CENTER FOR EMBEDDED NETWORKED SENSING UCLA USC UCR CALTECH UCM Sap Flow – Lots of ways to do it.

CENTER FOR EMBEDDED NETWORKED SENSING

UCLA USC UCR CALTECH UCM

Sap Flow – Lots of ways to do it

Water diffuses “down-hill”from high to low concentration (c)

over a distance (x)

Everything diffuses like Fick’s First Law:

Flow rate cx

Some Physics

Flow rate

w (psi) = the “concentration” of water

w (pure water) = 0.0 mega-Pascals

w (everything else) = negative MPa

w

x

w(wet soil) -0.1 MPa

w (atmosphere) -95 MPa

w(wet soil) -0.1 MPaw (root) -0.5 MPa

w (stem) -0.6 MPa

w (branch) -0.8 MPa



w (stem) -0.6 MPa

w (branch) -0.8 MPa


HIGH WATER FLOW

Transpiration(day)

stomata openresistance low


w (stem) -0.1 MPa

w (branch) -0.1 MPa


No/littletranspiration

(night)

stomata closedresistance high

very low water flow

w(dry soil) -1.5 MPaw (root) -1.9 MPa

w (stem) -2.0 MPa

w (branch) -2.2 MPa


Low water flow

Lowtranspiration(stressed)

stomata closed?resistance medium

Differentwater

sources

High soil water content

Low soil water

Transpiration for3 hours only

Transpiration for12 hours

Equal rates of water transport

Buy a pre-built system = $$,$$$

Sap Flow – Lots of ways to do it

Do it yourself = less $, but more work

Building sap flow probes

Heated probe drops in temperature (relative to unheated probe) when sap flows.

Heated probe temperature is higher during low or no sap flow.

Measurement systems

Installation

106,6,925,10.44,43.57,44.87,91.5,2.345,4.839,-.01,4.655,6.493,4.592,4.013,5.108,-.023,3.049,2.273,1.918,24.59,4.092,51.54,4.141,0,19.77,24.01,22.19,-6999,21.73,19.94,22.56106,6,930,30.75,55,52.52,95.6,2.322,5.046,-.003,5.062,5.862,4.684,4.098,5.371,-.013,4.217,3.602,2.283,24.24,4.365,49.6,4.487,0,20.16,25.47,22.15,-6999,21.92,20.3,23.53106,6,935,57.45,64.89,46.95,100.9,2.164,5.197,0,5.453,4.434,4.75,3.891,5.296,-.039,11.32,16.46,4.105,23.59,4.184,47.3,4.493,0,21.52,26.61,22.58,-6999,-6999,21.06,24.18106,6,940,26.73,76.5,35.93,96.9,1.99,5.322,-.013,5.736,5.115,4.802,3.73,4.963,-.161,39.57,48.53,8.5,23.16,4.335,44.8,4.46,0,24.59,27.25,22.95,-6999,-6999,22.51,24.86106,6,945,-85.9,89.1,26.18,94,1.885,5.43,-.003,5.963,7.21,4.874,3.704,4.799,-.158,38.02,47.56,8.65,23.25,4.993,42.54,4.723,0,25.13,27.07,22.93,-6999,-6999,22.76,24.77106,6,950,-99.7,102,26.68,92.2,1.848,5.519,-.007,6.16,7.54,4.93,3.68,4.726,-.158,36.3,46.41,8.74,23.46,5.94,40.49,5.394,0,24.8,28.44,23.61,-6999,-6999,23.85,25.56106,6,955,-95.1,114.3,26.34,89.5,1.858,5.614,.007,6.367,7.59,5.009,3.805,4.887,-.138,34.54,45.22,8.83,23.2,6.469,38.24,5.966,0,24.97,28.53,23.5,-6999,-6999,25.24,25.94106,6,1000,-97.9,124.8,22.95,79.8,1.838,5.657,-.007,6.429,7.6,5.061,3.973,5.551,-.141,32.69,43.83,8.89,22.63,6.591,35.76,6.166,0,24.71,28.26,24.02,-6999,-6999,25.71,25.55106,6,1005,-123.3,132,22.72,75.5,1.865,5.725,-.003,6.472,7.63,5.12,4.357,5.646,-.135,31.02,42.57,8.95,22.08,6.695,33.33,6.321,0,24.94,28.87,24.44,-6999,-6999,26.23,25.68106,6,1010,-159.4,136.4,21.96,75.5,1.884,5.808,-.01,6.873,7.64,5.173,4.272,5.722,-.141,29.39,41.38,9.02,21.42,6.797,30.9,6.452,0,25.4,28.95,24.46,-6999,-6999,26.84,26.24106,6,1015,-150.6,138.6,20.7,71.9,1.957,5.886,0,7.05,7.66,5.232,4.015,5.498,-.132,27.65,39.95,9.08,20.75,6.886,28.35,6.537,0,25.52,28.82,25.79,-6999,-6999,27.19,26.06106,6,1020,-163.4,137.4,18.98,64.11,2.124,5.965,-.007,7.22,7.67,5.291,3.943,5.241,-.135,26.01,38.6,9.17,20.01,6.994,25.93,6.616,0,26.19,29.48,25.87,-6999,-6999,27.54,26.19106,6,1025,-23.47,133.4,20.64,51.28,2.331,6.014,-.007,7.35,7.63,5.337,3.943,5.123,-.132,24.28,37.02,9.21,19.18,7.09,23.51,6.688,0,26.26,29.78,25.06,-6999,-6999,27.66,26.66106,6,1030,16.93,127.5,20.65,41.65,2.456,6.093,-.007,7.52,7.65,5.419,3.972,5.139,-.122,22.32,35.52,9.25,18.54,7.24,21.11,6.78,0,25.93,29.02,24.6,-6999,-6999,27.26,26.27106,6,1035,9.46,120.6,20.83,34,2.69,6.142,-.013,7.67,7.62,5.455,3.995,5.172,-.128,20.62,33.9,9.3,17.63,7.42,18.91,6.901,0,25.99,29.6,24.27,-6999,-6999,27.11,26.9106,6,1040,-26.43,112.8,20.08,30.07,2.975,6.188,-.01,7.82,7.61,5.504,4.241,5.231,-.118,18.97,32.26,9.32,16.85,7.58,16.66,6.993,0,26.07,29.47,24.64,-6999,-6999,26.91,26.58106,6,1045,-67.36,104.5,18.34,24.78,3.11,6.22,-.013,7.97,7.6,5.55,4.573,5.287,-.112,17.36,30.68,9.34,16.07,7.79,14.42,7.08,0,26.88,29.73,24.82,-6999,-6999,27.15,26.91106,6,1050,-51.68,96.9,19.24,18.44,3.192,6.256,-.007,8.11,7.61,5.609,4.829,5.378,-.105,15.85,29.08,9.38,15.3,7.97,12.4,7.13,0,26.45,29.31,24.93,-6999,-6999,26.75,26.59106,6,1055,-23.14,89.5,15.08,15.9,3.241,6.282,-.01,8.22,7.59,5.645,4.573,5.539,-.102,14.38,27.25,9.4,14.59,8.21,10.71,7.22,0,26.83,29.47,25.6,-6999,-6999,26.78,26.95106,6,1100,-29.76,82.4,14.69,12.53,3.274,6.312,-.003,8.31,7.58,5.704,4.356,5.536,-.099,13.03,25.45,9.42,13.7,8.41,9.26,7.38,0,26.82,30.22,25,-6999,-6999,26.82,27.67106,6,1105,-31.42,76,9.08,10.51,3.31,6.325,-.01,8.38,7.56,5.743,4.392,5.559,-.095,11.87,23.9,9.43,12.9,8.62,8.03,7.45,0,26.95,29.62,25.47,-6999,-6999,26.79,27.51106,6,1110,-36.27,69.86,7.71,9.08,3.363,6.335,-.013,8.44,7.55,5.795,4.467,5.598,-.089,10.8,22.13,9.44,12.13,8.77,7.26,7.46,0,27.71,29.85,25.84,-6999,-6999,27.45,27.34106,6,1115,-19.87,64.26,9.26,7.84,3.435,6.354,-.003,8.51,7.55,5.851,4.539,5.697,-.072,9.83,20.49,9.47,11.46,8.97,7.05,7.54,0,27.6,29.2,25.71,-6999,-6999,27.33,27106,6,1120,11.6,59.46,11.15,4.8,3.478,6.338,-.013,8.53,7.5,5.874,4.517,5.802,-.079,9.16,18.79,9.51,10.67,9.1,6.982,7.62,0,27.46,29.09,25.21,-6999,-6999,27.05,26.85106,6,1125,-76.6,55.6,14.5,12.38,3.54,6.347,-.01,8.54,7.48,5.923,4.543,5.867,-.072,8.96,17.18,9.57,10,9.23,7,7.7,0,28.22,30.6,26.06,-6999,-6999,27.85,28106,6,1130,-117.6,52.03,16.79,14.06,3.573,6.324,-.007,8.48,7.47,5.979,4.648,5.959,-.066,8.85,15.42,9.61,9.33,9.23,7,7.7,0,28.33,29.97,25.96,-6999,-6999,28.15,27.45106,6,1135,-16.64,49.28,9.6,16.76,3.616,6.324,0,8.5,7.45,6.002,4.618,5.962,-.056,8.85,13.94,9.86,8.9,9.74,7.11,8.03,0,28.17,29.04,25.41,-6999,-6999,28.09,26.34106,6,1140,-8.2,45.96,-3.807,14.2,3.629,6.327,-.01,8.62,7.46,6.064,4.661,5.906,-.066,8.8,12.6,10.59,8.52,9.66,7.08,7.87,0,27.68,28.79,25.63,-6999,-6999,27.83,26.45106,6,1145,-94,42.43,-1.952,-45.47,3.655,6.327,-.003,8.71,7.44,6.11,4.703,5.919,-.049,8.83,11.24,11.25,8.08,9.57,7.12,7.84,0,28.24,29.93,25.88,-658.3,-6999,28.65,27.31106,6,1150,-6999,38.58,-115.4,-6999,3.668,6.343,-.013,8.72,7.39,6.13,4.776,5.965,-.049,8.94,10.11,12.22,8.05,9.67,7.16,7.92,0,29.88,30.79,25.23,-94.4,-6999,29.98,26.43106,6,1155,-594.8,35.87,-20.01,-66.4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Data!

Temperature difference trace

zero sap-flow points (night)


Daily zero sap-flow subtracted


Sap flow:

u = 0.000119 × Z1.231

whereZ = (T0 – T) / T

Units of sap flow: m3 H2O m-2 sap wood area s-1

Empirical transformation

Sap flow trace

Units of sap flow: m3 H2O m-2 sap wood area s-1

1 m3 H2O = 1000 liters

10 cm sap woodthickness

80 cm

diam

r2 - r2 = 0.049 m2

Multiply results by 4900

Units of sap flow: liters s-1

Units transform

Sap flow – nice units

Is sap flow decreasing?

Interpreting sap flow: micromet

$6000

$15 $320

Light (PAR) sensing


dew point = 9.1°C

dew point = 15.3 °C

Interpreting sap flow: um?

But note: temperature fluctuations even when no power is applied to the heated probe – temperature gradients!

CENTER FOR EMBEDDED NETWORKED SENSING UCLA USC UCR CALTECH UCM Sap Flow – Lots of ways to do it.

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