Influence of alpine plants on soil nutrient concentrations in a monoculture experiment

The ability of different alpine species to influence soil nutrient concentr ations was quantified by growing monocultures of 17 species on a homogenize d acid alpine soil mixture. The experiment was carried out at 2750 m a.s.l. in the Teberda Reserve, Northwest Caucasus. Soil nutrient contents (NH4, N O3, P, Ca, Mg, and K) and pH were analyzed after 6 years. The same soil mix ture but without plants was used as a control. The plant species had signif icant effects on all soil proper-ties. Different species groups tended to d ecrease different nutrients to different extents, e.g. Matricaria caucasica had the lowest level for NO3 and Festuca ovina for P. Many species increas ed the cation content (Ca, Mg, K) in the soil in comparison with the contro l. Prevention of cation leaching seems to be the main mechanism of these in creases, because initial cation contents were higher than the final. All sp ecies, except Sibbaldia procumbens, increased soil pH in comparison with th e final control. Significant differences among taxonomic groups (families) were found for exchangeable Ca, Mg, and pH. Fabaceae decreased cation conte nts (Ca, Mg), but tended to increase nitrogen (NH4, NO3). Cyperaceae (Carex spp.) tended to decrease ammonium content, and both Asteraceae and Cyperac eae tended to decrease nitrate concentrations. The phosphorus content tende d to be reduced by grasses. There was no strong correspondence between prop erties of native soils of 4 alpine communities and nutrient concentrations for species preferring those communities.