| Landscape-level Planning |
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Computer model, constructed using the FARSITE fire modeling program, that shows how rate of fire spread slows in landscapes that have been partly treated for fire reduction. The box at the upper left shows how a fire spreads in an untreated landscape. The remaining three boxes show how the rate of spread is slowed when the landscape is treated with (b) continuous strips; (c) discontinuous, staggered strips; and (d) slanted, overlapping strips. In each case 19 percent of the landscape is treated. Figure 9 from Finney 2001. Across southwestern forests, many acres are in need of restoration. But the money and resources needed to treat them are limited. Where should we begin? The greatest single threat to the continued integrity of southwestern ponderosa pine forests—and to the people who live in them—is unnaturally intense fire, especially stand-replacing crown fire. For that reason, it makes sense to make reducing this threat our top priority. How, then, should the placement of treatments be planned in order to reduce fire risks? Some tools have been developed that can help managers in deciding where to place treatments for maximum fire protection. A study by Mark Finney of the Forest Service Fire Sciences Laboratory has found that implementing small, randomly placed fire-reduction treatments across 20 percent of the landscape has almost no effect on the spread rate of a large fire (Finney 2001). Implementing small but strategic treatments that complement one another across 20 percent of the landscape, on the other hand, can halve the spread rate (see illustration). Managers should plan such treatments to take into account topography, prevailing winds, and other factors. Placing treatment areas in patches across the landscape also aligns well with the needs of many wildlife species. A recent study by Norris Dodd of the Arizona Game and Fish Department shows that Abert’s squirrels find optimal habitat conditions where a mix of dense and open forest stands exists (Dodd 2003). Dodd suggests that restoring patches totaling a third of the landscape to an open condition, leaving a third in fairly dense stands, and treating the remaining third to achieve an intermediate density could benefit squirrel populations—and Finney’s work suggests that this level of restoration effort, if well planned, could also greatly reduce fire risks. The ForestERA project at Northern Arizona University also uses modeling tools to plan where treatments should be placed. This model can take into account a wide variety of ecosystem attributes, such as the locations of old-growth stands, habitat of such species as Abert’s squirrels and northern goshawks, and fuel loading. Such information, when mapped, can help managers decide where the highest-priority areas for treatment might lie. References:
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