Diurnal and inter-day hysteresis of species-specific stomatal conductance from sap-flow measurements illustrates hydraulic-stress responses strategies of trees

2020 ◽  
Author(s):  
Gil Bohrer ◽  
Theresia Yazbeck ◽  
Ana Maria Restrepo Acevedo ◽  
Ashley M. Matheny
Keyword(s):  
Soil Moisture ◽  
Stomatal Conductance ◽  
Land Surface ◽  
Sap Flow ◽  
Stress Recovery ◽  
Flow Measurements ◽  
Surface Models ◽  
Stem Water ◽  
Species Specific ◽  
Sap Flow Measurements

<p>Modeling of plant hydraulics is at the forefront of development in vegetation and land-surface models.  Numerical tools that consider water flow within the conductive system of plants, and particularly trees, have been developed and used in studies of hydraulic strategy and consequences of hydraulic behavior for drought tolerance. Several established land-surface models such as ED2, CLM, and E3SM have recently developed “hydro” versions and are ready to extrapolate the consequences of including tree hydraulic behaviors into large scale and global simulations. At the core of any plant hydrodynamic model is the assumption that stomatal conductance is dependent on xylem water potential. Further, “plant hydro” models assume that the effect of soil moisture on stomatal conductance is not direct but cascades through depletion of xylem water content in dry soil conditions.</p><p>We use observations of sap flow, soil moisture, and evapotranspiration at a mixed forest in the University of Michigan Biological Station (UMBS) at the footprint of the US-UMd flux tower to characterize the onset and advancement of hydraulic stress and post-stress recovery. We define stress by observing tree-level decrease of stomatal conductance during sunny days as soil-moisture deficit progresses. We use the Penman-Monteith (PM) formulation to calculate stomatal conductance given observed atmospheric forcing: air temperature, humidity, net radiation, soil heat flux, and aerodynamic resistance. Such PM-based approach effectively decouples changes in evapotranspiration due to atmospheric forcing vs. changes due to decreased stomatal conductance. Multiple years of sap-flow measurements in tens of trees of multiple species allow us to identify the species-specific characteristics of the onset of stress, and the hysteretic dynamics of stomatal conductance. The daily hysteresis indicates the severity of stress. Longer-term inter-day hysteresis of the relationship between noon-time stomatal conductance and soil moisture, before and after rain have alleviated the moisture stress, indicates species-specific strategies of hydraulic-stress recovery. Recovery time is related to the degree of stress, and can vary between a nearly reversible state and 1 to 2 days of recovery, to a long recovery of several days. We find large differences between species in the sensitivity to stress and in the strength of coupling between stem water content and stomatal conductance. These are consistent with the hydraulic strategy of the trees along the an/isohydric continuum.    </p><p>Identifying the hydraulic characteristics of water stress and direct observations of the coupling between stem water storage, conductance, and transpiration provide key observations with which to tune hydrodynamic models and allow process-based functional-type parameterization of stomatal conductance that accounts for tree hydrodynamics and hydraulic stress recovery.   </p>

Examination and parameterization of the root water uptake model from stem water potential and sap flow measurements

2012 ◽  
pp. n/a-n/a ◽  
Author(s):  
Yuting Yang ◽  
Huade Guan ◽  
John L. Hutson ◽  
Hailong Wang ◽  
Caecilia Ewenz ◽  
...  
Keyword(s):  
Water Potential ◽  
Water Uptake ◽  
Sap Flow ◽  
Root Water Uptake ◽  
Stem Water Potential ◽  
Flow Measurements ◽  
Stem Water ◽  
Sap Flow Measurements

scholarly journals CO<sup>2</sup> uptake of a mature <i>Acacia mangium</i> plantation estimated from sap flow measurements and stable carbon isotope discrimination

2014 ◽  
Vol 11 (5) ◽  
pp. 1393-1411 ◽  
Author(s):  
H. Wang ◽  
P. Zhao ◽  
L. L. Zou ◽  
H. R. McCarthy ◽  
X. P. Zeng ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Carbon Isotope ◽  
Sap Flow ◽  
Carbon Isotope Discrimination ◽  
Stable Carbon Isotope ◽  
Co2 Uptake ◽  
Sap Flux ◽  
Stable Carbon ◽  
Flow Measurements ◽  
Sap Flow Measurements

Abstract. A simple, nondestructive method for the estimation of canopy CO2 uptake is important for understanding the CO2 exchange between forest and atmosphere. Canopy CO2 uptake (FCO2) of a subtropical mature \\textit{A. mangium} plantation was estimated by combining sap flow measurements and stable carbon isotope discrimination (Δ) in Southern China from 2004 to 2007. The mechanistic relationship linking FCO2, Δ in leaf sap, and sap flow-based canopy stomatal conductance (Gs) was applied in our study. No significant seasonal variations were observed in Δ or in the ratio of the intercellular and ambient CO2 concentrations (Ci/Ca), although diurnal Ci/Ca varied between sunlit and shaded leaves. A sensitivity analysis showed that estimates of FCO2 were more sensitive to dynamics in Gs than in Ca and Δ. By using seasonally and canopy averaged Ci/Ca values, we obtained an acceptable estimate of FCO2 compared to other estimates. FCO2 exhibited similar diurnal variation to that of Gs. Large seasonal variation in FCO2 was attributed to the responsiveness of Gs to vapor pressure deficit, photosynthetically active radiation, and soil moisture deficit. Our estimate of FCO2 for a mature A. mangium plantation (2.13 ± 0.40 gC m−2 d−1) approached the lower range of values for subtropical mixed forests, probably due to lower mean canopy stomatal conductance, higher Ci/Ca, and greater tree height than other measured forests. Our estimate was also lower than values determined by satellite-based modeling or carbon allocation studies, suggesting the necessity of stand level flux data for verification. Qualitatively, the sap flux/stable isotope results compared well with gas exchange results. Differences in results between the two approaches likely reflected variability due to leaf position and age, which should be reduced for the combined sap flux and isotope technique, as it uses canopy average values of Gs and Ci/Ca.

scholarly journals CO<sub>2</sub> uptake of a mature <i>Acacia mangium</i> plantation estimated from sap flow measurements and stable carbon isotope discrimination

2013 ◽  
Vol 10 (7) ◽  
pp. 11583-11625 ◽  
Author(s):  
H. Wang ◽  
P. Zhao ◽  
L. L. Zou ◽  
H. R. McCarthy ◽  
X. P. Zeng ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Stable Isotope ◽  
Carbon Isotope ◽  
Sap Flow ◽  
Carbon Isotope Discrimination ◽  
Stable Carbon Isotope ◽  
Sap Flux ◽  
Stable Carbon ◽  
Flow Measurements ◽  
Sap Flow Measurements

Abstract. Canopy CO2 uptake (FCO2) of a subtropical mature \\textit{A. mangium} plantation was estimated by combining sap flow measurements and stable carbon isotope discrimination (Δ) in Southern China from 2004 to 2007. The mechanistic relationship linking FCO2, Δ in leaf sap, and sap flow based canopy stomatal conductance (Gs) was applied in our study. No significant seasonal variations were observed in Δ or in the ratio of the intercellular and ambient CO2 concentrations (Ci/Ca), although diurnal Ci/Ca varied between sunlit and shaded leaves. A sensitivity analysis showed that estimates of FCO2 were more sensitive to dynamics in Gs than in Ca and Δ. By using seasonally and canopy averaged Ci/Ca values, an acceptable estimate of FCO2 was obtained. FCO2 exhibited similar diurnal variation to that of Gs. Large seasonal variation in FCO2 was attributed to the responsiveness of Gs to vapour pressure deficit, photosynthetically active radiation, and soil moisture deficit. Our estimate of FCO2 for a mature A. mangium plantation (2.13 ± 0.40 g C m−2 day−1) approached the lower range of values for subtropical mixed forest, probably due to lower mean canopy stomatal conductance, higher Ci/Ca, and greater tree height than other measured forests. Our estimate was also lower than values determined by satellite-based modeling or component carbon analysis, suggesting the necessity of stand level flux data for verification. Qualitatively, the sap flux/stable isotope results compared well with gas exchange results. Differences in results between the two approaches reflected variability due to leaf position and age, which could be reduced for sap flux/stable isotope, which uses canopy average values of Gs and Ci/Ca.

Towards a consistent quantification of ecosystem transpiration and its uncertainty from the SAPFLUXNET database

2021 ◽  
Author(s):  
Rafael Poyatos ◽  
Víctor Granda ◽  
Víctor Flo ◽  
Maurizio Mencuccini ◽  
Jordi Martínez-Vilalta
Keyword(s):  
Sap Flow ◽  
Heat Dissipation ◽  
Basal Area ◽  
Tree Level ◽  
Science Data ◽  
Flow Measurements ◽  
Ecosystem Level ◽  
Species Specific ◽  
Main Component ◽  
Sap Flow Measurements

&lt;p&gt;Transpiration from forests and woodlands is the main component of terrestrial evapotranspiration. Ecosystem-scale transpiration estimates are needed to inform models and remote sensing products so that they can improve their quantification of the magnitudes, spatiotemporal patterns, and environmental sensitivity of transpiration at regional to global scales. Tree-level sap flow measurements can be used to estimate ecosystem transpiration in forests and woodlands and these data are now globally available in the SAPFLUXNET database (Poyatos et al. 2020). However, observational errors, sampling assumptions, and missing data propagate uncertainties in the upscaling process to the ecosystem level. Here we quantify ecosystem transpiration and its uncertainty, from hourly to annual scales, across SAPFLUXNET sites using two different approaches. In a first approach, we estimated hourly sap flow per unit basal area at the species level, which was then aggregated to the stand level using species-specific basal areas available in SAPFLUXNET metadata. In this approach, uncertainty was quantified from the observed variability in tree-level sap flow within a species. In a second approach, we used empirical relationships between tree diameter and sap flow to obtain stand-level transpiration and propagated the uncertainty in this relationship to the stand-level values. For both approaches, sap flow data obtained with uncalibrated heat dissipation probes were also adjusted using a recently published correction based on sap flow calibrations. The different upscaling methods, implemented in R code, will allow reproducible upscaling and uncertainty quantification from SAPFLUXNET datasets, paving the way towards a better understanding of ecosystem transpiration and its controls across the globe.&lt;/p&gt;&lt;p&gt;&lt;span&gt;Poyatos, R., Granda, V., Flo, V., [&amp;#8230;], Steppe, K., Mencuccini, M., Mart&amp;#237;nez-Vilalta, J. (2020). &lt;/span&gt;Global transpiration data from sap flow measurements: the SAPFLUXNET database, Earth System Science Data Discussions, 1&amp;#8211;57, .&lt;/p&gt;

scholarly journals Evaluation and Comparison of Noah and Pleim–Xiu Land Surface Models in MM5 Using GÖTE2001 Data: Spatial and Temporal Variations in Near-Surface Air Temperature

2007 ◽  
Vol 46 (10) ◽  
pp. 1587-1605 ◽  
Author(s):  
J-F. Miao ◽  
D. Chen ◽  
K. Borne
Keyword(s):  
Soil Moisture ◽  
Air Temperature ◽  
Land Surface ◽  
Model Performance ◽  
Surface Air Temperature ◽  
Near Surface ◽  
Surface Models ◽  
Urban Heat ◽  
Soil Moisture Initialization ◽  
Evident Difference

Abstract In this study, the performance of two advanced land surface models (LSMs; Noah LSM and Pleim–Xiu LSM) coupled with the fifth-generation Pennsylvania State University–National Center for Atmospheric Research Mesoscale Model (MM5), version 3.7.2, in simulating the near-surface air temperature in the greater Göteborg area in Sweden is evaluated and compared using the GÖTE2001 field campaign data. Further, the effects of different planetary boundary layer schemes [Eta and Medium-Range Forecast (MRF) PBLs] for Noah LSM and soil moisture initialization approaches for Pleim–Xiu LSM are investigated. The investigation focuses on the evaluation and comparison of diurnal cycle intensity and maximum and minimum temperatures, as well as the urban heat island during the daytime and nighttime under the clear-sky and cloudy/rainy weather conditions for different experimental schemes. The results indicate that 1) there is an evident difference between Noah LSM and Pleim–Xiu LSM in simulating the near-surface air temperature, especially in the modeled urban heat island; 2) there is no evident difference in the model performance between the Eta PBL and MRF PBL coupled with the Noah LSM; and 3) soil moisture initialization is of crucial importance for model performance in the Pleim–Xiu LSM. In addition, owing to the recent release of MM5, version 3.7.3, some experiments done with version 3.7.2 were repeated to reveal the effects of the modifications in the Noah LSM and Pleim–Xiu LSM. The modification to longwave radiation parameterizations in Noah LSM significantly improves model performance while the adjustment of emissivity, one of the vegetation properties, affects Pleim–Xiu LSM performance to a larger extent. The study suggests that improvements both in Noah LSM physics and in Pleim–Xiu LSM initialization of soil moisture and parameterization of vegetation properties are important.

scholarly journals On the utility of land surface models for agricultural drought monitoring

2012 ◽  
Vol 16 (9) ◽  
pp. 3451-3460 ◽  
Author(s):  
W. T. Crow ◽  
S. V. Kumar ◽  
J. D. Bolten
Keyword(s):  
Soil Moisture ◽  
Land Surface ◽  
Cross Correlation ◽  
Root Zone ◽  
Vegetation Indices ◽  
Agricultural Drought ◽  
Drought Monitoring ◽  
Global Evaluation ◽  
Land Surface Models ◽  
Surface Models

Abstract. The lagged rank cross-correlation between model-derived root-zone soil moisture estimates and remotely sensed vegetation indices (VI) is examined between January 2000 and December 2010 to quantify the skill of various soil moisture models for agricultural drought monitoring. Examined modeling strategies range from a simple antecedent precipitation index to the application of modern land surface models (LSMs) based on complex water and energy balance formulations. A quasi-global evaluation of lagged VI/soil moisture cross-correlation suggests, when globally averaged across the entire annual cycle, soil moisture estimates obtained from complex LSMs provide little added skill (< 5% in relative terms) in anticipating variations in vegetation condition relative to a simplified water accounting procedure based solely on observed precipitation. However, larger amounts of added skill (5–15% in relative terms) can be identified when focusing exclusively on the extra-tropical growing season and/or utilizing soil moisture values acquired by averaging across a multi-model ensemble.

Can heat-pulse sap flow measurements be used as continuous water stress indicators of citrus trees?

2012 ◽  
Vol 31 (5) ◽  
pp. 1053-1063 ◽  
Author(s):  
C. Ballester ◽  
J. Castel ◽  
L. Testi ◽  
D. S. Intrigliolo ◽  
J. R. Castel
Keyword(s):  
Water Stress ◽  
Sap Flow ◽  
Heat Pulse ◽  
Flow Measurements ◽  
Stress Indicators ◽  
Sap Flow Measurements ◽  
Citrus Trees

Sap Flow Measurements

2017 ◽  
pp. 99-112 ◽  
Author(s):  
Barbara Köstner ◽  
Eva Falge ◽  
Martina Alsheimer
Keyword(s):  
Sap Flow ◽  
Flow Measurements ◽  
Sap Flow Measurements
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