1. Fir Douglas or cedar red western?
Jason Lee Middle School
The Wolf Gang

2. INtroduction
We were interested in coring trees, so we did a comparative study of growth rate in Douglas Firs and Western Red Cedars.
Which has a faster growth rate; Douglas Fir or Western Red Cedar?
We think Cedars will have a faster growth rate because prior observation led us to believe that they are taller.

3. Definitions
DBH: diameter at breast height, used to measure tree diameter and circumference
Tree corer: used to drill a tree core sample to measure tree rings for age and growth rate
Sludge: thick, soft, wet “mud” or similar mix of liquid and solid components

4. Materials
Tree corer
DBH tape
Straws and tape
Pencil and paper

5. methods
Went to the forest and found 3 Cedar trees and 3 Douglas firs similar in volume
Found DBH of each tree to make sure they were between 11-12cm
Cored the tree and put sample in straws to carry back to the lab
Counted number of tree rings within 2cm of the bark
Calculated and compared average rate of growth in one year

6. Data

7. Results Douglas Fir- .15cm/year Western Red Cedar- .1cm/year
Our hypothesis was unsupported; though similar, Western Red Cedars have a slower rate of growth than Douglas Firs.

8. discussion Work more efficiently to have more time to find our species
Perform study in the old growth forest where we made prior observations
Take samples from trees in the same kind of environment (ie. sludge, sunny areas, dry areas)
How would height have affected this data?
What would have changed had we taken samples from more species?
How did growth in the sludge plot affect rate of Douglas Firs?

9. limitations Broken gear
Douglas First were all grown in the sludge plot
Difficult to find samples with similar DBH (11-12cm)
Time! Larger sample size
Errors in identifying species and counting tree rings
Prior observations were made in a different area than data collection
Accessing trees proved difficult

10. Larger implications
What does this mean to landowners, scientists, and foresters?
If you plant more Doug Firs than Cedars, you could get better economic benefits
What affects growth rate? Growing factors: sunlight, amount of rainfall, soil, elevation, natural disasters
Track growth factors such as nutrients, season of planting, seedling to maturation, type of environment

11. Questions?