Factors Affecting the Distribution and Abundance of Microlaena Stipoides (Labill.) R.br. On the Northern Tablelands of New South Wales.

Abstract

The distribution of Microlaena stipoides on the Northern Tablelands of NSW was examined in a survey of 101 paddocks on 33 properties. Relationships among the abundance of M. stipoides and spatial, climatic, soil and pasture management factors were determined using X2, regression and cluster analyses. Paddocks with more abundant M. stipoides were observed in the eastern and southern parts of the Tablelands where altitude (>750 m) and rainfall (>750 mm) are higher. Higher tree density was associated with more abundant M, stipoides as were native and natural compared with highly improved pastures. Frequent cultivation (regular and intermittent) was associated with absence or very low abundance of M. stipoides. On the other hand, paddocks which had not been cultivated for along time tended to have more M. stipoides than those that had been cultivated in the last five years. Total amount of superphosphate applied, type of grazing animal and grazing method were not associated with the abundance of M. stipoides. Acidic soils had more M, stipoides than soils of higher pH (up to 6.5). Combinations of site factors such as high elevation and rainfall, high tree density, minimum soil disturbance and acidic soil lead to abundant M. stipoides in pastures. Pasture communities in the north and west of the study area had a greater abundance of native warm season perennial grasses and less M. stipoides.