Kentaro Takagi

Kentaro Takagi
Hokkaido University | Hokudai · Field Science Center for Northern Biosphere

PhD

About

127
Publications
32,708
Reads
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3,200
Citations
Additional affiliations
January 2000 - present
Hokkaido University
Position
  • Asscociate Professor
April 1997 - December 1999
National Institute for Agro-Environmental Sciences in Japan
Position
  • Guest researcher

Publications

Publications (127)
Article
Full-text available
The occurrence of extreme warm events and early snowmelt is predicted to increase in high‐latitude ecosystems, even during periods of time when there is no coincident reduction in total precipitation. However, because extreme events like these occur unpredictably, little is known about how advancing snowmelt by a single extreme warm event, without...
Article
Full-text available
Data capturing multiple axes of tree size and shape, such as a tree's stem diameter, height and crown size, underpin a wide range of ecological research - from developing and testing theory on forest structure and dynamics, to estimating forest carbon stocks and their uncertainties, and integrating remote sensing imagery into forest monitoring prog...
Article
Full-text available
Clear-cut harvesting is one of the important types of forest management but is considered to be a large CO 2 source to the atmosphere. Understanding how this form of logging affects a site's CO 2 balance is critical for determining appropriate management scenarios, yet we have little understanding of how wood harvesting affects the ecosystem CO 2 b...
Article
A constant ratio of photosynthetically active radiation (PAR) to solar radiation (SR) (about 0.45-0.46) has been used in many ecological studies to convert SR into PAR by multiplication. The constant ratio is useful and convenient. However, there is no general agreement on whether the ratio is 0.45 or 0.46 and how distributed globally. Accordingly,...
Article
Full-text available
A constant ratio of photosynthetically active radiation (PAR) to solar radiation (SR) (about 0.45-0.46) has been used in many ecological studies to convert SR into PAR by multiplication. The constant ratio is useful and convenient. However, there is no general agreement on whether the ratio is 0.45 or 0.46 and how distributed globally. Accordingly,...
Article
Full-text available
Given the time scale based on the duration of exposure to global warming, natural climate-gradient studies and experimental manipulations have detected long-term (decades to centuries) and short-term (years to decades) ecological responses to global warming. Combination of these two complementary approaches within a single study may enable predicti...
Chapter
Hokkaido, the northernmost island in Japan, is located on the border between temperate and subarctic zones. Dominant soils distributed in Hokkaido have a wide variety such as Andosols, Fluvic soils, Brown Forest soils, and Peat soils. Paddy, upland, vegetable, dairy farming, and animal husbandry are being practiced on large scales according to the...
Article
Full-text available
Liquid crystal tunable filter (LCTF) can change the transmissible wavelength by changing the applied voltage to the filter, which enables the drastic increase in the observable wavelength resolution in a small size system and is considered to be a powerful tool for the spectral earth observation from flying units or microsatellites. However, there...
Article
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Globally, soils store two to three times as much carbon as currently resides in the atmosphere, and it is critical to understand how soil greenhouse gas (GHG) emissions and uptake will respond to ongoing climate change. In particular, the soil-toatmosphere CO2 flux, commonly though imprecisely termed soil respiration (RS), is one of the largest car...
Article
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Anthropogenic disturbances in forest management practices can affect wild edible plants. Soil scarification is a large-scale disturbance that may cause long-term reduction in productivity of edible dwarf bamboo, Sasa kurilensis , in northern Japan. For their effective and sustainable use, we need to understand the recovery process after such distur...
Article
Full-text available
Rising atmospheric CO 2 concentration ([CO 2 ]) enhances photosynthesis and reduces transpiration at the leaf, ecosystem, and global scale via the CO 2 fertilization effect. The CO 2 fertilization effect is among the most important processes for predicting the terrestrial carbon budget and future climate, yet it has been elusive to quantify. For ev...
Article
To validate and to improve ecological products obtained from satellites, such as a leaf area index (LAI), above‐ground biomass (AGB), and a fraction of photosynthetically active radiation (fAPAR), in‐situ accurate data are indispensable. They must be not a single point‐data but an areal data representing the satellite footprint. Their accuracy need...
Article
Full-text available
Dry deposition has an impact on nitrogen status in forest environments. However, the mechanism for the high dry-deposition rates of fine nitrate particles (NO3-) observed in forests remains unknown and is thus a potential source of error in chemical transport models (CTMs). Here, we modified and applied a multilayer land surface model coupled with...
Article
Bud-burst timing is one of the key factors to determine tree growth. Smaller trees are known to show earlier bud bursts, owing to the ontogeny in temperate forests. Snowpack is one of the factors affecting burst timing, especially that of small trees. Because small individuals were buried under snowpack until late spring, we hypothesized although t...
Article
Full-text available
In this study, we compared the accuracies of above-ground biomass (AGB) estimated by integrating ALOS (Advanced Land Observing Satellite) PALSAR (Phased-Array-Type L-Band Synthetic Aperture Radar) data and TanDEM-X-derived forest heights (TDX heights) at four scales from 1/4 to 25 ha in a hemi-boreal forest in Japan. The TDX heights developed in th...
Article
Full-text available
Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research sp...
Article
Full-text available
To understand the magnitudes of temporal variation in soil respiration (Rs) and its spatial heterogeneity, and the effect of abiotic and biotic factors to cause the variation in a young plantation recovering after the clear-cutting of a mature forest, we analyzed 8 year Rs, microclimate, and vegetation data obtained in a young hybrid larch plantati...
Article
Full-text available
Although dry deposition has an impact on nitrogen status in the forest environments, the mechanism for high dry deposition rates of fine nitrate aerosols (NO3⁻) observed in forests remains unknown and is a potential source of error in chemical transport models. Here we developed a new multi-layer land surface model coupled with dry deposition and a...
Article
Keywords: Winter climate change Functional trait Off-season Ecosystem function Carry-over effect A B S T R A C T Due to spring climate warming, snowpack has been decreasing and the snowmelt timing has simultaneously been advancing in the cool-temperate forests of northern Japan. To investigate the effect of advancing snowmelt at the end of the snow...
Article
Fine particulate matter (PM2.5) is one of most concerning air pollutants in East Asia. In order to further understand the dry deposition process of PM2.5, measurements were carried out in a cool-temperate forest located in a remote area of northern Japan. These measurements took into account the improvement of simulations by chemical transport mode...
Article
Full-text available
Over a period of 9 years covering both disturbed and undisturbed periods, we evaluated long-term variations in water and light use efficiency (WUE, LUE) in a cool-temperate mixed forest in northern Hokkaido, Japan: our study clarified the relationship of WUE and LUE to environmental and vegetation variables. WUE and LUE markedly decreased after def...
Article
Full-text available
Warmer and drier climates over Amazonia have been predicted for the next century with expected changes in regional water and carbon cycles. We examined the impact of interannual and seasonal variations in climate conditions on ecosystem-level evapotranspiration (ET) and water use efficiency (WUE) to determine key climatic drivers and anticipate the...
Article
Full-text available
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...
Article
Upland forests are thought to be methane (CH4) sinks due to oxidation by methanotrophs in aerobic soils. However, CH4 budget for upland forests are not well quantified at the ecosystem scale, when possible CH4 sources, such as small wet areas, exists in the ecosystem. Here, we quantified CH4 fluxes in a cool-temperate larch plantation based on four...
Article
Full-text available
Evaluation of carbon dioxide (CO2) sinks in forest areas of East and Southeast Asia (especially tropical regions) is important for assessing CO2 budgets at the regional scale. To evaluate the CO2 flux of large forest areas, we collected vertical CO2 profiles over the forest using a CO2 sonde and measured surface CO2 concentrations around the forest...
Article
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The net ecosystem CO2 exchange is the result of the imbalance between the assimilation process (gross primary production, GPP) and ecosystem respiration (RE). The aim of this study was to investigate temperature sensitivities of these processes and the effect of climate warming on the annual terrestrial net ecosystem CO2 exchange globally in the bo...
Article
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The lack of a standardized database of eddy covariance observations has been an obstacle for data-driven estimation of terrestrial CO2 fluxes in Asia. In this study, we developed such a standardized database using 54 sites from various databases by applying consistent post-processing for data-driven estimation of gross primary productivity (GPP) an...
Article
Full-text available
Fungi in soil play pivotal roles in nutrient cycling, pest controls, and plant community succession in terrestrial ecosystems. Despite the ecosystem functions provided by soil fungi, our knowledge of the assembly processes of belowground fungi has been limited. In particular, we still have limited knowledge of how diverse functional groups of fungi...
Data
ITS1 sequences of fungal OTUs. (FASTA)
Data
Photographs of the study site. (a) Making of the 9.80-m trench. (b) Entire picture of the 9.80-m trench. (c) Enlarged view of the soil profile. (TIF)
Data
Relationship between the number of sequencing reads and that of fungal OTUs. (TIF)
Data
Fungal community matrix and taxonomic information. (XLSX)
Data
Mantel’s correlogram analysis of the spatial auto-correlation of fungal community structure. Distance classes with significant Mantel’s correlation indices (r) are indicated by filled squares. (TIF)
Article
Full-text available
Key Message Elevated CO 2 concentration affected biomass partitioning in above-ground biomass, but size and number of water-conducting cells were unchanged in Larix kaempferi, Kalopanax septemlobus and Betula platyphylla. Abstract Using a Free-Air CO2 Enrichment (FACE) system, we studied the effect of elevated CO2 on the growth, leaf gas exchange a...
Article
The purpose of this study was to obtain basic information on acclimation capacity of photosynthesis of Siebold's beech seedlings to increasing light intensity under future elevated CO2 condition. We monitored leaf photosynthetic traits of Siebold's beech seedlings in changing light conditions (before the removal of shading trees, next year after th...
Article
Full-text available
Wild edible plants, ecological foodstuffs obtained from forest ecosystems, grow in natural fields, and their productivity depends on their response to harvesting by humans. Addressing exactly how wild edible plants respond to harvesting is critical because this knowledge will provide insights into how to obtain effective and sustainable ecosystem s...
Data
Photographs of bamboo and map of study site. (a) Matured bamboo grass (Sasa kurilensis) and (b) its young edible shoot. The height of a person in (a) is about 170 cm. (c) Location of study site in the Teshio experimental forest. Solid curve in (c) denotes a forest road. Solid and open squares indicate “harvest” and “control” research plots (10 × 10...
Data
Relative productivity of bamboo shoots. The relative productivity was the log-transformed proportion of shoot productivity in 2014 divided by that in 2013 for the same plot. Bars: SE values. (PDF)
Article
Full-text available
We examined the effects of elevated CO2 (eCO2) on the growth and photosynthetic responses of deciduous trees using a Free Air CO2 Enrichment (FACE). In the FACE, photosynthesis was down-regulated in several trees but not in alder. Except alder, the leaf nitrogen concentration decreased in eCO2. Alder underwent symbiosis with N-fixing microorganisms...
Article
Full-text available
Understanding how plants are constructed—i.e., how key size dimensions and the amount of mass invested in different tissues varies among individuals—is essential for modeling plant growth, carbon stocks, and energy fluxes in the terrestrial biosphere. Allocation patterns can differ through ontogeny, but also among coexisting species and among speci...
Article
Full-text available
Understanding how plants are constructed—i.e., how key size dimensions and the amount of mass invested in different tissues varies among individuals—is essential for modeling plant growth, carbon stocks, and energy fluxes in the terrestrial biosphere. Allocation patterns can differ through ontogeny, but also among coexisting species and among speci...
Article
Full-text available
Understanding how plants are constructed; i.e., how key size dimensions and the amount of mass invested in different tissues varies among individuals; is essential for modeling plant growth, estimating carbon stocks, and mapping energy fluxes in the terrestrial biosphere. Allocation patterns can differ through ontogeny, but also among coexisting sp...
Article
Full-text available
To clarify the role of dense understory vegetation in the stand structure, and in carbon (C) and nitrogen (N) dynamics of forest ecosystems with various conditions of overstory trees, we: (i) quantified the above- and below-ground biomasses of understory dwarf bamboo (Sasa senanensis) at the old canopy-gap area and the closed-canopy area and compar...
Article
Full-text available
Larch (Larix spp.) forests are predominantly distributed across high latitudes of Eurasia. They potentially have a strong influence on the terrestrial carbon and energy cycles, because of their vast area and the large carbon stocks in their peat soils in the permafrost. In this study, we elucidated intersite variation of ecosystem photosynthetic an...
Article
Trees are recognized as a carbon reservoir, and precise and convenient methods for forest biomass estimation are required for adequate carbon management. Airborne LiDAR (Light Detection And Ranging) is considered to be one of the solutions for large-scale forest biomass evaluation. To clarify the relationship between mean canopy height determined b...
Article
Full-text available
Temporal variations in the stable isotopic compositions of nitrate dissolved in stream water eluted from a cool-temperate forested watershed (8 ha) were measured to quantify the biogeochemical effects of clear-cutting of trees and subsequent strip-cutting of the understory vegetation, dwarf bamboo (Sasa senanensis), with special emphasis on changes...
Article
Full-text available
We evaluated the long-term (52-year) effect of climate, disturbance, and subsequent recovery on the carbon balance of cool temperate forests by using the process-based ecosystem model VISIT. The study sites were artificial larch forests planted after clear-cutting of mixed forest in Hokkaido, Japan. The model was validated, scenarios were computed,...
Article
Full-text available
To predict the performance of coppice forests with Japanese oak (Quercus mongolica var. crispula) in future changing environment, we studied the growth, photosynthesis, and powdery mildew (Erysiphe alphitoides) infection of sprouts of Japanese oak under free-air CO2 enrichment. Elevated CO2 reduced powdery mildew infection in both leaves of the sho...
Article
Full-text available
Temporal variations in the stable isotopic compositions of nitrate dissolved in stream water eluted from a cool-temperate forested watershed (8 ha) were measured to quantify the biogeochemical effects of clear-cutting of trees and subsequent strip-cutting of the understory vegetation, dwarf bamboo (Sasa senanensis), with special emphasis on changes...
Article
Quantifying regional evapotranspiration (ET) and environmental constraints are particularly important for understanding water and carbon cycles of terrestrial ecosystems. However, a large uncertainty in the regional estimation of ET still remains for the terrestrial ecosystems in China. This study used ET measurements of 34 eddy covariance sites wi...
Article
Full-text available
We evaluated the long-term effect of climate, disturbance, and subsequent recovery on the carbon balance of temperate-boreal forest using the process-based ecosystem model VISIT. The study sites are artificial larch forests, which were planted after clear-cutting of mixed forest, in Hokkaido, Japan. In this study, three experimental simulations wer...
Article
During the Asian monsoon period, intense precipitation commonly occurs for an extended period in accompaniment with a reduction in solar radiation. This suggests that wet surface evapotranspiration is an important contributor to the total evapotranspiration. Therefore, investigating evapotranspiration over a wet canopy surface is critical to achiev...
Article
Full-text available
Key message Elevated CO 2 enhances the photosynthesis and growth of hybrid larch F 1 seedlings. However, elevated CO 2 -induced change of tree shape may have risk to the other environmental stresses. Abstract The hybrid larch F1 (Larix gmelinii var. japonica × L. kaempferi) is one of the most promising species for timber production as well as absor...
Article
Full-text available
We conducted a soil warming experiment in a cool-temperate forested peatland in northern Japan during the snow-free seasons of 2007-2011, to determine whether the soil warming would change the heterotrophic respiration rate and its temperature sensitivity. We elevated the soil temperature by 3 degrees C at 5-cm depth by using overhead infrared heat...
Article
Full-text available
The datasets of net ecosystem CO2 exchange (NEE) were acquired from 21 forests, 3 grasslands, and 3 croplands in the eastern part of Asia based on the eddy covariance measurements of the international joint program, CarboEastAsia. The program was conducted by three networks in Asia, ChinaFLUX, JapanFlux, and KoFlux, to quantify, synthesize, and und...
Article
Full-text available
Based on the model–data comparison at the eddy-covariance observation sites from CarboEastAsia datasets, we report the current status of the terrestrial carbon cycle modeling in monsoon Asia. In order to assess the modeling performance and discuss future requirements for both modeling and observation efforts in Asia, we ran eight terrestrial biosph...