The mechanism of productivity formation of alpine meadow ecosystem

Dr Xinquan Zhao

Northwest Plateau Institute of Bi

ology, The Chinese Academy of

Sciences, Xining, 810001

Haibei Research Station

Environmental conditions of the

research area 

The Haibei alpine meadow ecosystem research

station is located with N latitude 3729'-3745' a

nd E longitude 10112'-10123'.

The altitude of area is 2900 - 3500 meters. It ha

s a continental monsoon climate, with severe a

nd long winters and short cool summers.

The average air temperature is -1.7 . ℃

Average annual precipitation ranges from 426

to 860 mm, 80% of which falls in the short sum

mer growing season from May to September.

Vegetations and Animals

Alpine meadow, dominated by Kobresia hu

milis and various grasses and forbs (depend

ing on grazing density) are widely distribut

ed in this region along the valley floor.

The shrub, Potentilla fruticosa are joined by

shrubby Salix species are locating on the no

rth hill.

The region marsh vegetation consists prima

rily of Kobresia tibetica and Pedicularis long

iflora.

Vegetations and Animals

The higher shrub lands on

the mountains surrounding the

valley are common summer

grazing lands. The meadow

vegetation is grazed in winter

and is privately owned. Sheep and yaks, the majorherbivorous animals in the

region, live on herbage, which

varies greatly with seasons.

Fig. 2 Seasonal Dynamics of Standing Crop Biomass and Crude Protein Content

0

50

100

150

200

250

300

Month

Stand

ing C

rop Bi

omass

(g/m

)

0

2

4

6

8

10

12

14

16

Standing Crop

Protein

Crud

e Prot

ein Co

ntent

(%)

0

500

1000

1500

2000

2500

3000

3500

May J une J ul y August September

Aboveground Bel owground

Fig. 1 The biomass of Kobrisa humilis meadow during growth season

Biom

ass

(g/m

2)

Fig.4 Changes of sheep live weight of different ages

0

10

20

30

40

50

60

70

80

Months

Live

-weig

ht (k

g)

Table 1 the ratio of herbage consumption to kilogram carcass of different ages of sheep

Age (year) 1 2 3 4 5 6 7

Herbage consumption(HC, kg)

 738

 2700

 4830

 6060

 7740

 9420

 1111

0

Carcass weight (CW, kg)

7.6 15.4 21.3 27.2 29.2 30.7 28.5

HC/CW 96.3

175.2 226.4 223.2 265.4 306.4 391.5

Fig. 5 The Consist of Biomass of Alpine MeadowUnder Different Grazing Densities

0

10

20

30

40

50

60

5.3 4.43 3.55 2.68 1.8

Grazing density (sheep/ha.)

Con

sist

of

Bio

ma

ss(%

)

Sedge Grasses Forb Shrub Litter

Fig. 6 The bimass of zokorat different stocking rates

0

500

1000

1500

2000

2500

3000

3500

5.3 4.43 3.55 2.68 1.8

Stocking rate(sheep/ha)

Bio

mas

s (g

wet

wei

ght

ha)

The monthly patterns of biomass changes of the plants are significantly different (P< 0.05) for various plants. The seasonal pattern showed that maximum (80%) above-ground production occurred during July to September when temperature and precipitation are most favorable for plant growth.

The ratio of herbage intake and live weight gain is very low due to the imbalance of herbage supply, both quantity and quality.

During the cold season, which lasts for more than 7 months, livestock live mainly on standing dead grasses and the livestock body weights loss is 50% to 80% of body weight gain during the warm season.

Conclusions

Case study 1Carbon flux in the alpine meadow (Kobresia humilis) ecosystem

Fig.5 Comparison of net CO2 flux (Fc) on ecosystem as a funciton of net radiation (Rn) on clear day(14 August) and cloudy day (29 August)

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0 100 200 300 400 500 600 700 800

Rn (w m-2)

Fc

(mg

m-2

s-1

)

Cloudy day

Clear day

Fig.6 Relationship between net CO2 flux (Fc) and air temperature (Ta) under the high solar radiation

(Rn>550w m-2) on clear day (14 August)

R2 = 0.4099

0.5

0.6

0.7

0.8

0.9

1.0

15 16 17 18 19 20 21 22 23 24

Ta ( C)

Fc

(mg

m-2

s-1)

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

0:00 2:00 4:00 6:00 8:00 10:0012:0014:00 16:0018:0020:0022:00 0:00

Time

Fc

(mg

m-2 s-1

)-200

0

200

400

600

800

1000

1200

Rn

(w m-2

)

8/14 Fc8/14 Rn

Clear daya

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

0:00 2:00 4:00 6:00 8:00 10:0012:0014:0016:0018:0020:0022:00 0:00Time

Fc

(mg

m-2 s-1

)

-200

0

200

400

600

800

1000

1200

Rn

(wm-2

)

8/29 CO28/29 Rn Cloudy dayb

Fig.4 Daily variation of net radiation (Rn) andCO2 flux (Fc) on clear day and cloudy day

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00

Time

VP

D (

KP

a)

-5

0

5

10

15

20

25

30

Ta (

℃ )

8/14 VPD

8/14 Ta

8/14 Ts (5cm)

Clearday

Fig.7 Daily variation of air temperature (Ta) and vapor pressure deficit (VPD) at 220 cm on clear

day (14 August) and cloudy day (29 August)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00

Time

VP

D (

kP

a)

-5

0

5

10

15

20

25

30

Ta (

C)

8/29 VPD

8/29 Ta

8/29 Ts(5cm)

Cloudy

Ecosystem Location NEE

（ gCO2m-2day-1)

Canopy height

(cm)

Leaf area index

(m2.m-2)

Reference

Alpine meadow

(Qinghai, China)

37º 29'N 101º 12'E

Al. 3250m

21.23 DOY 233

2.65 DOY 275

30 Ca.3 ?

C4-dominated tall grass prairie (KS USA)

39º 12'N, 396º 35'E

Al. 324m

17.8 DOY 226

-10.3 DOY290

40 1.54 Ham & Knapp (1998)

Larch forest

(Tomakomai, Japan)

42 44'N

141 31'E

115-140m

35.2-44.0

(June)

18-20 - Yamamoto et al. (2001)

Temperate deciduous forest

(Takayama, Japan)

36º 8'N,

137º 25'E

1420m

0.184 (1995) ～　0.485 (1998)

Yearly average

15-20 3.5

trees

Ca.2.0

Bamboo

Yamamoto et al. (2001)

Net Ecosystem Exchange of CONet Ecosystem Exchange of CO22

Some preliminary conclusions

The alpine meadow exhibited a fairly high daily Fc during the growing season as compared with other similar ecosystem. The decrease of Fc under the high radiation suggests the potential importance of photoinhibition and/or ecosystem respiration in the meadow. Further detailed investigation is needed to evaluate the carbon budget for the unique ecosystem.

Case study 2CLIMATIC AND GRAZING CONTROLS ON VEGETATIVE

ABOVEGROUND BIOMASS

30m

30m

O O O O

O O O O

O O O O

O O O O

40 cm

1.48m

meadow habitat (winter rangeland)

shrub habitat (summer rangeland)

High Graze History Site

Treatments:

* control

* chamber (warm)

* clip (graze)

* chamber x clip

Within site plot setup

Low Graze History Site

Open top chamber

Experimental Design

*graze control

The International Tundra Experiment (ITEX)Arctic and Subarctic Field Sites

Air Temperature – Treatment EffectsGrowing Season, All Sites

NO CLIP CLIP

AIR

TE

MP

ER

AT

UR

E

(o C

)

0

2

4

6

8

10

NO CHAMBER CHAMBER

NO CHAMBER CHAMBER

* ** *

(Klein, Xin-quan, Harte, unpublished data)

Soil Temperature – Treatment EffectsGrowing Season, 3 Sites

SO

IL T

EM

PE

RA

TU

RE

(o C)

0

2

4

6

8

10

NO CHAMBER CHAMBER

*

* *

(Klein, Xin-quan, Harte, unpublished data)MEADOWSHRUB

Soil Moisture – Treatment EffectsGrowing Season, All Sites

NO CLIP CLIP

GR

AV

IME

TR

IC M

OIS

TU

RE

(%

)

0

10

20

30

40

50

NO CHAMBER CHAMBER

Control Plots Only - Site Comparisons

0

50

100

150

200

250

300

350

400

450

500

High Graze Low Graze High Graze Low Graze

shrub

sedge

forb

grass

MEADOW SHRUB

dry

wei

ght (

g/m2

)

(Klein, Xin-quan, Harte, unpublished data)

Chamber Effects on Total AG Vegetative Biomass (2001)

NO CLIP CLIP0

50

100

150

200

250

300

NO CHAMBERCHAMBER

LOW & HIGH GRAZE MEADOWS

LOW GRAZE SHRUBLAND

HIGH GRAZE HISTORY

SHRUBLAND

* * *

Dry

wei

ght b

iom

ass

(g/m

2)

(Klein, Xin-quan, Harte, unpublished data)

Low Grazing History Total Biomass(minus sedge)

050

100150200250300350400450

shrub meadow

dry

wt

(g/m

2)

control

clip

chamber

chamber x clip

Low Grazed Shrub Site soil carbon

0

2

4

6

8

10

12

control clip chamber chamber x clip

g c

arb

on

/ g

so

il x

10

0

SpeciesAltitude

(m)

T（℃） CP（%）（ ±SD）

EE (%)（ ±SD）

Correlation analyses

T1-2 T3-4 T1-2 and CP T3-4 and CP T1-2 and EE T3-4 and EE  

Festucaovina

3 800 7.50 7.01 9.96 ± 1.35 3.60 ± 1.40

r = -0.927 4P＜ 0.01

r = -0.961 4P＜ 0.01

r = -0.940 6P＜ 0.05

r = -0.915 8P＜ 0.05

 

3 600 7.84 7.33 8.97 ± 0.66 3.68 ± 0.20  

3 400 8.56 7.69 8.90 ± 1.46 3.41 ± 0.35  

3 200 9.19 8.25 7.90 ± 0.73 3.22 ± 0.10  

Poaannua

3 800 7.50 7.01 10.49 ± 1.32 4.17 ± 0.45

r = -0.700 5P＞ 0.05

r = -0.728 2P＞ 0.05

r = -0.996 3P＜ 0.01

r = -0.993 3P＜ 0.01

 

3 600 7.84 7.33 8.35 ± 1.40 4.11 ± 1.42  

3 400 8.56 7.69 8.48 ± 0.73 3.95 ± 0.55  

3 200 9.19 8.25 8.27 ± 0.06 3.77 ± 0.25  

Koeleriacristata

3 800 7.50 7.01 8.87 ± 0.48 4.09 ± 0.05

r = -0.160 6P＞ 0.05

r = -0.138 6P＞ 0.05

r = -0.947 9P＜ 0.01

r = -0.911 9P＜ 0.01

 

3 600 7.84 7.33 7.13 ± 0.58 3.91 ± 1.01  

3 400 8.56 7.69 6.87 ± 0.67 3.45 ± 0.71  

3 200 9.19 8.25 8.3 ± 1.18 3.43 ± 0.09  

3 600 7.84 7.33 11.38 ± 2.92 4.19 ± 0.41  

3 400 8.56 7.69 9.72 ± 2.28 4.14 ± 0.25  

3 200 9.19 8.25 9.90 ± 1.61 3.98 ± 0.21  

Temperature and CP, EE contents of herbage grown at different altitudes

SpeciesAltitude

(m)

T（℃）ADF (%)（ ±SD）

ADL (%)（ ±SD）

Correlation analyses

T1-2 T3-4

T1-2 and

ADF

T3-4 and

ADF

T1-2 and

ADL

T3-4 and

ADL

Festucaovina

3 800 7.50 7.01 35.77 ± 1.27 8.62 ± 0.96

r = 0.864 9P＜ 0.05

r = 0.857 5

P＜ 0.05

r = 0.961 0

P＜ 0.01

r = 0.935 5P＜ 0.01

3 600 7.84 7.33 39.69 ± 1.41 10.17 ± 1.25

3 400 8.56 7.69 41.67 ± 1.63 12.80 ± 1.48

3 200 9.19 8.25 41.74 ± 1.45 13.25 ± 1.90

Poaannua

3 800 7.50 7.01 32.53 ± 1.58 7.60 ± 1.28

r = 0.963 9P＜ 0.01

r = 0.958 1

P＜ 0.01

r = 0.991 9

P＜ 0.01

r = 0.969 4P＜ 0.01

3 600 7.84 7.33 35.12 ± 1.23 8.20 ± 1.28

3 400 8.56 7.69 37.28 ± 1.22 10.88 ± 1.59

3 200 9.19 8.25 38.49 ± 1.24 12.18 ± 0.87

Koeleriacristata

3 800 7.50 7.01 43.65 ± 1.87 14.72 ± 0.96

r = 0.954 9P＜ 0.01

r = 0.914 9

P＜ 0.05

r = 0.906 5

P＜ 0.05

r = 0.873 5P＜ 0.05

3 600 7.84 7.33 44.39 ± 1.65 16.57 ± 1.39

3 400 8.56 7.69 47.98 ± 1.33 19.26 ± 1.30

3 200 9.19 8.25 48.30 ± 2.36 18.96 ± 1.39

3 600 7.84 7.33 30.94 ± 1.49 6.32 ± 1.53

3 400 8.56 7.69 37.08 ± 1.89 7.41 ± 1.06

3 200 9.19 8.25 36.43 ± 1.81 8.21 ± 1.42

Temperature and ADF, ADL contents of herbage grown at different altitudes

Conclusions Our results suggest that the response of AG biomass to warming is mediated by habitat type and site grazing intensity history. The warming-induced reduction in plant species richness is consistent across habitats and site grazing histories.

There were significant downtrends in crude protein, fat and nitrogen free extract contents of herbage along with the increase of temperature. It had a positive correlation between temperature and content of constructed carbohydrates

Case study 3

The influence of enhanced UV-B radiation on alpine meadow

0

2

4

6

8

S. superba G. straminea

Ph

oto

syn

thet

ic O

2 E

vo

luti

on r

ate

( m

ol

O 2 m

-2 s

-1)

ambient UV-B

enhanced UV-B

Fig. 1 Effects of enhanced UV-B radiation on photosynthetic O2

evolution rate of S. superba and G. straminea in K. humilismeadow. There was significant difference between ambient UV-B andenhanced UV-B treatment appeared only in S. superba . n=5, P <0.05.

0

2

4

6

8

S.superba G.straminea

Net photo

synth

esi

s ra

te

( m

ol C

O 2 m

-2 s

-1)

ambient UV-B

enhanced UV-B

Fig. 2 Effects of enhanced UV-B radiation on net photosynthesis rate ofS. superba and G. straminea in K. humilis meadow. The value aremeans ± SD. There was significant difference between ambient UV-B andenhanced UV-B treatment appeared only in G. straminea n=10, P<0.05.

Conclusions

Some species were exposed to a UV-B density 15.80 kJ/m2 every day, simulating a nearly 14% ozone reduction during plant growing season. The results showed both net photosynthetic rate and photosynthetic O2 evolution rate were not decreased after long period of treatment with enhanced UV-B radiation

Thank you!