Can bare ground cover server as a surrogate for plant biodiversity in grazed tropical woodlands?

Abstract

A bare ground index derived by remote sensing would provide a rapid methodology for assessing the biodiversity condition of an ecosystem, providing that ground cover is a satisfactory correlate with key biodiversity attributes. The relationship between plant species richness and the abundance of individual species was examined in relation to ground cover within silver-leaved ironbark (Eucalyptus melanophloia F. Muell.) woodlands in the Desert Uplands bioregion of north-eastern Australia. There was significant correlation between the bare ground index and ground cover and biomass measurements. Twenty-four species, including the perennial grasses Sehima nervosum (Rottler) Stapf, Themeda triandra Forssk. and Bothriocloa ewartiana (Domin) C.E. Hubb., were significantly and negatively correlated with bare ground. Scleroleana birchii (F. Muell.) Domin and Sida fibulifera Lindl.displayed significant positive relationships with increasing bare ground, and where abundant indicate heavy grazing in this land type. The study suggests that satellite-derived data does provide a meaningful methodology for assessing vegetation condition although it is strongly associated with seasonal conditions, but is only useful in relation to the regional average for a land type. The findings suggest that plant diversity is maintained at a relatively high level throughout most of these woodlands in the Desert Uplands.