Diurnal Patterns of Water Potential in Abiesconcolor and Pinusponderosa

1973 ◽  
Vol 3 (4) ◽  
pp. 556-564 ◽  
Author(s):  
John E. Barker
Keyword(s):  
Vapor Pressure ◽  
Water Potential ◽  
Environmental Conditions ◽  
Vapor Pressure Deficit ◽  
Square Root ◽  
Relative Lack ◽  
Independent Variables ◽  
Diurnal Patterns ◽  
Available Soil Moisture ◽  
Cohesion Theory

Diurnal patterns of water potential for Abiesconcolor and Pinusponderosa were studied in relation to concurrent environmental conditions. Up to 86% of variation in water potential was accounted for using irradiance, square root of vapor pressure deficit, height, and stomatal aperture as independent variables in A. concolor while up to 76% was accounted for in P. ponderosa using the same variables. Under comparable environmental conditions, A. concolor experienced lower water potentials than P. ponderosa due to its relative lack of stomatal control and its greater sensitivity to changes in vapor pressure deficit. Height effects were very nearly identical to those predicted by the cohesion theory. A procedure for estimating available soil moisture is suggested.

scholarly journals Mist, Vapor Pressure Deficit, and Cutting Water Potential Influence Rooting of Stem Cuttings of Loblolly Pine

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 890D-890
Author(s):  
Anthony V. LeBude* ◽  
Barry Goldfarb ◽  
Frank A. Blazich
Keyword(s):  
Vapor Pressure ◽  
Water Potential ◽  
Pinus Taeda ◽  
Loblolly Pine ◽  
Large Scale ◽  
Vapor Pressure Deficit ◽  
Adventitious Root Formation ◽  
Silica Sand ◽  
Stem Cuttings ◽  
Range Of Values

Producing high quality rooted stem cuttings on a large scale requires precise management of the rooting environment. This study was conducted to investigate the effect of the rooting environment on adventitious root formation of stem cuttings of loblolly pine (Pinus taeda L.). Hardwood stem cuttings of loblolly pine were collected in Feb. 2002 from hedged stock plants and stored at 4 °C until setting in Apr. 2002. One hundred stem cuttings per plot in each of two replications received 45, 61, 73, 102, 147, or 310 mL·m-2 of mist delivered intermittently by a traveling gantry (boom) system. Mist frequency was similar for all treatments and was related inversely to relative humidity (RH) within the polyethylene covered greenhouse. Rooting tubs in each plot were filled with a substrate of fine silica sand, and substrate water potential was held constant using soil tensiometers that activated a subirrigation system. Cutting water potential was measured destructively on two cuttings per plot beginning at 0500 hr every 3 hh until 2300 hr (seven measurements) 7, 14, 21, or 28 days after setting. During rooting, leaf temperature and RH were recorded in each plot to calculate vapor pressure deficit (VPD). Cutting water potential and VPD were strongly related to mist application. Cutting water potential was also related to VPD. Rooting percentage had a linear and quadratic relationship with mean cutting water potential and VPD averaged between 1000 and 1800 HR. Eighty percent rooting occurred within a range of values for VPD. Data suggest that VPD can be used to manage the water deficit of stem cuttings of loblolly pine to increase rooting percentage. These results may be applicable to other species and to other rooting environments.

A new perspective for transpiration estimation using an extended framework of isohydricity linking to drought-driven changes in VPD and leaf area

2020 ◽  
Author(s):  
Changming Li ◽  
Hanbo Yang
Keyword(s):  
Vapor Pressure ◽  
Leaf Area Index ◽  
Water Potential ◽  
Leaf Area ◽  
Vapor Pressure Deficit ◽  
Soil Water Potential ◽  
Area Index ◽  
Atmosphere Interaction ◽  
New Perspective ◽  
New Framework

<p>The framework of isohydry or anisohydry, which is usually defined as the sensitivity of leaf water potential (Ψ<sub>L</sub>) to soil water potential (Ψs), has been rapidly adopted to solve a range of eco-hydrologic problems. While its reliability to describe the impacts of land-atmosphere interaction and seasonal phenology on plants has been recently questioned. In this study, we propose an expansion of the modern isohydricity framework to coordinate the dynamics of Ψ<sub>L</sub> derived from vapor pressure deficit (VPD) and leaf area index (A<sub>L</sub>), respectively. The contributions of VPD and A<sub>L </sub>to the sensitivity of Ψ<sub>L</sub> to Ψs are calculated and further evaluated using the FLUXNET dataset, as to validate the applicability of the extended concept. Then, we suggested a new method to calculate transpiration based on the new framework to establish relationship between Ψ<sub>L</sub> and Ψs at ecosystem scale. Our results illustrate that the new framework is reasonable for describing the dynamics of Ψ<sub>L</sub> and provides a promising potential for transpiration estimation.</p>

scholarly journals COMPARING TWO TRANSECT METHODS FOR THE DETECTION OF RED-BACKED SALAMANDERS

2016 ◽  
pp. 27-30
Author(s):  
Jay D. McGhee ◽  
Michael D. Killian
Keyword(s):  
Vapor Pressure ◽  
Leaf Litter ◽  
Environmental Conditions ◽  
Vapor Pressure Deficit ◽  
Sampling Methods ◽  
Plethodon Cinereus ◽  
The Other ◽  
Monitoring Methods ◽  
Rainfall Events ◽  
Extensive Variation

Typical monitoring methods for terrestrial salamanders are subject to extensive variation, driven by the environmental conditions in effect during sampling. As rigorous salamander sampling methods are needed to monitor populations, there is a need to assess commonly used methods under a variety of environmental conditions. We hypothesized that of two methods used for capturing red-backed salamanders (Plethodon cinereus), leaf litter searches and natural cover searches, the latter would perform best for adults and in situations where moisture was limiting. We compared captures for paired transect surveys: one a leaf litter search and the other a natural cover search, relative to age, proximity to streams, rainfall events, vapor pressure deficit and season. We found that natural cover searches outperformed leaf litter searches when conducted away from streams and in the absence of rainfall. Natural cover searches performed better regardless of vapor pressure deficit and season (spring or fall). Natural cover searches detected more adults than juveniles. We recommend natural cover searches as more efficient than leaf litter searches.

scholarly journals Effect of canopy management in the water status of cacao (Theobroma cacao) and the microclimate within the crop area

2019 ◽  
Vol 97 (4) ◽  
pp. 701-710
Author(s):  
Alfredo Jiménez-Pérez ◽  
Manuel J. Cach-Pérez ◽  
Mirna Valdez-Hernández ◽  
Edilia De la Rosa-Manzano
Keyword(s):  
Vapor Pressure ◽  
Water Potential ◽  
Sap Flow ◽  
Theobroma Cacao ◽  
Vapor Pressure Deficit ◽  
Soil Water Potential ◽  
Flow Density ◽  
Closed Canopy ◽  
Sap Flow Density ◽  
Crop Area

Background: Cacao is an umbrophile species and therefore the handling of shade by producers can cause a microclimatic modification that influences the physiology of the plant. Questions: Can canopy management influence the microclimate of the crop area and the water content of cacao? Species of study: Theobroma cacao L. (Malvaceae). Study site: Comalcalco, Tabasco, Mexico; dry and rainy season 2018. Methods: Three sites were selected with an open canopy (OC) and three with a closed canopy (CC), where we determined air temperature and humidity, soil temperature, vapor pressure deficit, photosynthetically active radiation, soil water potential and leaf water potential in 15 cacao trees and the sap flow density in 12 trees, by canopy condition and by season. Results: Higher values of solar radiation, air and soil temperature, vapor pressure deficit and lower relative humidity were recorded under OC compared to CC, in both seasons. Differences in soil water potential between 10 and 60 cm depth in CC were recorded during the dry season. There was a lower sap flow density and daily water use in OC. The leaf water potential was similar between canopy conditions, in both seasons. Conclusions: Changes in canopy coverage significantly modify the microclimate of the crop area, a less stressful environment being generated under closed canopy conditions, influencing the sap flow density of cacao trees.

scholarly journals Ecophysiological Vulnerability to Climate Change in Mexico City’s Urban Forest

2021 ◽  
Vol 9 ◽  
Author(s):  
Victor L. Barradas ◽  
Manuel Esperon-Rodriguez
Keyword(s):  
Climate Change ◽  
Stomatal Conductance ◽  
Vapor Pressure ◽  
Water Potential ◽  
Tree Species ◽  
Environmental Variables ◽  
Vapor Pressure Deficit ◽  
Urban Forest ◽  
Urban Climate ◽  
Vulnerability To Climate Change

Urban forests play an important role in regulating urban climate while providing multiple environmental services. These forests, however, are threatened by changes in climate, as plants are exposed not only to global climate change but also to urban climate, having an impact on physiological functions. Here, we selected two physiological variables (stomatal conductance and leaf water potential) and four environmental variables (air temperature, photosynthetically active radiation, vapor pressure deficit, and water availability) to compare and evaluate the ecophysiological vulnerability to climate change of 15 dominant tree species from Mexico City’s urban forest. The stomatal conductance response was evaluated using the boundary-line analysis, which allowed us to compare the stomatal response to changes in the environment among species. Our results showed differential species responses to the environmental variables and identified Buddleja cordata and Populus deltoides as the least and most vulnerable species, respectively. Air temperatures above 33°C and vapor pressure deficit above 3.5 kPa limited the stomatal function of all species. Stomatal conductance was more sensitive to changes in leaf water potential, followed by vapor pressure deficit, indicating that water is a key factor for tree species performance in Mexico City’s urban forest. Our findings can help to optimize species selection considering future climate change by identifying vulnerable and resilient species.

scholarly journals A COMPUTER SIMULATION MODEL FOR EVALUATING GREENHOUSE IRRIGATION SCHEDULING TECHNIQUES

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 692f-692
Author(s):  
Steven E. Woerner ◽  
Douglas A. Hopper
Keyword(s):  
Computer Simulation ◽  
Vapor Pressure ◽  
Simulation Model ◽  
Environmental Conditions ◽  
Vapor Pressure Deficit ◽  
Irrigation Scheduling ◽  
Combination Method ◽  
Computer Simulation Model ◽  
Water Usage ◽  
Climatic Regions

A computer simulation model was developed to be used in evaluating irrigation scheduling techniques and assisting irrigation scheduling decisions under greenhouse conditions in Colorado. The model simulates variable greenhouse conditions and shows how each of four irrigation scheduling techniques responds to these conditions. Reports from the model detail numbers of irrigation events, sensitivities to parameters, and forecasts water usage. The model was also used to determine appropriate accumulation triggers for Colorado conditions. Four techniques evaluated here include: time clock control; accumulated radiation; accumulated vapor pressure deficit; combination method (radiation and vapor pressure deficit). The model has shown the combination method to be the most sensitive to changes in environmental conditions, while the time clock method proved to be least sensitive (and most wasteful of water). The model may evaluate additional irrigation scheduling techniques by including additional parameters in the model, and may readily be adapted to different climatic regions.

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