Stats 12.3 An introduction to: Greater carbon sequestration by Nitrogen fixing trees?
Channel: Dana Lee Ling
Date: 20/11/2020

Data: https://docs.google.com/spreadsheets/d/1RKMZbMrafMzuKmcWD4AjuKC6dFaJLrB8kXBUeDjoaK0/edit?usp=sharing
Original article: https://www.fs.fed.us/global/iitf/pubs/ja_iitf_2002_resh001.pdf
Falcataria moluccana, nitrogen fixing: 
https://www.inaturalist.org/observations?place_id=10322&subview=grid&taxon_id=157413&verifiable=any
Eucalyptus deglupta, not nitrogen fixing: 
https://www.inaturalist.org/observations?place_id=10322&subview=grid&taxon_id=123757&verifiable=any

In exercise 12.2 you explored whether global warming is happening in the home islands of Micronesia, specifically Pohnpei, due to increased carbon dioxide levels in the atmosphere. 

One way to reduce global warming is to remove carbon dioxide from the atmosphere. Plants remove carbon dioxide from the atmosphere. Plants convert the carbon into wood and leaves. The bigger the plant, the more carbon dioxide they remove. The largest plants are trees. All trees remove carbon dioxide. Two trees of the same size remove about the same amount of carbon dioxide. 

Some trees also pump carbon into the soil around their roots, using the soil as a place to store excess carbon. The data looks at whether the type of tree matters in terms of the amount of carbon dioxide pumped into the soil. In this study two types of trees were examined: nitrogen fixing trees and non-nitrogen fixing trees. Nitrogen is an element that is a fertilizer for plants. Some trees use cyanobacteria to produce their own nitrogen fertilizer, they are called nitrogen fixing trees. Some trees cannot produce their own nitrogen fertilizer, they are called non-nitrogen fixing trees.

This exploration is data on the amount of carbon stored (and lost) from the soil under these two types of trees year-on-year. Positive numbers are better: carbon was stored. Negative numbers are not as good: carbon was lost from the soil year-on-year. The data shows gain and loss for both tree types. So is one type better for storing carbon and is that difference statistically significant?