Land–atmosphere carbon and water flux relationships to vapor pressure deficit, soil moisture, and stream flow

Towards In Vivo Monitoring of Ions Accumulation in Trees: Response of an in Planta Organic Electrochemical Transistor Based Sensor to Water Flux Density, Light and Vapor Pressure Deficit Variation

Applied Sciences ◽

10.3390/app11114729 ◽

2021 ◽

Vol 11 (11) ◽

pp. 4729

Author(s):

Davide Amato ◽

Giuseppe Montanaro ◽

Filippo Vurro ◽

Nicola Coppedé ◽

Nunzio Briglia ◽

...

Keyword(s):

Vapor Pressure ◽

Flux Density ◽

Precision Agriculture ◽

Vapor Pressure Deficit ◽

Accumulation Rate ◽

Xylem Sap ◽

Water Flux ◽

Electrochemical Transistor ◽

Olive Trees

Research on organic electrochemical transistor (OECT) based sensors to monitor in vivo plant traits such as xylem sap concentration is attracting attention for their potential application in precision agriculture. Fabrication and electronic aspects of OECT have been the subject of extensive research while its characterization within the plant water relation context deserves further efforts. This study tested the hypothesis that the response (R) of an OECT (bioristor) implanted in the trunk of olive trees is inversely proportional to the water flux density flowing through the plant (Jw). This study also examined the influence on R of vapor pressure deficit (VPD) as coupled/uncoupled with light. R was hourly recorded in potted olive trees for a 10-day period concomitantly with Jw (weight loss method). A subgroup of trees was bagged in order to reduce VPD and in turn Jw, and other trees were located in a walk-in chamber where VPD and light were independently managed. R was tightly sensitive to diurnal oscillation of Jw and at negligible values of Jw (late afternoon and night) R increased. The bioristor was not sensitive to the VPD per se unless a light source was coupled to trigger Jw. This study preliminarily examined the suitability of bioristor to estimate the mean daily nutrients accumulation rate (Ca, K) in leaves comparing chemical and sensor-based procedures showing a good agreement between them opening new perspective towards the application of OECT sensor in precision agricultural cropping systems.

Land–atmosphere feedbacks exacerbate concurrent soil drought and atmospheric aridity

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1904955116 ◽

2019 ◽

Vol 116 (38) ◽

pp. 18848-18853 ◽

Cited By ~ 34

Author(s):

Sha Zhou ◽

A. Park Williams ◽

Alexis M. Berg ◽

Benjamin I. Cook ◽

Yao Zhang ◽

...

Keyword(s):

Soil Moisture ◽

Vapor Pressure ◽

High Probability ◽

Vapor Pressure Deficit ◽

Cmip5 Models ◽

Soil Drought ◽

Global Land ◽

High Vapor ◽

Mean Climate ◽

Negative Coupling

Compound extremes such as cooccurring soil drought (low soil moisture) and atmospheric aridity (high vapor pressure deficit) can be disastrous for natural and societal systems. Soil drought and atmospheric aridity are 2 main physiological stressors driving widespread vegetation mortality and reduced terrestrial carbon uptake. Here, we empirically demonstrate that strong negative coupling between soil moisture and vapor pressure deficit occurs globally, indicating high probability of cooccurring soil drought and atmospheric aridity. Using the Global Land Atmosphere Coupling Experiment (GLACE)-CMIP5 experiment, we further show that concurrent soil drought and atmospheric aridity are greatly exacerbated by land–atmosphere feedbacks. The feedback of soil drought on the atmosphere is largely responsible for enabling atmospheric aridity extremes. In addition, the soil moisture–precipitation feedback acts to amplify precipitation and soil moisture deficits in most regions. CMIP5 models further show that the frequency of concurrent soil drought and atmospheric aridity enhanced by land–atmosphere feedbacks is projected to increase in the 21st century. Importantly, land–atmosphere feedbacks will greatly increase the intensity of both soil drought and atmospheric aridity beyond that expected from changes in mean climate alone.

Redefining droughts for the U.S. Corn Belt: The dominant role of atmospheric vapor pressure deficit over soil moisture in regulating stomatal behavior of Maize and Soybean

Agricultural and Forest Meteorology ◽

10.1016/j.agrformet.2020.107930 ◽

2020 ◽

Vol 287 ◽

pp. 107930 ◽

Cited By ~ 2

Author(s):

Hyungsuk Kimm ◽

Kaiyu Guan ◽

Pierre Gentine ◽

Jin Wu ◽

Carl J. Bernacchi ◽

...

Keyword(s):

Soil Moisture ◽

Vapor Pressure ◽

Vapor Pressure Deficit ◽

Dominant Role ◽

Corn Belt ◽

Stomatal Behavior ◽

The U.S

Conflicting drivers of land carbon uptake variability reconciled by land-atmosphere coupling

10.5194/egusphere-egu2020-11172 ◽

2020 ◽

Author(s):

Vincent Humphrey ◽

Alexis Berg ◽

Philippe Ciais ◽

Christian Frankenberg ◽

Pierre Gentine ◽

...

Keyword(s):

Soil Moisture ◽

Vapor Pressure ◽

Water Availability ◽

Vapor Pressure Deficit ◽

Sensitivity Analyses ◽

Carbon Uptake ◽

Annual Variability ◽

Vegetation Activity ◽

The Impact

Obtaining reliable estimates of the sensitivity of carbon fluxes to water availability, temperature and vapor pressure deficit is essential for constraining climate-carbon feedbacks in Earth system models. However, these variables often co-vary because of soil moisture &#8211; atmosphere feedbacks, especially in situations where they are most susceptible to strongly impact ecosystems (e.g. during droughts and heatwaves), leading to potentially conflicting results when sensitivities are assessed independently. In particular, there is conflicting evidence on the role of temperature versus water availability in explaining these variations at the global scale.Here, we show that accounting for the effect of soil moisture &#8211; atmosphere coupling resolves much of this controversy. Using idealized climate model experiments, we find that variability in soil moisture accounts for 90% of the inter-annual variability in land carbon uptake, mainly through its impact on photosynthesis. Without SM variability, the inter-annual variability (IAV) of land carbon uptake is almost eliminated. We show that the effects of soil moisture can be decomposed into 1) a direct ecosystem response to soil water stress and 2) a dominant indirect response to extreme temperature and vapor pressure deficit triggered by land-atmosphere coupling and controlled by anomalous soil moisture conditions. &#160;Importantly, these two mechanisms do not necessarily have the same spatial extent, and some regions can be more sensitive to indirect effects than to direct effects.These two pathways explain why results from coupled climate models suggest a dominant role of soil moisture, while uncoupled simulations diagnose a strong temperature effect. These findings have strong implications for offline model sensitivity analyses as well as field scale manipulation experiments (i.e. rainfall exclusion studies) where the impact of drought on carbon exchange and vegetation activity is often studied by intervening solely on soil moisture content with little consideration of the physical feedbacks on temperature and air humidity occurring in natural conditions.

An analysis of Transpiration Decline Caused by Soil Moisture and Vapor Pressure Deficit Using Mathematical Model

PROCEEDINGS OF HYDRAULIC ENGINEERING ◽

10.2208/prohe.41.73 ◽

1997 ◽

Vol 41 ◽

pp. 73-78

Author(s):

Hiromu YOSHIDA ◽

Michio HASHINO ◽

Kazunao OCHI

Keyword(s):

Mathematical Model ◽

Soil Moisture ◽

Vapor Pressure ◽

Vapor Pressure Deficit

Assessing reliability of HRM sap-flow sensors under large range of vapor pressure deficit

10.5194/egusphere-egu2020-3617 ◽

2020 ◽

Author(s):

Rémy Schoppach ◽

Daniella Ekwalla Hangue ◽

Julian Klaus

Keyword(s):

Vapor Pressure ◽

Sap Flow ◽

Vapor Pressure Deficit ◽

Heat Waves ◽

Linear Trend ◽

Water Flux ◽

Gravimetric Method ◽

Flow Sensors ◽

Tree Transpiration ◽

Sap Flow Sensors

Evapotranspiration (ET) is a major water flux of ecosystems and represents globally 60-80% of the incoming precipitation lost by terrestrial environments. In forested lands, tree transpiration (TR) is the dominant component of ET, yet remains challenging to measure. Over the years, sap-flow sensors have become the standard tool for quantifying tree TR and different methods based on thermal approaches have been developed. Heat ratio methods (HRM) are considered as the most reliable and accurate method to quantify absolute flows. Leading commercial brands ensure an accurate measurement of positive flows up to 100 cm hr-1 but different studies have highlighted a saturation effect at high flows with threshold for accuracy remaining elusive[RS1]&#160;. Due to climate change, the occurrence, the severity and the duration of extreme events like heat waves and dry periods are expected to increase in future, so the potential for high TR rate periods will also increase. Therefore, it is crucial to determine the species-specific environmental conditions allowing a reliable measurement of TR in order to improve or understanding of eco-hydrological and physiological processes during high potential TR periods that can be crucial for vegetation survival. In this study, we tested the accuracy of HRM sap-flow sensors for beech (Fagus sylvatica) and oak (Quercus robur) tree species under extreme vapor pressure deficit (VPD) conditions in order to determine threshold for reliable measurements. In greenhouse conditions, we collected a complete and dense series of TR response to VPD between 0.7 to 8.3 kPa for potted beech and oak trees using three different methods: infrared gas analyser, gravimetric method, and HRM sap-flow sensors. Responses shown a linear trend at the low-canopy leaf level (41.5 and 45.1 mg H2O m-2 s-1 kPa-1 respectively for beech and oak) but a bi-linear conformation at the whole plant level (1st slope = 12.04 &#177; 0.7 mg H2O m-2 s-1 kPa-1 and break-point at 3.9 &#177; 0.07 kPa for beech trees). Sap-flow sensors using the HRM method displayed a clear inability to reliably measure flows under high VPD conditions. Thresholds of 2.25 &#177; 0.04 and 2.87 &#177; 0.14 kPa were identified as the maximum limit of method reliability for beech and oak respectively. In highly demanding environments, we suggest a bi-linear extrapolation beyond VPD threshold for better quantifying tree TR. Further experiments aiming at characterizing TR responses to VPD for a broad range of species and in different water deficit conditions are certainly needed for better understanding tree transpiration at the whole stand level.

Responses of petiole sap flow to light and vapor pressure deficit in the tropical tree Tabebuia rosea (Bignoniaceae)

10.7287/peerj.preprints.1017 ◽

2015 ◽

Author(s):

Adam Roddy ◽

Klaus Winter ◽

Todd Dawson

Keyword(s):

Vapor Pressure ◽

Sap Flow ◽

Vapor Pressure Deficit ◽

Water Flux ◽

Tropical Tree ◽

Environmental Drivers ◽

Ratio Method ◽

Flow Rates ◽

Leaf Level ◽

Tabebuia Rosea

Continuous measurements of sap flow have been widely used to estimate water flux through tree stems and branches. However, stem-level measurements lack the resolution necessary for accurately determining fine-scale, leaf-level responses to environmental variables. We used the heat ratio method to measure sap flow rates through leaf petioles and leaflet petiolules of saplings of the tropical tree Tabebuia rosea (Bignoniaceae) to determine how leaf and leaflet sap flow responds to variation in photosynthetically active radiation (PAR) and vapor pressure deficit (VPD). In the morning sap flow rates to east-facing leaves increased 26 minutes before adjacent west-facing leaves. Integrated daily sap flow was negatively correlated with daily mean VPD, and sap flow declined when VPD exceeded 2.2 kPa whether this occurred in the morning or afternoon, consistent with a feedforward response to humidity. Indeed, changes in VPD lagged behind changes in sap flow. In contrast, changes in PAR often preceded changes in sap flow. The sap flow-VPD relationship was characterized by two distinct patterns of hysteresis, while the sap flow-PAR relationship displayed three types of hysteresis, and the type of VPD hysteresis that occurred on a given day was correlated with the type of PAR hysteresis occurring on that day. These patterns highlight how multiple environmental drivers interact to control leaf sap flux and that the development of sap flow sensors capable of measuring individual leaves could drastically influence the amount of data recordable for these structures.

Sap Flow Dynamics and Responses to Grazing and Seasonal Changes in Soil Moisture for Acacia Ancistroclada and Comberatum Molle in a Kenyan Savanna

10.21203/rs.3.rs-48464/v1 ◽

2020 ◽

Author(s):

Joseph Ondier ◽

Dennis Otieno ◽

Daniel Okach ◽

John Onyango

Keyword(s):

Soil Moisture ◽

Vapor Pressure ◽

Flux Density ◽

Sap Flow ◽

Seasonal Changes ◽

Vapor Pressure Deficit ◽

Livestock Grazing ◽

Sap Flux ◽

Sap Flux Density ◽

Rainfall Patterns

Abstract The Kenyan savanna, which is dominated by Acacia ancistroclada and Comberatum molle, has experienced notable changes in rainfall patterns and increased livestock grazing. A significant decrease in trees spread from 5 % to less than 1 % has been documented for the ecosystem and could be linked to the increased livestock grazing and changes in rainfall patterns, however, scientific evidence is lacking. We utilized sap flow to analyze the hydraulic responses of the prevailing trees to livestock grazing and seasonal changes in soil moisture. Environmental factors including precipitation, air temperature, soil moisture at - 0.3 m, and vapor pressure deficit were simultaneously measured. The results showed that the diurnal variation in sap flux density exhibited a single peak curve at around midday and correlated strongly with vapor pressure deficit and air temperature. Sap flux density was higher in the grazed (27.47 ± 8.65 g m-2s-1) than the fenced plots (20.17 ± 7.27 g m-2s-1). In all the plots, sap flux density followed seasonality in rainfall patterns, increasing and decreasing in wet and dry seasons respectively. The higher crown projected area was responsible for higher sap flow in the grazed plots. The diurnal variation in sap flux density showed that sap flow was coupled to the atmosphere with relatively low boundary layer resistance and the seasonal variation in sap flow was controlled by stomatal regulation. These findings point to the possibility that the dominant tree species in Lambwe are isohydric species. However, additional measurements need to be conducted on the eligibility of the species to confirm the conclusion.

Multiscale analysis of evapotranspiration and carbon assimilation for a long time series of micrometeorological observation in a typical semi-arid Mediterranean ecosystem

10.5194/egusphere-egu2020-19244 ◽

2020 ◽

Author(s):

Roberto Corona ◽

Nicola Montaldo ◽

Gabriel G. Katul

Keyword(s):

Time Series ◽

Soil Moisture ◽

Vapor Pressure ◽

Spectral Density ◽

Time Scales ◽

Vapor Pressure Deficit ◽

Mediterranean Ecosystem ◽

The Mediterranean ◽

Annual Time ◽

Semi Arid

The evapotranspiration (ET) process is a key term of soil water balance. In the Mediterranean climates ET represents the main loss term, that could return up to 70% of annual precipitation to the atmosphere. Due to the high seasonal and annual variability of precipitation typical of this this ecosystems, ETmay be 90% of annual precipitation. Considering that in the Mediterranean areas most of the available water for drinking purpose and for agriculture depends on the water stored in the artificial basins during the rainy period, the quantification of ET and its dynamics is of great importance.ET exhibits a temporal pattern that varies from seconds to decades, and it is mainly dependent as well as by precipitation, also by its guiding factors (e.g. soil water moisture, solar radiation and vapor pressure deficit). Hence, identify the main factors that influence ET&#160; becomes fundamental to understand its temporal variability, and is needed when modeling ET over different timescales.The case study is the Orroli site in Sardinia (Italy), a typical semi-arid Mediterranean ecosystem, for which are available eddy covariance measurements of sensible heat (H), latent heat (LE) fluxes, and soil moisture, radiation, air temperature and air humidity measurements, over 15 years. The Mediterranean site is typically characterized by strong interannual variability of meteorological conditions, which can drastically impacts water resources variability during spring and summers, the key seasons for the water resources planning and management of the region.Based on the half-hour time series, the meteorological measurements were considered into investigation, and their variability has been detected at different time scale, from seconds to year. The conventional Pearson correlation coefficient between ET and its guiding factors has been estimated, and showed the main influence of soil moisture and vapor pressure deficit on ET process, and suggested that the their control on ET vary with timescale.Furthermore, the orthonormal wavelet transformation (a spectral analysis methodology), was used to investigate the time scale variability of ET in the frequency domain, and identify the role of its guiding factors for different time scales. The ET spectral density has significant peaks at the daily, seasonal and annual time-scales. In particular, the variability of the ET spectral density exhibits two order magnitude more than the daily variability. The wavelet cospectra of ET and its guiding factors showed that the interaction is strongest for the seasonal and the annual time scales.

Diel ecosystem conductance response to vapor pressure deficit is suboptimal and independent of soil moisture

Agricultural and Forest Meteorology ◽

10.1016/j.agrformet.2017.12.078 ◽

2018 ◽

Vol 250-251 ◽

pp. 24-34 ◽

Cited By ~ 18

Author(s):

Changjie Lin ◽

Pierre Gentine ◽

Yuefei Huang ◽

Kaiyu Guan ◽

Hyungsuk Kimm ◽

...

Keyword(s):

Soil Moisture ◽

Vapor Pressure ◽

Vapor Pressure Deficit