Field decomposition rates of single and mixed litter species under two contrasting climatic zones – wet tropical and semi arid

Soil Organic Carbon (SOC) stock assessment remains a complex research frontier because of diversity and distribution of vegetation types, their associated carbon inputs and interactions with the soil and climatic environment that govern decomposition rates. In the context of mine land rehabilitation, there is an opportunity to establish vegetation communities with a strategic aim to rapidly enhance SOC accumulation. Hence, as an initial step towards determining the effect of vegetation type on the rate of SOC accumulation, this study compared field decomposition rates of leaf litter from a range of forest and pasture vegetation species under contrasting climatic regimes; wet tropical (Java, Indonesia) and semi-arid (Central Queensland). Litter from dominant vegetation community types, with and without nitrogen-fixing species, was placed in mesh litter bags and pegged onto the soil surface for 8 weeks (Java) and 12 weeks (Queensland), at each of a forest and pasture site, in each country location. Australian litter was taken to Java but not vice versa. Soil types at the sites were Vertosol (Central Queensland) and red Ferrosol (Java). Decomposition, measured by litter bag mass loss at set time intervals showed that under wet tropical conditions, Australian litter decomposed up to 41% faster than Indonesian in a forested situation and up to 17% slower in a pasture situation while mixed litter decomposed faster than single species by up to 18% in forest and 21% in pasture. Under semi arid conditions mixed litter decomposed faster than single species and litter in pasture decomposed faster than in forest