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
Key Pieces of LWD (large woody debris) 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.
Key Pieces are defined by USFS as wood
pieces over 24" (approx. 60 cm) in diameter, measured 50
ft from the large end. 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 |
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