# Tree Biomass Challenge (Scientific)

Understanding the total amount of biomass (the total mass of all individuals) in forests is important for understanding the global carbon budget and how the earth will respond to increases in carbon dioxide emissions.

We don’t normally measure the mass of a tree, but take a measurement of the diameter or circumference of the trunk and then estimate mass using equations like M = 0.124 * D2.53.

1. Estimate tree biomass for each species in a 96 hectare area of the Western Ghats in India using the following steps.

• If the file `ramesh2010-macroplots.csv` isn’t already in your workspace then download a copy.
• Load the data into R.
• Write a function that takes a vector of tree diameters as an argument and returns a vector of tree masses.
• Create a `dplyr` pipeline that
• Adds a new column (using `mutate` and your function) that contains masses calculated from the diameters
• Groups the data frame into species using the `SpCode` column
• And then calculates biomass (i.e., the `sum` of the masses) for each species (using `summarize`)
• Stores the result as a data frame
• Display the resulting data frame

2. Plot a histogram of the species biomass values you just calculated.

• Use 10 bins in the histogram (using the `bins` argument)
• Use a log10 scale for the x axis (using `scale_x_log10`)
• Change the x axis label to `Biomass` and the y axis label to `Number of Species` (using `labs`)
Expected outputs for Tree Biomass Challenge