Influence of the Dominant Grass Festuca varia Haenke on the Spatial Pattern of Alpine Grasslands in the Northwestern Caucasus, Russia

Abstract

The influence of the dominant tussock grass Festuca varia Haenke on the species growing in its vicinity was investigated. Festuca varia forms round tussocks on gentle slopes and rows on steep slopes. The two forms differed in their effect on community structure and species composition. When tussocks were arranged in rows, different environmental conditions above and below the row were observed. Dense litter and shoot cover below the row change considerably the environment for the plants, so that species number above the row was higher than below the row. The distance between neighboring rows and row width determined also the species number in spaces between the rows. Round tussocks influenced other species mostly through litter production; distance to the neighboring round tussock was another determinant of species number. The number of species recorded within tussocks was lower than between them. However, 25% of the studied tussocks were inhabited and not less than 14 species was found within them. Festuca varia mostly limited species number and cover on a small scale, but did not influence the overall species composition in the grasslands. The pool of diaspores of accompanying species from the patches within the community may support the populations in the vicinity of F. varia tussocks.