REM 456 - Integrated Rangeland Management Stave Bunting Plant Response to Fire REM 456 - Integrated Rangeland Management

Depends on fire history of ecosystem Ecosystems with less frequent fire Tundra Deserts Plant success depends on ability to compete or adapt to climate…. Not necessarily able to survive fire Cold Desert Jen Peterson Hot Desert K. Launchbaugh Tundra Photo by Daniel R. Rathrauff, USGS

Depends on fire history of ecosystem Ecosystems evolves with frequent fire Grasslands Dry Forests Plants adapted to avoid or tolerate fire. Plants may even benefit fire: Germination – seeds scarified by fire Create Habitat – removing existing plants & releasing nutrients. photogallery.nrcs.usda.gov photogallery.nrcs.usda.gov

Fire characteristics Plant mortality Severity = impacts of heat from fire Fire that reaches 120 to 130F typically kills plant tissue. Residency time = how long fire burns in area Even low temperature fire can be damaging if it moves slowly across the landscape Fire behavior and landscape patterns Patchy fire can recover rapidly because seeds may be available in unburned areas Widespread fires can foster erosion and reduce seeds available in area. Season of fire and phenological stage of plants is important. Buds and leaves are more sensitive to fire when they are metabolically active.

Plant Adaptation to Fire - Avoidance Fuel characteristics affected by plant structure: Fuel Load = amount of live and dead fuel (weight/unit area) Fuel Size Class = Dead fuels divided into size classes based on diameter: (e.g., < 1/4-inch, 1/4 to 1-inch, 1 to 3 inches, and > 3 inches) photogallery.nrcs.usda.gov

Plant Adaptation to Fire - Avoidance Fuel Bed Depth = the depth of surface fuel layer i.e., the average height of surface fuels contained in the combustion zone of a spreading fire front S. Bunting

Plant Adaptation to Fire - Avoidance Packing Ratio = compactness of fuel bed

Plant Adaptation to Fire - Avoidance Bulk Density = the actual fuel weight per unit. WEIGHT per unit area ÷ fuel bed DEPTH

Plant Characteristics affect Fire Severity Severity of fire affected by plant characteristics: Morphological = Fire resistant bark Chemical = chemicals that reduce probability of combustion Waxy and stiff surfaces can reduce flammability Volatile compounds can increase flammability Jen Peterson Sheri Hagwood. Bureau of Land Management S. Bunting

Plant Characteristics affect Fire Severity Growth form Bunchgrasses vs Sodgrass Crested Wheatgrass vs Western Wheatgrass Jen Peterson K.Launchbaugh

Plant Characteristics affect Fire Severity Growth form Strong vs Dispersed Bunchgrass Idaho Fescue vs Bluebunch Wheatgrass Jen Peterson Jen Peterson

Plant Adaptation to Fire - Tolerance Growth after fire depend on: Location of buds Below ground buds – The upper 1 inch of soil typically only experiences a very brief increase in temperature during a fire on rangelands photogallery.nrcs.usda.gov

Plant Adaptation to Fire - Tolerance Basal sprouts (rabbitbrush or horsebrush) Rhizomes and other adventitious sprouting (pinegrass) Also affected by season – when are growing points elevated?

Plant Adaptation to Fire - Tolerance Fire-adapted seeds Hard seed coating that is scarified by fire Serotinous cones i.e., logdepole pine Seeds protected in canopy i.e., ponderosa pine

Plant Adaptation to Fire - Tolerance Julie Hankins Fire-adapted seeds (continued) Seeds that are wind dispersed i.e., fire weed (Epilobium angustifolium) Seed vulnerability is typically dependant on seed position and amount of moisture seeds contain

Plant Adaptation to Fire - Tolerance Carbohydrate Allocation Patterns Some plants can simply mobilize resources better than others. Julie Hankins

Other Factors Affect Plant Response Post-Fire Weather Post-Fire Animal Use Plant Competition

Summary Questions What time of year is fire most damaging to grasses and why? What time of year is fire most damaging shrubs and why? Deferring livestock grazing for several seasons after fire is a practice employed by land managers intended to promote plant vigor and ecosystem recovery. The concept of extended rest periods to compensate for the cumulative effect of both grazing and fire seems intuitive. However, extended rest periods may not be ecologically important to plant recovery and altered grazing systems can impose unwarranted financial hardship on livestock producers. In addition delayed grazing after fire can create a subsequent fuel load of standing dead grass. Removal of grazing after fire could also inadvertently promote weed establishment. Without grazing to suppress them, invasive or noxious weeds may take advantage of nutrient and water resources in the early spring when native species have not yet initiated growth. The challenge to land managers is to determine when and how to begin grazing after fire to maintain productivity of native perennial herbaceous species. 18

How Fire differs from Grazing as a Plant Disturbance

Fire Grazing Not selective for specific plants Selects palatable over unpalatable Removes dead and live tissue Live tissue preferentially removed Produces heat No heat produced Recycles nutrients in inorganic form Recycles nutrients in organic (feces) and inorganic (urine) forms Nutrients in a relatively even layer across the landscape Nutrient in patches Patchiness on landscape scale Patchiness on plant-scale Most likely in dry-hot season Occurs year round Generally reduces seed viability, though some seeds require fire to be viable Generally reduces seed viability though some seeds require consumption

REM 456 - Integrated Rangeland Management Stave Bunting Plant Response to Fire REM 456 - Integrated Rangeland Management