Evapotranspiration (ET) and regulating mechanisms in two semiarid Artemisia-dominated shrub steppes at opposite sides of the globe

Wilske, Burkhard; Kwon, Hyojung; Long, Wuqiang; Chen, Shiping; Lü, Nan; Lin, Guanghui; Xie, Jing; Guan, Wei; Pendall, Elise; Ewers, B. E.; Chen, Jiquan

doi:10.1016/j.jaridenv.2010.05.013

Cited by 24 publications

(11 citation statements)

References 54 publications

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“…In arid and semi-arid regions, ET is often limited seasonally by the availability of soil water in addition to temperature [25,26]. Although temperature is projected to increase in both seasons, results of projected evapotranspiration in dry-season follows the pattern of the projected precipitation due to limited available water.…”

Section: Discussionmentioning

confidence: 99%

Impact of Climate Change on Runoff in the Gilgel Abbay Watershed, the Upper Blue Nile Basin, Ethiopia

Ayele

Tung

et al. 2016

Water

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Hydrological assessment is critical to the successful implementation of adaption measures. In this study, projections of seven global circulation models (GCMs) associated with high and medium-low Representative Concentration Pathways (RCP 8.5 and RCP 4.5) for the period 2021-2040 and 2081-2100 were adopted to assess changes on runoffs in the Gilgel Abbay watershed, the upper Blue Nile basin. A weather generator was employed to generate daily temperature and precipitation to drive a hydrological model for impact assessment. Despite the projected magnitude of changes varied among different GCMs and RCPs, increasing runoffs in wet-season and decreasing in dry-season are observed in both periods, mainly attributed to the change in projected precipitation. Such changes are profound in cases of RCP 8.5 with respect to those of RCP 4.5 and in cases of 2081-2100 with respect to those of 2021-2040. Although the increasing runoffs would provide greater inflow to Lake Tana, the increase of precipitation in wet-season would imply a higher possibility of flash floods. On the other hand, decrease runoffs in dry-season further intensify existing shortage of irrigation water demand. These changes will have deleterious consequences on the economic wellbeing of the country and require successful implementation of adaption measures to reduce vulnerability.

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Section: Discussionmentioning

confidence: 99%

Impact of Climate Change on Runoff in the Gilgel Abbay Watershed, the Upper Blue Nile Basin, Ethiopia

Ayele

Tung

et al. 2016

Water

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“…The P-M model is used to estimate ET by Hydrus 1D. The P-M model was developed for well-watered crops and as a result tends to overestimate ET in non-irrigated wildland systems[ 48 , 49 ]. A ‘crop stress’ value is often used to modify the P-M model for use in wildland systems[ 42 ] but this is not an option in the Hydrus 1D model.…”

Section: Methodsmentioning

confidence: 99%

Modelling Water Uptake Provides a New Perspective on Grass and Tree Coexistence

Mazzacavallo

Kulmatiski

2015

PLoS ONE

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Root biomass distributions have long been used to infer patterns of resource uptake. These patterns are used to understand plant growth, plant coexistence and water budgets. Root biomass, however, may be a poor indicator of resource uptake because large roots typically do not absorb water, fine roots do not absorb water from dry soils and roots of different species can be difficult to differentiate. In a sub-tropical savanna, Kruger Park, South Africa, we used a hydrologic tracer experiment to describe the abundance of active grass and tree roots across the soil profile. We then used this tracer data to parameterize a water movement model (Hydrus 1D). The model accounted for water availability and estimated grass and tree water uptake by depth over a growing season. Most root biomass was found in shallow soils (0–20 cm) and tracer data revealed that, within these shallow depths, half of active grass roots were in the top 12 cm while half of active tree roots were in the top 21 cm. However, because shallow soils provided roots with less water than deep soils (20–90 cm), the water movement model indicated that grass and tree water uptake was twice as deep as would be predicted from root biomass or tracer data alone: half of grass and tree water uptake occurred in the top 23 and 43 cm, respectively. Niche partitioning was also greater when estimated from water uptake rather than tracer uptake. Contrary to long-standing assumptions, shallow grass root distributions absorbed 32% less water than slightly deeper tree root distributions when grasses and trees were assumed to have equal water demands. Quantifying water uptake revealed deeper soil water uptake, greater niche partitioning and greater benefits of deep roots than would be estimated from root biomass or tracer uptake data alone.

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“…Four meteorological variables are considered the main drivers of ET: (1) global radiation as the source of energy, (2) vapour pressure deficit (VPD), which describes the atmospheric demand, (3) wind speed which influences the boundary layer between the vegetation and the atmosphere and (4) soil water content or more precisely water availability to plants (Kelliher et al, 1993). Global radiation and VPD have been described as the main drivers of ET when enough water is available (Obrist et al, 2003;Olchev et al, 2008;Wieser et al, 2008) while soil water content is the main control in dry conditions (Baldocchi et al, 2004;Chen et al, 2008;Wilske et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Vegetation effects on the water balance of mountain grasslands depend on climatic conditions

et al. 2014

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International audienceMountain regions are key for humanity's water supply, and their water yield depends on climatic, soil and vegetation effects. Here we explore the effects of vegetation composition and structure on the water balance of high elevation grasslands with different climatic conditions across the Alps. Using a total of 220 deep seepage collectors with intact soil-vegetation monoliths in different types of mountain grasslands in the Austrian, French and Swiss Alps, we solved the water balance equation for evapotranspiration (ET) and related the results to biomass, the abundance of certain plant functional types and structural and functional vegetation properties. While daily mean ET during the growing season was similar at all sites, ET to precipitation ratios were significantly higher and ET to potential ET ratios significantly lower at the drier French sites than at the more humid Swiss and Austrian site. Large variability of ET, seepage and soil moisture within all sites pointed at a high influence of vegetation on the water balance. While ET increased significantly with biomass at all sites, the influence of other vegetation properties was site specific. At the more humid, subalpine Austrian site the effects of vegetation on ET were stronger and more diverse than at the higher elevation Swiss site and the drier French sites, where climatic drivers dominated ET. The potential to influence ET and water yield of mountain areas by manipulating the plant canopy with systematic land management is therefore higher in regions with good growing conditions than in areas with harsh climate

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Evapotranspiration (ET) and regulating mechanisms in two semiarid Artemisia-dominated shrub steppes at opposite sides of the globe

Cited by 24 publications

References 54 publications

Impact of Climate Change on Runoff in the Gilgel Abbay Watershed, the Upper Blue Nile Basin, Ethiopia

Impact of Climate Change on Runoff in the Gilgel Abbay Watershed, the Upper Blue Nile Basin, Ethiopia

Modelling Water Uptake Provides a New Perspective on Grass and Tree Coexistence

Vegetation effects on the water balance of mountain grasslands depend on climatic conditions

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