Ecotypic Variation and the Response of Tundra Plants to Climate Change

Ned Fetcher1, Cynthia Bennington2, James B. McGraw3, Milan Vavrek4, Kelli Cummings1, and Gaius R. Shaver5

1Wilkes University, 2Stetson University, 3West Virginia University, 4Glenville State College, 5Marine Biological Laboratory

Map of northern Alaska showing location of experimental gardens at Eagle Creek (EC), No Name Creek (NN), Coldfoot (CF), Toolik Lake (TL), Sagwon (SAG) and Prudhoe Bay (PB). The Continental Divide separates southern and northern ecotypes of Eriophorum vaginatum.

Plants form the base of Arctic tundra food webs and are the determinants of terrestrial primary productivity in the Arctic. Given this central role, the response of tundra plants to climate change will have regional and global implications. This project examines therole of ecotypic differentiation, i.e., local adaptation of plants to the environment, in modulating and potentially limiting the response of a plant species to climate change. In 1980, a reciprocal transplant experiment was set up to examine ecotypic differentiation in the tussock-forming sedge Eriophorum vaginatum along a latitudinal gradient. The experiment demonstrated strong genetic differentiation between populations of this widespread, abundant Arctic plant species. Since 1980 the Arctic climate has warmed significantly, and these temperature changes, along with associated changes in the soil environment, have caused measurable changes in Arctic plant communities. In 2009 and 2010 we re-censused the experiment to ask whether climate change has already resulted in a ‘mismatch’ between ecotypes and their original environment.

Questions

Are the original differences between populations of E. vaginatum from south and north of the Brooks Range maintained after 27 years?

Because of the warmer climate, do the southern ecotypes show improved performance relative to 27 years ago?

1993

Garden Mean Value for Tiller Size Index

200 300 400 500 600

Till

er

Siz

e In

de

x fo

r E

ach

Po

pu

latio

n

200

400

600

800

CF

CF

CF

CF

CF

CFEC

EC

EC

EC

EC

EC

SAG

SAGSAG SAG

SAG

SAG

NN

NN

NN

NN

NN

NN

PBPBPB

PB

PB PB

TL

TL

TL

TL

TL

TL

1983

Garden Mean Value for Tiller Size Index

200 300 400 500 600 700

Till

er

Siz

e In

de

x fo

r E

ach

Po

pu

latio

n

200

400

600

800

CFCFCF

CF

CF

CF

EC

EC

EC

EC

EC

EC SAG

SAG

SAG

SAG

SAG

SAG

NN

NN

NN

NN

NN

NN

PBPB

PB

PB

PB

PB

TLTLTL

TL

TL

TL

2010

Garden Mean Value for Tiller Size Index

200 300 400 500 600 700

Till

er

Siz

e In

de

x fo

r E

ach

Po

pu

latio

n

200

400

600

800

CF

CF

CF

CF

CF

CF

EC

EC

EC

EC

EC

EC

SAG

SAG

SAG

SAG

SAG

SAG

NN

NN

NN

NN

NN

NN

PB

PB

PB

PB

PB

PB

TL

TL

TL

TL

TL

TL

Eagle CreekNo Name CreekColdfootToolik LakeSagwonPrudhoe Bay

Tussock of Eriophorum vaginatum from Toolik Lake at the Eagle Creek garden showing early senescence in mid-August, 1982.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Mea

n(S

urvi

val_

A/P)

NO

RT H

SO

UT H

NO

RT H

SO

UT H

NO

RT H

SO

UT H

NO

RT H

SO

UT H

NO

RT H

SO

UT H

NN EC CF TL SAG

ConclusionsThe original differences between northern and southern ecotypes of Eriophorum vaginatum appear to be maintained after 30 years.

At some gardens there appears to be significant “home team advantage” whereby the native ecotype has greater survival than the alien ecotype.

There seems to be little evidence that the southern populations have an advantage as a result of recent warming on the North Slope.

Kelli Cummings and Cynthia Bennington measuring tiller size index on BP oil field at Prudhoe Bay. Students in the background are measuring photosynthesis.

Acknowledgements

Funding was provided by NSF grant #0908936. Additional support was provided by the Arctic Long Term Ecological Research program, funded by the National Science Foundation, Division of Environmental Biology.

Literature CitedFetcher, N. 1985. Effects of removal of neighboring species on growth, nutrients, and microclimate of Eriophorum vaginatum. Arctic and Alpine Research 17:7-17. Fetcher, N., and G. R. Shaver. 1990. Environmental sensitivity of ecotypes as a potential influence on primary productivity. American Naturalist 136:126-131.

Survival of tussocks from southern (EC, NN, CF) and northern populations (TL, SAG, PB) at five gardens in 2009. Prudhoe Bay garden was not censused in 2009.

Survival of both northern and southern ecotypes was high at Eagle Creek and Toolik Lake. At No Name Creek and Coldfoot the southern ecotypes had greater survival, while at Sagwon the northern ecotypes had greater survival.

Caitlin Peterson (Stetson University) at the Eagle Creek garden.

Methods

Tussock Survival

Tiller Size