[Fine root nitrogen contents and morphological adaptations of alpine plants].

Nitrogen and carbon contents of fine roots were studied for 92 alpine plant species in the Northwest Caucasus. Nitrogen content ranged from 0.43% (Bromus variegatus) to 3.75% (Corydalis conorhiza) with mean value 1.3%. Carbon content ranged from 40.3% (Corydalis conorhiza) to 51.7% (Empetrum nigrum) with mean value 43.4%. C:N ratio was found to be 34:1 which is higher than the worldwide mean. Eudicot's roots had higher N concentration (1.37 +/- 0.07) than monocot's ones (0.95 +/- 0.09). Among the life forms, carbon content increased in the following order: geophytes < hemicriptophytes < chamaephytes. Specific root length positively correlated with nitrogen root content and negatively--with carbon root content. Species with larger leaves and higher specific root area had more nitrogen and less carbon in roots in comparison with species with small leaves. There were positive correlations between leaf and root nitrogen, as well as carbon, contents. Regrowth rate; seed size, aboveground biomass, and vegetation mobility were not related with root nitrogen content. Our results corroborate the poor and rich soil adaptation syndromes. Species of competitive and ruderal (sensu Grime) strategies are more typical for alpine meadows and snow bed communities. They had higher nitrogen contents in leaves and roots, larger leaves with higher water content and higher rate of seed production. On the other hand, stress-tolerant plants had higher carbon and less nitrogen concentrations in their roots and leaves, smaller leaves and specific leaf area.

[Changes in eco-morphological parameters of alpine plants' leaves as an effect of fertilization].

Plants growing on rich soil usually have thin leaves with large specific leaf area. On the other hand, at intraspecific level; soil fertilization results in leaves size increasing which, in turn, can lead to reduction in specific leaf area. To what extent soil fertilization implies only leaves increasing in size and does not affect other eco-morphological characteristics is a question that is still open. To assess coherence between plants intraspecific reactions to changes in soil richness and general tendencies in changes of leaves parameters in communities with different productivity, an experiment has been conducted in alpine plant communities of the north-western Caucasus. Changes in leaf traits are studied in four types of alpine plant communities after long term application of mineral nutrients (NP and lime treatment). It is shown that in all species, except legume Hedysarum caucasicum, fertilization results in size leaf characteristics (leaf area, wet and dry mass) increase. Specific leaf area appears to decrease in plants inhabiting alpine heathlands and increase in plants inhabiting alpine snow beds and in dominant species of Geranium-Hedysarum meadows, Geranium gymnocaulon. After correction of specific leaf area that accounts for changes in leaf size, it becomes discernable that in most species the increase in leaf area per se results in specific leaf area reduction while changes in leaf structure under influence of fertilization leads to this trait increasing. Those species demonstrating the increase in specific leaf area as an effect of fertilization, also gain more in terms of biomass.