Physioecological mechanism Physioecological mechanism of the alpine treeline dynamics of the alpine treeline dynamics

under global climate changeunder global climate change

Swiss Federal Research Institute WSL

Dr. Mai-He Li

E-mail: maihe.li@wsl.ch

The 2nd Third Pole Environment WorkshopKathmandu, Oct. 26 – 28, 2010

1. Definition of the alpine treeline

2. Driving forces of treeline formation

3. Upword shifts of the alpine treelines, corresponding to global warming, in the Himalayas and worldwide

4. Physioecological machanisms of the alpine treeline shifts

5. Conclusions

Treelines across the globe ---a virtual site visitation

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1

2 3

4 5

6

7

8

11

10 12

131415

16 17

1819 20

Davos, Swiss Alps The Himalayas

Ch Koerner, J Paulsen 2004

Miehe et al. 2007. Mountain Res. & Develop. 27, 169-173

Kyi Chu, North of Lhasa29°42‘ N, 96°45 ‘ E

Holtmeier & Broll, 2009. Polarforschung 79, 139-153

Factors affecting trees at the alpine treelines

The alpine treeline position is very closely correlated to the 10°C

isotherm for the warmest month

The temperature at the alpine treelines varied from 6 to 13°C (±500 m in treeline elevation)

Koeppen 1923; Aulitzky 1961Wu 1983; Oshawa 1990

n=2n=211 1212

22

2266 33

22

00

22

44

66

88

Sea

sona

l mea

n te

mpe

ratu

re,

T (

°C)

Sea

sona

l mea

n te

mpe

ratu

re,

T (

°C)

7070 6060 5050 4040 3030 2020 1010 00 1010 2020 3030 4040Latitude (°Latitude (°CC))

00

100100

200200

300300

Gro

win

g pe

riod

G (

d)G

row

ing

perio

d G

(d)

SSNN

6.7 ± 0.8 °C 6.7 ± 0.8 °C

GG

TT

Ch Körner, J Paulsen (2004) J Biogeogr 31:713-732Ch Körner, J Paulsen (2004) J Biogeogr 31:713-732

A global mean of 6.7 °C soil temperature (-10 cm depth) for growing season at treeline

Source: Massachusetts Ave, Cambridge MA

Predicting changes in temperature

It is predicted that the temperatures in the Indian sub-continent will rise between 3.5 and 5.5°C by 2010, and on the Tibetan Plateau by 2.5°Cby 2050, and 5°C by 2010

Kumar et al. 2006

Location Authors, year Species Upword shift (m)

Period (year)

Rate (m/yr)

South Island, New Zealand

Wardle & Coleman, 1992

Nothofagus menziesii, N. solandri

7-9 1930-90 0.12-0.15

Italian Alps Leonelli et al. 2010 115 1901-2000 1.15

Glacier N.P. Montana

Bekker, 2005 Picea engelmannii, Pinus contorta, Abies lasciocarpa

7-16 1800-1980 0.28-0.62

Sunwapta Pass, Alberta

Luckman & Kavanagh, 2000

P. engelmannii, A. lasciocarpa

145 1700-1994 0.5

Uinta Mts. UT Munroe, 2003 P. engelmannii, A. lasciocarpa

61-183 1870-2001 0.5-1.4

SW Yukon Danby & Hik, 2007 Picea glauca 65-85 1920-2005 0.8-1.0

Scands Mts, Sweden

Kullman, 2001 Betula pubescens, Pinus sylvestris, Picea abies

100-165 1915-2000 1.2-1.9

Kootenay NP, B.C.

Roush, 2009 Larix lyallii, P. engelmannii, A. lasciocarpa

149 1909-1976 2.2-5.7

W. Himalayas of India

Dubey et al. 2003 14-19 Over 10 yrs

1.4-1-9

Baima Snow Mt, Yunnan

Baker & Moseley, 2007

67 Since 1923

Nanda Devi in C. Himalaya

Panigrahy et al., 2010

300 Since 1960

Himalayas, Nepal

Vijayaprakash & Ansari, 2009

Abies spectabilis N-aspect South-asp.

1.7 (N-s)2.3 (S-s)

Species No. Elevation (1970) Elevation (1992) Elevational shift (m)

Vaccinium uliginosum 11 2216 2216 0

Vaccinium vitis-idaea 30 1898 1885 -13

Vaccinium myrtillus 31 1972 2002 30

Rhododendron ferrugineum 30 2098 2098 0

Pinus cembra 31 2064 2005 -59

Hieracium pilosella 13 1851 1930 79

Scleropodium purum 26 1425 1630 205

Dupouey et al. 1997

Each species is likely to respond to climate change in its own way:

Treeline formationTreeline formation

Global driversGlobal drivers'general principle''general principle'

Regional driversRegional drivers'modulation''modulation'

General physioecologicalexplanation

Local environmentalexplanations

(1)(1) The The stressstress hypothesis hypothesis

(2) The (2) The maturationmaturation time hypothesis time hypothesis

(3)(3) The The disturbancedisturbance hypothesis hypothesis

(4)(4) The The reproduction/germinationreproduction/germination

hypothesishypothesis

Environmental explanation of treelineEnvironmental explanation of treeline

Körner Ch (1998) Oecologia 115:445Li MH, Krauchi N (2005) J.S.For.Tech.26, 36-42Li MH et al. 2008. Tree Physiology 28, 1287-1296 Li MH et al. 2008. Plant, Cell & Environment 31, 1377-1387

(5)(5)The The growthgrowth limitation hypothesis limitation hypothesis

(6)(6)The The carboncarbon balance hypothesis balance hypothesis

Biological explanation of treelineBiological explanation of treeline

Körner Ch (1998) Oecologia 115:445Li MH, Krauchi N (2005) J.S.For.Tech.26, 36-42Li MH et al. 2008. Tree Physiology 28, 1287-1296 Li MH et al. 2008. Plant, Cell & Environment 31, 1377-1387

1. The stress hypothesis

• Repeated damage

by freezing, frost desiccation or phototoxic effects after frost impair

tree growth

Tranquillini W.1979. Physiological ecology of the alpine timerlineKörner Ch. 1998. Oecologia 115, 445-459Li MH, Kräuchi N. 2005. J.S.For.Tech. 26, 36-42

Maturation of leaves,shoots, fruits, and buds

e.g. seed maturation of Pinus sylvestris needs at least 600 – 890 GDD (growing degree-days >5°C)

Odum 1979

2.2. The The maturationmaturation time hypothesis time hypothesis

Short gro

wing seaso

n

Tranquillini W.1979. Physiological ecology of the alpine timerlineKörner Ch. 1998. Oecologia 115, 445-459Li MH, Kräuchi N. 2005. J.S.For.Tech. 26, 36-42

Mechanic damage by wind, ice blasting, snow break and avalanches, fire……

Animal disturbances such as insectFungal pathogensMan-made impacts such as logging, grazing etc.

3.3. The The disturbancedisturbance

hypothesishypothesis

Tranquillini W.1979. Physiological ecology of the alpine timerlineKörner Ch. 1998. Oecologia 115, 445-459Li MH, Kräuchi N. 2005. J.S.For.Tech. 26, 36-42

Pollination, pollen tube growth, seed development, seed dispersal, germination and seedling establishment

4.4. The The reproductionreproduction hypothesis hypothesis

Tranquillini W.1979. Physiological ecology of the alpine timerlineKörner Ch. 1998. Oecologia 115, 445-459Li MH, Kräuchi N. 2005. J.S.For.Tech. 26, 36-42

5. Growth limitation5. Growth limitation

PhotosynthesisPhotosynthesis

GrowthGrowth

““Sink“ drivenSink“ driven

““Demand“ drivenDemand“ driven

PhotosynthesisPhotosynthesis

GrowthGrowth

““Source“ drivenSource“ driven

““Supply“ drivenSupply“ driven

6. Carbon limitation 6. Carbon limitation

Körner Ch (1998) Oecologia 115:445Li MH et al. 2008. Tree Physiology 28, 1287-1296 Li MH et al. 2008. Plant, Cell & Environment 31, 1377-1387

Source limitation hypothesis:Tree growth is considered source limited when carbon assimilation through photo-synthesis is insufficient to meet growth requirements.

Sink limitation hypothesis:

Trees are considered carbon sink limited when there is an abundant supply of the resources necessary to support growth, but growth itself is directly limited by environ-mental conditions.

Mito

tic t

ime

(h)

Mito

tic t

ime

(h)

Temperature (°C)Temperature (°C)

00

1010

2020

3030

Cel

l dou

blin

g tim

e (h

)C

ell d

oubl

ing

time

(h)

00

100100

200200

300300

00 1010 2020 3030 4040

Mitotic timeMitotic timeCell doubling timeCell doubling time

Ch Körner (2003) Ch Körner (2003) Alpine Plant LifeAlpine Plant Life. Springer, Berlin. Springer, Berlin

5050

100100

Ne

t-ph

oto

syn

thes

is (

%)

Ne

t-ph

oto

syn

thes

is (

%)

Late seasonLate season

End of winterEnd of winter

Mid seasonMid season

Non

-str

uctu

ral c

arbo

hydr

ates

+ li

pids

N

on-s

truc

tura

l car

bohy

drat

es +

lipi

ds

in s

tem

sap

woo

d (%

d.m

.)in

ste

m s

apw

ood

(% d

.m.)

AltitudeAltitude

00

22

44

00

22

44

00

22

44

NSCNSC

LipidsLipids****

****

******

HighHighLowLowHighHighLowLowHighHighLowLow

Pinus hartwegiiPinus hartwegiiMexico (19° N)Mexico (19° N)Pinus cembraPinus cembraAlps (46° N)Alps (46° N) Pinus sylvestrisPinus sylvestrisSweden (68° N)Sweden (68° N)

G Hoch & C Körner (2003) Oecologia 135:10-21

00

1010

2020

3030

4040

5050

00

1010

2020

3030

4040

5050

NS

C c

once

ntr

atio

ns (

mg

cm

NS

C c

once

ntr

atio

ns (

mg

cm

33 ))

43604360 45504550 4810481043604360 45504550 48104810

Elevation (m a.s.l.)Elevation (m a.s.l.)

BranchwoodBranchwood StemwoodStemwood

00

4040

8080

120120

160160

200200

G Hoch & Ch Körner (2005) Funct Ecol 19, 941-951

43604360 45504550 4810481043604360 45504550 4810481043604360 45504550 4810481043604360 45504550 48104810

LeavesLeaves

abab bb

aa

aaaa

a a aaaa aa

Polylepis tarapacana, Polylepis tarapacana, Volcano Sajama, BoliviaVolcano Sajama, Bolivia

00

1010

2020

3030

4040

5050

00

1010

2020

3030

4040

5050

Sug

ars

Sug

ars

Sta

rch

Sta

rch

NSC=Non-structural carbohydrates = solube sugars + starch

Gas exchange with altitude

Cabrera HM et al. 1998, Oecologia 114, 145-152

Acaena cylindrostachya

Senecio formosus

Maximum CO2 assimilation rates4200 m: 3.9 µ mol/m2 s3550 m: 5.2 µ mol/m2 s2900 m: 9.0 µ mol/m2 s

4200 m: 3.6 µ mol/m2 s3550 m: 5.8 µ mol/m2 s2900 m: 7.5 µ mol/m2 s

0

5

10

15

20

25

30

3800

m

3400

m

3800

m

3400

m

3800

m

3400

m

3800

m

3400

m

3800

m

3400

m

3800

m

3400

m

3800

m

3400

m

3800

m

3400

m

3800

m

3400

m

3800

m

3400

m

April July April July April July April July April July

Elevations of trees and sampling time

Sta

rch

/ S

ug

ars

/ NS

C c

on

cen

trat

ion

(%

d.m

.) Sugars

Starch

1-yr-old needles

Stem wood

Fine roots

a b

*

a a a a a ab b b b bb

AB

* ***

*

*

2-yr-oldneedles

3-yr-oldneedles

Li MH et al. 2008. Tree Physiology 28, 1287-1296 Li MH et al. 2008. Plant, Cell & Environment 31, 1377-1387

Picea balfouriana var. hirtella

Carbon shortage? - Yes!

Soluble sugars Starch NSC

April July April July April July

Three treeline cases combined (Lower E trees = lower elevation trees)

Treeline trees 11.09 10.51 3.61 4.19 14.70 14.70

Lower E trees 10.66 10.37 4.77 4.55 15.43 14.91

F1,89 3.53 0.24 31.00 1.35 6.80 0.31

p 0.07 0.63 <0.001 0.25 0.011 0.58

An overall trend in NSC – 3 treelines data pooledAn overall trend in NSC – 3 treelines data pooled

A winter C-shortageA winter C-shortage

Li MH et al. 2008. Tree Physiology 28, 1287-1296 Li MH et al. 2008. Plant, Cell & Environment 31, 1377-1387

A winter carbon shortage?orAn effect of phenological phase-shift?

Hoch G. 2003PhD thesisUni. Basel

??????

Camarero & Gutierrez (2002) Plant ecology 162: 247

Krummholz

SeedlingsDead individuals

Tree species line

Timberline

Adults

General conclusionGeneral conclusion

• The treeline trees may suffer from a The treeline trees may suffer from a winter winter carbon shortagecarbon shortage leading to treeline formation leading to treeline formation

• Global warming leads to Global warming leads to increase in treeline increase in treeline elevationelevation to keep pace with climate change to keep pace with climate change

• PPlants may also respond to climate change in lants may also respond to climate change in Himalayas viaHimalayas via

• Re-adaptationRe-adaptation• InvasionsInvasions• ExtinctionExtinction

Li MH et al. 2006. J Integrat Plant Biology 48, 255 - 259Li MH et al. 2008. Tree Physiology 28, 1287-1296 Li MH et al. 2008. Plant, Cell & Environment 31, 1377-1387

30

Modeled Climate-Induced Glacier and Vegetation Change in Glacier National Park, 1850-2100

http://www.nrmsc.usgs.gov/images/glacier_animation_slow.gif

Cavieres et al. 2000. Acta Oecologia 21, 203-211

Podocarpus oleifoliusPodocarpus oleifolius

2550 m a.s.l.2550 m a.s.l.

3200 m a.s.l.3200 m a.s.l.2400 m a.s.l.2400 m a.s.l.

3200 m a.s.l.3200 m a.s.l.

Espeletia neriifoliaEspeletia neriifolia

Richardson AD. 2004Plant & Soil 260, 291-299

P<0.05P<0.05P<0.05P<0.05

P<0.05P<0.05 P<0.05P<0.05

Abies balsamea Picea rubens

Shade needlesShade needles

Sun needlesSun needles