Journal of Tropical Ecology (2006) 22:177–189. Copyright © 2006 Cambridge University Press doi:10.1017/S0266467405003020 Printed in the United Kingdom Litter production, decomposition and nutrient release in cleared and uncleared pasture systems of central Queensland, Australia Kamaljit K. Sangha ∗1 , Rajesh K. Jalota † and David J. Midmore ∗ ∗ Plant Sciences Group, Primary Industries Research Centre, Central Queensland University, Rockhampton, Queensland 4702, Australia † Centre for Environment Management, Central Queensland University, Emerald Campus, Queensland 4720, Australia (Accepted 1 September 2005) Abstract: The temporal impact of clearing trees on litter production, litter decomposition and on C, N and P release through decomposition of litter was examined in the pasture systems of a semi-arid zone of central Queensland. Paired sites for cleared pastures (developed from clearing woodlands) and uncleared (intact woodland) pastures were selected to represent three dominant tree communities of the region i.e. Eucalyptus populnea, E. melanophloia and Acacia harpophylla, with three different time-since-clearing (5, 11–13 and 33 y) treatments. Yearly litter production was greater at uncleared sites (1732–1948 kg ha −1 y −1 for eucalypt and 2596 kg ha −1 y −1 for acacia communities) compared with cleared sites (1038–1282 kg ha −1 y −1 for eucalypt and 1100 kg ha −1 y −1 for acacia communities averaged over three time-since-clearing treatments). Rates of litter decomposition and of release of C, N and P from decomposing litter were higher at cleared than uncleared sites for all three tree communities. The cleared and uncleared sites did not differ significantly in total amount of C and N released per year since the concentrations of C and N were greater in litter from uncleared sites but the rate of release was less than that at cleared sites. Slow but continuous release of nutrients in eucalypt and acacia woodlands may be an adaptation of these communities to maintain the nutrient cycle and to avoid leaching of nutrients in the nutrient-poor soils of the region. Key Words: Litter decomposition, litter production, nutrient release, pasture systems, tree clearing INTRODUCTION Litter maintains nutrient and energy flow at the soil–plant interface, provides habitat for various soil organisms and protects soil from erosion. Agren & Bosatta (1996) described litter as ‘the bridge between plant and soil’. Litter production and decomposition varies with climate, season, substrate quality and type of vegetation (Hobbie 1992, Melillo et al. 1982, Upadhyay et al. 1989, Vitousek et al. 1994). Chemical composition of litter, which changes with type of plant com- munity, influences structure and activity of microbial communities inhabiting soils (Kutsch & Dilly 1999), and biological and physicochemical properties of topsoil (Heal & Dighton 1986). Knowledge of litter production and decomposition rates is important when estimating 1 Corresponding author. Kamaljit K. Sangha, Natural Resource Econo- mist, School of Business, James Cook University, Townsville 4811, Australia. Email: kamaljit.kaur@jcu.edu.au nutrient turnover, C and N fluxes, and C and N pools in different ecosystems. Conversion of woodlands/forests to open grasslands may negatively impact litter production and decomposi- tion at the expense of quick monetary gains obtained from increased production in cleared pastures. The change in vegetation structure from woodlands to open grasslands may not only lead to changes in quantity and composition of litter, but also to other ecosystem properties (e.g. soil microclimate, Vetaas 1992; and nutrient return, Kochy & Wilson 1997) that could influence ecosystem processes. In Queensland, 80 million ha of woodland communities (∼ 48% of the total area of the state) are used mainly to graze cattle for beef production. Since the beginning of the last century until 1985 various governmental policies and incentives for settlement schemes encouraged clearing of these woodlands on a large scale, to develop land for exotic pastures and cropping (Boulter et al. 2000). Clearing of woodlands continues at a high rate (528 000 ha y −1 cleared during 2001–2003; Depart- ment of Natural Resources and Mines 2005) to develop pastures. The economic gain from enhanced pasture