Forb responses to grazing and rest management in a critically endangered Australian native grassland ecosystem

Abstract

Worldwide, temperate grasslands have been extensively cleared for agriculture and urban expansion and the ‘Natural Temperate Grassland of the Victorian Volcanic Plain’ in south-eastern Australia has recently been listed as critically endangered. Because of land clearing, these grasslands now occupy <1% of their original distribution and much of the remaining grassland continues to be grazed by livestock. Although forbs (wildflowers) constitute most of the floristic richness in natural grasslands, few experimental studies have focused on their responses to strategic livestock grazing and rest. This paper reports on the outcomes of five grazing and rest management regimes imposed for 4 years at three sites on the Victorian Volcanic Plain. Seasonal grazing and rest management regimes resulted in significantly different native and exotic forb frequencies, but not richness. Native perennial and exotic annual forb frequency was higher when management incorporated grazing and rest periods (14 and 16% deviance explained), particularly with spring rest from grazing. However, the most important influence on native perennial and exotic annual and perennial forb frequency (46, 58 and 41% deviance explained) and native perennial and exotic annual species richness (62 and 35% deviance explained) was site. Differences among the three sites included soil, rainfall, size of remnant, presence of small burrowing mammals, management history and consequent species assemblages. Despite differences among sites, the results indicate that native perennial forb frequency may be increased using management regimes that incorporate both grazing and rest. However, targeted management may be necessary to reduce exotic annual forbs, also promoted by grazing with seasonal rest.

Decadal plant composition changes in grazed native grassland

“…spring) has been shown to maintain native forb richness and grass cover (Leonard & Kirkpatrick ; Zimmer et al . ; Mavromihalis et al . ; Fedrigo et al .…”

Experimental changes in disturbance type do not induce short‐term shifts in plant community structure in three semi‐arid grasslands of the Victorian Riverine Plain managed for nature conservation

“…2007; McIntyre & Lavorel 2007; Lewis et al. 2008; Zimmer et al. 2010), but the lack of application of fire as a disturbance may also be an important factor limiting change.…”

Long‐term stock grazing management in Travelling Stock Reserves and influence on conservation values

“…Grazing duration is also known to be as deleterious to pasture condition as grazing density (Scarnecchia & Kothmann 1986; Vallentine 2001). Therefore, we calculated a combined grazing intensity (GI) index and concluded that 11 TSRs were moderately (GI > 2; six sites) to heavily grazed (GI > 3, six sites).…”

“…Grazing in spring can deleteriously affect plant species when flowering and seed set take place (Bullock et al. 2001; Zimmer et al. 2010).…”

“…2004). Grazing has both negative, neutral and positive impacts on ecosystems depending on the nature of the grazing regime applied (Vallentine 2001). There is growing interest in using grazing as a tool to achieve production and conservation benefits, particularly in systems with a long history of grazing (Papanastasis 2009).…”