scholarly journals An analysis of the sensitivity of sap flux to soil and plant variables assessed for an Australian woodland using a soil - plant - atmosphere model

2008 ◽  
Vol 35 (6) ◽  
pp. 509 ◽  
Author(s):  
Melanie Zeppel ◽  
Catriona Macinnis-Ng ◽  
Anthony Palmer ◽  
Daniel Taylor ◽  
Rhys Whitley ◽  
...  
Keyword(s):  
Water Content ◽  
Water Use ◽  
Water Uptake ◽  
Soil Profile ◽  
Sap Flow ◽  
Large Scale ◽  
Seasonal Patterns ◽  
Management Options ◽  
Vegetation Water ◽  
Spa Model

Daily and seasonal patterns of tree water use were measured for the two dominant tree species, Angophora bakeri E.C.Hall (narrow-leaved apple) and Eucalyptus sclerophylla (Blakely) L.A.S. Johnson & Blaxell (scribbly gum), in a temperate, open, evergreen woodland using sap flow sensors, along with information about soil, leaf, tree and micro-climatological variables. The aims of this work were to: (a) validate a soil–plant–atmosphere (SPA) model for the specific site; (b) determine the total depth from which water uptake must occur to achieve the observed rates of tree sap flow; (c) examine whether the water content of the upper soil profile was a significant determinant of daily rates of sap flow; and (d) examine the sensitivity of sap flow to several biotic factors. It was found that: (a) the SPA model was able to accurately replicate the hourly, daily and seasonal patterns of sap flow; (b) water uptake must have occurred from depths of up to 3 m; (c) sap flow was independent of the water content of the top 80 cm of the soil profile; and (d) sap flow was very sensitive to the leaf area of the stand, whole tree hydraulic conductance and the critical water potential of the leaves, but insensitive to stem capacitance and increases in root biomass. These results are important to future studies of the regulation of vegetation water use, landscape-scale behaviour of vegetation, and to water resource managers, because they allow testing of large-scale management options without the need for large-scale manipulations of vegetation cover.

Continuous observation of canopy water content changes with GPS sensors

2021 ◽  
Author(s):  
Vincent Humphrey ◽  
Brian L. Dorsey ◽  
Christian Frankenberg
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Large Scale ◽  
Climatic Conditions ◽  
Leaf Water ◽  
Global Navigation Satellite Systems ◽  
Leaf Water Content ◽  
Vegetation Water ◽  
Canopy Water

<p>Canopy water content is a direct indicator of vegetation water use and hydraulic stress, reflecting how ecosystems respond and adapt to droughts and heatwaves. It represents an interesting target for Earth system models which attempt to predict the response and resilience of the vegetation in the face of changing climatic conditions. So far, in-situ estimates of vegetation water content often rely on infrequent and time-consuming samplings of leaf water content, which are not necessarily representative of the canopy scale. On the other hand, several satellite techniques have demonstrated a promising potential for monitoring vegetation optical depth and water content, but these large-scale measurements are still difficult to reference against sparse in-situ level observations.</p><p>Here, we present an experimental technique based on Global Navigation Satellite Systems (GNSS) to bridge this persisting scale gap. Because GNSS microwave signals are obstructed and scattered by vegetation and liquid water, placing a GNSS sensor in a forest and measuring changes in signal quality can provide continuous information on canopy water content and forest structure. We demonstrate that variations in GNSS signal attenuation reflect the distribution of biomass density and liquid water in the canopy, consistent with ancillary relative leaf water content measurements, and can be monitored continuously. Of particular interest, this technique can resolve diurnal variations in canopy water content at sub-hourly time steps. The few rainfall events captured during the 8-months observational record also suggest that canopy water interception can be monitored at 5 minutes intervals. We discuss future strategies and requirements for deploying such off-the-shelf passive bistatic radar systems at existing FluxNet sites.</p>

scholarly journals Intensified vegetation water use under acid deposition

2019 ◽  
Vol 5 (7) ◽  
pp. eaav5168 ◽  
Author(s):  
Matthew Lanning ◽  
Lixin Wang ◽  
Todd M. Scanlon ◽  
Matthew A. Vadeboncoeur ◽  
Mary B. Adams ◽  
...  
Keyword(s):  
Water Use ◽  
Acid Deposition ◽  
Large Scale ◽  
Water Cycle ◽  
Base Cations ◽  
Surface Energy Flux ◽  
Soil Calcium ◽  
Fossil Fuel Burning ◽  
Calcium Supply ◽  
Vegetation Water

Despite the important role vegetation plays in the global water cycle, the exact controls of vegetation water use, especially the role of soil biogeochemistry, remain elusive. In this study, we reveal a new mechanism of soil biogeochemical control of large-scale vegetation water use. Nitrate and sulfate deposition from fossil fuel burning have caused substantial soil acidification, leading to the leaching of soil base cations. Of these, calcium has a unique role in plant cells by regulating stomatal aperture, thus affecting vegetation water use. We hypothesized that the leaching of the soil calcium supply, induced by acid deposition, would increase large-scale vegetation water use. We present evidence from a long-term whole watershed acidification experiment demonstrating that the alteration of the soil calcium supply by acid deposition can significantly intensify vegetation water use (~10% increase in evapotranspiration) and deplete available soil water. These results are critical to understanding future water availability, biogeochemical cycles, and surface energy flux and to help reduce uncertainties in terrestrial biosphere models.

scholarly journals Development of the Community Water Model (CWatM v1.04) A high-resolution hydrological model for global and regional assessment of integrated water resources management

2019 ◽  
Author(s):  
Peter Burek ◽  
Yusuke Satoh ◽  
Taher Kahil ◽  
Ting Tang ◽  
Peter Greve ◽  
...  
Keyword(s):  
Water Resources ◽  
Open Source ◽  
Water Use ◽  
Large Scale ◽  
Hydrological Modeling ◽  
Hydrological Model ◽  
Integrated Water Resources Management ◽  
Water Model ◽  
Management Options ◽  
Community Water

Abstract. We develop a new large-scale hydrological and water resources model, the Community Water Model (CWatM), which can simulate hydrology both globally and regionally at different resolutions from 30 arc min to 30 arc sec at daily time steps. CWatM is open-source in the Python programming environment and has a modular structure. It uses global, freely available data in the netCDF4 file format for reading, storage, and production of data in a compact way. CWatM includes general surface and groundwater hydrological processes, but also takes into account human activities, such as water use and reservoir regulation, by calculating water demands, water use, and return flows. Reservoirs and lakes are included in the model scheme. CWatM is used in the framework of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP), which compares global model outputs. The flexible model structure allows dynamic interaction with hydro-economic and water quality models for the assessment and evaluation of water management options. Furthermore, the novelty of CWatM is its combination of state-of the-art hydrological modeling, modular programming, an online user manual and automatic source code documentation, global and regional assessments at different spatial resolutions, and a potential community to add to, change, and expand the open-source project. CWatM also strives to build a community learning environment which is able to freely use an open-source hydrological model and flexible coupling possibilities to other sectoral models, such as energy and agriculture.

scholarly journals Water use pattern of Pinus tabulaeformis in the semiarid region of Loess Plateau, China

2016 ◽  
Vol 25 (3) ◽  
pp. e077 ◽  
Author(s):  
Shengqi Jian ◽  
Xueli Zhang ◽  
Zening Wu ◽  
Caihong Hu
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Water Use ◽  
Loess Plateau ◽  
Sap Flow ◽  
Pinus Tabulaeformis ◽  
Flow Measurements ◽  
Stand Transpiration ◽  
The Mean

Aim of the study: We analyzed the water-use strategy of P. tabulaeformis and determine the relationships between environmental factors and transpiration rates in the P. tabulaeformis woodlands.Area of study: Loess Plateau region of Northwest China.Material and Methods: Sap flow density of the P. tabulaeformis trees was measured with Granier-type sensors. Stand transpiration was extrapolated from the sap flow measurements of individual trees using the following Granier equation.Main results: The mean sap flow rates of individual P. tabulaeformis trees ranged from 9 L day−1 to 54 L day−1. Photosynthetically active radiation and vapor pressure deficit were the dominant driving factors of transpiration when soil water content was sufficient (soil water content>16%), considering that soil water content is the primary factor of influencing transpiration at the driest month of the year. During the entire growing season, the maximum and minimum daily stand transpiration rates were 2.93 and 0.78 mm day−1, respectively. The mean stand transpiration rate was 1.9 mm day−1, and the total stand transpiration from May to September was 294.1 mm.Research highlights: This study can serve as a basis for detailed analyses of the water physiology and growth of P. tabulaeformis plantation trees for the later application of a climate-driven process model.Keywords: Sap flow; stand transpiration; environmental factor; Pinus tabulaeformis; Loess Plateau.

scholarly journals Model analysis of the effects of atmospheric drivers on storage water use in Scots pine

2007 ◽  
Vol 4 (4) ◽  
pp. 657-671 ◽  
Author(s):  
H. Verbeeck ◽  
K. Steppe ◽  
N. Nadezhdina ◽  
M. Op De Beeck ◽  
G. Deckmyn ◽  
...  
Keyword(s):  
Water Potential ◽  
Water Content ◽  
Water Flow ◽  
Water Use ◽  
Scots Pine ◽  
Sap Flow ◽  
Temperate Climate ◽  
Soil Drought ◽  
Incoming Radiation ◽  
And Storage

Abstract. Storage water use is an indirect consequence of the interplay between different meteorological drivers through their effect on water flow and water potential in trees. We studied these microclimatic drivers of storage water use in Scots pine (Pinus sylvestris L.) growing in a temperate climate. The storage water use was modeled using the ANAFORE model, integrating a dynamic water flow and – storage model with a process-based transpiration model. The model was calibrated and validated with sap flow measurements for the growing season of 2000 (26 May–18 October). Because there was no severe soil drought during the study period, we were able to study atmospheric effects. Incoming radiation and vapour pressure deficit (VPD) were the main atmospheric drivers of storage water use. The general trends of sap flow and storage water use are similar, and follow more or less the pattern of incoming radiation. Nevertheless, considerable differences in the day-to-day pattern of sap flow and storage water use were observed. VPD was determined to be one of the main drivers of these differences. During dry atmospheric conditions (high VPD) storage water use was reduced. This reduction was higher than the reduction in measured sap flow. Our results suggest that the trees did not rely more on storage water during periods of atmospheric drought, without severe soil drought. The daily minimum tree water content was lower in periods of high VPD, but the reserves were not completely depleted after the first day of high VPD, due to refilling during the night. Nevertheless, the tree water content deficit was a third important factor influencing storage water use. When storage compartments were depleted beyond a threshold, storage water use was limited due to the low water potential in the storage compartments. The maximum relative contribution of storage water to daily transpiration was also constrained by an increasing tree water content deficit.

scholarly journals Irrigation during Flowering Improves Subsoil Water Uptake and Grain Yield in Rainfed Soybean

Agronomy ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 120 ◽  
Author(s):  
Jin He ◽  
Yi Jin ◽  
Neil C. Turner ◽  
Feng-Min Li
Keyword(s):  
Grain Yield ◽  
Water Content ◽  
Soil Water Content ◽  
Water Use ◽  
Water Uptake ◽  
Dry Weight ◽  
Flower Number ◽  
Grain Number ◽  
Supplemental Irrigation ◽  
Pod Number

Water is the main factor limiting soybean yield and the timely supply of supplemental irrigation could increase the grain yield, but the effects of a supplemental water supply on soybean yields have not been well studied. Field and pot experiments were conducted to compare the grain yield, yield components, water use efficiency for grain yield (WUEG), flower number, filled-pod number, soil water content, and root dry weight at different depths with and without supplemental irrigation at flowering. Field experiments showed that compared to rainfed conditions, 40 mm of water applied during flowering significantly increased grain yield by 26%, WUEG by 12%, filled-pod number by 16%, grain number by 13.3%, and water uptake from soil by 11% in 2011, and increased grain yield by 22%, WUEG by 7%, filled-pod number by 26%, grain number by 27%, and water uptake by 21% in 2012. The soil water content in the subsoil (1.2–2.0 m) layers under the irrigated treatment was lower, indicating greater water extraction, than in the rainfed treatment and water uptake was significantly and positively correlated with yield in both years. In a pot experiment, flower and filled-pod number, water use during flowering and podding were significantly higher in the well-watered (WW) treatment than cyclic water stress (WS) treatment. Flower number and filled-pod number were significantly and positively correlated with water use during flowering and podding, respectively, under both the WW and WS treatments. The root dry weight was higher in the 0.2–0.8 m soil layer in the WW treatment than the WS treatment. We conclude that supplementary water at flowering increased the water uptake from deeper soil layers by increasing the distribution of roots in the subsoil layers that resulted in the production of more flowers and filled pods and increased the WUEG and grain yield.

Differences between two grain sorghum genotypes in adaptation to drought stress. II. Root water uptake and water use

1983 ◽  
Vol 34 (6) ◽  
pp. 627 ◽  
Author(s):  
GC Wright ◽  
RCG Smith
Keyword(s):  
Drought Stress ◽  
Grain Yield ◽  
Water Content ◽  
Soil Water ◽  
Water Use ◽  
Water Uptake ◽  
Root Water Uptake ◽  
Grain Sorghum ◽  
Sorghum Genotypes ◽  
Adaptation To Drought

A study of two sorghum hybrids, E-57 and TX-671, indicated that differences in grain yield under conditions of low rainfall were associated with increased extraction of soil water at depth. E-57 used less water before anthesis than did TX-671, which was more than compensated for by increased water use after anthesis. As soil water declined in a drying cycle, TX-671 tended to restrict its water use at a higher water content than E-57. The implication of these results is discussed.

Herbicide Effects on Water Use by Grass Sod and Red Clover (Trifolium pratense) Establishment

Weed Science ◽  
1986 ◽  
Vol 34 (1) ◽  
pp. 48-51 ◽  
Author(s):  
Mark C. Trimmer ◽  
Dean L. Linscott
Keyword(s):  
Water Potential ◽  
Water Content ◽  
Water Use ◽  
Avena Sativa ◽  
Soil Profile ◽  
Trifolium Pratense ◽  
Red Clover ◽  
Applied Water ◽  
Direct Seeded ◽  
Herbicide Effects

Red clover (Trifolium pratenseL.) was direct seeded into a grass sod after spraying with dalapon (2,2-dichloropropanoic acid), glyphosate [N-(phosphonomethyl) glycine], or paraquat (1,1′-dimethyl-4,4′-bipyridinium ion) at rates of 5.6, 2.2, and 0.6 kg ai/ha respectively. Dalapon applied a few days prior to planting did not improve red clover stands in comparison to seeding in unsprayed sod. Applying glyphosate a few days prior to seeding in spring and summer invariably increased red clover stands, but paraquat was effective in only one of four spring or summer applications. Glyphosate applied the fall preceding a spring or summer seeding produced red clover stands superior to those after all spring treatments. Where glyphosate or paraquat was applied, water content of the upper 20 cm of the soil profile was greater during the first 10 days after treatment, relative to unsprayed plots or those treated with dalapon. By 30 days after application, the glyphosate-treated sods used less soil water than those treated with paraquat. Applications of glyphosate and paraquat greatly suppressed water utilization by oats (Avena sativaL.) in the greenhouse, based on water potential of the potting soil. Dalapon had little effect on water use by oat seedlings in the greenhouse.

scholarly journals Stored water in the inner bark and sapwood: Atypical patterns of daily discharge and recharge, radial osmotic gradient and freezing resistance

2021 ◽  
Author(s):  
Sandra J. Bucci ◽  
Luisina Carbonell Silletta ◽  
Agustin Cavallaro ◽  
Nadia S. Arias ◽  
Paula Campanello ◽  
...  
Keyword(s):  
Water Content ◽  
Water Use ◽  
Sap Flow ◽  
Water Movement ◽  
Osmotic Gradient ◽  
Freezing Resistance ◽  
Inner Bark ◽  
Araucaria Araucana ◽  
Daily Discharge ◽  
Daily Water

Stored water in inner tissues can affect plant water balance and its freezing resistance. We studied the water storages in the inner bark and sapwood of Araucaria araucana, a species with thick inner bark. Specifically, we analyzed its daily behavior, the driving force to radial water movement and its freezing resistance. The whole-stem water content and diameter and sap flow increased in the morning and decreased in the afternoon. An osmotic gradient between stem tissues was involved in the morning water storage recharge. There were no lags in the onset of sap flow between different stem positions, however sap flow at 6m height was higher than basal sap flow in the afternoon, at the time that sapwood water content started to decline followed by the inner bark. Extracellular freezing was delayed down to -6˚C in the inner bark and to -8˚C in the leaves. The unusual diurnal pattern of internal water use may enhance freezing resistance as a consequence of the lower water content and higher osmotic potential when the lowest temperatures occur. The contribution of stem tissues to daily water use and the pattern of ice nucleation observed make this species less susceptible to drought and very low temperatures.

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