Climate Impacts on Forests

Gary LovettCary Institute of Ecosystem Studies

Science and Management Forum: Climate Change in the Hudson Valley

Data from Gosz et al 1978. Diagram from Molles 2006.

Data from Gosz et al 1978. Diagram from Molles 2006.

There are known knowns. These are things we know that we know. There are known unknowns. That is to say, there are things that we know we don't know. But there are also unknown unknowns. There are things we don't know we don't know.

Donald Rumsfeld

Some Known Knowns

1. Trees like CO2*

2. Most trees like a longer growing season*

3. Tree species vary in their response to CO2, temperature and water

4. Trees compete with their neighbors

* As long as they have enough water and nutrients and don’t get eaten by bugs

Examples of Carbon Dioxide Effects on Plants:Positive: • Tree growth increases by about 20%• Trees produce more pollen and seed• Trees use less water

Negative: •Ragweed produces more pollen•Poison ivy grows better and is more potent

Two Types of Effects: Carbon Dioxide Effect and Climate

Effect

Experimental pine forest site in NC

Known unknown: How long will the CO2 fertilization effect persist?

• Photosynthesis• Respiration• Seed production• Transpiration• Growing season• Decomposition• Microbial function• Nutrient cycling• Insect growth• Birds and mammals

Climate Change Affects Just About Everything in a Forest Ecosystem

Snow Cover Will Be Reduced

Area with snow on the ground for at least 30 days during the winter

Source: Union of Concerned Scientists 2007

Known unknown: What are the cascading effects of reduced snow cover on trees, soil, and mammals?

Tree Species Will Shift Northward

Predicted Change in Forest Types under Future Climate

Maps from Iverson and Prasad (2001)

Known unknown: Can species ranges change fast enough to keep up with climate?

Bird species will change along with the forests

From UCS 2007

Photo: Doug Burns

Local Vegetation Change: Good-bye to mountaintop spruce-fir forests in the Catskills

Bicknell’s thrush

Blackpoll warbler

From Vitale and Schlesinger 2011

Some bird species are arriving in Dutchess County earlier

May 1Apr 1Mar1

Known unknown: Will synchrony be maintained among leaves, bugs and birds?

Hemlock Woolly Adelgid

Northern extent set by climate

Known unknowns: • How fast will the adelgid evolve tolerance to cold temperatures?• Will a predator or disease emerge to stop the adelgid?• What other pests will invade due to warming temperatures?

Wild Card: Insects and Diseases

Mountain Pine Beetle Infestation

Hurricane Irene, 8/26/2011, NASA Goddard

Source : NEFA

Hubbard Brook, NH, 1998

Wild Card: Storms

Source: Union of Concerned Scientists

Management and Adaptation

• Reduce other stressesAcid rainAir pollutionOverabundance of deerInvasive species

• Use best harvest practices to minimize impacts

• Maintain unfragmented forests with a variety of habitats

Forested Areas in Town of Stanford. Map by Hudsonia, Ltd, 2005.