Studying Treeline to Assess Climate Change

By Jasmine McBeath

Mentors: Dr. Lisa GraumlichGreg PetersonErika Rowland

Overview of Climate ChangePerceptible climate change during a single lifetime:

• Annual average surface air temperature1

– 14˚C from 1961-1990– 14.5 ˚C in the 90s

• Other evidence2

– Rising sea levels– Decreased snow cover/retreating glaciers– Altered species’ distribution– Changes in the hydrological cycle and precipitation– Increased climate variability

• El Niño Southern Oscillation• North Atlantic Oscillation

1 Lovejoy, T. 2004. “What is Climate Change?” Climate Change and Biodiversity.

2 Lovejoy, T. 2004. “Recent Climate Trends.” Climate Change and Biodiversity.

Biotic Effects

Altered biological interactions and ↓ biodiversity:• Human induced change:

– Fragmented habitats– Introduction of exotic species– Added chemicals– Altered climate

• Migration response toward the poles and upslope• Birds, marine animals, insects• Reptiles and plants

• Studying the past reveals climate change and species’ migrations– Key organism: Trees

Current ProjectGoal: Improve accuracy of climate change models

Methods:– Tree-ring analysis

• Age structure and establishment patterns

– Experiments on treeline seedlings• Seedlings planted close to other trees, or under herbs• Microclimate altered with warming devices and watering

– Compare establishment patterns to climate patterns and species distribution

Step 1: Sampling Sites

Sites at Treeline

• Boundary from trees to plants• Limited by water, temperature, nutrients

• Mounted, prepared and sanded core samples

• Counted rings using microscope

Step 2: Recording DataTree cores

• Microtomed samples

• Counted rings using microscope

Step 2 Cont: Recording DataSeedlings

1mm

Diagram modified from

http://porpax.bio.miami.edu/~cmallery/255/255hist/255methods.htm

Step 3: Analysis and Context

• Comparing climate to tree growth

• Example Site: Bitterroots, MT– Look at regional climate changes– Look at establishment patterns

Higher Temperatures, Longer SummersClimate context of site

Increasing HeatClimate context of site

Retreating GlaciersClimate context of site

More SnowmeltClimate context of site

Step 4: Our Data Analysis

Tree Core

1mm1mm

Seedling Cores

Acknowledgments

I would like to thank Erika Rowland and Greg Peterson for their valuable input and guidance. I would also like to thank Dr. Lisa Graumlich and NASA for the opportunity to analyze this particular sample.