Radiation budget, soil heat flux and latent heat flux at the forest floor in warm, temperate mixed forest

Soil temperature is one of the most important factors governing biological activity in the soil. This study was conducted to investigate how forest clear-cutting changes soil temperature. Soil temperatures at 0.5, 1.0, 2.0, and 3.0 m depths were measured in two neighboring forest watersheds (35∞12ЈN, 140∞06ЈE) in Chiba Prefecture, Japan, from 1994 to 2000. One watershed was clear-cut 5 years after the observations began. After clear-cutting, the annual mean soil temperature at 0.5, 1.0, 2.0, and 3.0 m depths rose by about 2.2, 2.0, 1.7, and 1.4∞C, respectively. The maximum respective soil temperatures rose by about 3.2, 3.0, 2.2, and 1.8∞C. The minimum soil temperature rose slightly (Ͻ1∞C). The range of temperatures increased by 3.0, 2.4, 1.6, and 1.4∞C, respectively. In our study, forest clear-cutting raised maximum and average soil temperatures but hardly changed minimum soil temperature. This is probably because solar radiation dominated in the summer season and increased soil temperature; on the other hand, net longwave radiation, and releases of latent and sensible heat from the soil surface, were predominant in the cool season.

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“…L Ø , L π , H, and ιE are written as follows (see, e.g., Male and Granger 1981;Kondo and Watanabe 1992;Tamai et al 1998;Nakabayashi et al 1999):…”

Section: Discussionmentioning

confidence: 99%

The impact of forest clear-cutting on soil temperature: a comparison between before and after cutting, and between clear-cut and control sites

Hirano

Suzuki

2004

Journal of Forest Research

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“…The duff layer plays a pivotal role in the hydrology of the forest due to its location at the interface of the mineral soil and the atmosphere. It is directly impacted by latent heat fluxes and it impedes evaporative fluxes from the underlying mineral soil [ Tamai et al , 1998], slowing the potential rate of drying in the mineral soil. The duff has a low thermal conductivity and acts as an insulator between the atmosphere and mineral soil, leading to a reduction in the temperature, temperature fluctuations, and thermal gradient in the mineral soil [ Bonan and Shugart , 1989; Van Cleve et al , 1983].…”

Section: Introductionmentioning

confidence: 99%

Moisture cycles of the forest floor organic layer (F and H layers) during drying

Keith

Johnson

Valeo

2010

Water Resources Research

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[1] The forest floor in many ecosystems consists of a partially decomposed organic layer (duff), which together with the litter layer comprises the boundary between the atmosphere and the mineral soil. Processes controlling the duff water budget during dry periods (which occur during most of the summer) were investigated using field monitoring, field flow exclusion manipulations, and coupled, multiphasic water and heat budget modeling. The objective of this paper is to model the significant processes that govern the dynamics of the duff water budget during drying. During dry periods the moisture content of the duff's F layer cycles diurnally with minimal moisture movement between the duff and mineral soil. Field exclusion of dew, lateral flow, and mineral soil flow suggests that diurnal drying cycles during the dry period are driven by diurnal atmospheric energy fluxes leading to coupled heat and mass fluxes within the duff. The fine root system and lateral flow do not typically influence drying. TOUGH2 was used to develop a one-dimensional, multiphasic (both liquid and vapor) coupled water and heat budget model which confirmed that the vertical moisture fluxes lead to diurnal cycles.

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“…Because forest ecosystem types vary significantly depending on tree species, site conditions and the health status of trees, to understand the dynamics of energy and water cycling better, as well as to improve soil-vegetation-atmosphere transfer (SVAT) models used in climate models, comprehensive knowledge about the characteristics of the energy partitioning in various forest ecosystems is needed (Running et al, 1999;Baldocchi et al, 2001). Actually, many studies have already been performed in the past, especially in boreal and temperate forest regions (Pomeroy and Dion, 1996;Tamai et al, 1998;Nakai et al, 1999;Suzuki et al, 1999;Wilson and Baldocchi, 2000;Ohta et al, 2001;Humphreys et al, 2003). Recent developments in the eddy-covariance technique further allow long-term, continuous measurements of energy and water vapour fluxes to be made routinely (Aubinet et al, 2000;Baldocchi, 2003).…”

Section: Introductionmentioning

confidence: 99%

Energy budget above a temperate mixed forest in northeastern China

Guan

Han

et al. 2006

Hydrological Processes

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Abstract:Components of the energy budget were measured continuously above a 300-year-old temperate mixed forest at the Changbaishan site, northeastern China, from 1 January to 31 December 2003, as a part of the ChinaFlux programme. The albedo values above the canopy were lower than most temperate forests, and the values for snow-covered canopy were over 50% higher than for the snow-free canopy. In winter, net radiation R n was generally less than 5% of the summer value due to high albedo and low incoming solar radiation. The annual mean latent heat LE was 37Ð5 W m 2 , accounting for 52% of R n . The maximum daily evaporation was about 4Ð6 mm day 1 in summer. Over the year, the accumulated precipitation was 578 mm; this compares with 493 mm of evapotranspiration, which shows that more than 85% of water was returned to the atmosphere through evapotranspiration. The LE was strongly affected by the transpiration activity and increased quickly as the broadleaved trees began to foliate. The sensible heat H dropped at that time, although R n increased. Consequently, the seasonal variation in the Bowen ratioˇwas clearly U-shaped, and the minimum value (0Ð1) occurred on a sunny day just after rain, when most of the available energy was used for evapotranspiration. Negativeˇvalues occurred occasionally in the non-growing season as a result of intensive radiative cooling and the presence of water on the surface. Theˇwas very high (up to 13Ð0) in snow-covered winter, when evapotranspiration was small due to low surface temperature and available soil water. Vegetation phenology and soil moisture were the key variables controlling the available energy partitioning between H and LE. Energy budget closure averaged better than 86% on a half-hourly basis, with slightly greater closure on a daily basis. The degree of closure showed a dependence on friction velocity u Ł .

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Radiation budget, soil heat flux and latent heat flux at the forest floor in warm, temperate mixed forest

Cited by 19 publications

References 5 publications

The impact of forest clear-cutting on soil temperature: a comparison between before and after cutting, and between clear-cut and control sites

The impact of forest clear-cutting on soil temperature: a comparison between before and after cutting, and between clear-cut and control sites

Moisture cycles of the forest floor organic layer (F and H layers) during drying

Energy budget above a temperate mixed forest in northeastern China

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