Hokkaido University · Environmental Science
Professor Takashi Hirano's research lab specializes in tropical ecosystem biogeochemistry, with a primary focus on carbon cycle dynamics in tropical peatlands and forested wetlands. The lab investigates the impacts of land-use change, fire, and climate variability—particularly El Niño events—on peat decomposition, greenhouse gas emissions (CO₂ and CH₄), and the transition of peatlands from carbon sinks to sources. Using field measurements, eddy covariance techniques, and long-term monitoring, the lab aims to quantify ecosystem-scale fluxes and improve understanding of carbon balance under environmental stress. Their work contributes critical data for climate modeling and sustainable land management in Southeast Asia, especially in Indonesia’s peatland regions.
Figures are computed from collected data and may differ slightly.
Abstract Tropical peatlands, which coexist with swamp forests, have accumulated vast amounts of carbon as soil organic matter. Since the 1970s, however, deforestation and drainage have progressed on an enormous scale. In addition, El Niño and Southern Oscillation (ENSO) drought and large‐scale fires, which grow larger under the drought condition, are accelerating peatland devastation. That devastation enhances decomposition of soil organic matter and increases the carbon release to the atmospher
Abstract Tropical peatlands have accumulated huge soil carbon over millennia. However, the carbon pool is presently disturbed on a large scale by land development and management, and consequently has become vulnerable. Peat degradation occurs most rapidly and massively in Indonesia, because of fires, drainage, and deforestation of swamp forests coexisting with tropical peat. Peat burning releases carbon dioxide ( CO 2 ) intensively but occasionally, whereas drainage increases CO 2 emission stead
Abstract. Methane (CH4) emissions from natural landscapes constitute roughly half of global CH4 contributions to the atmosphere, yet large uncertainties remain in the absolute magnitude and the seasonality of emission quantities and drivers. Eddy covariance (EC) measurements of CH4 flux are ideal for constraining ecosystem-scale CH4 emissions due to quasi-continuous and high-temporal-resolution CH4 flux measurements, coincident carbon dioxide, water, and energy flux measurements, lack of ecosyst
We conducted a field experiment in a cool‐temperate deciduous forest to investigate the dynamic behavior of soil CO 2 and the vertical distribution of soil respiration. Soil CO 2 concentration ( C ) was measured half‐hourly at four depths for 6 months in 2000 with infrared gas analyzers installed below ground. Using C profiles, soil surface CO 2 efflux ( F 0 ), CO 2 production rates of the topsoil ( P A ), and CO 2 flux from the subsoil to topsoil ( F CA ) were evaluated half‐hourly by applying
In Southeast Asia, a huge amount of peat has accumulated under swamp forests over millennia. Fires have been widely used for land clearing after timber extraction, thus land conversion and land management with logging and drainage are strongly associated with fire activity. During recent El Niño years, tropical peatlands have been severely fire-affected and peatland fires enlarged. To investigate the impact of peat fires on the regional and global carbon balances, it is crucial to assess not onl
In Southeast Asia, peatland is widely distributed and has accumulated a massive amount of soil carbon, coexisting with peat swamp forest (PSF). The peatland, however, has been rapidly degraded by deforestation, fires, and drainage for the last two decades. Such disturbances change hydrological conditions, typically groundwater level (GWL), and accelerate oxidative peat decomposition. Evapotranspiration (ET) is a major determinant of GWL, whereas information on the ET of PSF is limited. Therefore
In the northern part of East Asia, forests dominated by larch are extensively distributed and probably play an important role in the global carbon cycle. However, a knowledge of the CO2 balance of larch forests based on long-term flux measurements is very restricted in East Asia. Thus, a long-term flux measurement has been started in 2000 at a larch plantation on a flat terrain in Hokkaido, Japan to obtain more information on the CO2 and energy balances of larch forests. From September 2000 to A
In the northern part of East Asia, forests dominated by larch are extensively distributed and probably play an important role in the global carbon cycle. However, a knowledge of the CO2 balance of larch forests based on long-term flux measurements is very restricted in East Asia. Thus, a long-term flux measurement has been started in 2000 at a larch plantation on a flat terrain in Hokkaido, Japan to obtain more information on the CO2 and energy balances of larch forests. From September 2000 to A
We measured soil CO 2 concentration at half‐hour intervals with infrared gas analyzers buried in soil at four depths throughout the snow cover season extending from early December to early April in a deciduous temperate forest. We evaluated soil CO 2 efflux or total soil respiration, topsoil (the A‐horizon) respiration, and subsoil (the C‐horizon) respiration using a modified flux gradient method. Thereby, we investigated seasonal and diurnal variations in these soil respirations under snowpack.
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