Growth response of rainforest cabinet timber species to fertiliser application in North Queensland plantations

Declining supplies of cabinet-timber from natural stands of tropical rainforest combined with an increasing global demand for all classes of timber has given rise to a significant interest in developing plantations of high-value cabinet timber species in many parts of the tropics. In many cases the plantations are being established on land with low inherent fertility or sites that have been degraded as a result of poor landuse practices. The use of fertilisers has the potential to increase the production on these sites, but our understanding of the rates, timing and types of fertiliser to use with different species on different soil or site types is poor. This paper describes results of experiments at three sites in the wet tropics of north Queensland with similar soil types to sites being used for plantation establishment in South East Asia. The experiments aimed to determine the response to varying rates of P fertiliser in three high-value rainforest cabinet timber species, the Australian natives: black bean (Castanospermum australe Cunn. ex C. Fraser), and kauri pine (Agathis robusta (C. Moore ex F. Muell.) Bailey) and the exotic West Indian cedar (Cedrela odorata L.). Responses to fertilisation varied between sites and between species. There was a more pronounced response to fertilisation on coarse-textured soils derived from granite parent materials than on finer extured soils derived from metamorphic or basalt substrates. We discuss these results in light of their implications for plantation management and for the design and implementation of further nutritional research.