude of environmental drivers. Mod...
Article
Full-text available
Vegetation in the arctic tundra typically consists of a small-scale mosaic of plant communities, with species differing in growth forms, seasonality, and biogeochemical properties. Characterization of this variation is essential for understanding and modeling the functioning of the arctic tundra in global carbon cycling, as well as for evaluating t...
Article
Full-text available
Wetlands are one of the most significant natural sources of methane (CH4) to the atmosphere. They emit CH4 because decomposition of soil organic matter in waterlogged anoxic conditions produces CH4, in addition to carbon dioxide (CO2). Production of CH4 and how much of it escapes to the atmosphere depend on a multitude of environmental drivers. Mod...
Article
Minerotrophic fens and ombrotrophic bogs differ in their nutrient status, hydrology, vegetation and carbon dynamics, and their geographical distribution is linked to various climate parameters. Currently, bogs dominate the northern temperate and southern boreal zones but climate warming may cause a northwards shift in the distribution of the bog zo...
Article
Full-text available
Previousstudies have shown that atmospheric nitrogen (N) deposition is detrimental to sphagna, which are a group of mosses that are important for carbon cycling in northern peatlands. Little is known about species interactions, such as relative responses of tall mossPolytrichum strictumMenzies ex Brid. and sphagna. We studied the effects of N depos...
Article
Full-text available
Sedges (Cyperaceae) are dominant plants in many northern wetlands and contribute to the carbon cycling in several ways. In order to more accurately estimate the carbon balance of a wetland it is essential to be able to simulate the temporal changes of the leaf area of the sedges. Our aim was to test the ability of a simple carbon dioxide (CO2) exch...
Article
Full-text available
Nitrogen (N) pollution of peatlands alters their carbon (C) balances, yet long-term effects and controls are poorly understood. We applied the model PEATBOG to explore impacts of long-term nitrogen (N) fertilization on C cycling in an ombrotrophic bog. Simulations of summer gross ecosystem production (GEP), ecosystem respiration (ER) and net ecosys...
Article
Full-text available
Three-dimensional reconstructions of peatland development patterns, carbon (C) dynamics and the related radiative forcing (RF) were analyzed to improve understanding of peatland-climate feedback mechanisms. We investigated vertical and horizontal peat growth patterns of a subarctic fen (Lompolojankka) located in Finnish Lapland. We calculated C acc...
Article
Full-text available
Nitrogen (N) pollution of peatlands alters their carbon (C) balances, yet long-term effects and controls are poorly understood. We applied the model PEATBOG to analyze impacts of long-term nitrogen (N) fertilization on C cycling in an ombrotrophic bog. Simulations of summer gross ecosystem production (GEP), ecosystem respiration (ER) and net ecosys...
Conference Paper
Background/Question/Methods Atmospheric nitrogen (N) deposition is increasing owing to fossil fuel burning and agriculture. In nutrient-limited peatland ecosystems, the excess of reactive N has been found to increase vascular plant growth, but decrease Sphagnum growth. Higher vascular plant abundance and higher nutrient content alter decomposabil...
Article
To study vegetation feedbacks of nutrient addition on carbon sequestration capacity, we investigated vegetation and ecosystem CO2 exchange at Mer Bleue Bog, Canada in plots that had been fertilized with nitrogen (N) or with N plus phosphorus (P) and potassium (K) for 7-12 years. Gross photosynthesis, ecosystem respiration and net CO2 exchange were...
Article
The role of lakes in landscape carbon (C) cycling and primary drivers behind freshwater C balance have remained poorly known, although lakes are an important landscape component and cover 10% of Finland's total area. We studied CO2 evasion and average Holocene C accumulation in 82 boreal lakes (0.04–1540 km2; max depth 1–93 m) located between the l...
Article
While regional and global estimates for carbon dioxide (CO2) and methane (CH4) emission from lakes are presently available, nitrous oxide (N2O) evasion from lakes and streams and the primary drivers regulating the fluxes have remained poorly studied. Freshwater N2O data are scarce and mostly based on short term measurements from a few lakes/rivers....
Article
Northern forests and peatlands are globally significant elements in carbon (C) cycling. Recent research has also highlighted the role of aquatic ecosystems in landscape C budgets. We measured contemporary carbon dioxide (CO2) and methane (CH4) exchange, lateral C transfer (dissolved organic carbon (DOC), CO2, CH4), and long-term C accumulation in a...
Article
Full-text available
Model validation experiments are fundamental to ensure that the peat growth models correspond with the diversity in nature. We evaluated the Holocene Peatland Model (HPM) simulation against the field observations from a chronosequence of peatlands and peat core data. The ongoing primary peatland formation on the isostatically rising coast of Finlan...
Article
Peatlands store about a third of global soil carbon. Our aim was to study whether the vegetation feedbacks of nitrogen (N) deposition lead to stronger carbon sink or source in a nutrient limited peatland ecosystem. We investigated vegetation structure and ecosystem CO2 exchange at Mer Bleue Bog, Canada, that has been fertilized for 7-12 years. We h...
Article
Full-text available
Lake depth is an important limnological attribute defining the structure and function of freshwater aquatic ecosystems. Lake levels have fluctuated and lake depths changed through the Holocene reflecting regional climate variations and sediment accumulation. Cladoceran remains preserved in sediments have been widely used for qualitative (P/L ratio)...
Article
Full-text available
Plants in nutrient-poor environments typically have low foliar nitrogen (N) concentrations, long-lived tissues with leaf traits designed to use nutrients efficiently, and low rates of photosynthesis. We postulated that increasing N availability due to atmospheric deposition would increase photosynthetic capacity, foliar N, and specific leaf area (S...
Article
Full-text available
We studied multiple variables in a sediment core from Lake Kipojärvi, northern Finland, to investigate Holocene ecosystem changes in relation to catchment characteristics and known climate variations. We focused on a forested catchment because previous paleolimnological studies conducted in Fennoscandia focused mainly on subarctic lakes within a ra...
Article
Full-text available
Anthropogenic nitrogen (N) loading has the potential to affect plant community structure and function, and the carbon dioxide (CO2) sink of peatlands. Our aim is to study how vegetation changes, induced by nutrient input, affect the CO2 exchange of a nutrient-limited bog. We conducted 9- and 4-year fertilization experiments at Mer Bleue bog, where...
Article
Sphagnum cuspidatum Hoffm. was recently shown to have methane (CH4) oxidation capacity due to inhabiting methanotrophic bacteria (Raghoebarsing et al. 2005). This is an significant finding as peatlands are a major natural source of CH4, an important greenhouse gas to the atmosphere. Emissions from Sphagnum-dominated mires are generally lower than t...
Article
Chamber method is commonly used to measure the CO2 exchange from plant communities. Due to low time resolution, actual measurements reflect only momentary CO2 exchange rates. Therefore, a common way to derive seasonal or annual estimates is to establish models describing the response of CO2 exchange to environmental variables, and then to reconstru...
Conference Paper
Background/Question/Methods Atmospheric nitrogen deposition may have serious implications for the species composition, primary production, and carbon dioxide exchange in northern peatlands. Our previous results after five years of fertilization at the Mer Bleue Bog indicated that high N (+PK) supply may reduce net ecosystem carbon uptake as a resul...
Article
Northern peatlands play a major role in the global carbon cycle as sinks for CO(2) and as sources of CH(4). These diverse ecosystems develop through accumulation of partially decomposed plant material as peat. With increasing depth, peat becomes more and more recalcitrant due to its longer exposure to decomposing processes. Compared with surface pe...
Article
Full-text available
This study explores the variability in concentrations of dissolved CH(4) and annual flux estimates in the pelagic zone in a statistically defined sample of 207 lakes in Finland. The lakes were situated in the boreal zone, in an area where the mean annual air temperature ranges from - 2.8 to 5.9 degrees C. We examined how lake CH(4) dynamics related...
Article
Atmospheric nitrogen (N) deposition has the potential to alter the structure and functioning of nutrient poor wetland ecosystems. It is important to quantify the effect of N input on ecosystem carbon (C) sequestration in these globally important C storages. We address this issue at the temperate Mer Bleue bog, ON, Canada. After 6 years of experimen...
Article
Full-text available
Methane (CH(4)) emissions from boreal wetlands show considerable seasonal variation, including small winter emissions. We addressed the seasonality of CH(4)-producing microbes by comparing archaeal communities and the rates and temperature response of CH(4) production in a boreal fen at three key phases of growing season and in winter. Archaeal com...
Article
Full-text available
This study explores the variability in concentrations of dissolved CH4 and annual flux estimates in the pelagic zone in a statistically defined sample of 207 lakes in Finland. The lakes were situated representatively in the boreal zone, where the mean annual air temperature ranges from −2.8 to 5.9°C. We examined how lake CH4 dynamics related to reg...
Article
Peatlands are one of the largest natural sources of methane to the atmosphere and methane is a significant component of the peatland carbon balance. We aimed to study the methane dynamics in a boreal, sedge- dominated fen, Siikaneva, by combining flux measurement using the eddy covariance (EC) technique and chambers, methane concentration measureme...
Article
1. We studied the patterns of litter decomposition in lake littoral habitats and investigated whether decay rates, as an integrating proxy for environmental conditions in the sediment, would co-vary with net carbon dioxide (CO2) exchange and methane (CH4) efflux. These gas fluxes are known to be sensitive to environmental conditions. Losses in the...
Article
Full-text available
This study aims to determine spatial and temporal variation in carbon dioxide (CO2) and methane (CH4) dynamics through a fen-lake continuum. Study was carried out in a catchment dominated by aapa mire over the period from spring 2005 to autumn 2006 in north boreal zone in Finnish Lapland. The study region characteristically has very high lake and m...
Article
We show that sediment respiration is one of the key factors contributing to the high CO2 supersaturation in and evasion from Finnish lakes, and evidently also over large areas in the boreal landscape, where the majority of the lakes are small and shallow. A subpopulation of 177 randomly selected lakes (<100 km2) and 32 lakes with the highest total...
Article
Littoral zones at the interface of the lake and the catchment are intensive sites for mineralization of organic matter, but the contribution of vegetated littoral zone to winter fluxes of carbon dioxide (CO2) and methane (CH4) from lake ecosystems into the atmosphere is poorly known. We studied littoral carbon gas fluxes and their spatial controls...
Article
Full-text available
1] Diurnal variation in methane fluxes can cause systematic errors in flux estimates, particularly at places with aquatic vegetation. Closed chamber measurements were made during the ice-free period in central Finland. Methane fluxes were quantified at an interval of a few hours for several boreal lakeshore communities consisting of Phragmites aust...
Article
Littoral wetlands comprise a terrestrial to aquatic continuum along which carbon dioxide is exchanged with the atmosphere and organic carbon is transferred to lakes. Net ecosystem productivity-the difference between atmospheric CO2 uptake and total ecosystem respiration-in these shore areas depends partly on the extent and duration of spring floodi...