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

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.

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

Materials Tree corer DBH tape Straws and tape Pencil and paper

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

Data

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.

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?

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

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

Questions?