Effect of Standing Litter on Rough Fescue Utilization by Cattle

Abstract

Fescue grasslands are well suited to dormant-season grazing, whereas spring defoliation is detrimental to rough fescue (Festuca campestris Rydb.). Dormant-season grazing may also condition fescue plants for subsequent selection in spring by removing standing litter (i.e., senesced biomass). This relationship must be understood in order to manage grazing and conserve rough fescue. This study determined the effects of standing litter on plant selection and utilization by cattle in spring. Forty dormant rough fescue plants were conditioned in fall by removing standing litter in a 4 (treatments) 3 10 (blocks) randomized complete block design. This design was repeated with the use of 2 separately grazed paddocks. Treatments were a control (no litter removal) and standing litter removed at 14-, 7-, and 2.5-cm stubble height. Nonparametric plant selection data were analyzed with the use of v 2 methods. Spring biomass utilization was estimated nondestructively through height-weight modeling techniques, and data were analyzed with the use of analysis-of-variance procedures. The stubble height of standing litter affected (P , 0.05) plant selection by cattle in the first 2 days of the trial when grazing pressure was light. By the end of the 6-d grazing period 96% of fescue plants were selected at least once. Additionally, 18% of plants were regrazed at least once after 3 days, and 48% after 6 days. Thus, the protective barrier effect of standing litter had limited effect on plant selection by cattle except when grazing pressure was light. However, the degree of spring biomass utilization increased with shorter stubble heights. After 6 days of grazing, the current growth of plants with standing litter removed at 2.5 cm was utilized at 64%, and control plants were utilized 9%. Therefore, at high grazing pressure the mass of standing litter influenced the degree of utilization, suggesting litter retention is important in limiting grazing impacts on rough fescue. Resumen Los pastizales de ''Fescue'' están bien adaptados al apacentamiento en la e ´poca de dormancia, mientras que la defoliació n en primavera es perjudicial para el ''Rough fescue'' (Festuca campestris Rydb.). El apacentamiento en durante la dormancia también puede acondicionar las plantas para la selecció n subsecuente en primavera al remover el mantillo en pie (i.e., la biomasa senescente); esta relació n debe ser entendida para manejar el apacentamiento y conservar el ''Rough fescue.'' Este estudio determinó los efectos del matillo en pie en la selecció n y utilizació n de las plantas por el ganado en la primavera. Cuarenta plantas de ''Rough fescue'' fueron acondicionadas en otoñ o removiendo el mantillo en pie de ellas y se asignaron a 4 tratamientos en 10 bloques bajo un diseñ o de bloques completos al azar. Los tratamientos fueron: control (sin remoció n del mantillo) y remoció n del mantillo en pie a 14, 7 y 2.5 cm de altura del rastrojo remanente, este diseñ o se repitió usando separadamente dos potreros apacentados. Los datos noparamétricos de la selecci...

Seasonal Patterns of Forage Availability in the Fescue Grasslands Under Contrasting Grazing Histories

“…Litter affects forage selection and the dietary quality of herbivores. Herbivores avoid selecting new plant growth with abundant litter in fescue grasslands (Moisey et al 2006), which reduces their foraging efficiency and affects their feeding distribution (Willms et al 1980b). In our study, the proportion of litter to ANPP was about five times greater within ungrazed exclosures than in adjacent grazed communities, and suggests that grazing indirectly enhanced the quality of forage available for herbivores in these grasslands even though the nutrient concentration and nutrient yield of current annual herbage was not altered.…”

“…However, the most important effect of grazing was to alter litter mass, and therefore the indirect effects that are mediated by litter, including grassland quality. Litter affects various grassland processes including herbivory (Willms et al 1980a;Moisey et al 2006) and the soil environment (Deutsch et al 2010), which may either enhance or diminish productivity. Forage production can be enhanced when soil water is conserved by reducing evaporation, or it may be diminished when litter constrains plant establishment and growth by limiting light penetration, reducing soil temperature (Knapp and Seastedt 1986), or imposing physical constraints through various mechanisms on seeds or plants (Facelli and Pickett 1991).…”

“…Fescue grasslands in southwestern Alberta are dominated by foothills rough fescue (Festuca campestris Rydb.). This species is a large caespitose plant with basal leaves that are highly sclerenchymatous, but it is relatively more preferred than plants of associated species in the community (Moisey et al 2006). However, rough fescue is sensitive when grazed during the growing season and will readily decline with heavy grazing pressure (Willms et al 1985).…”

“…cut in July had greater concentrations of crude protein and phosphorus, and less acid detergent fiber (ADF) in the following January than plants that had not been cut (Willms 1991). Moreover, the barrier effect of litter on forage selection by livestock is well documented (Willms et al 1980a;Ganskopp et al 1992;Moisey et al 2006). Combined, these effects can change large-scale ungulate movements (McNaughton 1976), with the potential for grazing to condition grasslands to benefit subsequent herbivory.…”

Effects of High Impact Grazing on Species Diversity and Plant Functional Groups in Grasslands of Northern Argentina

“…Due to the low year-round stocking rates in the grasslands of Northern Argentina, which are applied to adapt to the limited fodder availability during the winter, grasslands accumulate large amounts of plant material resulting from the vigorous growth of C 4 grasses during the summer growing season [26]. The surplus of standing biomass substantially decreases the amount of solar energy, as dead material shades out the sward, taller species dominate and reduce the presence of shorter species and thus biodiversity [27,28]. As compared to traditional methods to reduce standing dead biomass (SDB) such as burning, ploughing and mowing, high impact grazing (HIG) was analyzed as a successful alternative management option to reduce SDB [26].…”