Paul Gibson-Roy is project head of the Grassy Groundcover Research Project partnered by Greening Australia (Victoria) and University of Melbourne (500 Yarra Boulevard, Richmond, Vic. 3121, Australia; Tel: 03 92506946; Fax: 03 92506885; Email: email@example.com). John Delpratt and Greg Moore are associate members of the Melbourne School of Land and Environment at the University of Melbourne (500 Yarra Boulevard, Richmond, Vic. 3121, Australia; Email: firstname.lastname@example.org; email@example.com). Graham Hepworth is a member of the Department of Mathematics and Statistics at the University of Melbourne (Parkville, Vic. 3052, Australia; Email: firstname.lastname@example.org). This research arose from the need to progress the use of direct seeding in the restoration of species-rich temperate Australian grassland.
Does diversity influence soil nitrate, light availability and productivity in the establishment phase of Australian temperate grassland reconstruction?
Article first published online: 21 APR 2009
© 2009 Ecological Society of Australia
Ecological Management & Restoration
Volume 10, Issue 1, pages 41–50, April 2009
How to Cite
Gibson-Roy, B. P., Delpratt, J., Moore, G. and Hepworth, G. (2009), Does diversity influence soil nitrate, light availability and productivity in the establishment phase of Australian temperate grassland reconstruction?. Ecological Management & Restoration, 10: 41–50. doi: 10.1111/j.1442-8903.2009.00436.x
- Issue published online: 21 APR 2009
- Article first published online: 21 APR 2009
- functional diversity;
- grassland restoration;
- light extinction;
- soil nitrate;
- species diversity;
Summary The successful conservation and restoration of the temperate native grasslands of south-eastern Australia is critical to reversing the decline in range and diversity of these threatened plant communities. Yet the goals of high native species diversity and weed management are difficult to achieve in grassland restoration projects. To increase our understanding of whether synergies exist between these goals (i.e. whether early introduction of a larger number of species might improve both outcomes in the reassembly of native grassland), we examined the relationships between plant species number, functional group number and resource use during the establishment phase of direct-sown grassland. We did this by sowing a representative suite of species (at varying levels of species number and functional group number) into experimental plots and then measuring and analysing the extent to which the newly established assemblages captured available resources, i.e. used soil nitrate, absorbed light and produced biomass (vegetative cover). Statistically significant correlations were common between the predictor variables (species number, functional group number, percentage vegetative cover, plant number, presence of idiosyncratic (dominating) species) and responses (soil nitrate concentration, light reduction or ‘extinction’). Higher diversity was associated with lower soil nitrate, while percentage vegetative cover and the presence of idiosyncratic species best predicted light extinction. The relationship between diversity, and plant biomass (measured as vegetative cover) and plant number was positive in the first year of the study. The diversity/biomass relationship became negative in the second year due to the higher numbers and cover of ‘idiosyncratic’ species. The diversity/plant number relationship also became negative in the autumn of the second year and was reduced to a trend by the winter. We found that lower nitrate and increasing plant numbers and vegetative cover were most strongly linked to increasing species number in the early stages of this study. This suggests that introducing and maintaining high diversity early in a native grassland reassembly or enhancement project will improve the resistance (e.g. to weed) of these communities. At later stages of grassland development, this function may be provided by the more dominating idiosyncratic species. The maintenance of diversity, an important goal in its own right, will therefore necessitate managed disturbances to periodically reduce the vegetative dominance of idiosyncratic species, releasing resources for the diverse range of other species whose early introduction will have allowed them to persist in the soil seed bank or as suppressed rootstocks.