Variability in the Environmental Factors Driving Evapotranspiration from a Grazed Rangeland during Severe Drought Conditions

2007 ◽  
Vol 8 (2) ◽  
pp. 207-220 ◽  
Author(s):  
Joseph G. Alfieri ◽  
Peter D. Blanken ◽  
David N. Yates ◽  
Konrad Steffen
Keyword(s):  
Soil Moisture ◽  
Environmental Factors ◽  
Moisture Content ◽  
Land Surface ◽  
Soil Moisture Content ◽  
Severe Drought ◽  
Vapor Transfer ◽  
Drought Conditions ◽  
Using Data

Abstract Nearly one-half of the earth’s terrestrial surface is susceptible to drought, which can have significant social, economic, and environmental impacts. Therefore, it is important to develop better descriptions and models of the processes linking the land surface and atmosphere during drought. Using data collected during the International H2O Project, the study presented here investigates the effects of variations in the environmental factors driving the latent heat flux (λE) during drought conditions at a rangeland site located in the panhandle of Oklahoma. Specifically, this study focuses on the relationships of λE with vapor pressure deficit, wind speed, net radiation, soil moisture content, and greenness fraction. While each of these environmental factors has an influence, soil moisture content is the key control on λE. The role of soil moisture in regulating λE is explained in terms of the surface resistance to water vapor transfer. The results show that λE transitioned between being water or energy limited during the course of the drought. The implications of this on the ability to understand and model drought conditions and transitions into or out of droughts are discussed.

scholarly journals Numerical Simulations of Effects of Soil Moisture and Modification by Mountains over New Zealand in Summer

2011 ◽  
Vol 139 (2) ◽  
pp. 494-510 ◽  
Author(s):  
Yang Yang ◽  
Michael Uddstrom ◽  
Mike Revell ◽  
Phil Andrews ◽  
Hilary Oliver ◽  
...  
Keyword(s):  
Soil Moisture ◽  
New Zealand ◽  
Moisture Content ◽  
Air Temperature ◽  
Land Surface ◽  
Soil Moisture Content ◽  
Surface Air Temperature ◽  
Shortwave Radiation ◽  
Lower Sensitivity ◽  
The South

Abstract Historically most soil moisture–land surface impact studies have focused on continents because of the important forecasting and climate implications involved. For a relatively small isolated mountainous landmass in the ocean such as New Zealand, these impacts have received less attention. This paper addresses some of these issues for New Zealand through numerical experiments with a regional configuration of the Met Office Unified Model atmospheric model. Two pairs of idealized simulations with only contrasting dry or wet initial soil moisture over a 6-day period in January 2004 were conducted, with one pair using realistic terrain and the other pair flat terrain. For the mean of the 6 days, the differences in the simulated surface air temperature between the dry and moist cases were 3–5 K on the leeside slopes and 1–2 K on the windward slopes and the central leeside coastal region of the South Island in the afternoon. This quite nonuniform response in surface air temperature to a uniformly distributed soil moisture content and soil type is mainly attributed to modification of the effects of soil moisture by mountains through two different processes: 1) spatial variation in cloud coverage across the mountains ranges leading to more shortwave radiation at ground surface on the leeside slope than the windward slope, and 2) the presence of a dynamically and thermally induced onshore flow on the leeside coast bringing in air with a lower sensitivity to soil moisture. The response of local winds to soil moisture content is through direct or indirect effects. The direct effect is due to the thermal contrast between land and sea/land shown for the leeside solenoidal circulations, and the indirect effect is through the weakening of the upstream blocking of the South Island for dryer soils shown by the weakening and onshore shift of the upstream deceleration and forced ascent of incoming airflow.

scholarly journals Seasonal Volatile Emission Patterns of the Endemic New Zealand Shrub Dracophyllum subulatum on the North Island Central Plateau

2021 ◽  
Vol 12 ◽  
Author(s):  
Evans Effah ◽  
D. Paul Barrett ◽  
Paul G. Peterson ◽  
Murray A. Potter ◽  
Jarmo K. Holopainen ◽  
...  
Keyword(s):  
Soil Moisture ◽  
New Zealand ◽  
Environmental Factors ◽  
Moisture Content ◽  
Soil Moisture Content ◽  
Ambient Air ◽  
Sampling Occasion ◽  
Central Plateau ◽  
Volatile Emissions ◽  
The North

Volatile organic compounds (VOCs) produced by plants are essential indicators of their physiological response to environmental conditions. But evidence of natural variation in VOC emissions and their contributing factors is still limited, especially for non-cultivated species. Here we explored the natural volatile emissions of Dracophyllum subulatum Hook.f., an endemic shrub to the North Island Central Plateau of New Zealand, and determined some environmental factors driving the plant’s emissions. Volatile emissions of D. subulatum were measured on four separate occasions from December 2017 to September 2018 using the “push-pull” headspace sampling technique and analyzed using gas chromatography-mass spectrometry (GC-MS). D. subulatum was classified based on the volatiles measured on each sampling occasion using linear discriminant analysis (LDA). On each sampling occasion, we also recorded and compared ambient air temperature, herbivory damage, total soil nitrogen (N), available phosphorus (P), potassium (K), and soil moisture content. The relationship between environmental variables that differed significantly between sampling occasions and volatile emissions were estimated using generalized linear models (GLMs). Based on VOCs measured on each sampling occasion, we were able to distinguish different chemical profiles. Overall, we found that total emission and the relative proportions of all major chemical classes released by D. subulatum were significantly higher during summer. The GLMs reveal that differences in environmental factors between the four sampling occasions are highly associated with changing emissions. Higher temperatures in summer had a consistently strong positive relationship with emissions, while the impacts of soil moisture content, P and K were variable and depended on the chemical class. These results are discussed, particularly how high temperature (warming) may shape volatile emissions and plants’ ecology.

scholarly journals Role of Climatic Factors In The Toxicity of Fipronil Toward Earthworms In Two Tropical Soils: Effects of Increased Temperature And Reduced Soil Moisture Content

2021 ◽  
Author(s):  
Thuanne Braúlio Hennig ◽  
Paulo Roger Lopes Alves ◽  
Felipe Ogliari Bandeira ◽  
Liziara da Costa Cabrera ◽  
Jonas Simon Dugatto ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Moisture Content ◽  
Climatic Factors ◽  
Hazard Quotient ◽  
Tropical Soils ◽  
Effect Of Temperature ◽  
Water Holding ◽  
Water Contents

Abstract The aim of this study was to assess the effect of temperature on the toxicity of fipronil toward earthworms (Eisenia andrei) in two Brazilian soils (Entisol and Oxisol) with contrasting textures. In the case of Entisol, the influence of the soil moisture content on the toxicity was also investigated. Earthworms were exposed for 56 days to soils spiked with increasing concentrations of fipronil under scenarios with different combinations of temperature (20, 25 and 27 ºC) and soil moisture content (60 and 30% of water holding capacity (WHC) for Entisol and 60% WHC for Oxisol). The number of juveniles produced was taken as the endpoint and a risk assessment was performed based on the hazard quotient (HQ). In Entisol, at 60% WHC the fipronil toxicity decreased at 27 ºC compared with the other temperatures tested (EC50 = 52.58, 48.48 and 110 mg kg-1 for 20, 25 and 27 ºC, respectively). In the case of Oxisol at 60% WHC, the fipronil toxicity increased at 27 ºC compared with other temperatures (EC50 = 277.57, 312.87 and 39.89 mg kg-1 at 20, 25 and 27 ºC, respectively). An increase in fipronil toxicity was also observed with a decrease in soil moisture content in Entisol at 27 ºC (EC50 = 27.95 and 110 mg kg-1 for 30% and 60% WHC, respectively). The risk of fipronil was only significant at 27 ºC in Entisol and Oxisol with water contents of 30% and 60% WHC, respectively, revealing that higher temperatures can increase the risk of fipronil toxicity toward earthworms. The results reported herein show that soil properties associated with climatic shifts could enhance the ecotoxicological effects and risk of fipronil for earthworms, depending on the type of soil.

scholarly journals The role of soil moisture content on maize (Zea Mays L.) emergence and production

2019 ◽  
pp. 112-113
Author(s):  
Gabor Milics ◽  
Viliam Nagy ◽  
Tomas Orfanus ◽  
Lubomir Lichner ◽  
Peter Surda
Keyword(s):  
Zea Mays ◽  
Soil Moisture ◽  
Moisture Content ◽  
Soil Moisture Content ◽  
Zea Mays L

scholarly journals Anatomy of the 2018 agricultural drought in The Netherlands using in situ soil moisture and satellite vegetation indices

2020 ◽  
Author(s):  
Joost Buitink ◽  
Anne M. Swank ◽  
Martine van der Ploeg ◽  
Naomi E. Smith ◽  
Harm-Jan F. Benninga ◽  
...  
Keyword(s):  
Soil Moisture ◽  
The Netherlands ◽  
Moisture Content ◽  
Land Surface ◽  
Soil Moisture Content ◽  
Vegetation Indices ◽  
Agricultural Drought ◽  
Summer Drought ◽  
The Impact

Abstract. The soil moisture status near the land surface is a key determinant of vegetation productivity. The critical soil moisture content determines the transition from an energy-limited to a water-limited evapotranspiration regime. This study quantifies the critical soil moisture content by comparison of in situ soil moisture profile measurements of the Raam and Twenthe networks in the Netherlands, with two satellite derived vegetation indices (NIRv and VOD) during the 2018 summer drought. The critical soil moisture content is obtained through a piece-wise linear correlation of the NIRv and VOD anomalies with soil moisture on different depths of the profile. This nonlinear relation reflects the observation that negative soil moisture anomalies develop weeks before the first reduction in vegetation indices. Furthermore, the inferred critical soil moisture content was found to increase with observation depth and this relationship is shown to be linear and distinctive per area, reflecting the tendency of roots to take up water from deeper layers when drought progresses. The relations of non-stressed towards water-stressed vegetation conditions on distinct depths are derived using Remote Sensing, enabling the parameterization of reduced evapotranspiration and its effect on GPP in models to study the impact of a drought on the carbon cycle.

scholarly journals A comparative study on the role of electro-conductive plastics electrode in direct current electroosmosis

2020 ◽  
Vol 198 ◽  
pp. 01047
Author(s):  
Wei Bai ◽  
Tao Jian ◽  
Rongbing Lin ◽  
Xiaoqian Luo ◽  
Lingwei Kong
Keyword(s):  
Soil Moisture ◽  
Energy Consumption ◽  
Moisture Content ◽  
Soil Moisture Content ◽  
Metal Electrode ◽  
Residual Moisture ◽  
Factors Affecting ◽  
The Difference ◽  
Conductive Plastics

The electrode material is one of the critical factors affecting the electroosmosis efficiency. The electroosmotic test was conducted to compare the current, volume moisture content, and energy consumption of Electro-Conductive Plastics Electrode (ECPE) and metal electrode in the dispose of sludge. The results show that: the current decreases of ECPE is smaller than the metal electrode before 20h, and the difference value of moisture content between cathode and anode of ECPE is smaller when electroosmosis is stable. The energy consumption of ECPE is lower in the range of soil moisture content of 35% - 60%. The ECPE has a particular advantage in energy consumption and uniformity of soil moisture content, but has a disadvantage in residual moisture content as compared with the metal electrode.

scholarly journals Soil Moisture Content from GNSS Reflectometry Using Dielectric Permittivity from Fresnel Reflection Coefficients

2020 ◽  
Vol 12 (1) ◽  
pp. 122 ◽  
Author(s):  
Andres Calabia ◽  
Iñigo Molina ◽  
Shuanggen Jin
Keyword(s):  
Soil Moisture ◽  
Dielectric Permittivity ◽  
Moisture Content ◽  
Land Surface ◽  
Soil Moisture Content ◽  
High Sensitivity ◽  
P Value ◽  
Reflection Coefficients ◽  
Eastern Region ◽  
Fresnel Reflection

Global Navigation Satellite Systems-Reflectometry (GNSS-R) has shown unprecedented advantages to sense Soil Moisture Content (SMC) with high spatial and temporal coverage, low cost, and under all-weather conditions. However, implementing an appropriated physical basis to estimate SMC from GNSS-R is still a challenge, while previous solutions were only based on direct comparisons, statistical regressions, or time-series analyses between GNSS-R observables and external SMC products. In this paper, we attempt to retrieve SMC from GNSS-R by estimating the dielectric permittivity from Fresnel reflection coefficients. We employ Cyclone GNSS (CYGNSS) data and effectively account for the effects of bare soil roughness (BSR) and vegetation optical depth by employing ICESat-2 (Ice, Cloud, and land Elevation Satellites 2) and/or SMAP (Soil Moisture Active Passive) products. The tests carried out with ICESat-2 BSR data have shown the high sensitivity in SMC retrieval to high BSR values, due to the high sensitivity of ICESat-2 to land surface microrelief. Our GNSS-R SMC estimates are validated by SMAP SMC products and the results provide an R-square of 0.6, Root Mean Squared Error (RMSE) of 0.05, and a zero p-value, for the 4568 test points evaluated at the eastern region of China during April 2019. The achieved results demonstrate the optimal capability and potential of this new method for converting reflectivity measurements from GNSS-R into Land Surface SMC estimates.

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