Plant Water Use and “Behaviour”

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Solutions for soil, plant & meteorologywww.ictinternational.com.au

Plant Water Useand “Behaviour”

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Michael Forster PhD (UNSW)

Plant and Soil Scientist

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Tree Water Use• Total Tree Water Use

• Hydraulic Redistribution

– Soil

– Stem

– Leaf

• Water Potential Gradients

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Definition

• 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

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Definition• Water Potential Units of Measurement:

J/kg MPa Bars RH

-1 -0.001 -0.01 0.999993

-10 -0.01 -0.1 0.999926

Field Capacity -33 -0.033 -0.33 0.999756-100 -0.1 -1 0.999261

-1000 -1 -10 0.992638

Wilting Point -1500 -1.5 -15 0.988977-10000 -10 -100 0.928772

Air Dry -100000 -100 -1000 0.477632Oven Dry -1000000 -1000 -10000 0.000618

High Potential

Low Potential

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Soil-Plant-AtmosphereContinuum

Soil = -0.33 Bar

Trunk = -0.8 Bar

Leaf cell = -1.0 Bar

Leaf air = -7.0 Bar

Atmosphere = -100 Bar

High Potential

Low Potential

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Measuring Tree Water Use

• Heat Ratio Method (HRM)

• Heat Field Deformation (HFD)

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Measuring Tree Water Use

7.5 mm

22.5 mm

35 mm

12.5 mm

Inner

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a c

Temperature sensors

Downstream temperature probe

Upstream temperature

probe

Heater probe x

x

Bark + cambium

Sapwood Heartwood Centre of stem

Sapflow

db

HRM Technique

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HeartwoodSapwood

HRM Technique

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Example HRM Data

Time

Sap

Vel

ocity

(cm

per

hou

r)

Data downloaded intoSap Flow Tool software:

www.sapflowtool.com

For analysis and visual presentation

Warm weather

Nocturnal Sap Flow

Cool Weather

Diurnal Sap Flow

Rain event

http://www.sapflowtool.com/

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Case Study: Stem Hydraulic Redistribution

Image from Nadezhdina et al. 2009

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Root Sap Flow

Black Line: Northern

Grey Line: Southern


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Stem Sap Flow

Black Line: Northern

Grey Line: Southern


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More Case Studies: Hydraulic RedistributionPlease refer to Conference Proceedings

Leaf Mediated Hydraulic Redistribution

Root Mediated Hydraulic Redistribution

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Total Tree Water Use Case Study: Trees as “Biopumps”

• Antamina Mine

• Largest mine in Peru

• US$ 2.26bn investment

• Copper & Zinc

• Located 4,300m a.s.l.

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• Copper & Zinc transported via gravity and

water to sea port

• Filters separate solids from water

• What to do with all the water???


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• 174 acre afforestation

• 190,000 trees

• Several species

• Trees as Biopumps

• Mine production dependent

on Biopumps


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• Results from 6 months of

sampling

• Acacia: 3,200 litres

• Tamarix: 1,500 litres

• Algorrobo: 600 litres


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More Case Studies: Total Tree Water UsePlease refer to Conference ProceedingsNorthern United Forestry Group:Kamarooka Project

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Plant Water Use and “Behaviour”