ARS | Publication request: Fire seasonality effects on northern mixed prairie production and cover

Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: September 25, 2012
Publication Date: N/A

Technical Abstract: Seasonal timing is believed to affect plant response to fire. We compared biomass and cover of non-burned, summer (SUM), autumn (AUT), and spring (SPR) burned sites in northern mixed prairie. Criteria for fire timing were summer quiescence, autumn temperature (< -2oC), and spring initiation of Bouteloua gracilis growth. Fire treatments were thrice replicated on silty and dense clay ecological sites monitored two years following fire. All comparisons are relative to non-burned sites. Total current-year biomass was not affected by AUT, reduced 10% by SPR, and reduced 15% by SUM. Fire did not affect grass production (1126 ± 43 kg ha-1). SUM and AUT reduced forb production 65 and 52%. Bare ground increased with SUM (51%) and AUT (33%), but was similar to non-burned sites (12%) following SPR (14 ± 4%). Fire reduced litter cover similarly across fire seasons (55%) compared to no fire (76%) on the silty site, whereas litter cover on dense clay was least for SUM and AUT (34%), greater for SPR (63%), and greatest with no fire (78 ± 4%). Fire increased perennial C3 grass basal cover relative to no fire (0.6%), with SUM (2.8 ± 0.3%) having the greatest effect. Perennial C4 grass basal cover was less with no fire (1.1%) than either SPR (4.3%) or SUM (3.5%) and intermediate for AUT (2.4 ± 0.7%). Grass productivity was resistant to fire and combined cover data indicated native species were promoted by fire in any season (6.6%) compared to sites where fire was excluded (2.0 ± 1.1%).