Canopy uptake of $^{15}NH_{3}$ by four temperate tree species and the interaction with leaf properties

Tree canopies are believed to act as a sink of atmospheric ammonia (NH3). However, few studies have compared the uptake efficiency of different tree species. This study assessed the uptake of N-15-labelled NH3 at 5, 20, 50 and 100 ppbv by leaves and twigs of potted silver birch, European beech, pedunculate oak and Scots pine saplings in June, August and September 2008. Additionally, foliar uptake of C-13-labelled carbon dioxide ((CO2)-C-13) and leaf stomatal characteristics were determined per species and treatment date and the relation with (NH3)-N-15 uptake and estimated stomatal (NH3)-N-15 uptake were assessed. Both (NH3)-N-15 and (CO2)-C-13 uptake were affected by tree species and treatment date, but only (NH3)-N-15 uptake was influenced by the applied NH3 concentration. Depending on the treatment date, (NH3)-N-15 uptake by leaves and twigs was highest at 5 (September), 20 (June) or 50 (August) ppbv. Birch, beech and oak leaves showed the highest uptake in August, while for pine needles this was in June and, except at 5 ppbv in June, the (NH3)-N-15 uptake was always higher for the deciduous species than for pine. For all species except beech (CO2)-C-13 uptake was highest in August and on every treatment date the (CO2)-C-13 uptake by leaves of deciduous species was significantly higher than by pine needles. Leaf characteristics and (CO2)-C-13 uptake did not provide a strong explanation for the observed differences in (NH3)-N-15 uptake. This study shows that on the short-term a high interspecific variability exists in NH3 uptake, which depends on the time in the growing season.

Jaar van publicatie:2012

Trefwoorden:A1 Journal article

BOF-keylabel:ja

BOF-publication weight:1

CSS-citation score:1

Authors from:Higher Education

Toegankelijkheid:Closed