Effects of prescribed fire timing on vigor of the invasive forb sericea lespedeza (Lespedeza cuneata), total forage biomass accumulation, plant-community composition, and native fauna on tallgrass prairie in the Kansas Flint Hills

Abstract

The predominant grazing management practice of the Kansas Flint Hills involves annual prescribed burning in March or April with post-fire grazing by yearling beef cattle at a high stocking density from April to August. There has been a dramatic increase in sericea lespedeza (Lespedeza cuneata [Dumont] G. Don) coincident with this temporally-focused use of prescribed fire in the Flint Hills region. The species is an aggressive invader and a statewide noxious weed in Kansas. Control has generally been attempted using repeated herbicide applications. This approach has not limited proliferation of sericea lespedeza and resulted in collateral damage to non-target flora and fauna. Alternative timing of prescribed fire has not been evaluated for its control. Our objectives for this 4-yr experiment were to (1) document the effects of prescribed burning during early April, early August, or early September on vigor of sericea lespedeza, standing forage biomass, and basal cover of native graminoids, forbs, and shrubs and (2) measure responses to fire regimes by grassland bird and butterfly communities. Whole-plant dry mass, basal cover, and seed production of sericea lespedeza were markedly less (P < 0.01) in areas treated with prescribed fire in August or September compared with April. Forage biomass did not differ (P ≥ 0.43) among treatments when measured during July; moreover, frequencies of bare soil, litter, and total basal plant cover were not different (P ≥ 0.29) among treatments. Combined basal covers of C4 grasses, C3 grasses, annual grasses, forbs, and shrubs also did not differ (P ≥ 0.11) between treatments. Densities of grasshopper sparrow (Ammodramus savannarum), dickcissel (Spiza americana), and eastern meadowlark (Sturnella magna) were not negatively affected (P > 0.10) by mid-summer or late-summer fires relative to early-spring fires. There were no differences (P > 0.10) in densities of grassland-specialist butterfly species across fire regimes. Under the conditions of our experiment, prescribed burning during summer produced no detrimental effects on forage production, desirable non-target plant species, grassland birds, or butterfly communities but had strong suppressive effects on sericea lespedeza. Additional research is warranted to investigate how to best incorporate late-summer prescribed fire into common grazing-management practices in the Kansas Flint Hills.

Effects of late-season sheep grazing following early-season steer grazing on population dynamics of sericea lespedeza in the Kansas Flint Hills

“…In the case of sericea lespedeza, the selection translated to a meaningful decline ( P = 0.02) in basal cover ( Table 5 ). Alexander et al. (2021) and Duncan et al.…”

Growing Season Fires and Herbicide May not Be the Silver Bullet to Lespedeza cuneata Management

“…Some suggest that integrating herbicide into pyric herbivory management ( Cummings et al 2007 ) or burning during the growing season ( Alexander et al 2021 ) might be more effective at reducing L. cuneata invasion than traditional management regimes (e.g., dormant season fires only). However, experimental data exploring the interactive effects of fire timing, grazing, and herbicide are largely omitted from the invasive plant ecology literature, although their individual effects on plant communities are well documented ( Anderson 1990 ;Fuhlendorf et al 2002 ;Rinella et al, 2009 ;Towne and Owensby 1984 ;Dickson et al 2019 ).…”

“…Much of what is known about invasive plant species management, including L. cuneata, is limited to small-scale studies (i.e., < 100 m 2 ) that are not representative of, or easily transferrable to, large working landscapes by design ( Kettenring and Adams 2011 ). For example, studies suggesting that altering fire timing may result in effective L. cuneata control are limited to small-scale, laboratory settings ( Wong et al 2012 ) or field studies that are unrepresentative of working landscapes or typical management practices ( Alexander et al 2021 ). Therefore, we conducted a replicated field experiment to assess whether burning during the growing season, herbicide application, and the interactive effect of fire and herbicide 1) reduce L. cuneata across rangelands with pyric herbivory while 2) not negatively affecting other plant functional group abundances.…”

Sericea lespedeza control with postemergence and preemergence herbicide applications in fields managed for northern bobwhite

“…Invertebrates important for bobwhite chicks tend to avoid sericea relative to other plants (Bugg and Dutcher 1989). Given the requirement of early successional communities for bobwhite, sericea presents major limitations when managing for bobwhite across much of the South, Midwest, and Great Plains (Hessler et al 2004, Cummings et al 2007, GeFellers et al 2020, Alexander et al 2021).…”

“…Spot spraying postemergence herbicides commonly is used to follow initial applications (Ohlenbusch et al 2007, Brooke and Harper 2016). Targeted grazing and prescribed fire may reduce sericea coverage, but fire stimulates germination of sericea seed, and grazing is less effective unless plants are young and palatable (Cummings et al 2007, Bell 2012, Alexander et al 2021). Farris and Murray (2009) reported recently seeded sericea was controlled with preemergence applications of flumioxazin, imazapic, fluometuron, diuron, sulfentrazone, atrazine, metribuzin, and metolachlor.…”