Stomatal characteristics and transpiration of three species of conifer seedlings planted on a high elevation south-facing clear-cut

1987 ◽  
Vol 17 (10) ◽  
pp. 1273-1282 ◽  
Author(s):  
N. J. Livingston ◽  
T. A. Black
Keyword(s):  
Air Temperature ◽  
Vapour Pressure ◽  
Soil Water Potential ◽  
Vapour Pressure Deficit ◽  
High Elevation ◽  
Boundary Line ◽  
Silver Fir ◽  
Clear Cut ◽  
Physiological Variables ◽  
Stomatal Responses

Douglas-fir (Pseudotsugamenziessi (Mirb.) Franco), western hemlock (Tsugaheterophylla (Raf.) Sarg.), and Pacific silver fir (Abiesamabalis (Doug.) Forbes) seedlings were planted in the spring as 1-0 container-grown plugs on a south-facing high elevation clear-cut located on Mount Arrowsmith, Vancouver Island, British Columbia, and their stomatal responses to environmental and physiological variables were determined over two successive growing seasons. The stomatal responses of all three species to changes in environmental variables and time did not differ over the 2 years nor were there differences in response between seedlings planted a year apart. A simple multiplicative boundary-line model that related seedling stomatal conductance (gs) to measurements of hourly average solar irradiance, air temperature, vapour pressure deficit, and average root zone soil water potential accounted for over 70% of the variability in gs. When the number of hours from sunrise was included as an independent variable, over 85% of the variability in gs could be explained. Daily seedlings transpiration rates on a projected leaf area basis were successfully estimated by summing the product of the calculated average gs and D/(RvT′) where D is the vapour pressure deficit, Rv is the gas constant for water vapour, and T′ is the absolute air temperature.

Stomatal Responses to Environmental Variables in Shade and Sun Grown Coffee Plants in Mexico

1985 ◽  
Vol 21 (3) ◽  
pp. 249-258 ◽  
Author(s):  
Luis Fanjul ◽  
R. Arreola-Rodriguez ◽  
M. P. Mendez-Castrejon
Keyword(s):  
Stomatal Conductance ◽  
Air Temperature ◽  
Environmental Conditions ◽  
Vapour Pressure ◽  
Environmental Variables ◽  
Vapour Pressure Deficit ◽  
Net Photosynthesis ◽  
Stomatal Movement ◽  
Stomatal Responses ◽  
Coffee Plants

SUMMARYThe influence of air temperature (T), vapour pressure deficit (vpd), irradiance (Q) and leaf water potential (ψ) on diurnal stomatal movement of coffee plants was examined under field and controlled environmental conditions. Leaves of plants grown under shade had larger stomatal conductance (g) values than plants grown in open sun. Stomatal responses to vpd under constant temperature conditions were very strong, indicating that ambient humidity could play a major role in controlling stomatal aperture. Changes in g as vpd increased probably contributed to observed reductions in the rate of net photosynthesis (Pn), though the effect of vpd on Pn was smaller.

scholarly journals Different Temperature and Humidity Responses to the Clear-Cut and the Gap in a Scots Pine Forest: A Study Case in Central Poland

2020 ◽  
Vol 3 (1) ◽  
pp. 74
Author(s):  
Longina Chojnacka-Ożga ◽  
Wojciech Ożga
Keyword(s):  
Air Temperature ◽  
Vapour Pressure ◽  
Heat Waves ◽  
Experimental Studies ◽  
Vapour Pressure Deficit ◽  
Summer Period ◽  
Clear Cut ◽  
Central Poland ◽  
The North ◽  
Thermal Diversity

In recent decades, relatively few experimental studies have been carried out in which the micrometeorological conditions have been studied over different small clearings plots of the forest. As these conditions can significantly affect many processes in the ecosystem, two questions arise: (1) whether and how the microclimatic conditions differ in the clear-cut and the gap, and (2) how heterogeneous the distribution of these conditions is on these plots. The aim of this study was to determine the spatial variation of air temperature on the clear-cut and gap as well as to compare the distribution of thermal and humidity conditions in both areas. The research was carried out in central Poland on a clear-cut with a width of 60 m and on a gap of an ellipsoid shape (40 × 70 m). The measurements were carried out in two series: spring–summer, during the period when the height of the sun during the day conditioned the inflow of direct solar radiation to any surface (May–August 2006), and autumn, when direct radiation was limited by neighbouring stands (October–November 2006). Average values of air temperature on the gap in the spring–summer period differed in individual parts of 2.2 °C, while on the clear-cut by 1.0 °C. In the autumn, thermal diversity on both research plots was similar (average 0.8 °C). The thermal diversity within the research areas was particularly marked in the case of extreme air temperature values. We found the modest spatial diversification of humidity parameters: vapour pressure, relative humidity, and humidity deficit. The particularly large diversification of relativity humidity and vapour pressure deficit occurred during the spring–summer period in the context of heat waves. The least beneficial thermal and humidity conditions for growing plants occurred in the north-eastern (NE) parts of the clear-cut and gap, which is why it is necessary to take particular note of these locations when undertaking silviculture.

Water stress and survival of three species of conifer seedlings planted on a high elevation south-facing clear-cut

1987 ◽  
Vol 17 (9) ◽  
pp. 1115-1123 ◽  
Author(s):  
N. J. Livingston ◽  
T. A. Black
Keyword(s):  
Survival Rates ◽  
High Elevation ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Silver Fir ◽  
High Survival ◽  
High Survival Rate ◽  
Poor Survival ◽  
Tolerance Mechanisms ◽  
Clear Cut

Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), western hemlock (Tsugaheterophylla (Raf.) Sarg.), and Pacific silver fir (Abiesamabilis (Dougl.) Forbes) container-grown 1-0 seedlings were spring planted on a south-facing high elevation clear-cut located on Mount Arrowsmith, Vancouver Island, British Columbia. Treatments, which included inclining seedlings to the southwest, provision of shade cards, irrigation, and irrigation and shade cards combined, were applied to determine whether modification of seedling microclimate would increase survival. Highest survival rates, regardless of treatment, were shown by Douglas-fir. By April 1984, 72 and 82% of untreated Douglas-fir seedlings planted in 1981 and 1982, respectively, survived, whereas survival of treated seedlings ranged from 81 to 95%. The high survival rate in Douglas-fir appeared to be due to their high drought tolerance. The osmotic potential of unirrigated Douglas-fir seedlings declined by over 1.1 MPa during the course of the 1982 growing season in response to decreasing soil water potentials and consequently turgor was maintained in the foliage. Transpiration rates of these seedlings were never less than 50% of those that were irrigated. Western hemlock and Pacific silver fir seedlings exhibited very poor survival, possibly owing to the lack of stress avoidance and tolerance mechanisms. Survival rates of the two species were increased by shade cards and irrigation but never exceeded 64%.

Sensitivity of evapotranspiration and surface conductance to vapour pressure deficit across high latitude climatic gradients.

2021 ◽  
Author(s):  
Astrid Vatne ◽  
Lena M. Tallaksen ◽  
Norbert Pirk ◽  
Ane V. Vollsnes ◽  
Kolbjørn Engeland ◽  
...  
Keyword(s):  
Eddy Covariance ◽  
High Latitude ◽  
Vapour Pressure ◽  
Vapour Pressure Deficit ◽  
Surface Characteristic ◽  
Lower Latitude ◽  
Surface Conductance ◽  
Lower Sensitivity ◽  
Boundary Line ◽  
Area Index

<p>Evapotranspiration links the energy, water and carbon budgets of wetlands, a key ecosystem in high latitudes. While the evapotranspiration in high latitude wetlands is largely controlled by available energy, the surface also exerts a non-negligible control. The surface control on evapotranspiration, often represented by the surface conductance, is sensitive to environmental variables such as vapour pressure deficit (VPD). Previous studies have shown that higher surface conductance leads to higher evapotranspiration from high latitude wetlands than from high latitude forests during periods of high VDP. However, it is unclear how the surface conductance-VPD relation varies across climatic gradients. To study the sensitivity of surface conductance to increasing values of VPD, we use data from three recently established eddy covariance sites in Norway, situated along high latitude climatic gradients. The sites included are Hisåsen (680 m.a.s.l., N 61.11°, E 12.24°), Finse (1200 m.a.s.l., N 60.59°, E 7.53°) and Iškoras (360 m.a.s.l, N 69.34°, E 25.29°). We first estimate surface conductance from the eddy covariance data, by inverting the Penman-Monteith equation. We then apply a boundary line analysis to assess the sensitivity of the surface conductance to VPD. Our preliminary results show a lower sensitivity of surface conductance to VPD on the northernmost site, compared to the two sites at lower latitude. Further work is needed to relate the observed variations in surface conductance-VPD relation to surface characteristic, and we hypothesize that the observered lower sensitivity in surface conductance is related to lower values of leaf area index. This work is a contribution to the Strategic Research Initiative ‘Land Atmosphere Interaction in Cold Environments’ (LATICE) of the University of Oslo.</p>

scholarly journals Comparison of vapour pressure deficit patterns during cucumber cultivation in a traditional high PE tunnel greenhouse and a tunnel greenhouse equipped with a heat accumulator

2018 ◽  
Vol 16 (1) ◽  
pp. e0201 ◽  
Author(s):  
Paweł J. Konopacki ◽  
Waldemar Treder ◽  
Krzysztof Klamkowski
Keyword(s):  
Air Temperature ◽  
Vapour Pressure ◽  
Vapour Pressure Deficit ◽  
Optimal Level ◽  
Water Vapour Pressure ◽  
Heat Accumulator ◽  
Climate Conditions ◽  
Excessive Heat ◽  
Protected Cultivation ◽  
The Difference

Plant productivity in protected cultivation is highly influenced by air temperature and humidity. The conditions relating to the moisture content of the air in protected plant cultivation are preferably defined by vapour pressure deficit (VPD), which describes the difference between the maximal and actual water vapour pressure (kPa). VPD is widely used as the parameter describing the climate conditions favourable for the development of fungal diseases and for highlighting conditions unfavourable for plant development. In protected cultivation, both the air temperature and the humidity are influenced by heating systems, and one such system is a heat accumulator, which may store the excessive heat produced during the day by converting the solar energy inside the plastic tunnel, and using it when plant heating is required. The tunnel equipped with a heat accumulator maintained an optimal level of humidity for a longer period, and significantly reduced the time of excessive air humidity. The longest time with an optimal VPD was recorded in August in a tunnel with an accumulator – 30.5% of total time vs. 22.3% of time for control tunnel. The highest difference of total time where the VPD was too low (below 0.2 kPa) was recorded in July – 12.4% of time in a tunnel with an accumulator vs. 39.1% of time for control tunnel. The highest difference of total time with an excessive VPD (over 1.4 kPa) was recorded in May – 12.1% of time in a tunnel with an accumulator vs. 17.9% of time for control tunnel. However, a situation beneficial for plant growth occurred every month during the investigated season.

scholarly journals Effects of cloudiness on carbon dioxide exchange over an irrigated maize cropland in northwestern China

2011 ◽  
Vol 8 (1) ◽  
pp. 1669-1691 ◽  
Author(s):  
B. C. Zhang ◽  
J. J. Cao ◽  
Y. F. Bai ◽  
S. J. Yang ◽  
L. Hu ◽  
...  
Keyword(s):  
Air Temperature ◽  
Vapour Pressure ◽  
Ecosystem Respiration ◽  
Meteorological Data ◽  
Exchange Process ◽  
Vapour Pressure Deficit ◽  
Northwestern China ◽  
Carbon Dioxide Exchange ◽  
Carbon Uptake ◽  
Carbon Exchange

Abstract. Clouds can strongly influence solar radiation and affects other microclimatic factors (such as air temperature and vapour pressure deficit), and those changed environmental conditions may exert strong effects on carbon exchange between terrestrial ecosystems and the atmosphere. In this study, we analyzed how canopy photosynthesis and ecosystem respiration respond to changes in cloudy conditions, based on two years of eddy-covariance and meteorological data from an irrigated maize cropland in Yingke oasis of northwestern China. The results showed that net carbon uptake was more negative under cloudy than under clear conditions, it indicates that net carbon uptake increased under cloudy days. The rate of ecosystem respiration (Re) decreased under cloudy conditions due to decreased air temperature. However, photosynthesis was suppressed by the decreasing air temperature and vapour pressure deficit (VPD) under cloudy skies. Thus, the enhancement of net carbon uptake under cloudy skies mainly contributed from increasing photosynthesis with diffuse radiation. Those results improve our understanding of the effects of cloud cover on carbon exchange process in maize (C4) cropland, and improve our understanding of the driver improving net carbon uptake under cloudy conditions.

scholarly journals Stomatal responses to vapour pressure deficit are regulated by high speed gene expression in angiosperms

2015 ◽  
Vol 39 (3) ◽  
pp. 485-491 ◽  
Author(s):  
Scott A. M. McAdam ◽  
Frances C. Sussmilch ◽  
Timothy J. Brodribb
Keyword(s):  
Gene Expression ◽  
Vapour Pressure ◽  
High Speed ◽  
Vapour Pressure Deficit ◽  
Stomatal Responses
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