Doubling the estimate of invertebrate biomass in a rainforest canopy

Forest canopies represent the functional interface between 90% of the Earth's terrestrial biomass and the atmosphere(1) and include some of the most threatened of all terrestrial ecosystems(2). However, we lack even a basic understanding of how the biomass of plants and animals is distributed throughout forest canopies, even though this information is vital for estimating energy flow, carbon cycling, resource use and the transfer of materials within this ecosystem(3,4). Here we measure the biomass of invertebrates living in a common rainforest epiphyte, describe a striking relationship between fern size and the biomass of animals within the ferns, and reveal that one large epiphyte may contain an invertebrate biomass similar to that found in the whole of the rest of the tree crown on which it is growing. Using these data, we show that including the fauna of these epiphytes-a neglected component in rainforest ecosystems-can more than double our estimate of the total invertebrate biomass in an entire rainforest canopy.