Aleksi Räsänen

• PhD
• Associate Professor at University of Oulu

We analysed the history behind the current contrasting lichen covers of two adjacent reindeer herding districts at the Finnish–Norwegian border. We conducted vegetation field inventories across the border fence and reconstructed a lichen cover history from 1959 to 2020 using aerial and satellite images. The oldest images showed only a slight differ...

Peatlands are crucial ecosystems for biodiversity conservation and carbon storage but are largely degraded due to human impact. Climate change poses an additional threat to peatland biodiversity, affecting, for example, red-listed species. We investigate how the projected climate change and peatland restoration may jointly influence the habitat ava...

While peatland C cycling is generally well covered, understanding of the role of soil fertility in driving the spatial variation of C fluxes within peatlands remains scattered. Our aim was to examine the relative effects of fertility and microtopography on CO2 and CH4 exchange within a boreal fen and to link these effects to the spatial variation i...

There is a gap in understanding how different policies affect climate vulnerability and risk development, yet increasingly response is added to the risk framework. We propose a conceptual framework that explains how response and other policies affect risk determinants and demonstrate the application of the framework using a synthesis of empirical l...

Trees offer multiple benefits, including impacts on physical and mental health. In this interdisciplinary study, we explored the relationships humans develop with specific favourite trees based on our survey data (n = 158) collected in the Netherlands. Here, we examined action possibilities (affordances) provided by trees, including immaterial acti...

Restoration can initiate a succession of plant communities towards those of pristine peatlands. Field inventory-based vegetation monitoring is labour-intensive and not feasible for every restored site. While remote sensing has been used to monitor hydrological changes in peatlands, it has been less used to monitor post-restoration changes in vegeta...

Remote sensing (RS) can be an efficient monitoring method to assess the ecological impacts of restoration. Yet, it has been used relatively little to monitor post‐restoration changes in boreal forestry‐drained peatlands, and particularly the linkages between changes in RS and plant species remain vague. To understand this gap, we utilize data from...

Rapidly increasing knowledge on environmental problems and their potential solutions is underused by policy and practice. This mismatch constitutes a knowledge-action gap. To bridge the gap, the concept of actionable knowledge has been proposed, which is often understood as outputs, data, policy briefs, or other types of products. We instead propos...

Peatlands have suffered significant degradation globally due to human impacts, which has increased the need to monitor the condition and changes in peatland ecosystems. With remote sensing , point-based in-situ observations can be upscaled to larger areas but there is a need to develop scalable monitoring methods. We predicted wet flark area extent...

Peatlands play a key role in the circulation of the main greenhouse gases (GHG) – methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O). Therefore, detecting the spatial pattern of GHG sinks and sources in peatlands is pivotal for guiding effective climate change mitigation in the land use sector. While geospatial environmental data, which p...

Trees are natural objects that carry practical, cultural and spiritual meanings to humans. Trees are an elemental part of human daily life, both in urban and rural environments, and even in locations where forests are distant. Conflicts related to tree removal in the close environments of humans indicate that individual trees may have special signi...

Peatlands play a key role in the circulation of the main greenhouse gases (GHG) – methane (CH 4 ), carbon dioxide (CO 2 ), and nitrous oxide (N 2 O). Therefore, detecting the spatial pattern of GHG sinks and sources in peatlands is pivotal for guiding effective climate change mitigation in the land use sector. While geospatial environmental data, w...

To assess how peatland restoration affects the state of the peatlands, monitoring methods are needed. During the past four years, we tested different monitoring methods to assess the status of the restored peatlands. We investigated (1) what kind of hydrological, ecological, and remote sensing monitoring methods function well in monitoring such res...

Raised bogs are the most common combined mire type in Southern Finland. They are dependent on precipitation to provide water and nutrients. The surface of the raised bog is characterized by dry ridges, hummocks, and wet depressions, hollows. Climate warming reduces winter snowfall and increases evaporation, which is estimated to lower the water lev...

Nature-based solutions (NBS) are considered as means to tackle climate change and biodiversity loss while simultaneously enhancing human well-being. Yet, it is still poorly understood how NBS could be mainstreamed. We address this gap by proposing a framework on NBS and employing it in Finland's Kiiminkijoki River basin through participatory worksh...

Recently, increased attention has been drawn to the greenhouse gas emissions of the Land use, Land use Change and Forestry (LULUCF) sector. In the Finnish LULUCF sector, the soil-originated emissions from the after-use of cutover peatland have become a more relevant question. This is due to the rapid increase in the number of former peat-harvesting...

Climate scenarios predict that temperatures will rise and the subsequent heat periods that negatively impact human well-being will increasingly become common. The impact of heat in cities can be adapted to through urban planning, economic investments and other measures. The outcomes of adaptation should be monitored, for example, through indicators...

After drainage for forestry and agriculture, peat extraction is one of the most important causes of peatland degradation. When peat extraction is ceased, multiple after-use options exist, including abandonment, restoration, and replacement (e.g., forestry and agricultural use). However, there is a lack of a global synthesis of after-use research. T...

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 covered 7 km2 of borea...

Climate change will have adverse impacts on human health, which are amplified in cities. For these impacts, there are direct, indirect, and deferred pathways. The first category is well-studied, while indirect and deferred impacts are not well-understood. Moreover, the factors moderating the impacts have received little attention, although understa...

Currently, in Finland, thousands of hectares of peat production areas are being transformed to the after-use phase for which there are multiple options, such as restoration, afforestation, cultivation, and production of solar and wind power. In Finland, the landowner decides what after-use option is implemented. When the after-use of the peat produ...

Peatlands are one of the most significant terrestrial carbon pools, and the processes behind the carbon cycle in peatlands are strongly associated with different vegetation patterns. Handheld spectroradiometer data has been widely applied in ecological research, but there is a lack of studies on peatlands assessing how the temporal and spectral res...

Peatlands, with high spatial variability in ecotypes and microforms, constitute a significant part of the boreal landscape and play an important role in the global carbon (C) cycle. However, the effects of this peatland heterogeneity within the boreal landscape are rarely quantified. Here, we use field‐based measurements, high‐resolution land cover...

Although generally given little attention in vegetation studies, ground-dwelling (terricolous) lichens are major contributors to overall carbon and nitrogen cycling, albedo, biodiversity and biomass in many high-latitude ecosystems. Changes in biomass of mat-forming pale lichens have the potential to affect vegetation, fauna, climate and human acti...

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...

Peatland water table depth (WTD) and wetness have widely been monitored with optical and synthetic aperture radar (SAR) remote sensing but there is a lack of studies that have used multi-sensor data, i.e., combination of optical and SAR data. We assessed how well WTD can be monitored with remote sensing data, whether multi-sensor approach boosts ex...

Climate change can affect the mining sector in various ways. Physical impacts can be a threat to mines and personnel, transport infrastructure and supply chains, while the low-carbon transition may entail transition risks stemming from e.g., the need to respond to mitigation and adaptation policies, as well as opportunities in the form of increased...

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...

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...

Recent years have seen a massive development of geospatial sensing systems informing the use of space. However, rarely do these sensing systems inform transformation towards urban sustainability. Drawing on four global urban case examples, we conceptualize how passive and active sensing systems should be harnessed to secure an inclusive, sustainabl...

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...

Future climate risk is not only dependent on future climatic changes but also on how exposure and vulnerability develop in the future. There is a gap in understanding what drives future climate vulnerability, and how to account for its spatial emergence. This issue is particularly pertinent for cities due to the concentration of assets and populati...

A soil moisture estimation method was developed for Sentinel-1 synthetic aperture radar (SAR) ground range detected high resolution (GRDH) data to analyze moisture conditions in a gently undulating and heterogeneous subarctic area containing forests, wetlands, and open orographic tundra. In order to preserve the original 10-m pixel spacing, PIMSAR...

Effects of permafrost aggradation on greenhouse gas (GHG) dynamics and climate forcing have not been previously quantified. Here, we reconstruct changes in GHG balances over the late Holocene for a sub-arctic peatland by applying palaeoecological data combined with measured GHG flux data, focusing on the impact of permafrost aggradation in particul...

The assessments of future climate risks are common; however, usually, they focus on climate projections without considering social changes. We project heat risks for Finland to evaluate (1) what kind of differences there are in heat vulnerability projections with different scenarios and scales, and (2) how the use of socio-economic scenarios influe...

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...

Aboveground vegetation biomass in northern treeless landscapes – peatlands and Arctic tundra – has been modelled with spectral information derived from optical remote sensing in several studies. However, synthesized overviews of biomass patterns across circumpolar sites have been limited. Based on data from eight study sites in Europe, Siberia and...

Cross-scale interactions affect resilience in a wide array of social systems such as flood risk management, but it has been argued that studies of such interactions remain limited. Based on qualitative interviews, quantitative surveys, and policy document analysis, I employed the panarchy framework in an analysis of temporal changes and cross-scale...

Context Spatial patterns of CH 4 fluxes can be modeled with remotely sensed data representing land cover, soil moisture and topography. Spatially extensive CH 4 flux measurements conducted with portable analyzers have not been previously upscaled with remote sensing. Objectives How well can the CH 4 fluxes be predicted with plot-based vegetation m...

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...

Extreme weather events, such as storms, may cause material damage, injuries, and interfere with day-to-day operation of societies. Earlier research on natural hazards and climate change adaptation has found that demographic and socioeconomic factors influence the way individuals prepare for and are affected by natural hazards. However, research oft...

Katastrofitutkimus (disaster studies) pureutuu vaaroihin, katastrofeihin ja kriiseihin. Tutkimusalue ei ole vakiintunut yhteiskuntatieteiden osaksi Suomessa, mutta sillä on annettavaa erityisesti luonnonilmiöihin kietoutuneita katastrofeja tutkittaessa. Tämä katsausartikkeli tarkastelee, millaista suomenkielistä käsitteistöä katastrofeja tutkittaes...

Northern peatlands are projected to be crucial in future atmospheric methane (CH4) budgets and have a positive feedback on global warming. Fens receive nutrients from catchments via inflowing water and are more sensitive than bogs to variations in their ecohydrology. Yet, due to a lack of data detailing the impacts of moving water on microhabitats...

Early warning systems (EWSs) have been developed to trigger timely action to disasters, yet persistent humanitarian crises resulting from hazards such as drought indicate that these systems need improvements. We focus our research on the county of Turkana in Kenya, where drought repeatedly results in humanitarian crises, especially with regard to f...

Wetlands, including peatlands, supply crucial ecosystem services such as water purification, carbon sequestration and regulation of hydrological and biogeochemical cycles. Peatlands are especially important as carbon sinks and stores because of the incomplete decomposition of vegetation within the peat. Good knowledge of individual wetlands exists...

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...

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...

Northern peatlands are projected to be crucial in future atmospheric methane (CH4) budgets and have a positive feedback on global warming. Fens receive nutrients from catchments via inflowing water and are more sensitive than bogs to climate change-caused variations in their ecohydrology. Yet, due to a lack of data detailing the impacts of moving w...

Community resilience is often assessed in disaster risk management (DRM) research and it has been argued that it should be strengthened for more robust DRM. However, the term community is seldom precisely defined and it can be understood in many ways. We argue that it is crucial to explore the concept of community within the context of DRM in more...

Despite a notable increase in the literature on community resilience, the notion of 'community' remains underproblematised. This is evident within flood risk management (FRM) literature, in which the understanding and roles of communities may be acknowledged but seldom discussed in any detail. The purpose of the article is to demonstrate how commun...

Northern boreal peatlands have fine-scale spatial heterogeneity in land cover and vegetation patterns. We produced ultra-high spatial resolution vegetation and land cover maps in three different peatland sites in Finnish Lapland, using drone data, aerial images and lidar data, as well as satellite imagery. Our study was divided into four sub-studie...

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...

Questions 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 floristical...

This chapter discusses the emergence of national adaptation policy in the developed world. It presents findings from empirical studies that have examined the development of national-level strategies and focuses on understanding the process of institutionalization and implementation of national adaptation, particularly in the context of vertical gov...

Arctic areas have experienced greening and changes in permafrost caused by climate change during recent decades. However, there has been a lack of automated methods in mapping changes in fine-scale patterns of permafrost landscapes. We mapped areal coverage of bare peat areas and changes in them in a peat plateau located in north-western Russia bet...

Climate change is likely to increase the risks related to heat waves in urban areas. We map spatial pattern of heat wave vulnerability and risk in the Helsinki metropolitan area in southern Finland. First, we assess differences that zoning, i.e., differences in spatial units of analysis, and weighting, i.e., weights given to indicators when constru...

It has been argued that even centimeter-level resolution is needed for mapping vegetation patterns in spatially heterogeneous landscapes such as northern peatlands. However, there are few systematic tests for determining what kind of spatial resolution and data combinations are needed and what the differences in mapping accuracy are when different...

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...

The non-uniform spatial integration, an inherent feature of the eddy covariance (EC) method, creates a challenge for flux data interpretation in a heterogeneous environment, where the contribution of different land cover types varies with flow conditions, potentially resulting in biased estimates in comparison to the areally averaged fluxes and lan...

To tackle problems related to water quantity and quality, transformations in water management systems have become of increasing interest. Transformative capacity can be defined as the ability first to adapt to changes, and if needed, to carry out fundamental changes in a specific system. Using a framework of ten components of transformative capacit...

Across the Arctic, the net ecosystem carbon (C) balance of tundra ecosystems is highly uncertain due to substantial temporal variability of C fluxes and to landscape heterogeneity. We modeled both carbon dioxide (CO2) and methane (CH4) fluxes for the dominant land cover types in a ~100 km² sub‐Arctic tundra region in northeast European Russia for t...

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...

The non-uniform spatial integration inherent in the eddy covariance (EC) method provides an additional challenge for data interpretation when fluxes are measured in a heterogeneous environment, as the contribution of different surface types varies with flow conditions, potentially resulting in a bias as compared to the true areally averaged fluxes...

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...

Land use changes have been recognized to have considerable impacts on water; and vice versa, changes in water use and governance may have implications on land use and governance. This study analyzes recent land use/land cover (LULC) changes, and how changes in land use and water governance are perceived to affect land use and water-related risks in...

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...

Systemaattinen sää-ja ilmastoriskien arviointi ja hallinta ylläpitää kuntien toimintakykyä. Yhteiskunnan toimivuuden ja turvallisuuden ylläpitäminen edellyttää aktiivista varautumista sää -ja ilmastoriskeihin. Sää- ja ilmastoriskeistä kunnille ongelmallisimpia ovat sään ääri-ilmiöiden aiheuttamat vahingot ja haasteellisinta on rakennetun ympäristön...

Water-related risks and vulnerabilities are driven by variety of stressors, including climate and land use change, as well as changes in socio-economic positions and political landscapes. Hence, water governance, which addresses risks and vulnerabilities, should target multiple stressors. We analyze the institutional perceptions of the drivers and...

There is a call for climate services to facilitate climate risk assessment and management. Local governments are major actors in managing climate risk but there is less research on what kind of information is needed and used by municipalities. With the help of a quantitative survey and a post-survey workshop, we analyze the status of climate risk a...

Understanding climate risk is crucial for effective adaptation action, and a number of assessment methodologies have emerged. We argue that the dynamics of the individual components in climate risk and vulnerability assessments has received little attention. In order to highlight this, we systematically reviewed 42 sub-national climate risk and vul...

The ELASTINEN project examined the present state of the management of weather and climate related risks in Finland. It also analysed risk management measures and the roles of different actors. In addition, it examined how the costs and benefits of risk management measures are assessed and how risk management can enable new business. Maintaining a w...

We systematically reviewed current climate change literature in order to examine how multiple processes that affect human vulnerability have been studied. Of the 125 reviewed articles, 79 % were published after 2009. There are numerous concepts that point out to stressors other than climate change that were used in reviewed studies. These different...

We explained vascular plant species richness patterns in a 286 km2 fragmented landscape with a notable human influence. The objective of this study was two-fold: to test the relative importance of landscape, topography and geodiversity measures, and to compare three different landscape-type variables in species richness modeling. Moreover, we teste...