A Comparison of Vegetation Development on Coarse Coal Reject and Replaced Topsoil on an Open-Cut Coal Mine In Central queensland, Australia

摘要

In 1988, the University of queensland commenced a research program at Curragh coal mine in the bowen Basin of central Queensland to examine factors that would encourage the growth of a cover crop sufficient to control soil erosion, but not so competitive as to hinder the establishment of native species. Weed and grass growth from the soil seed store in replaced topsoil often has a negative impact on the establishment and survival of sown native tree and shrub species. In contrast, good establishment has been achieved using a surface mulch of coarse coal reject. Longer term data confirm the beneficial effect of coarse coal reject, with approxiamtely 4500 trees/ha on coarse reject after 10 years compared to 300 trees/ha on replaced topsoil. The difference is attributed largely to the competitive effects of the dense ground cover on topsoil at initial establishmetn. Howeve,r there are two potnetial problems for the long-term sustainability of communities on coarse coal reject. Firstly, reject is very low in utrients and microbial biomass, limiting the satisfactory development of nutrient cycling. Secodnly, it is often salien and will be likely to continue to generate salt with weatheirng, raising concerns over the success of secondary recruitment. It is concluded that coarse coal reject can play a role in successful tree and shrub establishment and hence in increasing the diversity of post-mining ecosystems. However, careful management is required to avoid the use of saline materials, and strategies need to be explored to increase its biological activity.