Budgets of nitrogen fluxes in riparian grey alder forests.
Löhmus, Krista; Kuusemets, Valdo; Ivask, Mari; Teiter, Sille; Augustin, Jürgen; Mander, Ülo
Transects were established on two hillslopes and two study nitrogen budgets in two complex riparian buffer zones receiving different nitrogen loading. In the heavily loaded site the average total-N content decreased from 23 mg l-1 to 3.1 mg l-1 in a 40-years-old riparian grey alder forest (80 % removal). At the site with low loading the average removal of total-N was 48 %. In both transects the budget of N fluxes was established. In the older forest it was estimated as high as 321.1 kg ha-1 yr-1, being 285.3 kg ha-1 yr-1 in the younger one. Considering all inputs and outputs, the N removal efficiency in grey alder stands slows down with increase of age. In the same time, immobilization in soil is increasing. This suggests that grey alder buffer communities should be managed by regeneration cutting and tending to keep their nitrogen removal rate high.