Canopy conductance and gas exchange of a Japanese cypress forest after rainfall‐induced wetness

Interception is an important hydrological process relating to canopy gas exchange and takes a significant part from precipitation. The real interception process by the needle leaves is worth discussing because their shape may allow interception by both surfaces and thus affects photosynthesis by blocking stomata. Therefore, the aim of this study is to figure out the distribution of interception at needle leaf and its relation with the gas exchange of wet canopy.We measured ecosystem flux and wetness from a Japanese cypress forest by the advanced water-proof enclosed gas analyzer (LI7200, LI-COR, the USA) and handmade wetness sensors. A SVAT (soil-vegetation-atmosphere transfer) multilayer model with two rainfall interception solutions (free gas exchange with interception only by the adaxial surface and no gas exchange with interception by both surfaces) has been used to figure out the distribution of rainfall interception, snow melting water distribution and photosynthesis process of wet canopy.The results include precipitation events from 4 years, showing that interception can happen not only on the adaxial surface but also on both surfaces. Meanwhile, when the intensity of rainfall events enhanced, the possibility of interception on both surfaces increased. Hence, such kind of needle leaf can process photosynthesis during the rainfall. Future studies should concentrate on improving the model for snow process and soil respiration. More comparison with other types of forests may also provide worthy results for learning how plants adjust photosynthesis to adapt the climate change.

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Canopy Gas Exchange and Water Use Efficiency of ‘Empire’ Apple in Response to Particle Film, Irrigation, and Microclimatic Factors

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.135.1.25 ◽

2010 ◽

Vol 135 (1) ◽

pp. 25-32 ◽

Cited By ~ 17

Author(s):

D. Michael Glenn

Keyword(s):

Gas Exchange ◽

Water Use Efficiency ◽

Water Use ◽

Growing Season ◽

Canopy Conductance ◽

Supplemental Irrigation ◽

Isotope Discrimination ◽

Wide Range ◽

Use Efficiency ◽

Seasonal Water Use

This study examined the interaction between a reflective particle film and water use efficiency (WUE) response of irrigated and non-irrigated apple trees (Malus ×domestica) over a wide range of environmental conditions. The objectives were to measure isotopic discrimination (Δ13C and δ18O), specific gas exchange, and WUE response of ‘Empire’ apple treated with a reflective particle film (PF), with and without supplemental irrigation, compared with an untreated control, with and without supplemental irrigation, over a range of leaf area indices (LAI), seasonal evapotranspiration (ETo), and vapor pressure deficits (VPD) to determine the mechanisms of action affecting WUE in apple. Short-term whole canopy gas exchange studies and isotope discrimination analysis were used to test the hypothesis that WUE was modified by the use of a PF. In whole canopy gas exchange studies, carbon assimilation (A) and transpiration tended to increase, and WUE and canopy conductance tended to decrease, with VPD within each LAI class from 2 to 6. For VPD > 1 kPa, the PF irrigated treatment consistently had the greatest WUE and other treatments were intermediate for LAI of 2 to 4. The PF irrigated and non-irrigated treatments had greater WUE than the control irrigated and non-irrigated treatments for VPD ≤ 2 kPa and there were no treatment effects for VPD > 2 kPa in the LAI range of 4 to 6. The PF non-irrigated was equivalent to the control non-irrigated treatment at VPD of 1 to 3 kPa, but was significantly lower at VPD of 3 to 4 kPa. PF irrigated and non-irrigated treatments had the greatest carbon isotope discrimination (Δ13C), the control non-irrigated treatment had the lowest Δ13C, and the control-irrigated treatment was intermediate. Oxygen isotope enrichment (δ18O) was positively correlated with the mean growing season VPD and mean growing season evapotranspiration. Δ13C was significantly and positively correlated with δ18O. Seasonal WUE was negatively correlated with Δ13C and there was an interaction with LAI. The seasonal water use of apple is better evaluated with stable isotope discrimination integrating seasonal variation rather that the use of whole canopy gas exchange measurements that measure WUE for brief periods of time. Δ13C was an accurate measurement of apple WUE and indicated that the PF irrigated treatment had the greatest Δ13C and so the lowest WUE compared with the control non-irrigated treatment at LAI from 4 to 6. The reduced WUE of the PF irrigated treatment compared with the control non-irrigated treatment is likely due to increased gS from lower canopy temperature and increased canopy photosynthetically active radiation diffusion that drove increased A. δ18O was an indicator of seasonal water use over six growing seasons due to its high correlation with ETo. In ‘Empire’ apple, A can be increased with PF and irrigation treatments, but at the cost of decreased WUE.

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Differences in seasonality and temperature dependency of stand transpiration and canopy conductance between Japanese cypress (Hinoki) and Japanese cedar (Sugi) in a plantation

Hydrological Processes ◽

10.1002/hyp.11162 ◽

2017 ◽

Vol 31 (10) ◽

pp. 1952-1965 ◽

Cited By ~ 4

Author(s):

Takami Saito ◽

Tomo'omi Kumagai ◽

Makiko Tateishi ◽

Nakako Kobayashi ◽

Kyoichi Otsuki ◽

...

Keyword(s):

Japanese Cedar ◽

Canopy Conductance ◽

Temperature Dependency ◽

Japanese Cypress ◽

Stand Transpiration

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Environmental Controls on the Seasonal Variation in Gas Exchange and Water Balance in a Near-Coastal Mediterranean Pinus halepensis Forest

Forests ◽

10.3390/f10040313 ◽

2019 ◽

Vol 10 (4) ◽

pp. 313 ◽

Cited By ~ 5

Author(s):

Mariangela N. Fotelli ◽

Evangelia Korakaki ◽

Spyridon A. Paparrizos ◽

Kalliopi Radoglou ◽

Tala Awada ◽

...

Keyword(s):

Gas Exchange ◽

Water Balance ◽

Climate Variability ◽

Sap Flow ◽

Pinus Halepensis ◽

Aleppo Pine ◽

Canopy Conductance ◽

Climate Variability And Change ◽

Environmental Controls ◽

Adult Trees

Aleppo pine (Pinus halepensis Mill.) is widespread in most countries of the Mediterranean area. In Greece, Aleppo pine forms natural stands of high economic and ecological importance. Understanding the species’ ecophysiological traits is important in our efforts to predict its responses to ongoing climate variability and change. Therefore, the aim of this study was to assess the seasonal dynamic in Aleppo pine gas exchange and water balance on the leaf and canopy levels in response to the intra-annual variability in the abiotic environment. Specifically, we assessed needle gas exchange, water potential and δ13C ratio, as well as tree sap flow and canopy conductance in adult trees of a mature near-coastal semi-arid Aleppo pine ecosystem, over two consecutive years differing in climatic conditions, the latter being less xerothermic. Maximum photosynthesis (Amax), stomatal conductance (gs), sap flow per unit leaf area (Ql), and canopy conductance (Gs) peaked in early spring, before the start of the summer season. During summer drought, the investigated parameters were negatively affected by the increasing potential evapotranspiration (PET) rate and vapor pressure deficit (VPD). Aleppo pine displayed a water-saving, drought avoidance (isohydric) strategy via stomatal control in response to drought. The species benefited from periods of high available soil water, during the autumn and winter months, when other environmental factors were not limiting. Then, on the leaf level, air temperature had a significant effect on Amax, while on the canopy level, VPD and net radiation affected Ql. Our study demonstrates the plasticity of adult Aleppo pine in this forest ecosystem in response to the concurrent environmental conditions. These findings are important in our efforts to predict and forecast responses of the species to projected climate variability and change in the region.

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Assessment of Canopy Conductance Responses to Vapor Pressure Deficit in Eight Hazelnut Orchards Across Continents

Frontiers in Plant Science ◽

10.3389/fpls.2021.767916 ◽

2021 ◽

Vol 12 ◽

Author(s):

Gaia Pasqualotto ◽

Vinicio Carraro ◽

Eloy Suarez Huerta ◽

Tommaso Anfodillo

Keyword(s):

Gas Exchange ◽

Vapor Pressure ◽

Vapor Pressure Deficit ◽

Leaf Gas Exchange ◽

Stomatal Closure ◽

Thermal Dissipation ◽

Canopy Conductance ◽

Correct Identification ◽

Potential Productivity ◽

Growing Seasons

A remarkable increase in vapor pressure deficit (VPD) has been recorded in the last decades in relation to global warming. Higher VPD generally leads to stomatal closure and limitations to leaf carbon uptake. Assessing tree conductance responses to VPD is a key step for modeling plant performances and productivity under future environmental conditions, especially when trees are cultivated well outside their native range as for hazelnut (Corylus spp.). Our main aim is to assess the stand-level surface canopy conductance (Gsurf) responses to VPD in hazelnut across different continents to provide a proxy for potential productivity. Tree sap flow (Fd) was measured by Thermal dissipation probes (TDP) probes (six per sites) in eight hazelnut orchards in France, Italy, Georgia, Australia, and Chile during three growing seasons since 2016, together with the main meteorological parameters. We extracted diurnal Fd to estimate the canopy conductance Gsurf.. In all the sites, the maximum Gsurf occurred at low values of VPD (on average 0.57 kPa) showing that hazelnut promptly avoids leaf dehydration and that maximum leaf gas exchange is limited at relatively low VPD (i.e., often less than 1 kPa). The sensitivity of the conductance vs. VPD (i.e., -dG/dlnVPD) resulted much lower (average m = −0.36) compared to other tree species, with little differences among sites. We identified a range of suboptimal VPD conditions for Gsurf maximization (Gsurf > 80% compared to maximum) in each site, named “VPD80,” which multiplied by the mean Gsurf might be used as a proxy for assessing the maximum gas exchange of the orchard with a specific management and site. Potential gas exchange appeared relatively constant in most of the sites except in France (much higher) and in the driest Australian site (much lower). This study assessed the sensitivity of hazelnut to VPD and proposed a simple proxy for predicting the potential gas exchange in different areas. Our results can be used for defining suitability maps based on average VPD conditions, thus facilitating correct identification of the potentially most productive sites.

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