FERTILIZATION AND IRRIGATION EFFECTS ON THE GERANIUM-HEDYSARUM MEADOWS, NORTHWESTERN CAUCASUS, RUSSIA
We investigated the response of alpine highly productive plant community to soil nutrient addition and irrigation. A 10 year experiment - including additions of calcium, phosphorus, nitrogen, phosphorus + nitrogen and irrigation - was conducted in northwestern Caucasus, Russia, at 2800 m above sea level. We found out that above-ground biomass did not change significantly. But the biomass increased by 25% in case of the treatment with calcium addition compared with the control, also the floristic richness in this treatment was not changed. Biomass of the main dominant <i>Geranium gymnocaulon</i> doubled in Ca and NP. <i>Campanula tridentata, Carum meifolium, Euphrasia ossica </i>and <i>Matricaria caucasica</i> increased in Ca; <i>Geranium gymnocaulon </i>in Са and NP; <i>Gagea fistulosa </i>in NP; <i>Agrostis vinealis </i>in N and NP; <i>Carex atrata, Nardus stricta </i>in N; <i>Phleum alpinum </i>in Р; <i>Leontodon hispidus </i>in irrigation treatment. Above-ground biomass of separate species was changed due to the number or mass of shoots changing. Biomass of <i>Geranium gymnocaulon </i>was<i> </i>changed mainly due to the mass of shoots changing, and on the contrary <i>Hedysarum caucasicum - </i>due to the shoot number changing. Sedges had a positive response to N. Legumes had a negative response to NP, N and Ca.