Atte Korhola
Datos Biográficos
| ID | 5597346 |
|---|---|
| NOMBRE | Atte Korhola |
| NOMBRES | Atte |
| APELLIDO | Korhola |
| FIRMA | KORHOLA A |
| AFILIACIONES | University of Helsinki |
| ORCID | 0000-0003-2577-6502 |
| VERIFICADO | Sí |
| TOTAL DE OBRAS | 21 |
| TOTAL DE CITAS | 91 |
| TOTAL COMO AUTOR | 21 |
| TOTAL COMO EDITOR | 0 |
| PRIMER AÑO DE PUBLICACIÓN | 1994 |
| AÑO MÁS RECIENTE DE PUBLICACIÓN | 2016 |
| ÍNDICE H | 5 |
Holocene fen–bog transitions, current status in Finland and future perspectives
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 zone. To more profoundly understand the sensitivity of peatlands to changes in climate, we first used …
New evidence of warm early-Holocene summers in subarctic Finland based on an enhanced regional chironomid-based temperature calibration model
Paleoclimate reconstructions based on biological proxies present methodological challenges, especially during non-analog conditions, such as the early Holocene. Here, two chironomid-based training sets from Finland were amalgamated to create a more accurate transfer function of summer air temperature. The aim was to reconstruct Holocene paleoclimate in northernmost Lapland, in an area that has been either too warm or too cold for reliable reconst…
A database and synthesis of northern peatland soil properties and Holocene carbon and nitrogen accumulation
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 of 268 peat cores from 215 sites located north of 45°N. It encompasses regions within which peat carbon data have only recently become available, such as the West Siberia Lowlands, the Hudson Bay Lowlands, Kamchatka in Far East Russia, and the Tibetan…
Continental-scale temperature variability during the past two millennia
Postglacial spatiotemporal peatland initiation and lateral expansion dynamics in North America and northern Europe
Peatlands are major ecosystems of the Northern Hemisphere and have a significant role in global biogeochemical processes. Consequently, there is growing interest in understanding past, present and future peatland dynamics. However, chronological and geographical data on peatland initiation are scattered, impeding the reliable establishment of postglacial spatiotemporal peatland formation patterns and their possible connection to climate. In order…
Past and Future Changes in Arctic Lake and River Ice
Effects of Changes in Arctic Lake and River Ice
Arctic Freshwater Ice and Its Climatic Role
Chironomid response to environmental drivers during the Holocene in a shallow treeline lake in northwestern Fennoscandia
The significance of different environmental drivers for the chironomid compositional changes during the Holocene was assessed using partial redundancy analysis. These drivers included pollen-inferred mean July air temperature, vegetation cover as pollen percentages, diatom-inferred water pH and total organic carbon (TOC), and sediment properties as loss on iginition (LOI). Variance partitioning showed that on the Holocene timescale, chironomid as…
High-resolution reconstruction of wetness dynamics in a southern boreal raised bog, Finland, during the late Holocene
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 the age—depth model were based on 40 AMS radiocarbon dates. Pollen analysis provided information on regional-scale vegetation changes. Macrofossil analysis revealed prominent changes in vegetation assemblages during the late Holocene, indicating fluctuat…
Impacts of Eutrophication on Diatom Life Forms and Species Richness in Coastal Waters of the Baltic Sea
Increased nutrient and sediment loading can affect the functioning and biodiversity of coastal ecosystems. Lacking long-term monitoring data, paleolimnological techniques enable the estimation of habitat and diversity change through time. Using these methods we assessed the effects of eutrophication on diatom community structure and species richness over the past ca. 200 years in coastal waters of the Gulf of Finland. The abundance of planktonic …
Temperature patterns over the past eight centuries in Northern Fennoscandia inferred from sedimentary diatoms
Establishing natural climate variability becomes particularly important in remote polar regions, especially when considering questions regarding higher than average warming. We present a high-resolution record of temperature variability for the past 800 yr based on sedimentary diatoms from a treeline lake in Finnish Lapland. The BSiZer multiscale smoothing technique is applied to the data to identify significant features in the record at differen…
Quantifying Background Nutrient Concentrations in Coastal Waters
Successful management of damaged coastal ecosystems requires reliable scientific evidence of their past state. Here we demonstrate that the sediment record of biotic indicators can be used to quantitatively reconstruct nutrient concentrations preceding the short time span covered by monitoring records. We generated a diatom-based weighted-averaging partial least squares transfer function model for total dissolved nitrogen with a prediction accura…
Quantifying Background Nutrient Concentrations in Coastal Waters
Successful management of damaged coastal ecosystems requires reliable scientific evidence of their past state. Here we demonstrate that the sediment record of biotic indicators can be used to quantitatively reconstruct nutrient concentrations preceding the short time span covered by monitoring records. We generated a diatom-based weighted-averaging partial least squares transfer function model for total dissolved nitrogen with a prediction accura…
Chironomids, temperature and numerical models
We reply to comments by Seppälä (2001) concerning the suitability of the surface-water temperature measurements and mean July air temperature estimates used by Olander et al. (1999) to derive quantitative chironomid-temperature transfer functions. We use new data for water temperatures based on two-hourly recordings from thermistors installed in 32 lakes and air-temperature data from an automatic weather station at one lake to refute Seppälä’s ac…
A Quantitative Holocene Climatic Record from Diatoms in Northern Fennoscandia
A diatom-based calibration model for predicting summer temperatures was developed using climatically sensitive subarctic lakes in northern Fennoscandia. The model was applied to a sediment core from a treeline lake to infer trends in Holocene climate. The record exhibits long-term variations, as well as a series of shorter-term fluctuations on a time scale of centuries. Summers were warmest in the area about 6200 cal yr B.P. and featured distinct…
An expanded calibration model for inferring lakewater and air temperatures from fossil chironomid assemblages in northern Fennoscandia
Chironomid-temperature inference models based on an expanded data set of surface-sediment and limnological data from 53 Subarctic lakes in northern Fennoscandia have been developed using eight different numerical techniques, each based on slightly different underlying statistical models or ecological assumptions. The study sites are mostly small, shallow, bathymetrically simple, oligotrophic lakes, with a pH range from 5.0 to 7.8, a total organic…
Evidence for a more recent occurrence of water chestnut (Trapa natans L.) in Finland and its palaeoenvironmental implications
Pollen and diatom analyses as well as radiocarbon datings were used to study the development of the ancient lake-basin Pyysuo in SW Finland with mass occurrence of Trapa natans subfossil fruits in its sediments. The basin was isolated from the Baltic Sea c. 4300 BP, after which it continued to develop as a shallow, eutrophic, alkaline and vegetation-rich small lake until the final overgrowth by a mire at c. 2500 BP. The fossil fruits of Trapa nat…
Holocene climatic variations in southern Finland reconstructed from peat-initiation data
Radiocarbon and pollen analytical dates of 71 basal-peat samples from 23 sites in the Boreal region of southern Finland were used to reconstruct patterns of peat initiation and the subsequent spread of peat during the Holocene. Only mires known for certain as having originated through paludification were considered. Three new sites (Isosuo, Tremanskärr and Kantosuo) were investigated in detail by means of stratigraphic, biostratigraphic and morph…
Estimating Long-Term Carbon Accumulation Rates in Boreal Peatlands by Radiocarbon Dating
We used direct radiocarbon dates of peat samples, pollen dates and land-uplift chronology from >1300 cores comprising all or most of the Holocene in the boreal region of Finland, Estonia and Maine (USA) to obtain long-term carbon accumulation rates for boreal peatlands. The “apparent” long-term rate of carbon accumulation (LORCA; g C m −2 a −1 ) ranged from 4.6 to 85.8 (mean 19.9 ± 10.7), depending on the geographical location, wetland type and t…
Radiocarbon Evidence for Rates of Lateral Expansion in Raised Mires in Southern Finland
Radiocarbon ages from the bottom peat deposits and detailed morphometric measurements at five peatlands in the boreal region of southern Finland were used to reconstruct the Holocene patterns of raised mire development. The results suggest that the areal expansion of the mires has been extremely rapid at times—up to several hundreds hectares per millennium—but the periods of more rapid expansion were not coincident among the mires. The rate of la…
A database and synthesis of northern peatland soil properties and Holocene carbon and nitrogen accumulation
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 of 268 peat cores from 215 sites located north of 45°N. It encompasses regions within which peat carbon data have only recently become available, such as the West Siberia Lowlands, the Hudson Bay Lowlands, Kamchatka in Far East Russia, and the Tibetan…
High-resolution reconstruction of wetness dynamics in a southern boreal raised bog, Finland, during the late Holocene
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 the age—depth model were based on 40 AMS radiocarbon dates. Pollen analysis provided information on regional-scale vegetation changes. Macrofossil analysis revealed prominent changes in vegetation assemblages during the late Holocene, indicating fluctuat…
Holocene climatic variations in southern Finland reconstructed from peat-initiation data
Radiocarbon and pollen analytical dates of 71 basal-peat samples from 23 sites in the Boreal region of southern Finland were used to reconstruct patterns of peat initiation and the subsequent spread of peat during the Holocene. Only mires known for certain as having originated through paludification were considered. Three new sites (Isosuo, Tremanskärr and Kantosuo) were investigated in detail by means of stratigraphic, biostratigraphic and morph…
Past and Future Changes in Arctic Lake and River Ice
Postglacial spatiotemporal peatland initiation and lateral expansion dynamics in North America and northern Europe
Peatlands are major ecosystems of the Northern Hemisphere and have a significant role in global biogeochemical processes. Consequently, there is growing interest in understanding past, present and future peatland dynamics. However, chronological and geographical data on peatland initiation are scattered, impeding the reliable establishment of postglacial spatiotemporal peatland formation patterns and their possible connection to climate. In order…
Effects of Changes in Arctic Lake and River Ice
Arctic Freshwater Ice and Its Climatic Role
Chironomid response to environmental drivers during the Holocene in a shallow treeline lake in northwestern Fennoscandia
The significance of different environmental drivers for the chironomid compositional changes during the Holocene was assessed using partial redundancy analysis. These drivers included pollen-inferred mean July air temperature, vegetation cover as pollen percentages, diatom-inferred water pH and total organic carbon (TOC), and sediment properties as loss on iginition (LOI). Variance partitioning showed that on the Holocene timescale, chironomid as…
Holocene fen–bog transitions, current status in Finland and future perspectives
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 zone. To more profoundly understand the sensitivity of peatlands to changes in climate, we first used …
Chironomids, temperature and numerical models
We reply to comments by Seppälä (2001) concerning the suitability of the surface-water temperature measurements and mean July air temperature estimates used by Olander et al. (1999) to derive quantitative chironomid-temperature transfer functions. We use new data for water temperatures based on two-hourly recordings from thermistors installed in 32 lakes and air-temperature data from an automatic weather station at one lake to refute Seppälä’s ac…
An expanded calibration model for inferring lakewater and air temperatures from fossil chironomid assemblages in northern Fennoscandia
Chironomid-temperature inference models based on an expanded data set of surface-sediment and limnological data from 53 Subarctic lakes in northern Fennoscandia have been developed using eight different numerical techniques, each based on slightly different underlying statistical models or ecological assumptions. The study sites are mostly small, shallow, bathymetrically simple, oligotrophic lakes, with a pH range from 5.0 to 7.8, a total organic…
Impacts of Eutrophication on Diatom Life Forms and Species Richness in Coastal Waters of the Baltic Sea
Increased nutrient and sediment loading can affect the functioning and biodiversity of coastal ecosystems. Lacking long-term monitoring data, paleolimnological techniques enable the estimation of habitat and diversity change through time. Using these methods we assessed the effects of eutrophication on diatom community structure and species richness over the past ca. 200 years in coastal waters of the Gulf of Finland. The abundance of planktonic …
Quantifying Background Nutrient Concentrations in Coastal Waters
Successful management of damaged coastal ecosystems requires reliable scientific evidence of their past state. Here we demonstrate that the sediment record of biotic indicators can be used to quantitatively reconstruct nutrient concentrations preceding the short time span covered by monitoring records. We generated a diatom-based weighted-averaging partial least squares transfer function model for total dissolved nitrogen with a prediction accura…
Estimating Long-Term Carbon Accumulation Rates in Boreal Peatlands by Radiocarbon Dating
We used direct radiocarbon dates of peat samples, pollen dates and land-uplift chronology from >1300 cores comprising all or most of the Holocene in the boreal region of Finland, Estonia and Maine (USA) to obtain long-term carbon accumulation rates for boreal peatlands. The “apparent” long-term rate of carbon accumulation (LORCA; g C m −2 a −1 ) ranged from 4.6 to 85.8 (mean 19.9 ± 10.7), depending on the geographical location, wetland type and t…
Radiocarbon Evidence for Rates of Lateral Expansion in Raised Mires in Southern Finland
Radiocarbon ages from the bottom peat deposits and detailed morphometric measurements at five peatlands in the boreal region of southern Finland were used to reconstruct the Holocene patterns of raised mire development. The results suggest that the areal expansion of the mires has been extremely rapid at times—up to several hundreds hectares per millennium—but the periods of more rapid expansion were not coincident among the mires. The rate of la…
Holocene climatic variations in southern Finland reconstructed from peat-initiation data
Radiocarbon and pollen analytical dates of 71 basal-peat samples from 23 sites in the Boreal region of southern Finland were used to reconstruct patterns of peat initiation and the subsequent spread of peat during the Holocene. Only mires known for certain as having originated through paludification were considered. Three new sites (Isosuo, Tremanskärr and Kantosuo) were investigated in detail by means of stratigraphic, biostratigraphic and morph…
Estimating Long-Term Carbon Accumulation Rates in Boreal Peatlands by Radiocarbon Dating
We used direct radiocarbon dates of peat samples, pollen dates and land-uplift chronology from >1300 cores comprising all or most of the Holocene in the boreal region of Finland, Estonia and Maine (USA) to obtain long-term carbon accumulation rates for boreal peatlands. The “apparent” long-term rate of carbon accumulation (LORCA; g C m −2 a −1 ) ranged from 4.6 to 85.8 (mean 19.9 ± 10.7), depending on the geographical location, wetland type and t…
Evidence for a more recent occurrence of water chestnut (Trapa natans L.) in Finland and its palaeoenvironmental implications
Pollen and diatom analyses as well as radiocarbon datings were used to study the development of the ancient lake-basin Pyysuo in SW Finland with mass occurrence of Trapa natans subfossil fruits in its sediments. The basin was isolated from the Baltic Sea c. 4300 BP, after which it continued to develop as a shallow, eutrophic, alkaline and vegetation-rich small lake until the final overgrowth by a mire at c. 2500 BP. The fossil fruits of Trapa nat…
An expanded calibration model for inferring lakewater and air temperatures from fossil chironomid assemblages in northern Fennoscandia
Chironomid-temperature inference models based on an expanded data set of surface-sediment and limnological data from 53 Subarctic lakes in northern Fennoscandia have been developed using eight different numerical techniques, each based on slightly different underlying statistical models or ecological assumptions. The study sites are mostly small, shallow, bathymetrically simple, oligotrophic lakes, with a pH range from 5.0 to 7.8, a total organic…
A Quantitative Holocene Climatic Record from Diatoms in Northern Fennoscandia
A diatom-based calibration model for predicting summer temperatures was developed using climatically sensitive subarctic lakes in northern Fennoscandia. The model was applied to a sediment core from a treeline lake to infer trends in Holocene climate. The record exhibits long-term variations, as well as a series of shorter-term fluctuations on a time scale of centuries. Summers were warmest in the area about 6200 cal yr B.P. and featured distinct…
Chironomids, temperature and numerical models
We reply to comments by Seppälä (2001) concerning the suitability of the surface-water temperature measurements and mean July air temperature estimates used by Olander et al. (1999) to derive quantitative chironomid-temperature transfer functions. We use new data for water temperatures based on two-hourly recordings from thermistors installed in 32 lakes and air-temperature data from an automatic weather station at one lake to refute Seppälä’s ac…
Quantifying Background Nutrient Concentrations in Coastal Waters
Successful management of damaged coastal ecosystems requires reliable scientific evidence of their past state. Here we demonstrate that the sediment record of biotic indicators can be used to quantitatively reconstruct nutrient concentrations preceding the short time span covered by monitoring records. We generated a diatom-based weighted-averaging partial least squares transfer function model for total dissolved nitrogen with a prediction accura…
Quantifying Background Nutrient Concentrations in Coastal Waters
Successful management of damaged coastal ecosystems requires reliable scientific evidence of their past state. Here we demonstrate that the sediment record of biotic indicators can be used to quantitatively reconstruct nutrient concentrations preceding the short time span covered by monitoring records. We generated a diatom-based weighted-averaging partial least squares transfer function model for total dissolved nitrogen with a prediction accura…
Temperature patterns over the past eight centuries in Northern Fennoscandia inferred from sedimentary diatoms
Establishing natural climate variability becomes particularly important in remote polar regions, especially when considering questions regarding higher than average warming. We present a high-resolution record of temperature variability for the past 800 yr based on sedimentary diatoms from a treeline lake in Finnish Lapland. The BSiZer multiscale smoothing technique is applied to the data to identify significant features in the record at differen…
High-resolution reconstruction of wetness dynamics in a southern boreal raised bog, Finland, during the late Holocene
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 the age—depth model were based on 40 AMS radiocarbon dates. Pollen analysis provided information on regional-scale vegetation changes. Macrofossil analysis revealed prominent changes in vegetation assemblages during the late Holocene, indicating fluctuat…
Impacts of Eutrophication on Diatom Life Forms and Species Richness in Coastal Waters of the Baltic Sea
Increased nutrient and sediment loading can affect the functioning and biodiversity of coastal ecosystems. Lacking long-term monitoring data, paleolimnological techniques enable the estimation of habitat and diversity change through time. Using these methods we assessed the effects of eutrophication on diatom community structure and species richness over the past ca. 200 years in coastal waters of the Gulf of Finland. The abundance of planktonic …
Chironomid response to environmental drivers during the Holocene in a shallow treeline lake in northwestern Fennoscandia
The significance of different environmental drivers for the chironomid compositional changes during the Holocene was assessed using partial redundancy analysis. These drivers included pollen-inferred mean July air temperature, vegetation cover as pollen percentages, diatom-inferred water pH and total organic carbon (TOC), and sediment properties as loss on iginition (LOI). Variance partitioning showed that on the Holocene timescale, chironomid as…
Past and Future Changes in Arctic Lake and River Ice
Effects of Changes in Arctic Lake and River Ice
Arctic Freshwater Ice and Its Climatic Role
Continental-scale temperature variability during the past two millennia
Postglacial spatiotemporal peatland initiation and lateral expansion dynamics in North America and northern Europe
Peatlands are major ecosystems of the Northern Hemisphere and have a significant role in global biogeochemical processes. Consequently, there is growing interest in understanding past, present and future peatland dynamics. However, chronological and geographical data on peatland initiation are scattered, impeding the reliable establishment of postglacial spatiotemporal peatland formation patterns and their possible connection to climate. In order…
New evidence of warm early-Holocene summers in subarctic Finland based on an enhanced regional chironomid-based temperature calibration model
Paleoclimate reconstructions based on biological proxies present methodological challenges, especially during non-analog conditions, such as the early Holocene. Here, two chironomid-based training sets from Finland were amalgamated to create a more accurate transfer function of summer air temperature. The aim was to reconstruct Holocene paleoclimate in northernmost Lapland, in an area that has been either too warm or too cold for reliable reconst…
A database and synthesis of northern peatland soil properties and Holocene carbon and nitrogen accumulation
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 of 268 peat cores from 215 sites located north of 45°N. It encompasses regions within which peat carbon data have only recently become available, such as the West Siberia Lowlands, the Hudson Bay Lowlands, Kamchatka in Far East Russia, and the Tibetan…
Holocene fen–bog transitions, current status in Finland and future perspectives
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 zone. To more profoundly understand the sensitivity of peatlands to changes in climate, we first used …
Geography (17 obras) · Geology and Paleoclimatology Research (16 obras) · Geology (14 obras) · Physical geography (14 obras) · Oceanography (13 obras) · Environmental Science (12 obras) · Geology (11 obras) · Holocene (11 obras) · Climate change (10 obras) · Oceanography (10 obras)