Effects of fire, grazing and topographic variation on vegetation structure in tallgrass prairie

Abstract

Questions How do fire and grazing by bison affect the composition and structure of tallgrass prairie plant communities and their temporal stability? Are these responses modulated by topographic location? Location Konza Prairie Biological Station, Kansas, USA. Methods Plant community composition was monitored in permanent plots in native grassland sites receiving different long‐term prescribed burning and bison grazing regimes across a topographic gradient (lowlands, slopes, uplands) following 20 yr of variable burning treatments and 13 yr of grazing by bison. A combination of multivariate analyses was used to determine how community structure, life forms and individual species responded to the accumulated effects of long‐term fire and grazing by native bison in upland, slope and lowland soils. Results Species diversity was maximized in sites that were infrequently burned and grazed by bison with the strongest response on infrequently burned slope sites, while diversity was lowest on frequently burned ungrazed sites and on frequently burned slope sites. In general, grass cover was highest in infrequently burned ungrazed sites and lowest on frequently burned grazed sites, while forb richness was highest in infrequently burned and grazed sites. Community response to fire and grazing differed across the topographic gradient. In general, frequent burning favoured C4 grasses, which reduced the abundance of C3 forbs, especially in lowland sites. Responses of dominant grasses and forbs to fire and grazing varied depending on topographic position. Community stability was positively correlated with species richness. Conclusions Overall, we found that fire and grazing are the main determinants of plant community composition and structure in this grassland system, but that topography mediates these effects. A combination of bison grazing and periodic fire is necessary to maximize diversity and community stability across this native grassland landscape.

Estimating Canopy Nitrogen Content in a Heterogeneous Grassland with Varying Fire and Grazing Treatments: Konza Prairie, Kansas, USA

“…The interaction between distribution of foliar nutrients (e.g., N) in a grassland canopy and the forage pattern of ungulate grazers is of special interest since these grazing activities alter the structure and composition of vegetation and therefore influence vegetation quality [37,38]. Grazed sites often yield higher nutritional value with greater plant species diversity than do ungrazed sites [39][40][41] due to the capability of plants to overcompensate with regrowth for low levels of herbivory [42].…”

“…Among grassland canopies, tallgrass prairie is especially heterogeneous, consisting of a diverse, intermingled mix of herbaceous and woody species. Several interacting biophysical factors, including fire, topography, and grazing determine this complex spatial distribution of canopy properties [38,43]. Tallgrass prairie canopies can have more than twenty species present in a single square meter, each with different growth forms and leaf structure, thus producing a closely intermingled mixture of species.…”

Landowners' perceptions of risk in grassland management: woody plant encroachment and prescribed fire

“…Much of the research on the use of fire in support of diverse habitats and ecosystem resilience has occurred on publicly owned or not-for-profit reserved lands (e.g., Fuhlendorf et al 2006, Munyati et al 2011, Collins and Calabrese 2012, Russell-Smith et al 2012. Private landowners managing forage resources have traditionally applied costly mechanical treatments and herbicides to control woody species, with limited effectiveness (Bernardo and Engle 1990).…”

Grazing primarily drives the relative abundance change of C4 plants in the typical steppe grasslands across households at a regional scale

“…glaucum, and S. collina, can be used as important indicators for monitoring Inner Mongolian grasslands Changes in a range of environmental factors, including grazing, temperature, road construction and precipitation, at both large scale and small scales, can affect changes in the biomass of C 4 plants (Jolly and Haxeltine 1997;Pushkina et al 2010;Sinninghe Damsté et al 2011;Collins and Calabrese 2012;Scheiter et al 2012;Way 2012). In our study, the CV of C 4 species was higher than that of C 3 species (Fig.…”

“…Disturbance, including grazing, fire, and roads related to landuse change, also have different effects on the growth and reproduction of C 3 and C 4 plants and can lead to changes in their relative abundance (Pushkina et al 2010;Collins and Calabrese 2012;Scheiter et al 2012;Way 2012). Animal grazing is the most dominant land use of grasslands (Mavromihalis et al 2013).…”