The Blood Pressure of Trees: PSY1 Stem Psychrometer Michael Forster ICT International Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 1 Water Potential Gradients • Water Potential: – Free energy associated with water – Free energy is the potential to do work – Water moves from higher to lower potentials – Water moves from mountains to ocean Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 2 Water Potential Gradients • Water Potential: – Plant water potential is a measure of how well-hydrated a plant is. – A plant that is more hydrated is healthier, grows faster, has higher reproductive output (yield), and can cope with diseases, pruning, disturbance etc, better Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 3 Water Potential Gradients • Water Potential Units of Measurement: J/kg MPa Bars RH -1 -0.001 -0.01 0.999993 -10 -0.01 -0.1 0.999926 -33 -0.033 -0.33 0.999756 -100 -0.1 -1 0.999261 -1000 -1 -10 0.992638 -1500 -1.5 -15 0.988977 -10000 -10 -100 0.928772 Air Dry -100000 -100 -1000 0.477632 Oven Dry -1000000 -1000 -10000 0.000618 High Potential Field Capacity Wilting Point Low Potential Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 4 Soil-Plant-Atmosphere Continuum Low Potential Atmosphere = -100 MPa Leaf air = -7.0 MPa Leaf cell = -1.0 MPa Trunk = -0.8 MPa Soil = -0.33 MPa High Potential Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 5 Water Potential & Trees Hydraulic Redistribution Low Potential Low Potential High Potential High Potential From: Caldwell, et al. 1998 Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 6 Water Potential & Trees Nadezhdina et al. (2009) New Phytologist 184: 932-943. Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 7 Water Potential & Trees Nadezhdina et al. (2009) New Phytologist 184: 932-943. Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 8 The Pressure Bomb Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 9 Research Background • Hawkesbury Forest Experiment • University of Western Sydney, Richmond, NSW • Whole Tree Chambers • CO2 Experiment Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 10 Research Background CO2 Experiment: • Ambient CO2: 380ppm • Elevated CO2: Am + 300ppm Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 11 Research Background Sap Flow CO2 Stomatal Conductance (Stomatal closure) Plant Water Potential Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 12 Stomatal Conductance Results Data from: LiCor 6400 Graph Source: David Ellsworth, UWS; Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 13 Sap Flow Results Graph Source: Michael Forster, UWS; Derek Eamus, UTS Data from: Dynagage Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 14 Water Potential Results Time of Day Data from: Pressure Bomb 17/12/2012 Leaf Water Potential (MPa) 8p m 7p m 5p m 3p m 1p m 11 am 9a m 7a m 5a m 0 -0.5 -1 -1.5 Solutions for soil, plant & environmental monitoring Ambient -2 Graph Source: Michael Forster, UWS; Derek Eamus, UTS -2.5 Elevated www.ictinternational.com 15 The Pressure Bomb Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 16 1 Day of Data Time of Day Leaf Water Potential (MPa) 8p m 7p m 5p m 3p m 1p m 11 am 9a m 7a m 5a m 0 -0.5 -1 -1.5 -2 Ambient Elevated -2.5 Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 17 PSY1 Stem Psychrometer Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 18 Stem Water Potential (MPa) 17 Days of Data from Psychrometer Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 19 Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 20 A Brief History… – First published: 1984 (Dixon & Tyree (1984) Plant, Cell & Environment 7: 693-697) – Professor Mike Dixon, University of Guelph, Canada – Difficult with 1980’s technology – Few publications Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 21 A Brief History… Micro-volt changes in temperature Micro-volt = one millionth of a volt = Volt x 10-6 PSY1 Stem Psychrometer was released in 2010 Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 22 PSY1 Stem Psychrometer Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 23 The Psychometric Method Condensation Dew Point = Condensation Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 24 The Psychometric Method Temperature = Dew Point = Relative Humidity= Water Potential = 25 C 23 C 89 % -16.0 MPa Temperature = Dew Point = Relative Humidity= Water Potential = 25 C 16 C 57 % -77.2 MPa Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 25 The Psychometric Method Ambient Temperature C-thermocouple Dew Point Corrections Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 26 Step 1: Dry Bulb Reference Temperature difference equals close to zero Electronic Dry Bulb Offset (EDBO) Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 27 Step 2: ΔT: Chamber vs Stem Temperature ΔT is temperature difference between chamber air and plant stem Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 28 Step 3: Peltier Cooling Pulse Condense water onto C-thermocouple for 10 seconds Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 29 Step 4: Wet Bulb Depression Measure how cold the C-thermocouple was in order to condense water How cold was C-thermocouple in order to change water from vapor to liquid phase Dew Point Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 30 Step 5: Ambient Temperature Measure temperature of chamber for ambient temperature Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 31 Review: The Psychometric Method Ambient Temperature C-thermocouple Dew Point Corrections Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 32 Review: The Psychometric Method STEP 1: Dry Bulb Reference Correction STEP 2: ΔT Correction STEP 3: Peltier Cooling Pulse Condensation STEP 4: Wet Bulb Depression Dew Point STEP 5: Ambient Temperature Ambient Temp Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 33 Does It Work? From Mike Dixon, University of Guelph 17/12/2012 Solutions for soil, plant & environmental monitoring www.ictinternational.com 34 1:1 Relationship Stem Water Potential (MPa, PSWC) -3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 -0.5 -1.0 -1.5 -2.0 1:1 Relationship Between PSWC and PSY1 -2.5 Data and information from Mike Dixon, Guelph University -3.0 Stem Water Potential (MPa, PSY1) Temperature Correction 0.0 Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 35 Exact Relationship Unpublished Data - Courtesy George Koch Northern Arizona University Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 36 Installation – Important! Install on XYLEM not phloem Chamber to be sealed against xylem Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 37 Installation – Important! Insulate against extreme temperature fluctuations Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 38 Stress and Recovery Well-hydrated The plant is becoming less hydrated Unpublished Data - Courtesy of Alec Downey and Alvaro Arias, species: coffee, location: Costa Rica Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 39 Tree Transplantations Images from www.treeworldinfo.com Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 40 Transplantations & Wireless Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 41 Experimental Treatments Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 42 Ivory Silk (Syringa reticulata) Treatment = YES fungus (mycorrhiza) Control = NO fungus (mycorrhiza) Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 43 Gravity & Stem Water Potential Tree Height Water Potential 40m -0.4MPa 30m -0.3MPa 20m -0.2MPa 10m -0.1MPa 0m 0.0MPa Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 44 Gravity & Stem Water Potential Baradur, Tree Top West Psychrometer at 88m Height 0.0 -0.2 -0.4 -0.6 -0.8 -1.0 -1.2 -1.4 -1.6 -1.8 -2.0 0 50 100 150 200 250 300 Daily cycles of water potential measured with ICT psychrometer on a branch at about 88 meter height in a 91 meter tall Sequoiadendron giganteum At Whitaker’sForest, California during the period Aug. 13 – Aug. 17, 2010. Unpublished Data - Courtesy George Koch North Arizona University Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 45 Gravity & Stem Water Potential Baradur, Tree Top West Psychrometer at 88m Height 0.0 -0.2 -0.4 -0.6 -0.8 -0.88MPa -1.0 -1.2 -1.4 -1.6 -1.8 -2.0 0 50 100 150 200 250 300 Difference due to: - Soil water deficit? - Stem storage deficit? - Stem resistance? (hydraulic conductivity) Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 46 Plant Parasites Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 47 Plant Parasites Figure from Forster 2012 17/12/2012 Solutions for soil, plant & environmental monitoring www.ictinternational.com 48 Plant Parasites Figure from Forster 2012 17/12/2012 Solutions for soil, plant & environmental monitoring www.ictinternational.com 49 Plant Parasites TREE BRANCH FUNGAL GALL DAY TIME: Positive flow into dry atmosphere Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 50 Plant Parasites TREE BRANCH FUNGAL GALL NIGHT TIME: Reverse flow into dry plant Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 51 ICT International Pty Ltd Solutions for soil, plant and environmental research www.ictinternational.com [email protected] Phone: 61 2 6772 6770 Fax: 61 2 6772 7616 PO Box 503, Armidale, NSW, Australia, 2350 INTERNATIONAL Solutions for soil, plant & environmental monitoring 17/12/2012 www.ictinternational.com 52
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