Apparent Change in Soil Depth and Soil Hardness in Forest Areas in Kampong Thom Province, Cambodia

Ohnuki, Yasuhiro; Kimhean, Chansopheaktra; Shinomiya, Yoshiki; Sor, Sethik; Toriyama, Jumpei; Ohta, Seiichi

doi:10.1007/978-4-431-46503-4_24

Cited by 10 publications

(7 citation statements)

References 19 publications

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“…Table 2 show that deep soil (250 cm) was wet even in the late dry season at this site. Moreover, Ohnuki et al (2007) noted seasonal variation in the soil hardness profile. They observed substantial transpiration of soil water around 0-4 m deep in the dry season at an evergreen forest site in central Cambodia.…”

Section: Resultsmentioning

confidence: 95%

Comparison of soil moisture effects on surface conductance between late dry and rainy seasons in an evergreen forest of central Cambodia

Tamai

Shimizu

Nobuhiro

et al. 2008

Paddy Water Environ

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Some forests in the Asian monsoon region are reported to transpire actively, even in the late dry season. The evergreen forest in central Cambodia is included in them. The surface conductance was estimated for an evergreen forest in central Cambodia in the late dry (May) and rainy (August) seasons, and the effects of environmental conditions on surface conductance were compared between seasons. The effects of soil moisture did not differ between seasons, indicating that soil water drought in the late dry season does not limit transpiration from the entire forest community. Evergreen forests in central Cambodia are thought to transpire actively in the late dry season.

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Section: Resultsmentioning

confidence: 95%

Comparison of soil moisture effects on surface conductance between late dry and rainy seasons in an evergreen forest of central Cambodia

Tamai

Shimizu

Nobuhiro

et al. 2008

Paddy Water Environ

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“…Near the deep soil/regolith profile, patchily distributed deciduous forests (Fig. 1) have deep sandy soil layers with penetration values that are fairly constant between the rainy and dry seasons (Ohnuki et al, 2007). Sandy soils keep similar soil hardness and consistency in dry, wet and saturated conditions because they have such small content of clay that can swell and shrink.…”

Section: Discussionmentioning

confidence: 99%

“…The survey sites were 69-101 m in elevation in a predominantly evergreen forest where deciduous forests and swamp forests coexist in a mosaic-like pattern. The surface geology is Quaternary and consists of river terraces overlaid with sedimentary rocks (Ohnuki et al, 2007). The distributed soils are Acrisols based on the Food and Agriculture Organization (FAO) and WRB classifications (Toriyama et al, 2007b).…”

Section: Study Areamentioning

confidence: 99%

“…In the Mekong River Basin in Cambodia in tropical monsoon Asia, evergreen forests are widely distributed in flatlands, and the water environment changes drastically between the rainy and dry seasons. Soil thickness and related data for this ecosystem are few (Ohnuki et al, 2007;Toriyama et al, 2007a,b). Thus, the present study has two objectives: 1) to measure certain soil physical properties and root systems on the wall of a deep soil profile (N9 m) in an evergreen forest to understand the role of deep soil layers in water storage and transpiration in Kampong Thom Province, central Cambodia; and 2) to comprehend the mechanisms underlying seasonal changes in soil thickness and soil hardness using a handy dynamic cone penetrometer in the rainy and dry seasons.…”

Section: Introductionmentioning

confidence: 99%

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Seasonal change in thick regolith hardness and water content in a dry evergreen forest in Kampong Thom Province, Cambodia

Ohnuki¹,

Shimizu²,

Chann³

et al. 2008

Geoderma

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“…Its landform is a flat to somewhat undulating alluvial plain. The surface geology is Quaternary and consists of a river terrace overlaid with sedimentary rocks (Ohnuki et al 2007). The observation study site was a dry evergreen forest in which Myristica iners, Dipterocarpus costatus, Anisoptera costata, and Vatica odorata are the major species ).…”

Section: Observation Site and Measurement Methodsmentioning

confidence: 99%

Seasonal fluctuation of groundwater in an evergreen forest, central Cambodia: experiments and two-dimensional numerical analysis

Araki

Shimizu

Kabeya

et al. 2008

Paddy Water Environ

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This study of a water cycle was conducted in an evergreen forest located in the Mekong River Basin in central Cambodia. At the observation site, we measured the dynamics of the spatial distribution of groundwater levels. The groundwater movement was analyzed two-dimensionally using boundary conditions and parameters that had been observed in the field. The climate in the research area is dominated by two seasons, which occur annually: a rainy and a dry season. The groundwater levels are generally high during the rainy season and low during the dry season. Groundwater levels were measured along a stream, which flowed through the study site. The streambed was visible at the head of the stream in January. At the next downriver well point, the streambed appeared in March. Finally, it became visible at all well points in April, meaning that surface runoff had disappeared temporarily and instead flowed underground during the ensuing dry period. Groundwater levels of the studied lateral flow perpendicular to the stream that seeped and infiltrated into the stream were 1.2-2.5 m deep (in April), which was the lowest level recorded for the year. During that period, the depth of the groundwater of the studied lateral flow fell by as much as 56 mm per month. In addition, the lateral flow groundwater infiltrated into groundwater of the stream during that period. The groundwater level fluctuation was estimated based on a two-dimensional analysis of lateral flow perpendicular to the stream using a numerical simulation model with soil physical parameters and observed boundary conditions. The observations of ground water fluctuations were well reproduced. Deep seepage of groundwater was estimated using a uniform boundary condition that allowed efflux through the bottom, estimated as being approximately 30 mm per year. The simulated deep seepage rate was considered plausible considering other hydrological components such as soil water storage fluctuation.

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Apparent Change in Soil Depth and Soil Hardness in Forest Areas in Kampong Thom Province, Cambodia

Cited by 10 publications

References 19 publications

Comparison of soil moisture effects on surface conductance between late dry and rainy seasons in an evergreen forest of central Cambodia

Comparison of soil moisture effects on surface conductance between late dry and rainy seasons in an evergreen forest of central Cambodia

Seasonal change in thick regolith hardness and water content in a dry evergreen forest in Kampong Thom Province, Cambodia

Seasonal fluctuation of groundwater in an evergreen forest, central Cambodia: experiments and two-dimensional numerical analysis

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