transpiration sap flow in trees

8/11/2019 Transpiration Sap Flow in Trees

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ISAAC 2006 Sapflow in Trees

Transpiration (Sapflow) inTrees


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Transpiration / Sapflow

EvaporationRainfall &

Irrigation

Transpiration

The evaporation ofwater from plants

occurring primarily at

the leaves throughopen stomata duringthe process of CO 2 gas

exchange during photosynthesis



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Meteorological Data



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Stem Water Potential



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Applications

Whole Tree Daily water use

Catchment Hydrology Research Mapping hydraulic architecture

Tracing water use from roots to leaves Identifying sides of tree where water is used

Identifying areas of decline within the tree thatmay require removal

Functional distribution of tree root systems



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Non-destructive determination of

Tree Functional Root Distribution

ISAAC 2006 Sapflow in Trees Projected Area

Soil MoistureSensors

Depth

Sapflow sensors

Width

Nadezhdina 2003


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Air Spade Excavation of Roots



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Lateral Root System Distribution



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Vertical Root System Distribution



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Anatomy of a Tree

(A) Outer Bark (B) Inner Bark (C) Cambium Layer (D) Sapwood (E) Heartwood

Sapwood thickness on average isonly 20 to 40 mm thick



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Sap Flow Variability(heterogeneity) Spatial

in radial direction variability around the stem circumference

Temporal due to water stress plant damage


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Radial Sap Velocity Gradient

05

10152025303540

0 5 10 15 20 25 30 35 40 50 60

Radial distance from edge of tree (mm)

S a p

V

e l o c

i t y

c

h r - 1

Sap Velocity



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Accounting for Radial Sapflow

Gradients

A1 A2

SapwoodHeartwood

Sapflow

Sensor A1 = Sapwood Annulus 1

A2 = Sapwood

Annulus 2ISAAC 2006 Sapflow in Trees


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Uniform Growing Conditions



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Non-Uniform Growing Conditions



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Sap flow heterogeneity - large trees

Pseudotsuga menziesii (Douglas fir)

Wind River, Washington, USA

Total height 58m, DBH = 250 cmTime period August 14 to Aug 24

Data courtesy Kucera - EMS


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How Do You Measure Sapflow



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HRM Needle Design


7 . 5 mm

2 2 . 5 mm

3 0 mm

7.5 mm

30 mm

22.5 mm


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HRM Theory

Heater probe

Temperaturesensors

Downstreamtemperature probe

Upstreamtemperature

probe

x

x

Bark +

cambium

Sapwood Heartwood Centre of stem

Sapflow

c d

a b



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Calibration Data



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Installation


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Installation in Small Stems

& Roots


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Sapflow Units of Measure

Vh - Raw Heat Pulse Velocity (cm hr -1)

Relative sapflow trend

Vs - Corrected Sap Velocity Absolute sap velocity (cm hr -1) rate of use

- Sapflow (cm 3 hr -1 or litres hr -1) Volumetric, total amount of water use



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Converting Sap Velocity to Sapflow

Corrected sap velocity Vs (say 10 cm hr -1) sapwood area A sw (say 220 cm 2) = 2,200 cm 3hr -1 for annulus 1

+

Vs (say 5 cm hr-1

) A sw (say 40 cm2) = 200cm 3 hr -1 for annulus 2

Whole Tree sapflow =2,400 cm 3 hr -1 or 2.4 litres hr -1 .



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Where is the Data?

Sapflow Data of Urban Trees

0

50

100

150

200

250

300

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Time (days)

S a p

f l o w

( l i t r e s

d a y -



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Published Tree Sapflow RatesSpecies

Height(m)

Diameter (cm)Sapwood Area

(cm2)Sapflow (litres day -1)

Acacia dealbata - 25 279 59

Betula alba - - - 70

Eperua purpurea - - 1,521 1,180Eucalyptus camaldulensis - - - 29

Eucalyptus globulus - - - 37

Eucalyptus grandis 34 30 - 141

Eucalyptus grandis 56 41 371 174

Eucalyptus regnans 58 89 618 285

Ficus insipida 30 54 2,100 164

Grevillia robusta - - - 12

Picea abies 25 - - 63

Pinus radiata 25 42 1,089 349

Pseudostsuga menziesii 28 38 - 64

Pseudostsuga menziesii 76 134 4,020 530

Quercus petraea 15 9 10

Quercusrobur

33 - - 400

ISAAC 2006 Sapflow in Trees Excerpt from Wullschleger et.al 1998


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Misras Findings

The sapflow of trees causes a shrinkage of soiland movement in and around foundations

Melaleucas can extract more soil water thanUlmus and hence is more likely to causeshrinkage and soil movement.

More needs to be understood about the crownroot ratio and sapflow


Exposed Maple Tree Shaded Maple Tree


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Exposed Maple Tree Shaded Maple Tree

Garden

Pavement PavementRoad

Lawn Lawn

Sapflow = 140 litres day -1

12,500 litres year -1Sapflow = 65 litres day -1

5,740 litres year -1

North West South EastCermak et.al 2000ISAAC 2006 Sapflow in Trees


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Cermaks Conclusions Sapflow measurements are very suitable in city trees

integrated value of water consumption

minimal environmental disturbance and cost.

Radial sapflow shows where trees draw water from

deeper layers of sapwood are supplied by deeper roots shallower sapwood layers supplied by surface roots.

Can provide an early warning technique to enableintervention before damage occurs to buildings



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Unpublished DataNSW DPI Species Water Use Trial


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Diurnal Saplfow of Eucalyptus albens

-5

0

5

10

15

20

25

30

Time (minutes)

H e

a t P u

l s e

V e l o c

i t y ( c m

/

rain event

Midday

Midnight


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Diurnal Sapflow of Corymbia maculata

-4

-2

0

2

4

6

8

10

12

14

16

Time (Minutes)

H e a

t P u

l s e V

e l o c

i t y ( c m

/

rain event

Midday

Midnight


Case Study


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Case Study

Tall Trees in California Tallest Tree Species

112.87 m, Sequoia sempervirens = coast redwood 99.4 m, Pseudotsuga menziesii = Douglas-fir 97.0 m, Eucalyptus regnans = mountain ash 96.6 m, Picea sitchensis = Sitka spruce

94.9 m, Sequoiadendron giganteum = giant sequoia



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Data: Courtesy HumboldtState Uni 2006


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Data: Courtesy HumboldtState Uni 2006


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SAPFLOWNovember through February

up to 1069 liters H 2Otranspired per day

up to 297 liters H 2O

absorbed by leaves per day


Future Research


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Future Research

Measure sapflow and soil moisture of key treespecies used in urban plantings.

Collect data for different regions for eachspecies

Compare data to engineering data on both soilskrinkage and building structural damage

Link with universities and research centres Use your skills to collect data and uni skills to

analyse.


Further Reading


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Further Reading

www.ictinternational.com.au/plants.htm

www.ictinternational.com.au/hrm30.htm

www.ictinternational.com.au/hrmref.htm

www.ictinternational.com.au/TallTrees.htm

http://www.ictinternational.com.au/plants.htmhttp://www.ictinternational.com.au/hrm30.htmhttp://www.ictinternational.com.au/hrmref.htmhttp://www.ictinternational.com.au/TallTrees.htmhttp://www.ictinternational.com.au/TallTrees.htmhttp://www.ictinternational.com.au/hrmref.htmhttp://www.ictinternational.com.au/hrm30.htmhttp://www.ictinternational.com.au/plants.htm


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The fact that trees are large and not easy tohandle increases the difficulties (of measuringwater requirements of trees), but they should not

be insurmountable; for no really satisfactoryresults can be expected until more data are

obtained on forest ( and Urban ) trees and standsunder natural conditions, supplemented by

laboratory work on a scale comparable with the

size of the problemRaber 1937 USDA

Wullschleger et.al 1998ISAAC 2006 Sapflow in Trees

transpiration sap flow in trees

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