Login | Create Account (DAF staff only)

Impacts of grazing management options on pasture and animal productivity in a Heteropogon contortus (black speargrass) pasture in central Queensland. 2. Population dynamics of Heteropogon contortus and Stylosanthes scabra cv. Seca.

Orr, D.M. and Yee, M.C. and Rutherford, M.T. and Paton, C.J. (2010) Impacts of grazing management options on pasture and animal productivity in a Heteropogon contortus (black speargrass) pasture in central Queensland. 2. Population dynamics of Heteropogon contortus and Stylosanthes scabra cv. Seca. Crop & Pasture Science, 61 (3). pp. 255-267.

Full text not currently attached. Access may be available via the Publisher's website or OpenAccess link.

Article Link(s): http://dx.doi.org/10.1071/cp09194

Publisher URL: http://www.publish.csiro.au

Abstract

The dynamics of Heteropogon contortus and Stylosanthes scabra cv. Seca populations were studied in a subset of treatments in an extensive grazing study conducted in central Queensland between 1988 and 2001. These treatments were 4 stocking rates in native pasture and 2 of these stocking rates in legume oversown and supplement/spring burning treatments. For the 1999-2000 summer, population data for H. contortus in 5 of these native pasture and supplement/burning treatments were compared with those for an additional burnt treatment. Seasonal rainfall throughout this study was below the long-term mean and mean annual pasture utilisation ranged from 24 to 61%. Increasing stocking rate from 5 to 2 ha/steer in native pasture reduced H. contortus plant density. Increasing stocking rate reduced seedling recruitment as a result of its effect on soil seedbanks. Seedling recruitment was the major determinant of change in plant density, although some individual H. contortus plants did survive throughout the study. Burning in spring 1999, particularly at light stocking rate, promoted seedling recruitment above that in both unburnt native and legume oversown pasture and resulted in increased H. contortus plant density. In the legume oversown treatments, S. scabra cv. Seca density increased rapidly from 15 plants/m2 in 1988 to 140 plants/m2 in 2001 following a lag phase between 1988 and 1993. This increased S. scabra density was associated with an eventual decline in H. contortus plant density through reduced seedling recruitment. It was concluded that H. contortus population density is sustainable at stocking rates of 4 and 5 ha/steer (30% pasture utilisation) and that spring burning at light stocking rate can promote H. contortus populations. Increasing densities of S. scabra need to be managed to prevent its dominance.

Item Type:Article
Corporate Creators:DEEDI
Additional Information:© The State of Queensland (Dept of Employment, Economic Development and Innovation). © CSIRO Publishing.
Keywords:Burning; grazing; legumes; oversowing; pastures; plant density; population density; population dynamics; productivity; recruitment; seed banks; seedlings; stocking rate.
Subjects:Animal culture > Rangelands. Range management. Grazing
Animal culture > Cattle
Deposited On:08 Sep 2010 05:43
Last Modified:17 Mar 2011 06:52

Repository Staff Only: item control page