Analysis

III. Calculations and Analyses

A. Calculations

Basal Area (m2)	=	dbh (cm) x dbh (cm) x 0.00007854
Basal Area (ft2)	=	dbh (in) x dbh (in) x 0.005454
Species Frequency	=	# of plots in which is species is tallied divided by the total number of plots
Species Density	=	total # of stems tallied for a single species divided by the total area of the inventoried plots
Species Basal Area	=	total basal area for a single species divided by the total area of the inventoried plots
Relative Frequency	=	Species Frequency for a single species divided by the sum of the Species frequencies for all species.
Relative Density	=	Species Density for a single species divided by the sum of the Species densities for all species.
Relative Basal Area	=	Basal area for a single species divided by the sum of the basal areas for all species.
Importance Value	=	Relative Frequency +Relative Density + Relative Basal Area for a species

B. Analyses (Sample questions for you to consider).

1) How do the two landscape positions differ in total stem density and basal area? Do the two positions support the same amount of tree growth? If not, what factors might explain the difference? (Hint: Are they the same age? How does the difference in landscape position impact available light, water, or nutrients?)

2) Compare the ranking of the trees in the two landscape positions. Which species have the highest overall importance values at the two sites. Are they the same, or different? Do the species have the same ranking in density as in basal area? (Do the most numerous species have the highest basal area?)

Use references containing information on the growth requirements of the different tree species you identified and see if you can explain the observed species patterns. An excellent source of information is the Silvics of North America (Burns and Honkala 1990). It can be online in its full text version at the following web site: http://www.na.fs.fed.us/spfo/pubs/silvics_manual/table_of_contents.htm