Appendix I - CWHR Assessment
APPENDIX I
CALIFORNIA WILDLIFE HABITAT RELATIONSHIPS (CWHR) ASSESSMENT OF UNTHINNED HABITATS AND CREATION OF SMALL GROUP OPENINGS AND DEFENSIBLE FUEL PROFILE ZONES (DFPZ'S)

The CWHR System and Assumptions of the Model

The CWHR system includes habitat relationships models for over 600 wildlife species in California. CWHR was designed as a planning tool to predict wildlife species communities, habitat suitabilities, and differences in habitat values between two situations for geographic locations and habitats in California. The system provides species' habitat suitability ratings for feeding, cover, and foraging in varying habitat types and seral stages. These suitability ratings are converted to numeric values, and the three values are averaged to calculate overall habitat values for each habitat type and seral stage for particular species. The CWHR system can be used to predict differences in habitat values between two habitat conditions, and can indicate which species may be negatively or positively affected, based on differences in habitat values between the two habitat conditions. Numerical values used in the system are: 1.0 (high suitability, optimal for species occurrence); 0.66 (moderate suitability, suitable for species occurrence, can support moderate population densities at moderate frequencies); 0.33 (low suitability, marginal for species occurrence, can support relatively low population densities at low frequencies); 0.00 (unsuitable for species occurrence). Specific assumptions of the models are:

1. Habitat ratings reflect values for only that species.
2. Habitats for species that require juxtaposition of two or more habitats were individually rated as if the other habitats were available in the proper mix.
3. Ratings were developed assuming that all special habitat elements were present in adequate amounts if they are typical components of the habitat.
4. Habitats were rated assuming that adequate habitat amounts and patch sizes exist.
To assess potential effects of proposed treatments (group selection and creation of DFPZ's) on a wide range of species, required the running of several queries using the California Wildlife Habitat Relationships (CWHR) system database. The species list for the analysis area was generated using the CWHR system to identify species and their habitats potentially affected by project activities. Results below include a summary of effects to all species identified as potentially present in the area, Threatened, Endangered, and Sensitive (TES) species, prey species of TES species, Management Indicator Species (MIS), and species identified in the SNEP report as definitely declining or likely declining. To determine potential significance of decreases or increases in habitat values that the model indicated, the estimate of significance occurred when a change in habitat value resulted in a change in habitat ratings class (such as a change from Moderate suitability to High suitability). Numerical categories for the habitat ratings were those used by Garrison (1994): greater than or equal to 0.67 (High); 0.34-0.66 (Moderate); and less than or equal to 0.33 (Low). Therefore, a change in estimated habitat value from 0.50 to 0.70 would indicate a change in ratings from Moderate to High suitability.

Defensible Fuel Profile Zones (DFPZ's)

The first query using the CWHR system compared habitat values of unthinned stands to thinned stands, as a means of predicting potential effects which may result from creation of linear or area DFPZ's (Table I-1). Habitat types for this assessment included Sierran mixed-conifer, red fir, and eastside pine. Seral stages used for Condition 1 ("pre-harvest") for each habitat type were M (40-59 percent canopy closure) and D (60-100 percent canopy closure). Seral stages used for Condition 2 ("post-harvest") were P (25-39 percent canopy closure) and M. Several assumptions were made. One was that thinning to create DFPZ's would reduce a D seral stage to an M, and an M seral stage would be reduced to a P. The second was that if thinning took place in an S (10-24 percent canopy closure) or P seral stage, the post-harvest stand would retain the same canopy closure designation. The last assumption was that all habitat elements (such as snags and downed logs) would be present in both pre- and post-harvest conditions. Therefore, predicted changes in habitat values were based entirely upon the reduction of canopy closures.

Results indicate that 247 species of wildlife would be affected the reduction of canopy closures. Of these, 65 had declining trends in habitat values, 40 had no change in habitat values, and 142 had increasing trends in habitat values. Results are summarized below for species of concern. The one TES species which had a reduction (high to moderate) in the estimated habitat ratings class was northern goshawk.

The two MIS species which had an increase (moderate to high) in estimated habitat ratings class were mule deer and mountain quail.

The TES prey species which had a decrease in estimated habitat ratings class were Douglas' squirrel and northern flying squirrel (high to moderate). The TES prey species which had an increase in estimated habitat ratings class were golden-mantled ground squirrel, dusky-footed woodrat, yellow-pine chipmunk, deer mouse, porcupine, and quail (all moderate to high).

The SNEP report listed 18 species of birds as being either definitely or likely declining in the Sierras. One of the six avian species considered to be definitely declining, and which had an increase in estimated habitat ratings class, was red-breasted sapsucker (moderate to high). Two of the twelve likely declining species had an increase in estimated ratings class, dark-eyed junco (moderate to high) and brown-headed cowbird (low to moderate). Swainson's thrush, another species identified as likely declining in the SNEP report, exhibited a decrease (moderate to low) in estimated ratings class.

Table I-1. Two Condition Habitat Value Comparison of Unthinned Stand vs. DFPZ
# Species w/ Decreasing Habitat
Values
# Species w/ Decreased
Ratings Class
# Species w/ Increasing Habitat
Values
# Species w/ Increased
Ratings Class
No 
change
in habitat
values or ratings
TES
7
1
5
0
5
MIS
4
0
9
2
0
TES Prey Species 
7
2
14
5
4
SNEP Definitely Declining Bird Species
2
0
4
1
0
SNEP Likely
Declining
Bird Species
5
1
5
2
1

Group Selection

The second query using the CWHR system was designed to predict changes in habitat values that may result from implementing group selection. Habitat types for this assessment included Sierran mixed-conifer, red fir, and eastside pine. Seral stages used for Condition 1 ("pre-harvest") for each habitat type were M (40-59 percent canopy closure) and D (60-100 percent canopy closure). Seral stages used for Condition 2 ("post-harvest") were S (10-29 percent canopy closure) and WHR size class 1, Seedling shrub (seedlings or sprouts less than 3 years). In this query, acknowledging the upper diameter limits that would exist in a group selection prescription (see CASPO), it was assumed that up to ten trees/acre could be left in a group selection. The last assumption was that all habitat elements (such as snags and downed logs) would be present in both pre- and post-harvest conditions. Therefore, predicted changes in habitat values were based entirely upon the reduction of canopy closures and conversion to size class 1.

Results indicate that 257 species of wildlife would be affected the reduction of canopy closures. Of these, 83 had declining trends in habitat values, 38 had no change in habitat values, and 136 had increasing trends in habitat values. Results are summarized below for species of concern.

The four TES species which had a reduction in the estimated habitat ratings class were northern goshawk (high to moderate), California spotted owl, American marten, and Pacific fisher (all moderate to low).

The two MIS species which had an increase (moderate to high) in estimated habitat ratings class were hairy woodpecker and mountain quail. The one MIS species that showed a decrease in the estimated habitat ratings class was osprey (moderate to low).

The TES prey species which had an increase in estimated habitat ratings class were golden-mantled ground squirrel, dusky-footed woodrat, and deer mouse (all moderate to high), and northern pocket gopher, montane vole, mountain pocket gopher, and brush rabbit (all low to moderate). Species that exhibited a decrease in estimated habitat ratings class were Douglas' squirrel, Steller's jay, and northern flying squirrel (all high to moderate).

One avian species considered to be definitely declining in the SNEP report (Graber 1996) and which had an increase in estimated habitat ratings class was red-breasted sapsucker (moderate to high). Three likely declining species which had an increase in estimated ratings class were Steller's jay (high to moderate), dark-eyed junco (moderate to high), and brown-headed cowbird, and house finch (both low to moderate). Three species identified as likely declining in the SNEP report, and which exhibited a decrease in estimated ratings class were golden-crowned kinglet (high to moderate), and Swainson's thrush and black-headed grosbeak (both moderate to low).

Table I-2. Two Condition Habitat Value Comparison of Unthinned Stand vs. Group Selection
# Speciesw/ Decreasing Habitat
Values
# Speciesw/ Decreased Ratings Class
# Species w/ Increasing Habitat
Values
# Speciesw/ Increased
Ratings Class
No change
in habitat
values or ratings
TES
6
4
5
0
6
MIS 
6
1
7
2
0
TES Prey 
Species 
9
5
15
7
1
SNEP Definitely Declining Bird Species
2
0
4
1
0
SNEP Likely
Declining
Bird Species
6
4
5
3
0

References

California Wildlife Habitat Relationships Program. 1997. Version 6.0, California Department of Fish and Game, Sacramento, CA.

Garrison, Barry. 1994. Determining the biological significance of changes in predicted habitat values from the California Wildlife Habitat Relationships System. Calif. Fish and Game 80 (4):150-160.

SNEP, Graber 1996

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