Saturday, May 8, 2010

SPLAT-related thesis completed

Nicole Vaillant completed her Ph.D. thesis at Sagehen in 2008: Sagehen Experimental Forest Past, Present, and Future: An Evaluation of the Fireshed Assessment Process.

The study evaluates the Sagehen basin fire history, uses high resolution aerial laser mapping & an extensive dataset of actual fuel & vegetation measurements at hundreds of sites in the basin to compare fire models, & evaluates different possible SPLAT treatments. Strategically Placed Land Area Treatments (SPLATs) are a way of restructuring the forest to interrupt fire behavior, restore resiliency & more closely approximate natural forest structure.

Here's an excerpt from the thesis introduction:

"The first chapter investigates the past through a fire history reconstruction of lower elevation Jeffrey pine (Pinus jeffreyi) and Jeffrey pine – mixed conifer stands within Sagehen. Using fire perimeter maps and dendrochronology, the historic fire regime (frequency and seasonality) was determined. This chapter explores the influence of Native American land use practices, Comstock Era logging, fire suppression and climate indices (Pacific Decadal Oscillation and the Palmer Drought Severity Index) on the fire regime at Sagehen.

The second chapter focuses on the present comparing three geographic information system (GIS) data sets utilized in the fireshed assessment process available for Sagehen. Eight GIS data layers are required to model fire behavior in FlamMap (Finney 2006), a landscape-level fire behavior and propagation model. The eight layers required include: elevation, slope, aspect, canopy cover, canopy base height, canopy height, canopy bulk density and fuel model. The three GIS data sets being compared in this chapter included:
1) data created using LiDAR and plot information for Sagehen,
2) pre-existing Landscape Fire and Resource Management Planning Tools Project (Landfire) data (Ryan et al. 2006), and
3) pre-existing Tahoe National Forest Stewardship and Fireshed Assessment data (Bahro et al. 2007).

The three GIS data sets were evaluated against the extensive grid of fuel and vegetation plots to test the correlation of canopy cover, fuel model, canopy base height, canopy height and canopy bulk density to current conditions. Modeled fire behavior metrics (fire type, flame length and fireline intensity) were compared between the three GIS data sets to better understand the implications of different source data on management decisions made during the fireshed assessment process.

The third chapter will again concentrate on the present comparing six SPLAT treatment plans created for Sagehen. Four of the plans were created by the Tahoe National Forest in conjunction with University of California, Berkeley using the fireshed assessment process. These four plans take into account accessibility, cost, landownership and ecological objectives. The second two plans were theoretical. The first is based on the pattern outlined by the fundamental research on the SPLAT theory (Finney 2001). This plan does not consider any of the above limitations. The second was created using the treatment optimization model within FlamMap (Finney 2007). This SPLAT plan excludes areas not available for treatment including watercourse protection zones, archeological sites and locations protected for sensitive or endangered plant and animal species. Potential fire behavior metrics (fire type, flame length, fireline intensity and arrival time) were modeled in FlamMap to evaluate the effectiveness of the six SPLAT plans.

The fourth chapter assesses the longevity of treatment effectiveness to reduce potential fire behavior for one of the fireshed assessment SPLAT treatments into the future. A forest vegetation growth simulator was utilized to model natural regeneration and growth of trees in Sagehen from 2005 through 2055 for the untreated and treated landscapes. Modeled fire behavior (fire type, flame length and fireline intensity) was used to assess the effectiveness of the treated landscape compared to the untreated landscape from 2005 to 2055.

There is much to be gained by integrating the past, present and future of Sagehen Experimental Forest into a spatial and temporal evaluation of the fireshed assessment and SPLATs. To my knowledge, no other watershed has the amount of information available for such a detailed analysis. Nor has there been a detailed evaluation of proposed SPLAT treatments created through the fireshed process. This study would be a first for both SPLAT placement and fireshed analysis, and should be of great value to land managers."

1 comment:

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