Subsurface imaging of vegetation, climate, and root‐zone moisture interactions

Jayawickreme, Dushmantha H.; Dam, Remke L. Van; Hyndman, D. W.

doi:10.1029/2008gl034690

Cited by 76 publications

(65 citation statements)

References 23 publications

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“…ERI is a well-established method used for commercial water and mineral prospecting. Its adoption in environmental hydrology (Slater et al 2000) and ecohydrological and biological research , Jayawickreme et al 2008, Robinson et al 2008, however, is relatively recent.…”

Section: Geophysical Characterization Of Salt Distributionsmentioning

confidence: 99%

Changes in hydrology and salinity accompanying a century of agricultural conversion in Argentina

Jayawickreme

Santoni

Kim

et al. 2011

Ecological Applications

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Abstract. Conversions of natural woodlands to agriculture can alter the hydrologic balance, aquifer recharge, and salinity of soils and groundwater in ways that influence productivity and sustainable land use. Using a land-use change chronosequence in semiarid woodlands of Argentina's Espinal province, we examined the distribution of moisture and solutes and estimated recharge rates on adjacent plots of native woodlands and rain-fed agriculture converted 6-90 years previously. Soil coring and geoelectrical profiling confirmed the presence of spatially extensive salt accumulations in dry woodlands and pervasive salt losses in areas converted to agriculture. A 1.1-km-long electrical resistivity transect traversing woodland, 70-year-old agriculture, and woodland, for instance, revealed a low-resistivity (high-salinity) horizon between ;3 m and 13 m depth in the woodlands that was virtually absent in the agricultural site because of leaching. Nine-meter-deep soil profiles indicated a 53% increase in soil water storage after 30 or more years of cultivation. Conservative groundwater-recharge estimates based on chloride tracer methods in agricultural plots ranged from ;12 to 45 mm/yr, a substantial increase from the ,1 mm/yr recharge in dry woodlands. The onset of deep soil moisture drainage and increased recharge led to .95% loss of sulfate and chloride ions from the shallow vadose zone in most agriculture plots. These losses correspond to over 100 Mg of sulfate and chloride salts potentially released to the region's groundwater aquifers through time with each hectare of deforestation, including a capacity to increase groundwater salinity to .4000 mg/L from these ions alone. Similarities between our findings and those of the dryland salinity problems of deforested woodlands in Australia suggest an important warning about the potential ecohydrological risks brought by the current wave of deforestation in the Espinal and other regions of South America and the world.

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Section: Geophysical Characterization Of Salt Distributionsmentioning

confidence: 99%

Changes in hydrology and salinity accompanying a century of agricultural conversion in Argentina

Jayawickreme

Santoni

Kim

et al. 2011

Ecological Applications

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“…Yi et al (2007) pointed out that surface cover condition play a dominant role in affecting ground thaw by using the CLM3 model simulations. Thus, permafrost degradation under climate warming can affect processes such as surface water and energy flux, and plant-development processes in tundra regions (Jayawickreme et al, 2008). However, the dynamic interactions between vegetation and active soil temperature remain largely unresolved because it is difficult to quantify the variation in soil texture and hydrological flux under different vegetation types and structures (Bakalin and Vetrova, 2008;Jayawickreme et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

“…Thus, permafrost degradation under climate warming can affect processes such as surface water and energy flux, and plant-development processes in tundra regions (Jayawickreme et al, 2008). However, the dynamic interactions between vegetation and active soil temperature remain largely unresolved because it is difficult to quantify the variation in soil texture and hydrological flux under different vegetation types and structures (Bakalin and Vetrova, 2008;Jayawickreme et al, 2008). Further studies in different regions are necessary to ascertain the laws governing water cycling within the permafrost-vegetation-atmosphere system, and its influence on global climate change (Bubier et al, 1999;Oeche et al, 2000;Christensen et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Impacts of changes in vegetation cover on soil water heat coupling in an alpine meadow of the Qinghai-Tibet Plateau, China

Wang

Liu

et al. 2009

Hydrol. Earth Syst. Sci.

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Abstract. Alpine meadow is one of the most widespread grassland types in the permafrost regions of the QinghaiTibet Plateau, and the transmission of coupled soil water heat is one of the most crucial processes influencing cyclic variations in the hydrology of frozen soil regions, especially under different vegetation covers. The present study assesses the impact of changes in vegetation cover on the coupling of soil water and heat in a permafrost region. Soil moisture (θ v ), soil temperature (T s ), soil heat content, and differences in θ v -T s coupling were monitored on a seasonal and daily basis under three different vegetation covers (30, 65, and 93%) on both thawed and frozen soils. Regression analysis of θ v vs. T s plots under different levels of vegetation cover indicates that soil freeze-thaw processes were significantly affected by the changes in vegetation cover. The decrease in vegetation cover of an alpine meadow reduced the difference between air temperature and ground temperature ( T a−s ), and it also resulted in a decrease in T s at which soil froze, and an increase in the temperature at which it thawed. This was reflected in a greater response of soil temperature to changes in air temperature (T a ). For T a−s outside the range of −0.1 to 1.0 • C, root zone soil-water temperatures showed a significant increase with increasing T a−s ; however, the magnitude of this relationship was dampened with increasing vegetation cover. At the time of maximum water content in the thawing season, the soil temperature decreased with increasing vegetation. Changes in vegetation cover also led to variations in θ v -T s coupling. With the increase in vegetation cover, the surface heat flux decreased. Soil heat storage at 20 cm in depth increased with increasing vegetation cover, and the heat flux that was downwardly transmitted de-

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“…The ERT technique which is recently applied to soil science could be an alternative. Difficulties such as clay content as well as other soil properties affecting apparent soil electrical resistivity, however, may act as confounding factors in its relationship to soil water content and plant root system (Jayawickreme et al, 2008;Schwartz et al, 2008, Basso et al, 2010Jayawickreme et al, 2010). Only few studies available on the use of ERT to investigate the plant root system which are also conducted under the limited condition may not be enough to fully extend our knowledge on the development of plant root zone and its activities.…”

Section: Introductionmentioning

confidence: 99%

Use of Two Dimensional Electrical Resistivity Tomography to Identify Soil Water Dynamics and the Effective Plant Root Zone

Yoon¹,

Zhang²,

Han³

et al. 2012

Korean Journal of Soil Science and Fertilizer

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The identification of effective root zone would clarify dynamics of plant available water and soil water balance. Using the relationship between soil properties and electrical resistivity (ER) the purpose of this research is to identify soil zone affected by a plant root activity using electrical resistivity tomography (ERT) technique. Four plastic containers were prepared for two different soil textures (clay and sandy loam) and one container for each texture was selected for planting four corn seedlings (Zea mays L.) and the others were prepared for the blank. For ERT monitoring, we prepared 0.8 m plastic sticks with 17 electrodes installed with 5 cm space. The Ministing (AGI Inc., Texas) instrument for electrical resistivity measurement and semi-auto converter of electrode arrangement were set up for dipole-dipole array. During 2 months of the corns growing, ERT monitoring was made 3 to 4 days after the irrigation practice. Despite of the same amount water supplied into soils, two textures showed very different apparent resistivity values due to different clay content. The apparent electrical resistivity is consistently lower in clay loam comparing to sandy loam soil implying that plant root does not significantly alter the overall trend of resistivity. When plant root system, however, is active both soils with plants showed 2-7 times higher electrical resistivity and higher coefficient variation than soils without plant, implying the effect of root system on the resistivity, in which may caused by . This result suggests plant root activities regulating the soil water dynamics mainly control the variation of electrical resistivity over soil textural difference. Therefore the identification of water uptake zone would highly be correlated to plant root activities, thus ERT will be feasible approach to identify spatial characteristics of a plant root activity.

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Subsurface imaging of vegetation, climate, and root‐zone moisture interactions

Cited by 76 publications

References 23 publications

Changes in hydrology and salinity accompanying a century of agricultural conversion in Argentina

Changes in hydrology and salinity accompanying a century of agricultural conversion in Argentina

Impacts of changes in vegetation cover on soil water heat coupling in an alpine meadow of the Qinghai-Tibet Plateau, China

Use of Two Dimensional Electrical Resistivity Tomography to Identify Soil Water Dynamics and the Effective Plant Root Zone

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