Geological Society of America Fall 2009 Meeting, Portland, Oregon
Session No. 39 Sequential Photography
Historic Land-Cover Analysis of the Luckiamute River Basin, Central Oregon Coast Range: Preliminary Results
from the Earth Science Program for Undergraduate Research at Western Oregon University
1,
1
Ryan ,
2
Ian ,
3
E. ,
Taylor, Stephen B. Stanley,
MacNab,
Dutton, Bryan
(1) Earth and Physical Science Dept, Western Oregon University, Monmouth,
OR 97361, taylors@wou.edu, (2) Allied Waste, Inc., 29175 Coffin Butte Rd., Corvallis, OR, 97330, (3) Biology Dept, Western Oregon University
Figure 1. Location map of the Luckiamute Watershed, western Oregon.
2. INTRODUCTION
Mountainous watersheds are fundamental landscape elements that form
an important setting for local ecological interactions, human occupation, and
water resource development. Since 2001, the Luckiamute River basin (Ad =
815 sq. km) in the central Oregon Coast Range has been used as a natural
laboratory for undergraduate studies in surficial processes at Western Oregon
University (Figure 1). A significant portion of this research has focused on the
occurrence and spatial distribution of invasive plants (Taylor et al., 2007;
Taylor and Dutton, 2009). Plant distribution is a function of disturbance
patterns over time by geomorphic and anthropogenic processes, as they
affect soil substrate, species diversity, nutrient availability, canopy shading
Bridgeport
Reach
Western
Oregon
University
A. Comparative Site Summary - Cultivated Land
Hoskins Reach
%Cultivated Land
1936
2000
Helmick
Reach
Bridgeport* Reach
%Cultivated Land
77.2
67.2
Helmick Reach
%Cultivated Land
72.3
78.3
Soap Creek
%Cultivated Land
61.2
70.2
Luckiamute Landing
%Cultivated
79.6
76.4
55.0
68.7
B. Comparative Site Summary - Forest Cover
Luckiamute
Landing
Hoskins Reach
%Forest Cover
1936
2000
Soap
Creek
Bridgeport* Reach
%Forest Cover
22.8
32.8
Helmick Reach
%Forest Cover
27.7
21.7
Soap Creek %Forest Luckiamute Landing
Cover
%Forest Cover
38.8
29.8
20.4
23.6
41.1
29.3
C. Comparative Site Summary - Riparian Forest Buffer Width
A
Hoskins Reach
Riparian Forest
Buffer Width (m)
Hoskins
Reach
B
1936
2000
Bridgeport* Reach
Riparian Forest
Buffer Width (m)
76.0
74.5
Helmick Reach
Riparian Forest
Buffer Width (m)
248.9
104.6
Soap Creek Riparian Luckiamute Landing
Forest Buffer Width Riparian Forest
(m)
Buffer
Width (m)
486.3
253.1
151.4
215.5
382.3
211.1
D. Comparative Site Summary - Synopsis of Results
Figure 3. Locations of land-cover study reaches in the Luckiamute basin. Sequential
aerial photographs were collected at approximate decadal intervals for the following
flight years: 1936, 1948, 1955, 1963, 1970, 1990, and 2000. Study reaches are
color-coded to match those of tabulated results in Table 1.
1963 – Helmick Reach
+10% Forest Cover
< -1% Buffer Width
NET CANOPY GAIN
-6% Forest Cover
-9% Forest Cover
+3.2% Forest Cover
-42% Buffer Width
-52% Buffer Width
+142% Buffer Width
NET CANOPY LOSS NET CANOPY LOSS NET CANOPY GAIN
Total Land Area
Classified (sq. km)
1936
2000
Helmick Reach
Luckiamute Landing
-11.8% Forest Cover
-55.2% Buffer Width
NET CANOPY LOSS
Average Riparian
Forest Buffer
Width (m)
269.0
171.7
-63.9% Buffer Width
Average % Forest
Cover
% Cultivated Land
21.3
56.6
68.7
71.1
31.3
28.9
-2.4% Forest Cover
Figure 4. Example aerial photograph and land-cover classification sheme from the
Helmick reach site along the Luckiamute River. Archival photos were scanned at 600
dpi, georegistered, and orthorectified using an affine transformation. Land-cover
classes included: “Forest” – sparse, moderate, dense, and “No Canopy” – cultivated
land. The green arrow illustrates an example of the contiguous riparian forest buffer
width that was measured at 1 km increments along the channelway.
5. RESULTS
Significant differences were identified in land-cover patterns and forest
buffer widths amongst the five study sites (Table 1). Results for the 19362000 observation period are summarized as follows: (1) Hoskins reach: avg.
forest canopy area = 29%, avg. forest buffer width = 75 m, 10% increase in
forest cover, no change in riparian buffer width; (2) Bridgeport reach: avg.
forest canopy area = 25%, avg. forest buffer width = 177 m, 6% decrease in
forest cover, 42% decrease in riparian buffer width; (3) Helmick reach: avg.
forest canopy area = 33%, avg. forest buffer width = 310 m, 9% decrease in
forest cover, 52% decrease in riparian buffer width; (4) Soap Creek: avg.
forest canopy area = 22%, avg. forest buffer width = 183 m, 3 % increase in
forest cover, 142% increase in riparian buffer width; and (5) Luckiamute
Landing: avg. forest canopy area = 35.2%, avg. forest buffer width = 297 m,
12% decrease in forest cover, 55% decrease in riparian buffer width.
Pooling of most recent 2000 data for the five study sites (~57 sq. km
total) documents that the Luckiamute riparian zone currently averages 29%
forest cover, 71% cultivated land, and a riparian forest buffer width of 172 m.
The watershed as a whole, based on the 5-site tallies, has lost 2.4% of it’s
riparian forest canopy and 64% of the riparian buffer width since 1936. The
biggest loss is associated with the Luckiamute Landing site at the mouth of
the river, with ~12% canopy loss and 55% decrease in riparian buffer width.
The Hoskins site is located farthest up-basin and is associated with a net
increase in forest canopy, however, this reach is characterized by the
narrowest riparian buffer widths of the group (i.e. agricultural fields are
cultivated closest to the channel zone at this locality).
L.
La
nd
in
g
re
ek
C
So
ap
el
m
ic
k
19
36
20
00
0
0
19
36
20
00
19
36
20
00
10
19
36
20
00
10
19
36
20
00
20
19
36
20
00
20
19
36
20
00
30
k
ic
m
el
g
in
d
n
La
.
L
400
300
B
t
or
p
ge
rid
ap
o
S
200
100
H
ns
40
30
H
19
36
20
00
40
50
19
36
20
00
50
60
H
os
ki
60
rid
ge
po
rt
70
B
70
% Forest Cover
80
Riparian Forest Buffer Width (m)
Forest - Sparse
90
80
500
No Canopy
100
L.
La
nd
in
g
C
re
ek
So
ap
H
el
m
ic
k
po
rt
B
rid
ge
100
Forest - Dense
Soap Creek
*Bridgeport site data from 1944, earliest available, all others from 1936
90
Five riparian sites were selected for land-cover analysis: (1) “Hoskins
reach” (50-62 km upstream from mouth), (2) “Bridgeport reach” (45-47 km
upstream), (3) “Helmick reach” (15-30 km upstream), (4) “lower Soap Creek”
(13-15 km upstream), and (5) “Luckiamute Landing” (0-4 km upstream)
(Figure 3). Aerial photography was derived from state archival collection at
the University of Oregon. Photos were scanned at 600 dpi; georegistered
and orthorectified using the U.S. Geologic Survey 7.5-minute digital raster
graphics as a calibration base. Details of the rectification methodology are
provided by Stanley et al. (2009). The master stream channels were digitized
for each flight year, and a 500-m buffer created about the polylines to serve
as an observational window and bounding polygon. Land cover was
subsequently digitized by heads-up techniques and visual analysis of
orthophotographs. Landuse polygons were classified as either “forest
canopy” or “cultivated open land” (Figure 4). Percent coverages and percent
changes were measured for each time period. Riparian forest-buffer widths
were also measured at 1-km increments, transverse to channel reaches.
Bridgeport* Reach
E. Luckiamute Basin-Wide Averages (pooled 5-site data)
3. ENVIRONMENTAL SETTING
The Luckiamute River comprises a portion of the Willamette basin in
west-central Oregon (Figure 1). This seventh-order watershed (sensu
Strahler, 1957) drains eastward from the Coast Range into the Willamette
River and occupies a total drainage area of 815 km2. Land surface
elevations range from 46 m (150 ft) at the confluence with the Willamette
River to 1016 m (3333 ft) at Fanno Peak. The Luckiamute has an average
gradient of 3 m/km, a total stream length of 90.7 km, and an average basin
elevation of 277 m (910 ft) (Rhea, 1993; Slack et al., 1993).
The Coast Range portion of the Luckiamute watershed lies in the Tsuga
heterophylla Zone of Franklin and Dyrness (1988). Dominant forest species
include Pseudotsuga menziesii (Douglas fir), Tsuga heterophylla (western
hemlock), and Thuja plicata (western red cedar), with lesser occurrence of
Abies grandis (grand fir). These species formed part of the classic old
growth timber stands that were logged extensively in the Pacific Northwest
during the early 1900's. Lower reaches of the Luckiamute watershed lie in
agricultural crop and pasture land, with local patches of mixed Quercus
garryana (Oregon white oak) and urban mosaic species.
Since European settlement, the dominant economic activities in the
Willamette Valley have centered on agriculture in the lowlands and timber
harvesting in upland forests. Over the past several decades, industrialization
and rapid population growth have resulted in significant impact to the habitat
of the region. A large portion of the upper Luckiamute is owned by private
timber companies and 67% of the watershed classified as forest. In contrast,
the eastern valley section is comprised of a mix of agricultural lands (15% of
total), native vegetation (3%), and urban development (1%) (Urich and
Wentz, 1999). Upper-reach vegetation is comprised of 60% agricultural land
and 40% conifer-hardwood forest, and that of the lower is 85% cultivated and
15% hardwood. Primary commodities in the agricultural zones include grass
seed, wheat, hay, oats, and mixed crops (clover, sweet corn, mint, alfalfa,
filberts) (Wentz et al., 1998).
Hoskins Reach
H
os
ki
ns
Figure 2. A. Oblique aerial photograph overlooking a portion of the Luckiamute
Basin. Note agricultural landuse in lowlands and forestry management in the uplands.
B. Photo of the main stem of the Luckiamute River channel at Helmick reach.
4. METHODS
From Luckiamute Watershed Council
Table 1. Summary of Land-Cover Change Analysis for Luckiamute Basin (1936-2000).
19
36
20
00
Mountainous watersheds are fundamental landscape elements that form
an important setting for local ecological interactions, human occupation, and
water resource development. Since 2001, the Luckiamute River basin (Ad =
815 sq. km) in the central Oregon Coast Range has been used as a natural
laboratory for undergraduate studies in surficial processes at Western Oregon
University. This phase of the project presents preliminary results of land-cover
analysis using decadal scale, sequential aerial photography gathered over a
time span of 64 years (1936, 1948, 1955, 1963, 1970, 1990, 2000).
Total length of the Luckiamute main stem is ~91 km. Five riparian sites
were selected for land-cover analysis: (1) “Hoskins reach” (50-62 km
upstream from mouth), (2) “Bridgeport reach” (45-47 km upstream), (3)
“Helmick reach” (15-30 km upstream), (4) “lower Soap Creek” (13-15 km
upstream), and (5) “Luckiamute Landing” (0-4 km upstream). Upper reach
vegetation is comprised of 60% agricultural land and 40% conifer-hardwood
forest, and that of the lower is 85% cultivated and 15% hardwood. A set of
historic aerial photos were orthorectified and georegistered using GIS
techniques. River channels were digitized and 500-m buffers created to form
bounding riparian polygons. Land cover polygons were delineated and
classified as either “forest canopy” or “cultivated open land”. Percent areal
coverages and riparian forest buffer widths were measured for each time
period. Significant differences were identified in land-cover patterns between
the five study sites.
Results for the 1936-2000 observation period are summarized as follows:
(1) Hoskins reach: avg. forest canopy area = 29%, avg. forest buffer width =
75 m, 10% increase in forest cover, no change in riparian buffer width; (2)
Bridgeport reach: avg. forest canopy area = 25%, avg. forest buffer width =
177 m, 6% decrease in forest cover, 42% decrease in riparian buffer width;
(3) Helmick reach: avg. forest canopy area = 33%, avg. forest buffer width =
310 m, 9% decrease in forest cover, 52% decrease in riparian buffer width;
(4) Soap Creek: avg. forest canopy area = 22%, avg. forest buffer width =
183 m, 3 % increase in forest cover, 142% increase in riparian buffer width;
and (5) Luckiamute Landing: avg. forest canopy area = 35.2%, avg. forest
buffer width = 297 m, 12% decrease in forest cover, 55% decrease in riparian
buffer width. Pooling of most recent 2000 data for the five study sites (~57
sq. km total) documents that the Luckiamute riparian zone averages 29%
forest cover, 71% cultivated land, and a riparian forest buffer width of 172 m.
These data suggest that the lower reaches of the Luckiamute riparian
zone are experiencing significant deforestation as part of agricultural
practices. While the percent forest canopy in the Hoskins reach was
comparatively lower during most of the observation period, upland tree
farming and reforestation activities have maintained riparian tree cover in the
past 30 years. Results of this study have important implications for invasive
plant studies and watershed restoration planning.
(solar influx), and riparian hydrology (Pabst and Spies, 1998). Anthropogenic
disturbance in the Luckiamute basin is associated with rural residential
development, agricultural activities, and timber harvesting (Figure 2). This
phase of the project presents preliminary results of land-cover analysis using
decadal scale, sequential aerial photography gathered over a time span of
64 years (1936, 1948, 1955, 1963, 1970, 1990, 2000). Research objectives
include: (1) compiling set of historical aerial photographs for each sample
locality, and (2) documenting changes in historical land use. Land-use data
from this study will be used in future analyses to identify spatial associations
between invasive species and independent watershed variables.
% Cultivated Land
1. ABSTRACT
H
C
ek
re
ns
ki
s
o
0
36 00
19 20
36 00
19 20
36 00
19 20
36 00
19 20
36 00
19 20
Figure 5. Histograms illustrating historic changes in riparian land cover at the five
study sites in the Luckiamute Basin. Bar colors match those in Table 1 and Figure 3.
6. Discussion
Riparian forest zones in the Pacific Northwest are important for
watershed function and provide a wide range of ecosystem benefits,
including reduced channel erosion, canopy shading / reduced water
temperatures, wood recruitment sources, and aquatic habitat structure for
salmonid fisheries (Gregory et al., 1991). Maintenance of forest canopy is
also important with respect to plant species richness and limiting the
occurrence of invasives due to disturbed gap openings (Pabst and Spies,
1999).
The historic land-cover changes documented herein, suggest that the
lower reaches of the Luckiamute riparian zone are experiencing significant
deforestation as part of agricultural practices. While the percent forest
canopy in the Hoskins reach was comparatively lower during most of the
observation period, upland tree farming and reforestation activities have
maintained riparian cover in the past 30 years.
Ongoing habitat assessment work by local watershed councils, private
landowners, and Oregon State Parks suggests that salmonid fisheries are
significantly diminished in the Luckiamute basin. Invasive plant work by the
authors suggests a similar state of degradation with respect to native plant
populations. As such, results of this study have important implications for
watershed restoration planning. Any future work in the Luckiamute basin
should include riparian tree planting to increase both the canopy density and
to expand the width of the forest buffer zone perpendicular to channels.
7. CONCLUSION
Sequential photographic analysis of land-cover changes in the Luckiamute River basin suggests that the lower
reaches are experiencing significant deforestation in the riparian zone as part of agricultural practices. Forest canopy
area has diminished up to 12% and riparian buffer widths have decreased by 50% between 1930 and 2000. While the
percent forest canopy in the Hoskins reach (upper basin) was comparatively lower during most of the observation
period, upland tree farming and reforestation activities have maintained riparian cover over the past 30 years. Results of
this study have important implications for invasive plant studies and watershed planning. Any future restoration work in
the Luckiamute should include extensive riparian tree planting to reverse the historic trends.
Helmick
Survey
Sites
0.3
0.3
0
0.3
1936
0
0.3
8. ACKNOWLEDGMENTS
0.6 Kilometers
1955
Western Oregon University project participants include Katie Noll, Ian Macnab, Ryan Stanley, Steve Taylor, and
Bryan Dutton. Alicia Thompson assisted with graphical design and logistical support. Portions of this project were
funded by the College of Liberal Arts and Sciences and the Faculty Development Fund at WOU.
0.6 Kilometers
1948
9. REFERENCES CITED
200 0 200400 Meters
400
0
400 800 Meters
1963
Franklin, J.F., and Dyrness, C.T., 1988, Vegetation of Oregon and Washington, second edition: Oregon State Univ. Press, Corvallis, Oregon, 216 p.
100
Gregory, S.V., Swanson, F.J., McKee, W.A., Cummins, K.W., 1991, An ecosystem perspective of riparian zones: BioScience, v. 41, p. 540-551.
1956 Total Survey Area = 3.61 km2
90
400
0
400
800 Meters
Pabst, R.J., and Spies, T.A., 1998, Distribution of herbs and shrubs in relation to landform and canopy cover in riparian forests of coastal Oregon:
Canadian Journal of Botany, v. 76, p. 298-315.
% Land Cover Class
80
100
0
300
1936
Total Survey Area = 3.65 km2
600 Meters
100
90
2
1948 Total Survey Area = 5.88 km
90
80
70
60
50
300
40
30
% Land Cover Class
% Land Cover Class
80
0
70
60
Rhea S., 1993, Geomorphic observations of rivers in the Oregon Coast Range from a regional reconnaissance perspective: Geomorphology, v. 6, p.
135-150.
60
50
40
1963 Total Survey Area = 10.67 km2
30
90
20
80
300 600 Meters
50
10
40
0
No Forest
Canopy
30
20
Forest
Canopy
20
10
10
0
Forest
Canopy
60
Strahler, A.N., 1957, Quantitative analysis of watershed geomorphology: American Geophysical Union Transactions, v. 38, p. 913-920.
50
40
30
400 0 400 800 Meters
20
No Forest
Canopy
Forest
Canopy
Stanley, R., and Taylor, S.B., 2009, Land Cover Analysis Utilizing Geographic Information Systems and Historic Aerial Photography: A Case Study of
Riparian Zones in the Luckiamute River Basin, Central Oregon Coast Range: Abs. with Programs, Geological Society of America, v. 41, no. 7.
Riparian Buffer
Survey Area
70
0
No Forest
Canopy
Slack, J.R., Lumb, A.M., and Landwehr, J.M., 1993, Hydro-climatic data network (HCDN): Streamflow data set, 1874-1988: U.S. Geological Survey
Water Resources Investigations Report 93-4076, 85 p.
100
% Land Cover Class
300
70
10
1936
3.65 km2
1948
5.88 km2
1955
Swanson, F.J., Franklin, J.F., and Sedell, J.R., 1990, Landscape patterns, disturbance, and management in the Pacific Northwest, USA, Changing
landscapes: Springer-Verlag, p. 191-213.
Taylor, S.B. and Dutton, B.E., 2009, Invasive plant distribution in the Luckiamute River basin, central Oregon Coast Range: Preliminary analysis of
geomorphic and land-use variables: Association of American Geographers, Abstracts with Programs, National Meeting, Las Vegas, NV.
3.61 km2
0
No Forest
Canopy
Forest
Canopy
1963
10.67 km2
1970
10.66 km2
1990
14.53 km2
2000
Taylor, S.B., Dutton, B.E., Noll, K., and Pirot, R., 2007, Riparian Plant Distribution in the Luckiamute River Basin, Central Oregon Coast Range:
Preliminary Analysis of Geomorphic and Anthropogenic Controls on Adventive Species Propagation in an Unregulated Watershed: Geological
Society of America, Abstracts with Programs, v. 39, no. 6.
Urich, M.A., and Wentz, D.A., 1999, Environmental setting of the Willamette Basin, Oregon: U.S. Geological Survey Water-Resources Investigations
Report 97-4082-A, 20 p.
Wentz, D.A., Bonn, B.A., Carpenter, K.D., Hinkle, S.R., Janet, M.L., Rinella, F.A., Uhrich, M.A., Waite, I.R., Laenen, A., and Bencala, K.E., 1998, Water
quality in the Willamette Basin, Oregon, 1991-1995: U.S. Geological Survey Circular 1161, on line atURL:http://water.usgs.gov/pubs/ circ1161,
updated June 25, 1998.
16.69 km2
RESEARCH OBJECTIVES
• Compile set of historical aerial photographs for each sample locality
• Classify and document changes in
historical landuse
100
• Identify spatial associations between
1970 Total Survey Area = 10.66 km2
90
invasive species and land-use variables
70
60
1970
1990 Total Survey Area = 14.53 km2
90
80
70
60
50
2000
40
90
800
10
0
Forest
Canopy
800 1600 Meters
1
0
0
800
HELMICK REACH RESULTS
80
1600 Meters
70
60
45
50
40
30
20
10
1 km
0
No Forest
Canopy
400 0 400 800 Meters
500
50
Forest
Canopy
400
40
% Forest Cover
35
300
30
25
20
200
Riparian Buffer Width
15
100
10
5
Year
2000
Case Example: Sequential aerial photography and historic land-cover classification
of the Helmick reach study site, Luckiamute River, Oregon. Refer to Figure 3 for location map.
0
0
1990
400 0 400 800 Meters
Riparian Forest Buffer Width (m)
No Forest
Canopy
0
2000 Total Survey Area = 16.69 km2
30
20
800
100
1980
Forest
Canopy
• Scanning and digitization (600 dpi)
• Orthorectification and georegistration
• Landuse classification / vectorization
• Statistical analysis of land-cover change
100
1970
No Forest
Canopy
1994
1960
0
(sources: USGS, Farm Services Admin.)
1950
10
Helmick_landuse_1948.shp
Forest canopy-dense
Forest canopy-moderate
Forest canopy-sparse
No forest canopy-cultivated
No forest canopy-undifferentiate
1940
20
• Air photo acquisition from UO archives
1930
400 0 400 800 Meters
% Land Cover Class
40
30
METHODOLOGY
Percent Forest Canopy Cover
50
% Land Cover Class
% Land Cover Class
80