Effects of Prescribed Burning on Stream Water Quantity, Quality, and fuel loads in a Small Piedmont Watershed in North Carolina

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1 Effects of Prescribed Burning on Stream Water Quantity, Quality, and fuel loads in a Small Piedmont Watershed in North Carolina Matthew Haunsperger Johnny Boggs, Ge Sun, Michael Gavazzi USDA Forest Service Glenn Catts, Joseph Roise, James McCarter North Carolina State University Photo by: Robert Mickler Background The south is a heavily forested landscape that leads the nation in implementing prescribed burning as an effective management tool to reduce fire risk and severity, and potentially increase water yield from forest lands. The fire effects on the landscape can vary greatly depending on fuels, fuel loads, soil properties, topography, climate, weather and fire frequency and intensity (Richter et al. 1982). Very few studies have been performed on water quantity, water quality and fuel loads in watersheds in the Piedmont of North Carolina. Photo by: Robert Mickler 1

2 Would burning in a watershed affect water quality and quantity? Would repeated burning affect water quality and quantity? How does the timing and severity of burns affect the likely hydrologic and water quality responses? Photo by: Matthew Haunsperger Questions to Ask Photo by: Johnny Boggs, USDA Forest Service Prescribed burning significantly increases soil moisture, peak flow, and total water yield due to a reduction of understory and over story plant transpiration and loss of soil duff layers in the months following a burn. Prescribed burning does not significantly increase sediment and nutrient (N, P, NO₃, NH₄+, C) concentrations (mg L ¹) in the months following a burn. Prescribed burning significantly increases sediment and nutrient (N, P, NO₃, NH₄+, C) loads (kg ha ¹yr ¹) due to elevated runoff and reduced plant nutrient uptake in the months following a burn. Prescribed burning significantly reduces small, medium, and large fine woody material, litter, and shrub fuel loads but does not significantly reduce coarse woody material and over story biomass. Hypotheses 2

3 Fire Intensity measure of the rate of heat released by a fire. Includes both radiant and convectional heat. Most common: fireline intensity (kw/m or Btu/s/ft). Directly proportional to fuels heat of combustion, the amount of fuel consumed, and a fires rate of spread. Fuels, weather, topography (Forest Encyclopedia Network, D. Kennard) Fire Severity - Integrates fuel and soil conditions before a fire, energy released during and after flaming combustion, and visible effects after a fire. Prescribed fires are usually low severity fires by design. (Forest Encyclopedia Network, D. Kennard) DEFINITIONS (Forest Encyclopedia Network, D. Kennard) RESEARCH Elliott and Vose, In Second Interagency Conference on Research in watersheds 3

4 Elliott and Vose, In Second Interagency Conference on Research in watersheds Gavazzi and McNulty 2014, International Association of Wildland Fire, Missoula, Montana, USA 4

5 Study Location Location of Prescribed Fire Studies in the South The experimental design consisted of: A pair of watersheds (reference and treatment) A calibration or pre-burn period A treatment (prescribed fire) A post-burn period In the pre-burn phase (2007-June 16, 2015), discharge and the water quality parameters from the paired watersheds were calibrated. To calibrate the watersheds, a set of linear relationship/models (y = mx + b) between daily discharge and monthly TSS and nutrient concentrations and loads from each pair were generated with all probability values (p) being < The differences between measured with burn and modeled without burn during the post-treatment period (June 16, 2015-June 16, 2016) will represent the treatment effect. Experimental Design 5

6 Hill Demonstration Forest HF2 HFW2 Watershed site (ha/ac) 12/30 40/100 Stream length (m/ft) 260/ /3149 Stand type Stand Age 35 Slope (%) 13 Geologic Features Dominate Soil Series Soile characteristics Mixed-pine hardwood Carolina Slate Belt Tatum and Appling Non expansive clays, no perched water, deep soils, and discharge water slowly throughout the year due to large amounts of stored water in bedrock and topographic control. HF2 HFW2 Photos by: Johnny Boggs, USDA Forest Service 6

7 Field Data PRE-TREATMENT 7

8 Plot Design for Quantifying Fuel Loads Pre-Burn Fine Woody Material (FWM) and Coarse Woody Material (CWM) Johnny Boggs, USDS Forest Service 8

9 Streamflow Treatment 9

10 Watershed: 100 acres/40 ha Allowed to burn: ac/33.52 ha. Accomplished ac/16.79 ha Just over 50% of the forested area. Low intensity, low severity fire, even though temperatures approached 100 degrees on the burn day (June 16, 2015) 10

11 PRELIMINARY RESULTS Year HF2 HFW2 HF2 HFW2 HF2 HFW2 HF2 HFW2 HF2 HFW2 HF2 HFW2 (measured) (measured) (measured) (measured) (measured) (measured) (measured) (measured) (measured) (measured) (measured) (measured) TOC, mg/l NH₄, mg/l NO₃, mg/l TP, mg/l TKN, mg/l TSS, mg/l Pre-Treatment Mean Post-Treatment

12 WHAT S TO COME? Continue to collect streamflow and water quality data through June 16, Understand and adjust fuel load model from North east to determine total FWD, CWD, fuel bed height post-treatment Alternate methods of analysis for streamflow, water quality, fuel loads. ANCOVA Double-Mass Curve T-test (water quality and fuel loads) Work Cited Richter, D.D., Ralston, C.W., Harms, W.R Prescribed fire: effects of water quality and forest nutrient cycling. Science 215: Elliott, Katherine J.; Vose, James M Fire effects on water quality: a synthesis of response regulating factors among contrasting ecosystems. In: Second Interagency Conference on Research in the watersheds, May 16-18, p. Searcy, James K., and Clayton H. Hardison. Double-Mass Curves, Southern Fire Exchange, Encyclopedia of Southern Fire Science, Questions? 12