#CHEATGRASS/FIRE TIEE MODULE
#R script
#set your working directory to the folder where you saved this file on your computer
setwd("/Volumes/homes/CheatfireDataACTIVE/Analysis/MODISba_play/TIEE")
#read table into R
#you will have to save the excel sheet of data called "Whisenent 1990 data" as just a .csv file
cdata <- read.table("data_whisenant1990.csv", header=TRUE, sep=",", na.strings="NA", dec=".", strip.white=TRUE, stringsAsFactors = F)
cdata
############################
#1. Linear regression model of fire frequency as a function of fine fuel frequency
#do an xy plot of the data
plot(fire_freq~fuel_cover, data=cdata)
#fit a best-fit line through the points of data
abline(lm(fire_freq~fuel_cover, data=cdata))
#conduct a linear regression model
m1 <- lm(fire_freq~fuel_cover, data=cdata)
#the summary call gives a summary of the model fit
#in this case the shape of the line follows this function:
# y = mx + b
# y = 0.0086x - 0.28; Adjusted R-squared = 0.86
summary(m1)
############################
#2. Box plots showing the mean (or average) with upper and lower extremes of the data
#Mean fine fuel frequency where cheatgrass is (y) and is not (n) the dominant grass
bwplot(fuel_cover~cheat_dom, data=cdata,
main="Boxplot 1",
xlab="Bromus tectorum Dominance",
ylab="Fine Fuel Frequency (%)")
#Mean fine fuel quantity where cheatgrass is (y) and is not (n) the dominant grass
bwplot(fuel_mass~cheat_dom, data=cdata,
main="Boxplot 2",
xlab="Bromus tectorum Dominance",
ylab="Fine Fuel Quantity (lb/acre)")
#calculate median and mean values
#subset data into two parts based on cheatgrass dominance
bty <- subset(cdata, cdata$cheat_dom == "y")
btn <- subset(cdata, cdata$cheat_dom == "n")
#Median and Mean values for fine fuel frequency (Boxplot 1)
median(bty$fuel_cover)
median(btn$fuel_cover)
mean(bty$fuel_cover)
mean(btn$fuel_cover)
#Median and Mean values for fine fuel quantity (Boxplot 2)
median(bty$fuel_mass)
median(btn$fuel_mass)
mean(bty$fuel_mass)
mean(btn$fuel_mass)
#Mean fire frequency where cheatgrass is (y) and is not (n) the dominant grass
bwplot(fire_freq~cheat_dom, data=cdata,
main="Boxplot 3",
xlab="Bromus tectorum Dominance",
ylab="Fire Frequency (fires/year)")