Climate change, invasive species and forests

Lee E. Frelich

Director, The University of Minnesota Center for Hardwood Ecology

Vice President, Eastern Native Tree Society

Chair, Board of Directors, Great River Greening

Dave HansenUniv. of MN

John Knuerr

Svante August Arrhenius(Nobel prize, Chemistry,1903)

Developed the hothouse theory forCO2 in 1896, and in 1905 predicted that raising CO2 content of the atmospherewould cause an increase in mean globaltemperature similar in magnitude tomodern predictions

Evidence that CO2 increase and climate change are caused by humans

1. Keeling curve corresponds to population and known emissions of CO2

2. Suess effect

3. Temperature profile of the atmosphere—warmer lower atmosphere and cooler stratosphere

4. Existing ‘Greenhouse effect’ of 56 degree F before human enhancementof heat trapping gases in the atmosphere

5. Models with human greenhouse gas enhancement match observed temperatures over the last 100 years, models with only naturalforcings on climate do not

Climate change occurs in the context of large year toyear variability—summer temperatures for 2009

Summer 2009—Example of regional temperature anomalies versus global mean in a warming climate. A cold summer in central and eastern North America, although 80% of the world had above average temperatures.

…and spatial variability

http://www.cgd.ucar.edu/ccr/ammann/millennium/CODES_MBH.html

Comparison of the original Mann ‘hockey stick’ reconstruction of temperature(red) with implementation of valid criticisms of the PC methodology (green).From Wahl and Amman 2006.

Tree ring analyses showing climate over the several hundred years

Osborne and Briffa 2006, instrumental record for northern hemisphere (red)and for records closest to proxy sites (green).

Tree ring analyses from 14 sites

Oerlemans, 2005 temperature reconstruction of global mean temperaturebased on 169 glaciers.

Borehole temperature data from Huang, Pollock and Shen, Nature, 2000

Temperature evidence from boreholes

From McCarthy, 2009, Science

Modeling of temperatureshowing how natural andhuman influences work together.

Natural versus human CO2 forcing on the climate

British Meteorological Office, December 2009

Migration maps for tree response to past climate change in 1000s years before present (M.B. Davis 1983)

Spruce White pine

Current and simulated future range of black spruce, from Lenihan and Neilson 1995.

300 mile shift is equal todistance moved in ~ 2000years in paleorecord

Forest cover of central North America (green)DeFries, R., M. Hansen, J.R.G. Townshend, A.C. Janetos, and T.R. Loveland (2000), 1 Kilometer Tree Cover Continuous Fields, 1.0, Department of Geography, University of Maryland, College Park, Maryland, 1992-1993.

It is possible that the pbf will move 500 km to the north and east, deforesting an area 2X the size of California

Native species have migrated in the past without going extinctwhat’s different now?

Rate of climate change—many species cannot migrate fast enoughFragmented environment—makes species to movement more difficultHabitat loss—less habitat now and can support fewer speciesInvasive species—can reproduce and move fast, they have opportunity

to displace native species during times of rapid change Exotic diseases and pests—can spread faster in a warmer climateDeer grazing—will increase in the north, can extirpate native plants

David Augustine

TNC

Minneapolis Star tribune

Before and after the 1999 blowdownin the Boundary Waters, northern MN

Wind plus fire = major forest transformationNick Fisichelli and Roy Rich, Cavity Lake Burn, Seagull Lake, July 2007.Photo: Dave Hansen, University of MN

Several forces are at work that may push MN foreststowards savanna:

If soils become drier for any reason sites can support fewer trees:

Warmer soilsHigher evaporation to precipitation ratioEuropean earthworms stripping the insulating duff layer

More drought = trees under stress and forest dieback

Photo: Dave Hansen

Native insects play a major role in forest changeBenign native insects can have outbreaks in a warmer climate.For example, mountain pine beetle in British Columbia—a native insect that caused massive tree mortality over 30 million acres of lodgepole pine forest, and could threaten jack pinein MN

Sylvania Wilderness maple and hemlock forest in 1988

Sylvania in 2006

Global warming orGlobal worming?

Earthworms are ecosystem engineers that can alter the structure of soil, and change the H2O, N and P cycles, Cdynamics and seedbed characteristics on a regional scale

Soil profile, no earthworms (left), with earthworms (right).The loss of the duff layer will affect summer soil temperature

Photos: Dave Hansen, University of MN

00.20.40.60.8

11.21.41.6

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Invasion timing (years)

Rin

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idth

inde

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Worm freeworm invaded

Earthworm invasion in maple forest causes a decreasein tree ring width and loss of seedling density and herb specieson the forest floor

Recent literature shows that Earthworms also facilitate germination and establishment of European buckthorn and garlic mustard by changing the seed bed

Kathleen Knight

Photos: The Nature Conservancy

Exotic earthworms + deer =major transformation of theforest. Bare soil and lowernutrient status should favor hemlock over maple, but deer favor maple.

Both dominant species aredisfavored, combined withwarmer climate and sandysoils, probably meansSylvania will become oaksavanna in the future

Paul Jost

Summary of impacts on Lake Statestree species

Global warming and rate of migration:All species Sudden oak death: red oak, pin oakDeer: white cedar, yellow birch, white pine, oaksBalsam woolly adelgid: balsam firEmerald ash borer: green ash, black ash, white ashAsian long-horned beetle: red maple,sugar maple, aspenHemlock woolly adelgid: hemlockMountain pine beetle: jack pineNative insects: eastern larch, others Earthworms: sugar maple and others

Overall scheme for change at the prairie-forest border proposed by Frelich and Reich

We can expect a messy transitionHistory shows that development of a new ecosystem takes 100sto 1000 years to develop

Dave Hansen

Lee Frelich

Old

Transitional

New

Layne Kennedy

Lee Frelich and clones at work during Ham Lake Fire, Seagull Lake, May 6, 2007

Questions?