1. N fix and turnover
To address HP1, we will quantify N fixation rates in feather mosses along a post-fire successional chronosquence and along a natural fertility gradient, we will also sample surface humus and soils for C and N content, soluble N and C, and in-situ N mineralisation. These measurements will allow us to relate N fixation rate to site fertility.
We will take intact cores of understory vegetation and soils to use in laboratory incubations to determine the role of disturbance, e.g. drought, on the release of N from mosses.
3. Isotope dilution
15N pool dilution will be used to quantify gross nitrification and consumption in the humus layer along the fire chronosequence. These measurements will allow us to relate inorganic N and turnover to time since disturbance