1. MONITORING POST-TREATMENT EFFECTIVENESS FOR PONDEROSA PINE FORESTS WITHIN THE GREATER FLAGSTAFF FORESTS PARTNERSHIP WILDLAND/URBAN INTERFACE HALL, Patricia A. [1], Anne MOTTEK LUCAS [2], Stephen E. GATEWOOD [3], Anthony DICKENS [4] and Ryan RUSSART [4] INTRODUCTION Fire management throughout the Southwest has assumed a new focus - reactive wildfire suppression gradually being replaced by proactive fuel reduction and forest restoration. Land managers are thinning stands to various prescribed tree densities followed by prescribed ground fire to obtain the specific objectives of reduced wildfire hazard and increased forest health. Unfortunately, neither time nor has funding been available to revisit treated areas to assess the results of these activities. In 2006 the Greater Flagstaff Forests Partnership’s Monitoring and Research Team (GFFP MRT) received a grant from the National Forest Foundation to monitor post- treatment fire behavior. The GFFP MRT designed a project that evaluated treatment effects on fire behavior and wildlife suitability for seven different treatments applied by land managers within the 180,00 acre GFFP designated wildland/urban interface that surrounds the city of Flagstaff. METHODS Data Collection - Physical Characteristics Sampling Design:  Sampling grid (1 per stand)  (15) 0.1 acre plots for trees with dbh ≥ 5.0 inches species crown ratio dbh tree height height to crown base  (15) 0.01 acre plots centered in 0.1 acre plots for live or dead stems dbh between 1.0 and 5.0 inches  60 meter spacing between plots and between grid and vegetative edges  Treatments (see Table 1):  1 control  6 treatments Burn only Thin YP Burn to thin Thin BA Hand thin Fuel reduction  Replicates: 3 replicates per treatment Data Collection Details:  1-year post-burn  May – July 2006  H & K Consulting, L.L.C.  Coconino Rural Environmental Corps  Data entry into Microsoft EXCEL©: Sue Rodman Data Collection Protocol:  Stand characteristics: Stand structure, composition and fuel loading  Common Stand Exam (USDA 2005)  50 foot Brown’s transect for down woody material  Fuel model (Anderson 1982, Scott and Burgan 2005)  Canopy cover with 4 spherical densiometer readings  Stand physiognomy:  Slope  Aspect RESULTS Physical Characteristics Summary (see Table 3) Stand Characteristics:  Composition: dominated by ponderosa pine (Pinus ponderosa) with inclusions of Gambel oak (Quercus gambelii), aspen (Populus tremuloides) and a number of juniper species (Juniperus sp.).  Structure: Basal area: 32 – 168 ft 2 /ac Canopy closure: 18 – 63% Tree density: 28 – 242 trees/ac Tree canopy: Tree height: 36.5 – 56.1 ft Depth: 23.4 – 30.1 ft Base height: 13.0 – 29.2 ft Data Analyses - Habitat Suitability Forest Ecosystem Restoration Analysis Program at Northern Arizona University (ForestERA) habitat model input:  Abert squirrel (Sciurus aberti) density  Basal area  Pronghorn antelope (Antilocapra Americana) suitability  Slope  Canopy cover  Avian species richness  Slope  Basal area Habitat Suitability Summary (see Table 6) Plants:  Exotic species richness (see Figure 3): 0.40 – 3.71 species  Non-native species found in every stand  Highest in burn only treatment  Lowest in control Animals:  Avian species richness (see Figure 4): 6.8 – 10.5 species  Highest in burn to thin treatment  Lowest in control  Pronghorn habitat suitability: 0.05 – 1.0  Highest in fuel reduction treatment  Lowest in control  Abert squirrel density: 1.35 – 7.77 squirrels/acre  Highest in control  Lowest in fuel reduction treatment Data Analyses - Fire Behavior Calculations for NEXUS© runs:  Canopy biomass  Crown bulk density (Fulé et al. 2001)  Aggregated fuel model  Average canopy base height for lowest quintile of canopy base height values for stand Other NEXUS© inputs:  Environmental conditions typical in pre- monsoon June (see Table 2) Table 2. Environmental Conditions that Define the 97 Percentile for the Month of June Pre-monsoon MetricValue 1 hour dead material moisture content 2.2% 10 hour dead material moisture content 3.0% 100 hour dead material moisture content 4.7% Live herbaceous material moisture content50% Live woody material moisture content (range 30-300%)120% Wind speed25 mph Wind direction225˚ Fire Behavior Summary (see Table 5) Fire characteristics (see Table 4 for definitions):  Fire type: surface  Percent of crown burned: 0 – 0.05  Rate of spread: 0.73 – 15.44 ft/min  Highest in control  Lowest in burn to thin treatment  Flame length: 0.73 – 4.60 ft  Varied little between treatments  Torching index: 32.50 – 1248.63 mph (see Figure 1)  Highest in thin BA treatment  Lowest in thin YP treatment  Crowning index: 31.57 – 123.57 mph (see Figure 2)  Highest in fuel reduction treatment  Lowest in control DISCUSSION Physical Characteristics Summary Control stands  Highest crown bulk density and biomass  Highest crown base height Thin to burn  Lowest crown base height  Second highest tree density Fuel reduction  Lowest crown bulk density and biomass  Lowest basal area  Lowest tree density Generally, crown bulk density and biomass are inversely related to thinning intensity. However, this pattern did not emerge from the data. The exhibited relationship may reflect the conditions that existed in the stands before treatment. Treatment Fire Behavior Summary All treatments  Ignition would result in surface fire  Torching and crowning indices > 30 mph (highest wind gust in June) Hand thin  Passive crown fire and torching would result from ignition in 1 of 3 replicates under sustained winds of 30 mph 1 Burn only & thin YP  Torching would result from ignition in 1 of 3 replicates under sustained winds of 30 mph 1 Control  Torching would result from ignition in 1 of 3 replicates under sustained winds of 30 mph 1  Passive crown fire would result from ignition in 2 of 3 replicates under sustained winds of 30 mph 1 1 Local wildland fires in 1996 exhibited sustained winds of 30 mph and higher gusts. Although torching and crowning indices generally depend upon crown base height, the highest indices corresponded to the smallest crown bulk density and crown biomass values. Treatment Habitat Suitability Summary Control  Highest Abert squirrel densities  Highest canopy closure, tree density and basal area Burn to thin & burn only  Highest avian species richness  Surface fuels removed by burning  No trees removed Fuel reduction  Most suitable for pronghorn  Lowest canopy closure Burn only  Highest exotic species richness Table 1. Descriptions of Treatments Evaluated by GFFP MRT in 2006 Treatment Abbreviation Land ManagerTreatment Description Control  No treatment Burn OnlyUSFS 1  Prescribed ground fire only  No thinning Burn to ThinAANG 2  Moderate intensity surface fire Hand ThinFFD 3  Hand thinning from below up to 10” dbh Thin YPUSFS  Mechanical thin from below within and around yellow pines (YP) and Gambel oaks (GO) to reduce fire hazard and resource competition  Create openings where possible Thin BAUSFS  Mechanically thin to 40-100 basal area (BA) to allow for dense clumps and openings  Mechanically thin from below around yellow pines to reduce resource competition  Create grassy openings in 10% of the area  Mechanically thin from below around Gambel oaks to reduce fire hazard and resource competition Fuel Reduction USFS  Mechanically thin from below to leave an even-aged stand of large trees with 40-80 residual BA  Retain 30-40% canopy cover  Use uneven spacing  Leave clumps with very little crown interlock 1 USDA Forest Service, Coconino National Forest 2 Arizona Army National Guard 3 Flagstaff Fire Department ASSUMPTIONS, CONDITIONS & LIMITATIONS  Pre-treatment stand environmental conditions were not equivalent, therefore, treatments cannot be directly compared.  The results and analyses are preliminary.  Fuel model selection was based on stand conditions but aggregated for presentation of data.  The data collected represents a snap-shot in time.  The data was collected in spring and early summer (May – July, 2006).  The data was collected early post-treatment (1-2 years post-burn). FUTURE ANALYSES  Statistical comparisons within the control, burn only, thin BA and thin YP treatments where pre-treatment stand conditions can be assumed equivalent  Using ForestERA models to apply the results to treatments implemented on broader landscapes southwest of Flagstaff  Comparisons of pre- and post-treatment stand exam data based on availability LITERATURE CITED Anderson, H. E. 1982. Aids to Determining Fuel Models for Estimating Fire Behavior. USDA Forest Service General Technical Report INT-122, 22p. Intermountain Forest and Range Experiment Station, Ogden, UT. Fulé, P. Z., C. McHugh, T. A. Heinlein and W. W. Covington. 2001. Potential fire behavior is reduced following forest restoration treatments. In: Ponderosa pine ecosystems restoration and conservation: Steps toward stewardship. comps. R.K. Vance, W.W. Covington and C.B. Edminster, 28-35. Proceedings RMRS-22. US Forest Service, Rocky Mountain Research Station. Scott, J. H. and R. E. Burgan. 2005. Standard Fire Behavior Fuel Models: A Comprehensive Set for Use with Rothermel’s Surface Fire Spread Model. USDA Forest Service General Technical Report RMRS-153, 80p. Rocky Mountain Research Station, Fort Collins, CO. USFS. 2005. Common Field Exam Field guide Region 3, Version 1.7. USDA Forest Service Natural Resource Information System: Field Sampled Vegetation. 166p. [1] H & K Consulting, L.L.C., 5937 E. Abbey Rd., Flagstaff, Arizona 86004; hkconsultingllc@yahoo.com [2] Social Research Laboratory, Northern Arizona University, P.O. Box 15301, Flagstaff, Arizona 86011; anne.mottek-lucas@nau.edu [3] Greater Flagstaff Forests Partnership, Inc., 1300 S. Milton Rd., Suite 218, Flagstaff, Arizona 86001; steveg@gffp.org [4] Coconino Rural Environmental Corps, 2625 E. King St., Flagstaff, Arizona 86004 Table 4. Definitions of Fire Behavior Metrics MetricUnitsDefinition Fire type Type of fire – surface, passive, active Percent crown burned%The fraction of the crown that would be burned by the type of fire given above Rate of spreadFt/minThe rate at which the given fire would spread through the stand Flame lengthFtThe length of the flames produced in the fire Torching indexMi/hrThe wind speed required to initiate tree torching or passive crown fire behavior Crowning indexMi/hrThe wind speed required to support a crown fire spreading through the crown or active crown fire behavior Table 5. Treatment Fire Behavior under June 97% Pre-monsoon Weather Conditions TreatmentFire Type % Crown burned Rate of Spread (ft/min) Flame Length (ft) Torching Index (mph) Crowning Index (mph) ControlSurface015.444.6040.6731.57 Burn onlySurface013.514.0763.3050.07 Burn to thinSurface00.730.77593.1042.60 Hand thinSurface010.973.7338.5363.93 Thin YPSurface014.534.4732.5051.70 Thin BASurface00.760.771248.6362.57 Fuel reductionSurface02.081.63432.13123.57 Table 6. Treatment Habitat Suitability SlopeCanopyAvian RichnessPronghornAbert SquirrelExotic Richness Treatment(%)Closure (%)(# species)SuitabilityDensity (#/ac)(# species) Control16.662.56.80.057.770.40 Burn only 4.137.49.50.784.643.71 Burn to thin 5.041.210.50.734.530.49 Hand thin 8.740.38.50.603.531.64 Thin YP10.647.58.90.524.661.53 Thin BA 6.738.08.50.784.212.42 Fuel reduction 4.917.98.511.352.84 Table 3. Treatment Physical Characteristics TreatmentFuel Models Basal Area (ft 2 /ac) Tree Density (trees/ac) Crown Base Height (ft) Tree Height (ft) Crown Bulk Density (kg/m 3 ) Crown Biomass (tons/ac) Control2/TU1168.0242.229.252.60.08425.53 Burn only2/TU1101.8100.425.453.90.03662.85 Burn to thin9/TL199.6160.213.036.50.03142.55 Hand thin2/TU178.3 81.617.544.20.05302.64 Thin YP2/TU1102.2100.724.552.10.04212.28 Thin BA9/TU192.9 85.626.056.10.04253.47 Fuel reduction8/NB932.4 28.219.046.60.01191.04 Calculations for NEXUS© runs:  Canopy biomass: 1.04 – 5.53 tons/acre  Crown bulk density: 0.0119 – 0.0842 kg/m 3  Aggregated fuel model:  Anderson 1982: 2, 8 & 9  Scott and Burgan 2005: TU1, TL1 & NB9  Average canopy base height for lowest quintile: 13.0 – 29.2 ft back to top RESULTS (cont’d) Control Fuel Reduction top of next column over one column