Minna Väliranta
A5002587128- Geology and Paleoclimatology Research
- Peatlands and Wetlands Ecology
- Coastal wetland ecosystem dynamics
- Climate change and permafrost
- Geological formations and processes
- Fire effects on ecosystems
- Pleistocene-Era Hominins and Archaeology
- Botany and Plant Ecology Studies
- Archaeology and ancient environmental studies
- Tree-ring climate responses
- Isotope Analysis in Ecology
- Methane Hydrates and Related Phenomena
- Atmospheric and Environmental Gas Dynamics
- Geological Studies and Exploration
- Forest Ecology and Biodiversity Studies
- Cryospheric studies and observations
- Paleontology and Stratigraphy of Fossils
- Lichen and fungal ecology
- Marine and environmental studies
- Protist diversity and phylogeny
- Historical and Archaeological Studies
- Soil and Water Nutrient Dynamics
- Pacific and Southeast Asian Studies
- Environmental DNA in Biodiversity Studies
- Climate variability and models
University of Helsinki
2016-2025
Ecosystem (Spain)
2024
Lehigh University
2019
The Arctic Eider Society
2016
Laurentian University
2016
Helsinki University Hospital
2013-2014
University of Greenwich
2013-2014
ECRI Institute
2002-2012
University of Gothenburg
2009
Stockholm University
2009
Here, we present results from the most comprehensive compilation of Holocene peat soil properties with associated carbon and nitrogen accumulation rates for northern peatlands. Our database consists 268 cores 215 sites located north 45°N. It encompasses regions within which data have only recently become available, such as West Siberia Lowlands, Hudson Bay Kamchatka in Far East Russia, Tibetan Plateau. For all peatlands, content organic matter was estimated at 42 ± 3% (standard deviation)...
Abstract. Peatlands are a major terrestrial carbon store and persistent natural sink during the Holocene, but there is considerable uncertainty over fate of peatland in changing climate. It generally assumed that higher temperatures will increase peat decay, causing positive feedback to climate warming contributing global cycle feedback. Here we use new extensive database profiles across northern high latitudes examine spatial temporal patterns accumulation past millennium. Opposite...
A high-resolution plant macrofossil analysis was applied to investigate wetness dynamics in a southern Finnish boreal bog, Kontolanrahka, during the last 5000 years. The chronological control and age—depth model were based on 40 AMS radiocarbon dates. Pollen provided information regional-scale vegetation changes. Macrofossil revealed prominent changes assemblages late Holocene, indicating fluctuations water-table. reconstruction suggests that at coring point, which nowadays is relatively wet...
Abstract The Younger Dryas (YD) cold reversal interrupts the warming climate of deglaciation with global climatic impacts. sudden cooling is typically linked to an abrupt slowdown Atlantic Meridional Overturning Circulation (AMOC) in response meltwater discharges from ice sheets. However, inconsistencies regarding YD-response European summer temperatures have cast doubt whether concept provides a sufficient explanation. Here we present results high-resolution simulation together new July...
Glacial−interglacial variations in CO 2 and methane polar ice cores have been attributed, part, to changes global wetland extent, but the distribution before Last Glacial Maximum (LGM, 21 ka 18 ka) remains virtually unknown. We present a study of peatland extent carbon (C) stocks through last glacial cycle (130 present) using newly compiled database 1,063 detailed stratigraphic records peat deposits buried by mineral sediments, as well model. Quantitative agreement between modeling...
Abstract Permafrost dynamics play an important role in high‐latitude peatland carbon balance and are key to understanding the future response of soil stocks. aggradation can control magnitude feedback peatlands through effects on peat properties. We compiled plant macrofossil records for northern permafrost zone (515 cores from 280 sites) classified samples by vegetation type environmental class (fen, bog, tundra boreal permafrost, thawed permafrost). examined differences properties (bulk...
We compared DNA, pollen and macrofossil data obtained from Weichselian interstadial (age more than 40 kyr) Holocene (maximum age 8400 cal yr BP) peat sediments northern Europe used them to reconstruct contemporary floristic compositions at two sites. The majority of the samples provided plant DNA sequences good quality with success amplification rates depending on age. sequencing analysis five taxa older site nine younger site, corresponding 7% 15% total number identified by three proxies...
Peatlands are major ecosystems of the Northern Hemisphere and have a significant role in global biogeochemical processes. Consequently, there is growing interest understanding past, present future peatland dynamics. However, chronological geographical data on initiation scattered, impeding reliable establishment postglacial spatiotemporal formation patterns their possible connection to climate. In order comprehensive account histories North America northern Europe, we collected set 1400...
Holocene summer temperature reconstructions from northern Europe based on sedimentary pollen records suggest an onset of peak warmth around 9,000 years ago. However, pollen-based are largely driven by changes in the proportions tree taxa, and thus early-Holocene warming signal may be delayed due to geographical disequilibrium between climate populations. Here we show that quantitative summer-temperature estimates macrofossils aquatic plants many cases ca. 2 °C warmer early (11,700-7,500 ago)...
The lake sediments of Hässeldala Port in south-east Sweden provide an archive local and regional environmental conditions ~14.5-9.5 ka BP (thousand years before present) allow testing DNA sequencing techniques to reconstruct past vegetation changes. We combined shotgun with plant micro- macrofossil analyses investigate dating the Allerød (14.1-12.7 BP), Younger Dryas (12.7-11.7 BP) Preboreal (<11.7 BP). Number reads taxa were not associated sample age or organic content. This suggests that,...
Abstract High-latitude peatlands are changing rapidly in response to climate change, including permafrost thaw. Here, we reconstruct hydrological conditions since the seventeenth century using testate amoeba data from 103 high-latitude peat archives. We show that 54% of have been drying and 32% wetting over this period, illustrating complex ecohydrological dynamics high latitude their highly uncertain responses a warming climate.
Model validation experiments are fundamental to ensure that the peat growth models correspond with diversity in nature. We evaluated Holocene Peatland (HPM) simulation against field observations from a chronosequence of peatlands and core data. The ongoing primary peatland formation on isostatically rising coast Finland offered us an exceptional opportunity study succession along spatial continuum compare it past revealed by vertical sequences. current vegetation assemblages, seashore 3000...
Abstract. Reanalysis data show an increasing trend in Arctic precipitation over the 20th century, but changes are not homogenous across seasons or space. The observed hydroclimate expected to continue and possibly accelerate coming only affecting pan-Arctic natural ecosystems human activities, also lower latitudes through atmospheric ocean circulations. However, a lack of spatiotemporal observational makes reliable quantification change difficult, especially long-term context. To understand...
Abstract Boreal species were repeatedly exposed to ice ages and went through cycles of contraction expansion while sister alternated periods contact isolation. The resulting genetic structure is consequently complex, demographic inferences are intrinsically challenging. range Norway spruce ( Picea abies ) Siberian obovata covers most northern Eurasia; yet their geographical limits histories remain poorly understood. To delineate the hybrid zone between two reconstruct joint history, we...
Abstract The Eemian (the Last Interglacial; ca. 129–116 thousand years ago) presents a testbed for assessing environmental responses and climate feedbacks under warmer-than-present boundary conditions. However, syntheses the remain hampered by lack of data from high-latitude land areas, masking response in Arctic. Here we present high-resolution (sub-centennial) record palaeoclimate northern Finland, with multi-model reconstructions July January air temperature. In contrast mid-latitudes...
Abstract Northern boreal peatlands are important ecosystems in modulating global biogeochemical cycles, yet their biological communities and related carbon dynamics highly sensitive to changes climate. Despite this, the strength recent direction of these feedbacks still unclear. The response climate warming has received relatively little attention compared with other northern peatland types, despite forming a large hemisphere‐wide ecosystem. Here, we studied two ombrotrophic variability over...
Northern peatlands store globally-important amounts of carbon in the form partly decomposed plant detritus. Drying associated with climate and land-use change may lead to increased fire frequency severity rapid loss atmosphere. However, our understanding patterns drivers peatland burning on an appropriate decadal millennial timescale relies heavily individual site-based reconstructions. For first time, we synthesise macrocharcoal records from across North America, Europe, Patagonia reveal...
A series of abrupt climate events linked to circum-North Atlantic meltwater forcing have been recognised in Holocene paleoclimate data. To address the paucity proxy records able characterise robustly regional impacts these events, we retrieved a sub-centennial resolution, well-dated core sequence from Lake Kuutsjärvi, northeast Finland. By analysing range paleo-environmental proxies (pollen, plant sedimentary ancient DNA, macrofossils, conifer stomata, and non-pollen palynomorphs), supported...
Abstract Question: How do we distinguish between concurrent allogenic and autogenic forcings behind changing patterns in plant community structures during mire development? Location: Lakkasuo raised bog, southern Finland. Methods: Two radiometrically dated peat profiles were studied using high resolution macrofossil analysis. A combination of partial direct indirect gradient analyses (CCA DCA) was applied to quantify the role different drivers vegetation changes. Results: Autogenic...