Influence of soil nutrient availability on generative production in an alpine heath, the North-Western Caucasus

Abstract

An alpine lichen heath response to changes in the soil nutrient and water availability was examined, focused on changes in generative production (number of generative shoots and seed production). A four-year experiment was conducted at a lichen heath at approximately 2,800 meters above sea level. The experimental treatment consisted of Ca, P, N, NP amendments and irrigation. The experiment indicated that the generative production of alpine heath plants was strongly affected by nutrient availability. All graminoids analyzed in the experiment (Festuca ovina, Helictotrichon versicolor, Luzula spicata and sedges) showed a strong positive response to the NP-treatment. Alchemilla caucasica and Ranunculus oreophilus were positively affected by the NP treatment, Trifolium polyphyllum and Anemone speciosa by the N treatment and Antennaria dioica by the P treatment. Irrigation did not have any effect on generative shoot abundance, except for Euphrasia ossica, which showed a strong increase. Fertilization had significant effects on seed production, which however did not directly correlate with changes in abundance of generative shoots. NP treatment increased seed production of Festuca ovina and decreased seed production of Campanula tridentata. Irrigation, P and Ca treatments lead to an increase in seed production of Anemone speciosa. Seed production of Carum caucasicumdecreased in response to all the treatments.