Nitrogen relations of ruderal communities (Rumicion alpini) in the Northern Calcareous Alps.

The total nitrogen and nitrate turnovers of three plots of plant communities typical of cattle resting sites in the Bavarian Alps were investigated. Annual net N mineralisation of the soil and N content of the above-ground phytomass at maximum development are low in the Senecio cordatus dominated community "W" at 1,450 m altitude (80 and 57 kg N/ha respectively) and highest in the nearly pure Rumex alpinus stand "K" (1,240 m) (156 and 148 kg N/ha). The subalpine mixed Rumex alpinus community "S" (1,790 m) is intermediate with low mineralisation but high N content in the aboveground parts (69 and 128 kg N/ha). In general the mineralisation values are below those from other comparable plant communities. The main component of N mineralisation is nitrification in all three plots.The nitrate content in the phytomass at full development increases from 0.1 g/m2 in W to 0.3 g/m2 in S and to 1.0 g/m2 in K. With one exception (Adenostyles alliariae) no species showed a real nitrate accumulation in the leaf laminae towards the end of the growing season.