Atsuko Sugimoto

Hokkaido University | Hokudai · Arctic Research Center

Built upon a 5‐year field investigation and a 13‐year satellite dataset, this study examines the intricate interrelationships among ecophysiological parameters of Larix gmelinii trees and the prevailing ecosystem, climatic, and environmental factors present in the Indigirka lowlands of northeastern Siberia. It identified spatial‐temporal patterns i...

The taiga ecosystem in northeastern Siberia, a nitrogen-limited ecosystem on permafrost with a dry climate, changed during the extreme wet event in 2007. We investigated the normalized difference vegetation index (NDVI) as a satellite-derived proxy for needle production and compared it with ecosystem parameters such as soil moisture water equivalen...

The taiga ecosystem in northeastern Siberia, a nitrogen-limited ecosystem on permafrost with a dry climate, changed during the extreme wet event in 2007. We investigated the normalized difference vegetation index (NDVI) as a satellite-derived proxy of needle production and compared it with ecosystem parameters such as soil moisture water equivalent...

Changes in winter precipitation (snow) may greatly affect vegetation by altering hydrological and biochemical processes. To understand the effects of changing snow cover depth and melt timing on the taiga forest ecosystem, a snow manipulation experiment was conducted in December 2015 at the Spasskaya Pad experimental larch forest in Eastern Siberia...

The taiga forest, a semi-arid and nitrogen-limited ecosystem on permafrost, has changed under extreme wet events. This study aims to understand the changes that occurred in a larch forest in Eastern Siberia after the wet event of 2006–2007. In the summer of 2018, studies were conducted at the Spasskaya Pad Experimental Forest Station near Yakutsk,...

Microbial symbionts are essential for plant niche expansion into novel habitats. Dormant propagules of ectomycorrhizal (EM) fungi are thought to play an important role in seedling establishment in invasion fronts; however, propagule bank communities above the treeline are poorly understood in the Eurasian Arctic, where treelines are expected to adv...

Ectomycorrhizal (EM) fungal communities have been studied worldwide; however, those in the very cold and dry continental climate zone of northern Eurasia remain understudied. We investigated EM fungal community structure on plant roots and its determinants in eastern Siberia. We identified 291 EM fungal taxa belonging to 37 fungal genera from nine...

The oxygen isotopic composition of tree-ring cellulose (δ18Ocell) has been widely used to reconstruct historical environmental changes; however, the control factors on δ18Ocell have not been fully constrained—especially in high latitudes. To evaluate the influence of metabolic processes and related environmental factors on δ18Ocell, we analyzed the...

Terrestrial forest ecosystems are crucial to the global carbon cycle and climate system; however, these ecosystems have experienced significant warming rates in recent decades, whose impact remains uncertain. This study investigated radial tree growth using the tree-ring width index (RWI) for forest ecosystems throughout the Northern Hemisphere to...

Changes in winter precipitation (snow) may greatly affect vegetation by altering hydrological and biochemical processes. To understand the effects of changing snow cover depth and melt timing on the taiga forest ecosystem, a snow manipulation experiment was conducted in December 2015 at the Spasskaya Pad experimental larch forest in Eastern Siberia...

Arctic tundra wetlands may be an important source of dissolved organic carbon (DOC) in Arctic rivers and the Arctic Ocean under global warming. We investigated stable water isotopes and DOC concentration in wetlands, tributaries, and the mainstream at the lower reaches of the Indigirka River in northeastern Siberia during the summers of 2010–2014 t...

Arctic and boreal permafrost ecosystems in Eastern Siberia, considered crucial to the climate system and global carbon cycle, are particularly vulnerable to climate change. This study investigates carbon dioxide (CO2) exchange fluxes over northeastern Siberia from 2013 to 2015 in a taiga–tundra boundary ecosystem for which such measurements are sca...

With the global warming, the frequent and severe river floods in Arctic regions have affected the distribution of willows in river lowlands. To investigate the effect of floods, especially waterlogging, on nitrogen conditions for willows, we measured their foliar nitrogen content and isotopic composition (δ15N), under various hydrological condition...

Arctic wetlands are significant sources of atmospheric methane and the observed accelerated climate changes in the arctic could cause a change in methane dynamics. Methane oxidation would be the key process to control methane emission from wetlands. In this study, we determined the potential methane oxidation rate of the wetland soils of a taiga–tu...

Land carbon cycle components in an Earth system model (ESM) play a crucial role in the projections of forest ecosystem responses to climate/environmental changes. Evaluating models from the viewpoint of observations is essential for an improved understanding of model performance and for identifying uncertainties in their outputs. Herein, we evaluat...

Accurate calculation of leaf area index (LAI) in boreal forests, which are vulnerable to climate change and have insufficient ground-truth data, is an important but challenging task when evaluating the spatio-temporal variability of ecosystem structures and functions (photosynthesis and evapotranspiration). By applying a direct method, we calculate...

Detecting year-to-year variability of the timing of the start of the growing season (SGS) and the end of the growing season (EGS) is an important task in accurately evaluating ecosystem functions and services under climate change in vulnerable ecosystems in Siberia. We constructed a degree-day model for estimating the SGS and EGS dates at a deciduo...

Arctic terrestrial ecosystems near the treeline in river lowlands are vulnerable to the changing climate and seasonal extreme events, including flooding. We set up a simple camera monitoring system to record the timings and durations of the leafy period and the spring flush of river water at three observation sites (Boydom [B]: 70.64°N, 148.15°E; K...

The Kyoto (1997) and Paris (2015) protocols, signed by Russia, are the basis for the national low-carbon economy concepts development. Russian regions considerably differ in social and economic conditions, structure and scale of economy. Thus, the sectorial and territorial detailization on the emissions is relevant for the Sakha Republic (Yakutia),...

Black carbon (BC) particles, commonly known as soot, are emitted from incomplete combustion of fossil fuels and biomass. They efficiently absorb solar radiation and thus heat the atmosphere. BC particles emitted at midlatitudes and in the Arctic are deposited onto snow in the Arctic, accelerating snowmelt in early spring by absorbing solar radiatio...

Flooding is one of the greatest disasters that produces strong effects on the ecosystem and livelihoods of the local population. Flood frequency is expected to increase globally making its risk assessment an urgent issue. In spring‐summer 2017, an extreme flooding occurred in the Indigirka River lowland of Northeastern Siberia that inundated a larg...

The warming trend in the Arctic region is expected to cause drastic changes including permafrost degradation and vegetation shifts. We investigated the spatial distribution of ice content and stable isotopic compositions of water in near-surface permafrost down to a depth of 1 m in the Indigirka River lowlands of northeastern Siberia to examine how...

Recent studies suggest that forest vulnerability to tree mortality has increased as a result of extreme climate events such as severe drought and heavy rain. However, little is known about the mortality processes, particularly when they are induced by heavy rain. A dendroecological analysis was conducted on living and dead trees in a Siberian larch...

Tritium dating requires a good understanding of the tritium and water inputs into hydrologic systems, including their main trends due to latitudinal, seasonal and altitudinal effects. Although tritium reached ambient levels at the end of the 20th century, tritium released from nuclear facilities and bomb tests since then has the potential to confou...

Arctic wetlands are significant sources of atmospheric methane and the observed accelerated climate changes in the arctic could cause the change in methane dynamics, where methane oxidation would be the key process to control methane emission from wetlands. In this study we determined the potential methane oxidation rate of the wetland soils of a t...

The response of CH4 emission from natural wetlands due to meteorological conditions is important because of its strong greenhouse effect. To understand the relationship between CH4 flux and wetting, we observed interannual variations in chamber CH4 flux, as well as the concentration, δ13C, and δD of dissolved CH4 during the summer from 2009 to 2013...

An extreme flooding event occurred from June to July 2017 in the Indigirka River lowland of northeastern Siberia. We used Landsat 8 satellite surface reflectance data to detect the flood inundation area and extract water color for delineating different water sources. We also took direct samples of dissolved methane concentrations in the river water...

The tree-ring width index (RWI) and satellite-derived vegetation indices, such as the Normalized Difference Vegetation Index (NDVI), are used as long-term indicators of the past forest carbon uptake. However, fundamental questions remain with respect to what is represented by the RWI and NDVI at the ecosystem level. To address this question, we com...

Taiga–tundra boundary ecosystems are affected by climate change. Methane (CH4) emissions in taiga–tundra boundary ecosystems have sparsely been evaluated from local to regional scales. We linked in situ CH4 fluxes (2009–2016) with vegetation cover, and scaled these findings to estimate CH4 emissions at a local scale (10 × 10 km) using high-resoluti...

The response of CH4 emission from natural wetlands to meteorological conditions is important because of its strong greenhouse effect. To understand relationship between CH4 flux and wetting, we observed interannual variations in chamber CH4 flux, and concentration, δ¹³C, and δD of dissolved CH4 in summers from 2009 to 2013 at the taiga-tundra bound...

Tree-ring width indices (RWI) are widely used as long-term indicators of past forest ecosystem response to climate change. Due to their larger spatial scales, gridded climate data have been preferred over station data. However, it is not clear how climate dataset type affects correlations between climate variables (e.g., temperature and precipitati...

Although stable carbon isotopic composition (δ ¹³ C) of plants has been widely used to indicate different water regimes in terrestrial ecosystems over the past four decades, the changes in the plant δ ¹³ C value under waterlogging have not been sufficiently clarified. With the enhanced global warming in recent years, the increasing frequency and se...

Site No., location, distance to river, dominant species, production, ANPP, and LAI for three 2.5 m × 2.5 m plots in summer of 2016.

The river water level (cm) from 1st June to 31st July, for the average in 2010–2014, 2015 and 2016. The average river water level during 2010-2014 was shown in circles, the water level in 2015 and 2016 was shown in triangles and diamonds, respectively. The arrow lines indicate the observed growing season, with fast growing period in wide arrow line...

River water level data from 2010 to 2016. Raw data for Figure A2.

Photosynthesis light response curve of willows under the light levels from 10 to 955 μmol m−2 s−1. Photosynthesis light response curve of the willows S. boganidensis (red cycles), S. glauca (green triangles), and S. richardsonii (blue squares) under the light levels from 10 to 955 μmol m−2 s−1. The values were reported as means ± SD.

Results of foliar δ13C values (‰) on single shoot from bottom to top. Raw data for Figure A3.

Results of foliar δ13C values (‰). Including samples collected in 2015, 2016 and leaves for ADC measurements.

Data for photosynthesis light response curve of the willows S. boganidensis (red cycles), S. glauca (green triangles), and S. richardsonii (blue squares).

Details of sampling site with site No., sampling data, river name, hydrological information, willow species (sampling number) and location of this study. I and K river represent Indigirka and Kryvaya river.

The foliar δ13C values (‰) of the leaves according to the leaf-open order. The foliar δ13C values (‰) of the leaves according to the leaf-open order, upon single shoot at each point of PA (empty symbols) and PC (filled symbols) in SBoydom (circles) and SKA (triangles). The different points are shown in different symbols.

Data for ADC monitoring at SPh-PA, PB and PC under different hydrological conditions. ADC monitoring includes especially photosynthetic activity and stomatal conductance.

We report long-term continuous phenological and sky images taken by time-lapse cameras through the Phenological Eyes Network (http://www.pheno-eye.org. Accessed 29 May 2018) in various ecosystems from the Arctic to the tropics. Phenological images are useful in recording the year-to-year variability in the timing of flowering, leaf-flush, leaf-colo...

The terrestrial forest ecosystems in the northern high latitude region have been experiencing significant warming rates over several decades. These forests are considered crucial to the climate system and global carbon cycle and are particularly vulnerable to climate change. To obtain an improved estimate of the response of vegetation activity, e.g...

An Arctic terrestrial model intercomparison project (GTMIP), designed for enhanced collaborations between modeling and field scientists, and for assessment of uncertainty and variations in current terrestrial models to improve, was carried out with 21 domestic and international participants, ranging from physical to biogeochemical to hybrid models....

Carbon dioxide (CO2) fluxes by different methods vary largely at global, regional and local scales. The net CO2 fluxes by three bottom-up methods (tower observation (TWR), biogeochemical models (GTM), and a data-driven model (SVR)), and an ensemble of atmospheric inversions (top-down method, INV) are compared in Yakutsk, Siberia for 2004-2013. The...

We describe the physiological responses of boreal conifers to climate change for the past 112 years using ring width and carbon isotope ratios (δ13C) chronologies at six forest sites in northern Eurasia and Canada. Responses differed among regions, depending on their climatic and/or geographic characteristics. Tree radial growth decreased over the...

Circumboreal forest ecosystems are exposed to a larger magnitude of warming in comparison with the global average, as a result of warming-induced environmental changes. However, it is not clear how tree growth in these ecosystems responds to these changes. In the present study, we investigated the sensitivity of forest productivity to climate chang...

Spatial and temporal variations of the isotopic composition of precipitation were investigated to better understand their controlling factors. Precipitation was collected from six locations in Hokkaido, Japan, and event-based analyses were conducted for a period from March 2010 to February 2013. Compared to the three sites at Pacific Ocean side, re...

The spatial patterns of plant and soil δ(15)N and associated processes in the N cycle were investigated at a forest-grassland boundary in northern Mongolia. Needles of Larix sibirica Ledeb. and soils collected from two study areas were analysed to calculate the differences in δ(15)N between needle and soil (Δδ(15)N). Δδ(15)N showed a clear variatio...

Here, the authors describe the construction of a forcing data set for land surface models (including both physical and biogeochemical models; LSMs) with eight meteorological variables for the 35-year period from 1979 to 2013. The data set is intended for use in a model intercomparison study, called GTMIP, which is a part of the Japanese-funded Arct...

Here, the authors describe the construction of a forcing data set for land surface models (including both physical and biogeochemical models; LSMs) with eight meteorological variables for the 35-year period from 1979 to 2013. The data set is intended for use in a model intercomparison study, called GTMIP, which is a part of the Japanese-funded Arct...

simulation of satellite data and with socio-economic data such as population, migration and urbanization led problems related to quality of life in Samara city and derive landscape trajectory and urban expansion. Supervised classification methodology has been employed using maximum likelihood technique in ArcGIS 10.1 Software for five different tim...

Monitoring of land use/cover change is very important for sustainable development planning study. This research work is to understand natural and environmental vulnerability situation and its cause such as intensity, distribution and socio-economic effect in the Indigirka River basin, Eastern Siberia, Russia based on remote sensing and Geographical...

As part of the terrestrial branch of the Japan-funded Arctic Climate Change Research Project (GRENE-TEA), which aims to clarify the role and function of the terrestrial Arctic in the climate system and assess the influence of its changes on a global scale, this model intercomparison project (GTMIP) is designed to (1) enhance communication and under...

Here, the authors describe the construction of a forcing dataset for Land Surface Models (including both physical and biogeochemical models; LSMs) with eight meteorological variables for the 35 year period from 1979 to 2013. The dataset is intended for use in a model intercomparison (MIP) study, called GTMIP, which is a part of the Japanese-funded...

We present a large-scale dendroclimatic reconstruction of July temperatures from 42–52°N to 140–145°E in the Northwest Pacific region for the period from 1800 to 1996. A multiple regression model with principal components (PCs) of a tree-ring chronology network was used for the reconstruction, which accounted for 31.7% of the temperature variance i...

To better understand the factors controlling the growth of larch trees in Arctic taiga-tundra boundary ecosystem, we conducted field measurements of photosynthesis, tree size, nitrogen (N) content, and isotopic ratios in larch needles and soil. In addition, we observed various environmental parameters, including topography and soil moisture at four...

Understanding geocryological characteristics of frozen sediment, such as cryostratigraphy, ice content, and stable isotope ratio of ground ice, is essential to predicting consequences of projected permafrost thaw in response to global warming. These characteristics determine thermokarst extent and controls hydrological regime—and hence vegetation g...

Rapid and dramatic climate changes in the Arctic and the projection of their impacts on lower-latitude regions require careful evaluation, understanding, and use of multidisciplinary, internationally coordinated efforts. The third International Symposium on Arctic Research (ISAR-3), devoted to these objectives, was held on January 14-17, 2013 in To...

Isotopic composition of atmospheric water vapour (δ18OV) was observed at a larch forest near Yakutsk in eastern Siberia during the late summer periods of 2006, 2007 and 2008. The δ18OV [and deuterium excess (d-excess)] values observed in 2006 and 2008 positively (and negatively) correlated with mixing ratio of atmospheric water vapour, whereas, in...

This charter analyzes the results of social research on environmental consciousness of Yakut people. Environmental consciousness regulates people’s behavior in ecologically significant situations. Results of the sociological survey show that local people of Yakutia observe some changes in environment, caused by intensive industrial development and...

[1] A stable carbon isotope ratio (δ13C) chronology for the past 100 years was developed from larch tree rings in eastern Siberia (near Yakutsk, 62°14′N, 129°37′E), to reconstruct past soil moisture water equivalent (SWE). Based on the correlation analyses between SWE and tree ring δ13C, we developed a linear regression model for SWE in the late gr...

A new method of soil water extraction for oxygen and hydrogen isotopic analysis has been developed; this method uses a helium flow system as an alternative to the conventional vacuum extraction method. The method significantly increases the efficiency of sample preparation and simplifies the extraction. During the water distillation, a helium carri...

Deciduous forest covers vast areas of permafrost under severe dry climate in eastern Siberia. Understanding the water cycle in this forest ecosystem is quite important for climate projection. In this study, diurnal variations in isotopic compositions of atmospheric water vapour were observed in eastern Siberia with isotope analyses of precipitation...

The inorganic nitrogen (N) cycle and its dynamics in the soil were observed in the ecosystem at the Spasskaya Pad experimental forest near Yakutsk in northeastern Siberia in order to estimate the N availability for the larch (Larix cajanderi Mayr.) The soil pool of bulk N in the forest accounted for up to 866 g N m−2 (0–50 cm), whereas up to 1.7% (...

We present a dendroclimatic reconstruction of Palmer Drought Severity Index (PDSI) in Yakutsk (62° 14′N, 129° 37′E), East Siberia using a larch tree-ring (latewood) δ13C chronology (1780–2008 AD). The correlation function analysis showed significant positive correlations between earlywood, latewood and total ring width and July PDSI of the previous...

Methane is effective greenhouse gas (GHG), which is 20 times stronger than carbon dioxide. Being stored in permafrost areas and released as the result of the global warming, it accelerates the processes. Organic matter stored in the permafrost may also be converted to released by permafrost degradation, which in tern results emissions of GHG. We pr...

Tree-ring chronologies of ring width and stable carbon isotope ratios (δ13C) over the past 160 years were developed using living larch trees at two forest sites, each with different annual precipitation, in eastern Siberia: Spasskaya Pad (SP) (62°14´N, 129°37´E); and Elgeeii (EG) (60°0´N, 133°49´E). Intrinsic water use efficiency (iWUE) was derived...

Global warming is likely to transform Siberian environments. Recent eco-hydrological evidence indicates that water and carbon cycles have been changing rapidly, with potentially serious effects on the Siberian flora and fauna. We have comprehensively analysed dendrochronological, hydrological, and meteorological data and satellite remote sensing da...

The relationship between δD and δ18O values (per mille deviation from SMOW) was investigated on falling snow particles from a separate convective cloud collected at 2 stations along a moving cloud trajectory. Observations were made in 1983 in Hokuriku, Japan and in 1985 and 1986 in Hokkaido, Japan. The δD and δ18O values of snow particles from a se...

Interannual variations in soil moisture and vegetation parameters were observed for 9 years in a larch forest near Yakutsk, Russia in Eastern Siberia, to investigate the response of the ecosystem. Soil moisture varied depending on both the amount of summer rainfall in the year and soil moisture at the end of the previous summer carried over as ice....

It is important to estimate the amount of CH4 released following the use of groundwater and to understand the dynamics of groundwater CH4 from the viewpoints of biogeochemical C cycle and global warming. We determined CH4 concentration in 216 groundwaters used for agriculture in Aichi Prefecture, central Japan, and analyzed the spatial and seasonal...

To clarify how hydrological processes affect biogenic methane (CH4) production and emission from soil surfaces, we analyzed the δ13C of CH4 and CO2 and chemical constituents dissolved in groundwater at a wetland in the headwater catchment of a temperate forest in Japan. We estimated the contribution of acetate fermentation using the δ13C isotope ma...