Almost 12.5% of the area in Queensland is under Mulga Lands. Owing to the enhanced rate of tree clearing to establish pastures and cultivate crops in the recent years, it is timely to quantify root and litter turnover under different land uses so as to assess their impact on greenhouse gases emission and mitigation and natural resource management.

Fine root production and turnover was calculated in four different land use systems (mulga forest, buffel pasture, lucerne pasture and wheat cropping) using a compartment-flow model. In the top 30 cm of soil, annual fine root production was highest in buffel grass (~ 2630 kg/ha/yr) which was 3.6 and 6.5 times higher than for mulga and lucerne pasture. However, annual fine root disappearance for lucerne was about twice as high as for mulga or buffel.

Field decomposition studies show that buffel and mulga root materials decomposed much slower compared to wheat and lucerne roots. Average biomass loss of ‘tops’ material per day was highest in lucerne followed by buffel, mulga phyllodes, wheat and mulga twigs. The decomposition rates of roots and litter from different vegetation sources appear to be a function of plant biochemistry and temperature and rainfall conditions in the field. Preliminary data analysis has suggested a negative relation between lignin and plant decomposition, however, developing a relationship between decomposition rate, plant biochemistry and climate data will assist us in understanding the decay cycle of plant material in different land use practices.