Not our cup of tea: the Tea Bag Index (Kueskamp et al. 2013) for assessing decomposition is problematic in most environments, due to macrofauna

1. The Tea Bag Index (Keuskamp et al. 2013) has been developed to allow worldwide comparable data on litter decomposition and has become an important part of several citizen science projects. This commentary shows that it is unsuitable for assessing total decomposition in most environments as it does not account for the role of macrofauna in the decomposition process. 2. Tea bags were placed following the standardised protocol in old growth forest in Borneo (Sabah, East Malaysia). 3. The results shows that more than half of the bags were attacked by termites and they tended to remove the majority of the tea, rendering the Tea Bag Index incalculable. 4. The Tea Bag Index can measure the microbial component of decay, but will significantly underestimate total decay rates in most environments. This method will not give an accurate estimate of decomposition in most biomes.