boreal forests 09.ppt

1

Boreal ForestsThe Great Lung of the North

11/20/09 1

Importance of Boreal Forests• Second largest biome behind tropical forests

and occupies 11% of land surface (Bonan and Schugart p ( g1989)

• Contains 13% of carbon stored in biomass 43% of carbon stored in soils (Schlesinger, 1997)

• Pan Artic Hydrologic Domain is Most Land Dominated and Pristine Ocean System (Vörösmarty

11/20/09 2

Dominated and Pristine Ocean System (Vörösmarty 2000)

• Expected to experience the greatest amount of warming; 4-7 ºC (http://www.acia.uaf.edu/default.html)

2

North American Boreal Forest

11/20/09 3

Another Method of Spotting the Boreal Forest…

11/20/09 4

3

Boreal Forest Characteristics• ~ 12 x 108 ha, exclusively in northern

hemisphere• Short growing seasons (50 days),

permafrost in areas• Fire is most important natural disturbance;

may burn 25,000-50,000 ha per yearSoils are Histosols Entisols and

11/20/09 5

• Soils are Histosols, Entisols and Spodosols

Boreal Forest Characteristics Cont.• Low species diversity, 9 dominant trees in

north American and 14 in Eurasia

• Structural Characteristics include low leaf area index and spiral canopies

• Bryophytes are small amount of

11/20/09 6

• Bryophytes are small amount of aboveground biomass but play important ecological roles

4

Dominant Trees of the North American Boreal Forest

11/20/09 7

Picea marianablack spruce

Pinus banksianajack pine

Populus tremuloidesTrembling aspen

Important Bryophytes of the North American Boreal Forest

11/20/09 8

Sphagnum sppSphagnum moss Pleurozhium schreberi

Feathermoss

5

11/20/09 9

Boreal Forest Landscapes

11/20/09 10

6

Boreal Forests are Cold, Dry, and Wet?

11/20/09 11

Laramie Annual Precipitation = 277 mmAnnual Temperature = 4.7 ºC

If the continental boreal forestIf the continental boreal forest receives the same precipitation as a desert, then why does it look like a large expanse of wetland?

11/20/09 12

7

Reasons for Apparent Wetness in Boreal Forest

• Flat topography• Water evaporates more slowly in cold

climates• Sphagnum and feathermoss store water,

prevent evaporation, and form peat which prevents drainage

11/20/09 13

prevents drainage• Permafrost prevents drainage and stores

water

Climate change and carbon cycling

11/20/09 14IPCC 2007

8

11/20/09 15

Northern high latitudes are warming and greening

NDVI = Normalized Difference VegetationDifference Vegetation Index, • Ratio of red to near infrared wavelength reflectance, • Indicates “greenness”• Measured from satellites since early 1980’s

11/20/09 16

Warming is pronounced in spring and fall, lengthening the growing season

Myneni et al., 1997

9

NDVI is increasing at high latitudes Average NDVI for 1990’s

11/20/09 17Myneni et al., 1997

Boreal Ecosystem Atmosphere Study (BOREAS)

11/20/09 18

What are some advantages and disadvantages of the BOREAS experimental design to address questions about global change?

10

Photosynthesis in Boreal Forest Requires Winter Recovery Period

11/20/09 19Bergh et al. 1999

11/20/09 20

11

11/20/09 21http://fire.ak.blm.gov

11/20/09 22

12

11/20/09 23

11/20/09 24

13

11/20/09 25

11/20/09 26

14

11/20/09 27

Effects of Boreal Forest Succession on Annual Water and Carbon Fluxes

Burn Year Age of Stand

Leaf Area Index

Transpiration(mm yr-1)

NPP(g m-2 yr-1)(mm yr ) (g m yr )

1989 11 0.4 24 189

1981 20 1.4 97 5211964 36 2.0 224 3731930 80 7.5 332 2951850 150 6 1 183 229

11/20/09 28

Annual Precipitation= 400 mm

1850 150 6.1 183 229

Medicine Bow MountainsAnnual Transpiration ~ 200 mm with LAI = 7.3 and Annual Precipitation= 580 mm

B. Ewers, unpublished data