Abstract:
Forest and wildlife habitat analyses were conducted
at the H.J. Andrews Experimental Forest in the Central
Cascade Mountains of Oregon using remotely sensed data and
a geographic information system (GIS). Landsat Thematic
Mapper(TM) data were used to determine forest successional
stages, and to analyze the structure of both old and young
conifer forests. Two successional stage maps were
developed. One was developed from six TM spectral bands
alone, and the second was developed from six TM spectral
bands and a relative sun incidence band. Including the
sun incidence band in the classification improved the
mapping accuracy in the two youngest successional stages,
but did not improve overall accuracy or accuracy of the
two oldest successional stages. Mean spectral values for
old-growth and mature stands were compared in seven TM
bands and seven band transformations. Differences between
mature and old-growth successional stages were greatest
for the band ratio of TM 4/5 (P = 0.00005) and the
multiband transformation of wetness (P = 0.00003). The
age of young conifer stands had the highest correlation to
TM 4/5 values (r = 0.9559) of any of the TM band or band
transformations used. TM 4/5 ratio values of poorly
regenerated conifer stands were significantly different
from well regenerated conifer stands after age 15
(P = 0.0000). TM 4/5 was named a "Successional Stage
Index" (SSI) because of its ability to distinguish forest
successional stages.
The forest successional stage map was used as input
into a vertebrate richness model using GIS. The three
variables of 1) successional stage, 2) elevation, and 3)
site moisture were used in the GIS to predict the spatial
occurrence of small mammal, amphibian, and reptile species
based on primary and secondary habitat requirements.
These occurrence or habitat maps were overlayed to tally
the predicted number of vertebrate at any given point in
the study area. Overall, sixty-three and sixty-seven
percent of the model predictions for vertebrate occurrence
matched the vertebrates that were trapped in the field in
eight forested stands. Of the three model variables, site
moisture appeared to have the greatest influence on the
pattern of high vertebrate richness in all vertebrate
classes.
