Loblolly Tree Growth

Coursera Data Products Project

Loblolly Pine trees are one of the most commerically important trees in the southern United States, so Loblolly Pine tree farms are very common in this area. Tree growth is usually calculated with respect to log of time, but most people think linearly. This algorithm allows to select number of years for tree growth and shows the predicted tree height on linear plot and log-scale plot. The minimum time is 1 year with maximum time is 100 years, interval is 0.5 years.

R has a built in dataset for Loblolly tree growth with measurements through 25years:

data(Loblolly)
summary(Loblolly)

     height           age            Seed   
 Min.   : 3.46   Min.   : 3.0   329    : 6  
 1st Qu.:10.47   1st Qu.: 5.0   327    : 6  
 Median :34.00   Median :12.5   325    : 6  
 Mean   :32.36   Mean   :13.0   307    : 6  
 3rd Qu.:51.36   3rd Qu.:20.0   331    : 6  
 Max.   :64.10   Max.   :25.0   311    : 6  
                                (Other):48  

library(ggplot2)
t1 <- Loblolly
m1 <- lm(height ~ I(log(age)), data=t1)
t1$predict <- predict(m1, t1)
qq <- qplot(age, height, colour=Seed, data=t1) + 
    geom_line(data=t1, aes(x=age, y=predict), colour="red", lwd=1) + 
    labs(x="Age (years)") + labs(y="Height (ft)") + 
    labs(title="Loblolly Tree Height")