700 Road Ecological Thinning
Project, Cedar River Watershed
Rolf Gersonde, Silviculturist
Cedar River Municipal Watershed
Seattle Public Utilities – Cedar and Tolt
Municipal Watershed
Key Features of SPU-HCP (2000)
• Safe and secure water
supply
• 50-year term
• Ecological reserve
• Restoration
commitments
Bull trout
Common loon
Chinook
– Roads, streams,
riparian and upland
forests
Spotted owl
Forest Restoration Goals
• LSF Conditions
–
–
–
–
Tree size
Spatially clumped
Foliage height diversity
Decadence
• Ecosystem Functions
• Biological Diversity
• Ecosystem Resilience
700 Rd Project Location in the CRW
700 Road Ecological Thinning Project (2004)
Species:
WH, DF, RC, SF, RA
Structure:
65 year single cohort,
BA 210-360 sqft/ac
QMD 9.3” – 14.3”
SDI 400 - 620
Stakeholder involvement process
Comments at Ecological Thinning Workshop (7/18/2004)
•Prescriptions are too conservative. You should experiment with
thinning more heavily.
•Prescriptions not conservative enough – they should be limited to
never cutting any “big” trees.
•You don’t need to experiment. You can learn from what other
landowners have done.
•Second-growth forests created from clearcutting are on “natural”
trajectories and don’t need intervention.
•There is more wildlife in my back yard than I have seen in the
second growth in the watershed.
•You need to create openings to provide habitat diversity and
support wildlife.
•We need to know exactly how any money made from sale of trees
will be used.
Stakeholder involvement process
Summary of changes
•Reduce area to be ecologically thinned
•Reduce number of acres where trees will be yarded
•Create numerous variably-shaped small gaps and skips
•Create Unit E9 at the top of the ridge
•Add variable sized skips around existing unique habitat features
•Increase basal area targets
•Lower diameter limit for cutting
700 Road Ecological Thinning Project (2006)
Treatments:
230 ac. Thinning with
Skips and gaps
120 ac. Cut and Leave
Reserve areas
Structure type ratio by treatment unit
Structure Types 700 Rd Project by Unit
100%
80%
Gaps
60%
Trails
Skips
40%
Thin
20%
0%
E1
E2
E3
E4
E5
E6
E7
E8
E9
Scales of Variability
Thinning-pool spacing with skips and gaps
Unit E1a
700 Rd
Diameter distribution by species
Differentiation into crown and size classes
Thinning pool varies by species, create bimodal distribution
Pre-thin diam. distribution
80
70
RA
TPA
60
NF
50
SF
40
RC
30
DF
20
WH
10
0
2
4
6
8
10 12 14 16 18 20 22 24 26 28 30
DBH class
Example of thinning prescription (E1)
Structural Features
Large skip and gap
Thinned matrix
Conceptual layout of thinning Unit E6
Effect of canopy density on understory light environment
Stand Visualization
System
60
40
20
tRAYci Light Model
0
0
50
100
150
Distribution of light intensity at different
stand densities
25
BA 327
BA 250
BA 180
BA 120
BA 60
Frequency
20
15
10
5
0
0.0
0.1
0.2
0.3
Fraction of above canopy light
0.4
0.5
Wind Disturbance Regime
E2 - Live tree height distribution by DBH
140
Ave tree height (f
120
100
80
DF
60
RC
40
WH
70:1 line
20
0
4
6
8 10 12 14 16 18 20 22 24 26 28 30 32 34
1" diameter class
Topex: Jean-Claude Ruel, Steve Mitchell, and Naa Lanquaye-Opoku
Diameter increment (mm/10yrs)
Average crown diameter (feet)
Effect of tree position relative to gap edge
on diameter growth and average crown width
24
20
16
12
E dge
M a tr ix
40
30
20
10
0
E dge
Graph shows median and quartiles, data are taken from mature
Douglas-fir stand at CRMW; diameter increments are
significantly different at p=0.032; average crown width are
significantly different at p=0.0004.
M a tr ix
Diameter increment (mm/10yrs)
Disaggregated growth modeling in FVS
50
40
30
36.1
30.0
20
30.0
24.6
10
0
Aggregated
Skip
Matrix
Edge
Down wood volumes:
11% ground cover, 45 tons or 6000 bf/ac on 120 acres
80% of average “westside conifer-hardwood” forests
(Ohmann and Waddell 2002)
Contractual Issues
Surplus timber production
(2.5 mmbf) requires approval
from City Counsel (ordinance)
FSC Certification (2006)
Request for Proposal
Long-term relationship with
contractors
Operator Certification
A&R Cable Thinning
Forest Restoration Uncertainties
• Understory response
• Effect of CWD on
understory developement
• Proportion of structure
types
• Gap size/diversity
• Maintaining growth rates
• Disturbance interactions