Evapotranspiration and soil water relationships in a range of disturbed and undisturbed ecosystems in the semi-arid Inner Mongolia, China

Lü, Nan; Chen, Shiping; Wilske, Burkhard; Sun, Ge; Chen, Jiquan

doi:10.1093/jpe/rtq035

Cited by 87 publications

(64 citation statements)

References 50 publications

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“…While maximum temperature showed non-significant downward trends, minimum temperature showed statistically significant increasing trends in most of the basin, suggesting an overall average temperature increase in the basin. As mentioned above, this would eventually affect ET processes with implications for soil water and streamflow changes [51][52][53].…”

Section: Minimum Temperaturementioning

confidence: 99%

Rainfall and Temperature in the Limpopo River Basin, Southern Africa: Means, Variations, and Trends from 1979 to 2013

Mosase

Ahiablame

2018

Water

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Understanding temporal and spatial characteristics of regional climate is essential for decision making in water resource management. Established statistical and GIS techniques were used to evaluate annual and seasonal variations of rainfall and temperature in time and space from 1979 to 2013 in the Limpopo River Basin (LRB). Annual means of rainfall in the LRB varied between 160 and 1109 mm, generally from west to east of the basin during the study period. Annual minimum and maximum temperature ranged from 8 • C in the south to 20 • C in the east of the basin, and 23 • C in the south of the basin to 32 • C in the east. The respective coefficients of variation (CVs) of these variables showed an inverse pattern to the annual values, with rainfall having high CV values (28% to 70% from east to west of the basin) compared to temperature CV values. Seasonal variations followed similar patterns as annual variations for the individual variables examined. Trend analysis showed upward trends for both annual and seasonal rainfall in most parts of the basin, except for the winter season which showed a decreasing trend. Analysis of minimum temperature on an annual basis and for the winter season and spring season shows upward trends during the study period over the whole basin while minimum temperature for summer and autumn showed decreasing trends. Maximum temperature, by contrast, showed decreasing trends on an annual, summer, autumn, and spring basis but an increasing trend for winter during the study period in most parts of the basin.

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Section: Minimum Temperaturementioning

confidence: 99%

Rainfall and Temperature in the Limpopo River Basin, Southern Africa: Means, Variations, and Trends from 1979 to 2013

Mosase

Ahiablame

2018

Water

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“…Several studies (Liu et al, 2013;Mathieu and Bariac, 1996;Allison and Barnes, 1985) have shown that transpiration do not cause isotopic fractionation of soil water. The isotopes δD and δ 18 O can be a powerful tool to determine the water sources utilized by plants in the field, since δD and δ 18 O values of xylem water reflect those of the water sources utilized (Gierke et al, 2016;Yang et al, 2011;Lu et al, 2011). The naturally occurring vertical gradients of δD and δ 18 O in soil water provide similar information about plant water uptake depth from soils.…”

Section: Introductionmentioning

confidence: 99%

Soil water migration in the unsaturated zone of semiarid region in China from isotope evidence

Yang

2017

Hydrol. Earth Syst. Sci.

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Abstract. Soil water is an important driving force of the ecosystems, especially in the semiarid hill and gully region of the northwestern Loess Plateau in China. The mechanism of soil water migration in the reconstruction and restoration of Loess Plateau is a key scientific problem that must be solved. Isotopic tracers can provide valuable information associated with complex hydrological problems, difficult to obtain using other methods. In this study, the oxygen and hydrogen isotopes are used as tracers to investigate the migration processes of soil water in the unsaturated zone in an arid region of China's Loess Plateau. Samples of precipitation, soil water, plant xylems and plant roots are collected and analysed. The conservative elements deuterium (D) and oxygen ( 18 O) are used as tracers to identify variable source and mixing processes. The mixing model is used to quantify the contribution of each end member and calculate mixing amounts. The results show that the isotopic composition of precipitation in the Anjiagou River basin is affected by isotopic fractionation due to evaporation. The isotopic compositions of soil waters are plotted between or near the local meteoric water lines, indicating that soil waters are recharged by precipitation. The soil water migration is dominated by piston-type flow in the study area and rarely preferential flow. Water migration exhibited a transformation pathway from precipitation to soil water to plant water. δ 18 O and δD are enriched in the shallow (< 20 cm depth) soil water in most soil profiles due to evaporation. The isotopic composition of xylem water is close to that of soil water at the depth of 40-60 cm. These values reflect soil water signatures associated with Caragana korshinskii Kom. uptake at the depth of 40-60 cm. Soil water from the surface soil layer (20-40 cm) comprised 6-12 % of plant xylem water, while soil water at the depth of 40-60 cm is the largest component of plant xylem water (ranging from 60 to 66 %), soil water below 60 cm depth comprised 8-14 % of plant xylem water and only 5-8 % is derived directly from precipitation. This study investigates the migration process of soil water, identifies the source of plant water and finally provides a scientific basis for identification of model structures and parameters. It can provide a scientific basis for ecological water demand, ecological restoration, and management of water resources.

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“…In semi-arid and arid ecosystems the fraction of precipitation lost as ET accounts for over 90% of annual precipitation for periods longer than seasons (Kurc and Small, 2004;Huxman et al, 2005). It is important to quantify the variability of ET in these dryland ecosystems because ET affects both plant productivity and energy balance of a region (Lu et al, 2011). Furthermore, hydrological state variables such as soil moisture content and fluxes such as streamflow, and biological processes such as nutrient fluxes and forest productivity are tightly linked via ET in an ecosystem (McNulty et al, 1994;Wilson and Baldocchi, 2000;Wagle and Kakani, 2014).…”

Section: Introductionmentioning

confidence: 99%

Energy partitioning and its controls over a heterogeneous semi‐arid shrubland ecosystem in the Lake Naivasha Basin, Kenya

et al. 2016

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This paper reports on the energy balance and partitioning analysed from 3-year micrometeorological flux measurements of energy and water fluxes over a heterogeneous semi-arid shrubland ecosystem in Lake Naivasha basin. The measurements enabled the characterization of the seasonal and interannual variability of the energy and water fluxes of the ecosystem covering two wet years (2012 and 2013) and one drought year (2014). On an annual scale, more than 60% of net radiation (Rn) was partitioned as latent (LE) and sensible (H) energy flux, with the latter being the larger consumer of Rn (~34%) and dominant for most months. The transition from H to LE dominance occurred from early noon to late afternoon in the wettest months of April and May. The residual energy balance closure term (C) accounted for between 25 and 40% of the Rn with the imbalance tending to be highest during periods of high insolation. Annual evapotranspiration was estimated at 873 mm, 632 mm and 537 mm for year 2012, 2013 and 2014 respectively. This accounted for at least 80% of the annual precipitation received for the respective years. Surface conductance (g s ) scaled significantly with leaf expansion and Priestley-Taylor α coefficient, but was limited during periods of drought because of inadequate soil moisture suggesting that, change in LE was paralleled by changes in green leaf area index. Low values of decoupling coefficient (Ω) during these periods indicated that evapotranspiration was strongly controlled by g s and vapour pressure deficit (VPD). However, under non-limiting moisture conditions evapotranspiration was decoupled from the atmosphere. This suggested that during the dry seasons and periods of prolonged drought, a lack of moisture in combination with high VPD leads to significant decreases in stomatal conductance that eventually limits partitioning of available energy into LE in the semi-arid ecosystem part of the Lake Naivasha basin. However, during wet season these factors are non-limiting and radiation is the dominant control of energy partitioning into LE in the ecosystem. The coupling and decoupling pattern provide insights towards formulating models that quantify evapotranspiration for ecosystems that experience seasonal shifts in controlling factors.

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Evapotranspiration and soil water relationships in a range of disturbed and undisturbed ecosystems in the semi-arid Inner Mongolia, China

Cited by 87 publications

References 50 publications

Rainfall and Temperature in the Limpopo River Basin, Southern Africa: Means, Variations, and Trends from 1979 to 2013

Rainfall and Temperature in the Limpopo River Basin, Southern Africa: Means, Variations, and Trends from 1979 to 2013

Soil water migration in the unsaturated zone of semiarid region in China from isotope evidence

Energy partitioning and its controls over a heterogeneous semi‐arid shrubland ecosystem in the Lake Naivasha Basin, Kenya

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