BIOL 360 Lecture 5: Stats refresher and nutrient cycle
Stats refresher
1. Correlation
a. P and r value- how strong and what direction is the correlation
2. Regression
a. R^2 and p value and y=mx+b
b. Ts very clear which is independent (x) and which is dependent (y)
3. T-test
a. Groups a and b boxplots to determine if 2 variables are the same or different
b. P=?
i. Large p: same
ii. Small p: different
4. Diversity calculations
a. A vs B vs C
b. F(richness, abundance, evenness):
5. Sigma- standard deviation
a. Mean and then stuff to the left and right of it
b. -2 SD→ +2 SD: 95%
6. CV= coefficient of variation variance
a. CV= SD/mean= normalized SD
b. How heterogeneity is the variable set
Nitrogen cycle
• N in atmosphere (79%)
o Natural: N fixed in plants in soil
o Artificial: Haber Bosch process- applied to fields, farms, crops
• Excess fertilizer moves into streams through runoff, excreta from farm animals and
humans (municipal waste), wastewater effluent
• Excess nitrogen in water→ eutrophication→ algal blooms→ dead zones due to less
oxygen
o Less oxygen because-
▪ Less sunlight- less oxygen production under water
▪ When algal blooms die, the decaying matter leads to less oxygen
Phosphorus cycle
• P stored mostly in rocks- gets into stream from natural weathering of rocks
• Estimeated that we will use all phosphorus by 3500
• Mine the rocks→ make fertilizer→ runoff and excreta into water→ eutrophication→ the
phosphate can then go through deposition and become part of the rock again
• Key: fertilizer→crops→excreata→fertilizers and water ways (this is a cycle)
Wetland- ground saturation to the surface (land that’s dilled with water most of the time
1. Swamp- trees, fresh or brackish
