We obtained tabular stream inventory
data from the
U.S. Forest
Service Region 6 office. We used lookup functions, pivot
tables and conditional formulas in Excel to manipulate these
data and produce average values for each aquatic habitat
parameter for each 6th field. We then joined the table of
average values to the
6th
field GIS layer, allowing us to color code 6th fields
by average aquatic habitat characteristics. The numeric
value shown in each 6th field is the "survey extent", calculated
by dividing the total length of streams surveyed by USFS
Region 6 in each 6th field by the length of streams mapped
in the
1:100k streams
coverage. Due to the limited number of streams shown in
the 1:100k layer, this value may be more than 100%.
The colors show the average number of
LWD (large woody debris) pieces per 100m of stream length,
by 6th field. You could change the ranges used to color
code the 6th fields, to bring out differences in a particular
portion of the study area.
USFS defines Large Woody Debris as any
wood over 12" in diameter, measured 25 feet from the large
end. The USFS stream inventory methods are different from
the ODFW aquatic habitat inventory methods, so the two datasets
must be interpreted separately and can not be presented
in the same image. Also, USFS data should not be analyzed
using the ODFW habitat benchmarks, because the distribution
of the data is different (see frequency charts).
Please address questions or comments
to:
Dr. Ralph Garono
Principal Investigator
Earth Design Consultants, Inc.
rgarono@earthdesign.com
Laura Brophy
Principal Investigator
Green Point Consulting
brophyl@peak.org |
homepage 
