Environmental Engineering Reference
In-Depth Information
Shape
Mean
Standard Deviation
Standard Error
Variance
n
Square
Circle
Rectangle
3. Using a statistical package and coded data (e.g. 1
¼
square, 2
¼
circle, 3
¼
rectangle), conduct a one-way ANOVA to determine if the different shapes
yielded different mean densities.
Shape code
Density
4. In order to detect differences in population spatial pattern, calculate the Variance:
Mean Ratio (VMR) of the plant density in quadrats of different shapes.
If variance is high compared to the mean, then the population is clumped in
pattern. If variance is low compared to the mean, then the population is regularly-
distributed. If the VMR
1, then the population is randomly-dispersed.
Does spatial pattern change with quadrat shape?
Shape
Mean
Variance
VMR
Spatial pattern
Square
Circle
Rectangle
5. If your statistical package allows, conduct a non-parametric Levene's test to
determine whether the three different quadrat sizes gave significantly different
variances.
6. Interpret your results. Did quadrat shape significantly affect plant population
density or spatial pattern estimates? Why do you think this is?
7. What type of quadrat shape would you use in future studies and why?
Field Lab 2: Tree Populations & Succession
Objectives
Use plotless methods for assessing population size.
Use a compass to establish transects.
Map plant populations using GPS and GIS.
Interpret population data in order to predict future successional trends.
