Time for tea! Exploring rates of carbon decomposition in different saltmarsh community types.
As part of the Victorian Coastal Wetland Restoration Program, researchers in the Blue Carbon Lab are studying how carbon retention varies among saltmarsh community types. This information is important when planning the restoration of coastal wetland habitats.
Following the TeaComposition H2O protocols, it involves a novel, scientific technique for measuring carbon decomposition at low cost with the use of tea bags (Keuskamp et al. 2013).
In early March 2020, the BCL team buried 240 tea bags (120 green tea and 120 rooibos tea) in 6 different saltmarsh community types including herbland, tussock, coastal dry, hypersaline, shrubland and salt evaporation ponds.
The team will go back and collect the tea bags over the course of the next 12 months. The trick is to ensure that the location of the tea bags deployed is adequately marked so that they can easily be found and retrieved after 1, 3, 6, and 12 months. Every time we return to find our tea bags there seems to be a surprise! Last time, one of our tea bags was pushed out of the mud by a crab, and another was half gone from a bite mark.
When tea bags are collected from the field, they are brought to Deakin’s laboratory and washed to remove sediments and roots as best as possible. Once the tea bags are clean, they are dried in an oven at 60oC for several days until the tea is dry. The tea is then removed from the bag and inspected to remove any roots that may have grown into the tea. Once the tea has been sorted through, it is weighed and the weight is recorded in our data spreadsheet.
Once we have retrieved and weighed all the tea bags deployed we will then process the data and calculate the carbon decomposition rates from the different saltmarsh community types. If there is little tea left, it means that the microbe community present is very active and can rapidly munch the organic carbon (e.g. tea) available in the saltmarsh soil. If a lot of tea remains it means that the microbe activity is quite slow and that blue carbon is being stored.