2008 CPPA PIs’ Meeting

Climate Prediction Program for the Americas

Coupling soil and canopy processes to nutrient dynamics: impacts of rootnutrient dynamics: impacts of root

moisture uptake and hydraulic redistributionredistribution

Praveen KumarDarren DrewryDarren Drewry

Department of Civil and Environmental EngineeringUniversity of Illinoisy

Urbana, IllinoisE-mail: kumar1@uiuc.edu

30 years ago

Woody Thickening, Australia

Present day

Long et al., Science, 2006 2

3

Understanding Biophysical Coevolution: Model For Couple Water, Carbon, Energy and Nutrient Dynamics

Canopy-Top Forcing:NEE LE H

SW down Ta VPD CaCanopy-Atmosphere

Exchange of CO2, latent and sensible heat

Ca U PPT

Soil Carbon andSoil Carbon and Nitrogen Transformations, Uptake and Transport

ImmobilizationSoil moisture

Transport

SOM Pools

Mineral N

Litter Deposition

Mineral N Uptaketransport, uptake, and passive redistribution

Mineralization

Leaching 4

Canopy Flux Model

dzc

5

Canopy & Root System Structure

Normalized Leaf Area Density

Beta FunctionBeta Function[Massman, 1982]

[Stenberg et al, 1994]

Logistic Function

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Root Density [Schenk and Jackson, 2002]6

Canopy Scaling

We have examined processes occuring on a single “leaf”

Now we can compose a complete canopy as multiple layers of “leaves”:

--> Radiation attenuation, Turbulent Mixing, Wind Speed Profile

PAR NIR LW

Mixing of canopy microclimate states

(Ca, Ta, ea) by turbulent eddies

U 7

Canopy Scaling

Canopy-top measurements provide model forcing data (upper BCs):

SWdn, LWdn, Ca, Ta, ea, U, U*

And the model alidation dataAnd, the model validation data:

Fc, LE, H --> Eddy covariance: vertical integral of sources/sinks

h Fc Sc (z)dz0

hc c0

LE Sv (z)dz0

h0

H Sh (z)dz0

h

8

Effects of Enriched Ambient CO2

Bondville Ameriflux TowerBondville Ameriflux TowerSoyFACE site

9

PAR NIR LW

UU

10

PAR NIR LW

U

11

12

13

14

15

Modeling Framework: Coupled Photosynthesis - Stomatal Conductance - Leaf Energy Balance

gbh

Leaf Energy Balance + BLC

Leaf Energy Balance

Boundary Layer Conductance

(free / forced convection)

gbv

convection)

Tl gbv

Q:PAR

Required

Inputs Cigs

Outputs

Biochemical Ph t th i

Stomatal C d t

CiTl gs

PARNIRLW

TaRha

Tl

AnHLEPhotosynthesis

(Farquhar et al)

Conductance

(Ball/Berry/Collatz)

An

aCa U

LE

Leaf Ecophysiology16

CO2 - Control: average of all noon values for each simulation day

gbh g

Leaf Energy Balance + BLC

(+0 [mol m-2 s-1])

Leaf Energy Balance

Boundary Layer Conductance

(free / forced convection)

gbv( 0 [mol m s ])

convection)

Tl gbv

Q:PAR

Required

Inputs

Ci (+163 5Outputs

(+0.25 [C]) (+0 [mol m-2 s-1])

Biochemical Ph t th i

Stomatal C d t

Cigs

PARNIRLW

TaRha

Ci (+163.5 [ppm])

gs (-0.05 [mol m-2 s-1])

Tl (+0.25 [C])

Tl (+0.25 [C]) (+163.5 [ppm])(-0.05 [mol m-2 s-1])

Photosynthesis

(Farquhar et al)

Conductance

(Ball/Berry/Collatz)

An (-3.34 [ l 2 1])

aCaU An (-3.34

[µmol m-2 s-1])H (+56.3 [W m-2]

+190 [ppm]

[µmol m-2 s-1])Leaf Ecophysiology

[ ]LE (-56.3 [W m-2]

17

Extending Control Volume to Include ABL Dynamics

Tropospheric Properties: Jump Discontinuities and Lapse Rates

Warm, Dry Air

hABL

Ca, Ta, ea, SWdn, LWdn

H LE NEE

18

Drier, warmer BL

Hamb LEamb NEEamb

Helev LEelev NEEelev

19

Hydraulic Redistribution

Canopy-Atmosphere Exchange of CO2, latent and sensible heat:

Canopy-Top Forcing:

NEE LE

SW down Ta

VPD LE H

VPD Ca U

ImmobilizationSoil moisture

SOM Pools

Mineral N

Litter Deposition

Mineral N UptakeSoil moisture transport, uptake and passive redistribution Mineralization

Leaching

redistribution

20

Plant roots are much deeper than traditionally thought in our modeling approaches. In particular, this is true for water-limited environments

a nia do ri ka Mexico

York lina

ia ngtonal Eve

rgreen

Forest

al Deci

duou

s Fore

st

al Gras

sland

/Savan

a

rate G

rassla

ndrat

e Deci

duou

s Fore

st

rate C

onife

rous F

orest

nd l Forest

a

0

Arizon

aCali

forni

Colorad

oFlor

idaIow

aMiss

ouri

Nebras

kaNew

Me

New Y

orOreg

onS. C

aroli

Texas

Virgini

aW

ashing

0

10

Tropica

lTrop

ical

Tropica

lDese

rtShru

bsTem

pera

Tempe

raTem

pera

Croplan

dBore

al F

Tundra

5

10

pth

(m)

10

20

30h (m

) Approximate Maximum Rooting Depth for

Current Climate Models

15

20M

ax. R

oot D

epObserved Max. R ti D th

30

40

Roo

t Dep

th

Maximum Root DepthAverage Root depth

25

M Rooting Depths for USA

53 m 61 m

50

60

21

3070

Based on the study by Canadell et al. (1996) & Kleidon and Heimann (1998)

Hydraulic Redistribution is the passive transport of soil water via plant roots from wet soil layers to dry soil layers.

22Movement of water via the plant roots from the more moist soil layers to drier soil layers during dry and wet seasons.

Hydraulic Redistribution by plant roots can be modeled by coupling water flow within the soil media and the root media, where flow in both media is governed by water potential gradient and hydraulic conductivity of the system.

Flow in the t lroot xylem

Flow in the Hydraulic R di t ib tisoil pores Redistribution

Flow into the root from the

soil

23SoilRoot

Flow in soil media is modeled as :Ji-1Δzi-1 θi-1, ψi-1 Ji-1Δzi-1 θi-1, ψi-1

JiΔzi

qi-1

θi, ψi

Ks,i-1

JiΔzi

qi-1

θi, ψi

Ks,i-1

Jz

qt

soil

)(1 , xylemsoilrootradsoil

soil Kz

Kzt

Ji+1Δzi+1

qi

θi+1, ψi+1

Ks,i

Ji+1Δzi+1

qi

θi+1, ψi+1

Ks,i

W fl i di b d l dWater flow in root media can be modeled as a pipe flow: Δzi-1

qi-1

ψi-1 Ji-1 Krad,i-1

Kax,i-1

Δzi-1

qi-1

ψi-1 Ji-1 Krad,i-1

Kax,i-1

Jqroot

)(1xylem

Δzi

Δ

qi

ψi Ji

J

Krad,i

K

Kax,i

Δzi

Δ

qi

ψi Ji

J

Krad,i

K

Kax,i

Jz

24

)(1 ,, xylemsoilrootradxylem

rootaxial Kz

Kz

Δzi+1 ψi+1 Ji+1 Krad,i+1Δzi+1 ψi+1 Ji+1 Krad,i+1

CASE STUDY SITE:

Boundary of t d it

140

160

180

m)

Fresno

study site

40

60

80

100

120

Prec

ipita

tion

(mm

0

20

Jan

Feb Mar AprMay Jun Jul Aug Sep OctNov Dec

25The major PFTs at the site include C3 grasses (52%), needle leaf evergreen temperate trees (46%), and broadleaf deciduous temperate trees (2%)

Without HR With HR

L1

L2

Mid-Night

Mid-Day MeanL1

L2

Mid-Night

Mid-Day

Mean

L3

L4

L5

ndex

L3

L4

L5

ndex

L6

L7

L8 Soil

Lay

er I

n

L6

L7

L8 Soil

Lay

er I

n

L9

L10

L11

S

L9

L10

L11S

0 0.2 0.4

L11

L12

0 0.2 0.4 0 0.2 0.4 -0.2 0 0.2 0.4

L11

L12

-0.2 0 0.2 0.4 -0.2 0 0.2 0.4

26Uptake (mm/day) Uptake (mm/day)

( y)Without HR With HRy

L1

L2

WetSeason[Jan]

DrySeason

[Jul]

MeanL1

L2

WetSeason[Jan]

DrySeason

[Jul]

Mean

L3

L4

L5dex

L3

L4

L5dex

L6

L7

L8oil L

ayer

Ind

L6

L7

L8Soil

Lay

er I

n

L8

L9

L10

So

L9

L10

L11

S

-0.5 0 0.5 1

L11

L12

-0.5 0 0.5 1 -0.5 0 0.5 10 0.2 0.4

L11

L12

0 0.2 0.4 0 0.2 0.4

27

Uptake (mm/day)Uptake (mm/day)

20051979

1979 2005

2820051979

Comparison of simulated and observed latent heat flux for the Sierra Nevada studysite for the different simulation cases.

29

Vegetation C and N Cycling

Examine effects of hydraulic redistribution (HR) on:

– vertical patterns of C and N– NO3

- leachingNO3 leaching – Mineral N uptake

Canopy litter deposition

Root Distribution

Mineral N (NH4

+ and NO3-)

productionH2ON Upake

Root litter deposition

Nutrient Dynamics

Canopy-Atmosphere Exchange of CO2, latent and sensible heat:

Canopy-Top Forcing:

NEE LE

SW down Ta

VPD LE H

VPD Ca U

ImmobilizationSoil moisture

SOM Pools

Mineral N

Litter Deposition

Mineral N UptakeSoil moisture transport and passive redistribution

Mineralization

Leaching 31

Subsurface Carbon & Nitrogen Cycling

H2O N

QNH4

+QuickTime™ and a

TIFF (Uncompressed) decompressorare needed to see this picture.

4NO3

-

Subsurface Carbon & Nitrogen Cycling

Organic matter decomposition and mineral NOrganic matter decomposition and mineral N uptake are functions of , TsH2O N

Soil Moisture

NH4+

No HR

HR

NO3-

Soil Moisture Limitation for Decomposition

No HR

HR

“HR” vs “NO HR”: N Uptake and Leaching

“HR” vs “NO HR”: N Uptake and Leaching

SummarySummary

• Multilayer vegetation-soil-nutrient modelMultilayer vegetation soil nutrient model incorporating deep rooting and hydraulic redistributionredistribution.

• Model designed to capture transient behavior in energy water and nutrientbehavior in energy, water and nutrient dynamics arising from alteration in biophysical response due to elevation inbiophysical response due to elevation in CO2 and temperature

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