Habitat connectivity on the Sierra Nevada

By Steve Benner, Forest Issues Group

 

The checkerboard problem has been a concern of mine personally for several years. The Forest Issues Group has recently prioritized the problem as fundamental to our interest in encouraging good management of the Forest. Our concern, bottom line, involves the potential for a breakdown of the Sierra Nevada Ecosystem.

 

The ownership problem is not a new issue for the Forest Service, which has been working around the checkerboard for years. We've seen concern expressed by the Forest Service over the last five or ten years, and I recall talking about this problem with agency employees 15 or 20 years ago. Also the area we're talking about has been recognized as problematic by the Forest Service and been designated an area of concern for California spotted owl management based on ownership fragmentation. And the problem has influenced the allocation map for the Framework amendment.

 

It's an ongoing problem that's making management more frustrating as resources on the private fragments are depleted, and options for integrated landscape management disappear with each passing harvest season. We now have additional reasons to be concerned.

 

Jerry Bloom and I have been mapping SPI projects in the checkerboard areas of the Tahoe National Forest for the Forest Issues Group. As this map develops, the group has noticed a recent infilling of private squares with treatment polygons, indicating conversion of these sections from their present habitat status, and resulting in a reduction of management options.

 

I will talk more about this later, but first here's a brief analogy. It has to do with the unraveling of complex systems.

 

When I worked for CalTrans, plowing snow around Tahoe and Truckee, there was often a point during a heavy snowstorm when the cry went out "if we don't get on it we're going to lose the road". Losing the road, whether it was a small county road or highway 80, was like a symbol of failed strategy. In the rare case that the strategy actually failed during a heavy snowfall and the system broke down, there was a trigger incident: a plow truck lost traction, one piece of road shut down, an accident tied up a lane, or a blower broke down.  Just a minor event in the midst of a heavy snow, but it ramified through the system in a chain reaction so in maybe 30 minutes it was clear that the road was lost.

 

No one can predict such a stochastic event, the point at which a system goes off into the weeds and results in personal or societal woe, and it's probably foolish to try. On the other hand, if we're watching the system and see signs of malfunction, we should feel a responsibility to take a closer look and to begin to talk about appropriate remedies.

 

Again, we're not presenting this information as a Forest Issues Group original. (In fact, the Forest Service has begun to record the removal of California spotted owl habitat through private actions in the Biological Evaluation for at least one Forest Service action, the Washington Fuels Reduction project.) Our contribution to the equation is only to suggest that the level of urgency may now be high, and the time for action ripe.

 

Accordingly we have identified through our mapping effort three SPI THP's that are currently in the approval stage by CDF. They are called Scraps, Cavemen, and Jackson. We have developed comments on these plans identifying the potential for them to contribute to the degradation the Sierra Nevada ecosystem. Could these 3 projects trigger a breakdown of the system? If not, where should the line be drawn, if at all?

 

The Forest Issues Group suggests that present habitat fragmentation on the Tahoe National Forest, together with the potential for further habitat degradation from logging, and the additional barrier imposed by the I-80 corridor, represents a risk to the integrity of the Sierra Nevada Ecosystem.

 

Fragmentation on a section-wide scale and the resulting loss of management options on public lands, we submit, could result in a splitting into two isolated populations of dependant species to the north and south of the Tahoe. Species affected by the checkerboard problem might include:

 

Species affected by the I-80 barrier might include all of the above species plus small rodents. Species such as small rodents with smaller territorial extents (i.e. higher population density) will of course have much higher remnant populations, with accordingly lower loss of genetic diversity.

 

As we know there is plenty of evidence, based largely on MacArthur and Wilson's theory of island biogeography and Brown's application of the theory to topographic isolation, that population fitness is directly proportional to the genetic diversity of the population. Loss of half of its gene pool would likely lead to inbreeding depression especially in a population of mustelids (e.g. skunk, wolverine, badger, weasel, ferret, fisher, mink, marten), species with typically low natural genetic diversity. Reduced population fitness results from a loss of heterozygosity and the resulting reduction in the population's ability to adapt to stochastic environmental stress.

 

In short, we submit, current adverse conditions on the Tahoe could lead to a sudden and drastic decrease in genetic diversity in the isolated populations north and south of the Tahoe, and a resulting decrease in the ability over time of these populations to response to increased or novel environmental stress.

 

It should be made clear that we are not presuming that this effect already exists. Nor do we offer evidence to support such a presumption. But it's equally clear that, by the time hard evidence of a fractured ecosystem does develop, it may be too late for practical remediation. What we hope to initiate at this time is the opening of a dialog between interested parties to address the checkerboard problem on the Tahoe.

 

We suggest the following preliminary actions:

 

1. Take a quiet moment and visualize the Sierra Nevada Range as an integrated ecosystem. Imagine that the range 1) generally defines the extent of all forest planning, and that it 2) specifically provides the framework for cumulative impacts for a set of species dependent on the forests of the range.

 

2. Assess the seriousness of the checkerboard problem. Utilize informal communication between  the Forest Service and some outside experts like Jared Verner, Reed Noss, Peter Brussard, Michael Soule, Michael Gilpin, Reginald Barrett, Michael Barbour, Dennis Murphy, Dick Tracy, Paul Ehrlich, Don Ehrman and/or others to establish an informal consensus on the significance of the problem and whether to proceed with further action. Topics to address would include:

a)     Current and foreseeable impacts resulting from the ownership pattern -  Ongoing disappearance of management options.

b)     Difference in management philosophy of interlocked owners -  Even versus uneven-aged management.

c)      Difficulties, caused by the ownership pattern, in assessing cumulative impacts.

d)     Current status of impacted species - California spotted owl, Fisher.

e)     Possibility of quantifying current state of isolation by genetic analysis of fishers -  Marten.

f)        Ecosystem isolation in other mountain areas.

i. Browns work in Nevada

ii.Brussard's students work in Carson Range.

 

3. Prioritize the problem according to the results of the consensus. This appears to be the natural entry point for the Forest Service.

 

4. If we are determined to resolve the problem there are many ways to proceed. But the basic goal should be the establishment of a collaborative structure between the Forest Service, SPI, and CDF, and protocols for management of the interlocked parcels.

a)     Work it into the Forest Plan

b)     Utilize EMDS. The Forest Issues Group might be able to help with this.

c)      Utilize the concept of habitat easements, rather than exchange or purchase.

d)     Assess the extent of the remaining California spotted owl habitat and draw durable polygons that ensure the Tahoe's contribution to ecosystem-wide protection for the species. Use these polygons as anchors for a Forest-wide cross-ownership matrix between polygons adapted from the 50-11-40 rule proposed by Jack Ward Thomas for the Northern Spotted Owl. This is another effort to which EMDS and the Forest Issues Group might be able to contribute.

 

5. Consult with CalTrans about the use of wildlife overpasses over the I-80 corridor.

 

The following are some tools to utilize:

 

 

Steve Benner

Forest Issues Group