By Bill Stewart, Co-Director, UC Center for Forestry, originally published at http://www.calforests.org/what-twenty-years-of-concerted-public-safety-oriented-forestry-looks-like/ on September 13, 2013
The 2013 Rim Fire that burned across large areas of the Stanislaus National Forest and Yosemite National Park brought national attention to the issue of how to increase the resiliency of forests to survive wildfires. There is considerable well-documented evidence that fuels are no longer limiting fires in the Western US and that they are getting larger and more expensive to manage (e.g. Miller et al. 2009, Miller et al. 2011). For example, a recent analysis concluded that “the percentage of high-severity fire in conifer-dominated forests was generally higher in areas dominated by smaller-diameter trees than in areas with larger-diameter trees.” (Miller et al. 2011). There is also considerable evidence that treatments that preferentially take out the smaller diameter trees (‘thin from below’) and focus on trees with signs of incipient mortality can significantly reduce the fire risk while still preserving most of the ecological characteristics of large tree dominated stands (e.g. Stephens et al. 2009, Moghaddas et al. 2010, Stephens et al. 2012a, Stephens et al. 2012b, Stephens et al. 2012c). In plain English, there is too much kindling in our forests and reducing fuel levels can extend the lifetimes of the big trees in forest stands.
While federal agencies often depend on prescribed fire and light thinning to increase fire resiliency, private and public land managers who produce sawlogs destined for renewable building products are interested in a wider range of approaches. Burning up trees that could have provided sustainable building products, renewable energy, and sufficient revenue to cover management costs is not a scenario favored by most forest landowners. Often lost in the discussion of the impact of the Rim Fire in Yosemite National Park is the opportunity to integrate fire risk reduction with sustainable and profitable forest management.
From our surveys of family forest owners we know that half of forest landowners want to do vegetation management to reduce fire risk (Ferranto et al. 2012). They want to work together with their neighbors and local fire districts. We noted that most of these landowners also value environmental attributes such as fish and wildlife habitats, native plants, and aesthetics in addition to the revenue generating potential of their lands. However, most of these owners are wary of using prescribed fire by itself or in combination with thinning treatments. Not surprisingly, landowners are also averse to losing money on any major resource management activity. They often reinvest timber revenues to reduce risks in areas but they will rarely borrow money from other assets they have and invest in fire risk reduction (Stewart et al. 2012, Stewart and Nakamura 2012).
The 4,270 acre Blodgett Forest Research Station is owned by the University of California and is managed to demonstrate the full range of management approaches that can be used by forest land managers and owners to accomplish their unique goals. We have worked hard to make the results on a wide variety of forest related themes available on our web sites, through publications, and with field trips for landowners, professionals and other interested parties. At Blodgett, one project that always gets considerable attention on field trips is our twenty year effort to create a fire resilient corridor into the office and residential area within the Blodgett Forest Research Station.
Figure 1: Blodgett manager Rob York explaining how the treatments to create the more open stand on the right reduced fire risk and still maintained a fast growing stand. The denser stand to the left of this photo has not been managed since it grew back a century ago.
Following extensive logging with railroads and steam engines from 1900 to 1933, the young stands at Blodgett were compartmentalized and assigned to a wide range of even-aged, uneven-aged, and reserve management. Harvest activity on the regenerating forest began in earnest in 1962 and has continued annually to the present. The wide range of treatments applied consistently over time, coupled with comprehensive permanent plots established beginning in 1974 has enabled the longest available empirical assessment of diverse forest management impacts and tradeoffs in productive forests of the Sierra Nevada.
An ever present challenge is the fact that in the high fire season we house up to 45 researchers in the middle of our forest. In the mid 90’s, we recognized the risk of having 45 non-fire fighters in the middle of a dense forest is risky and decided that public safety must trump research goals around the buildings and along the access road. We used a combination of commercial harvests coupled with surface fuel treatments and have now thinned these stands from below (keeping the large health trees) three times. Our detailed inventory data shows that we have been able to maintain high growth rates, large average tree size, high biomass volume per acre, and good separation between the crowns of the large trees. This will allow us to successfully evacuate if a wildfire ever swept through.
The comparison of the 1993 aerial view and the 2012 aerial view after three harvests clearly shows the four historical images with the project unit outlined in white at the end of this document show the progression of the fuelbreaks in between our other research treatments.
Figure 2: 1993 aerial view of Blodgett Forest and the main entrance road
Figure 3: 2012 aerial view of the fuel reduction corridor along the entrance road
From our detailed records of the forest conditions as well as what we harvested, we know that these treatments have paid for themselves. Even with a only 40, and now 30 large trees per acre, these stands are still capturing much of the growth potential as the large and healthy trees continue to put on girth and height.
Lessons
While Blodgett was able to design the fuel breaks under a larger timber harvest plan (THP) that covered many other units, other landowners could be dissuaded from undertaking this public safety oriented actions due to the complexity of filing for a full blown THP. State and federal agencies often spend $500 to $1,500 per acre to reduce fire risks, but public funds are scarce and the task is large. Much greater sums can be spent putting out fires. As a public policy, making it easier for forest landowners to invest their own revenue in risk reduction and improving the quality of their stands to get larger trees, better habitat, and protected water quality makes sense.