This dataset measures the decomposition of experimental wood blocks, Pinus radiata, over a period of one year in lowland, old growth, tropical rainforest. Wood blocks are placed on the ground or suspended above the ground in mesh bags that either allow or prevent entry of macro-invertebrates. The decomposition of ground placed wood blocks is measured during a period of drought and non-drought. Dry weight of wood blocks is measured at the start and end of the year and proportional weight loss is calculated. Accompanying decomposition data is a data set measuring temperature and relative humidity at 5 m vertical intervals from the ground to the canopy. This data is a contribution from the UK NERC-funded Biodiversity And Land-use Impacts on Tropical Ecosystem Function (BALI) consortium (http://bali.hmtf.info).