SNFPA Draft Supplemental Environmental Impact Statement

June 2003

Chapter 3: Affected Environment

3.2.2. Forest Service Sensitive Species

3.2.2.1. Fisher (Martes pennanti)

This section updates and supplements the information found in the FEIS in Volume 3, Chapter 4, Part 4.3, pp. 2-6.

Scientific literature pertinent to management of Pacific fisher was reviewed to ensure that the best available information was used in determining effects of the proposed revisions in standards and guidelines for the Sierra Forest Plan Amendment (SNFPA).

The SNFPA described the Desired Future Condition for the Southern Sierra Fisher Conservation area (SSFCA) (ROD pg 8) as . . . "Within each watershed, a minimum of 50% of the mature forested area is at least foraging quality fisher habitat [presumed to be 40% canopy closure or better] and at least an additional 20% is resting or denning quality habitat [presumed to be 60% canopy closure]." Forest Carnivore Den sites (ROD pg 10) desired condition included . . . at least two large (>40"dbh) conifers/ac. and one or more oaks (> 20" dbh). Canopy closure exceeds 80%." The guidelines for the Southern Sierra Fisher Conservation Area (ROD, Appendix A, A-45) direct the Forests to retain 60 % of each planning watershed in CWHR size class 4 or greater and canopy cover greater or equal to 60 percent. There was also a discrepancy in the description of the Southern Fisher Conservation Area described as 3,500' (ROD pg 4) and 4,500' (ROD A-45).

Ongoing research by various scientists has either clarified a number of lingering questions regarding the uncertainty of fisher habitat characteristics or brought forth new information on the biology of the species.

Zielinski et. al, (in prep), found fisher home ranges selected for higher canopy closure than the surrounding area and averaged 66% in canopy closure greater than 60% ( range 53% - 84 total, 40-71% for males and 61-81% for females) but percent of the landscape in 60% canopy closure at the watershed scale was less. Analysis for the Giant Sequoia National Monument indicate only one watershed out of 46 meets the 60% canopy closure guideline despite a relatively high density of fisher in areas surveyed. This is also true of the Kern Plateau, which is considerably drier and more open. Mazzoni et. al (2002) as cited in the forest carnivore working group notes noted fisher home ranges in the Kings River Demonstration Project averaged 43% of the area with 60% canopy cover and 47% of the area when hardwoods were added to the calculation of cover class. Self & Kerns (2002) indicated that fisher in NW California selected areas with canopy closure greater than 60% for rest sites over 60% of the time but that the study area had only 50% of the area in canopy closure greater than 40%. Self and Kerns (2002) noted that rest sites were selected for high canopy closure (generally > 60%) but they were often .1-2 acre clumps within a stand classified as P (25-40% canopy closure).

Truex (presentation to TWS) noted that models based on canopy closure, large trees and other habitat elements accurately described use of habitat by the Tule River subpopulation. Habitat use by fisher on the Sierra National Forest was significantly below predicted levels based on habitat modeling. Since initial survey efforts in the early 1990's met with little success while more current survey efforts have shown greater success, there is some speculation that the Sequoia population is dispersing northward. This is somewhat supported by lower success or detection rates despite suitable habitat along a northward gradient through the sierra National Forest. Habitat modeling on the Kern Plateau underestimated population density in an area with drier, more open habitat. Self and Kerns also showed greater habitat use that would be predicted in open habitats where legacy elements and patches of dense habitat provided suitable rest sites.

There is a fair range in percentage of the landscape in dense canopy closure where occupancy by fisher is still supported. The southern Sierra site appears to have the highest density/ smallest female home range. This may be an indicator of higher quality habitat and as such present conditions reflecting a better long term objective or goal but as acknowledged in Zielinski et al (in prep) the majority of the stands were in small to intermediate trees (CWHR size class 4, 11-24" dbh) with a high vulnerability to stand replacing fire. As such, managing for high densities of small to medium trees at mid slope is likely to be a prescription for disaster, both for fisher and surrounding communities, due to high susceptibility to stand replacing wildfire. Both Zielinski et al (in prep) and Self and Kerns (2002) noted a high use of stands in the intermediate size class (CWHR 4), but in each study, the trees actually used were among the largest available. As such, management for stands of larger trees or highly variable stands with clumps of denser vegetation focused around large trees, may provide lower vulnerability to stand replacing fire while meeting fisher habitat needs over the long term.

Zielinski et al (in prep) noted fisher in the Tule River Study site at 3,200' and Mazzoni (2002) noted fisher in the Kings River Demo Project down to 3,600' but habitat at that elevation varies considerably north to south, by aspect and landform. For the most part the woodland and forest communities frequented by fisher on the Sequoia begin at an elevation of approximately 4,000-5,000 feet, rising north to south. Fisher have been documented in chaparral but at a very low rate compared to woodland and forest. They also have been documented in red fir above 8,000 feet.

USDA Forest Service · Pacific Southwest Region