Vegetation of sandy outcrops in Pechora tundra

The paper deals with the syntaxonomy of vegetation on the sandy outcrops in the Pechora (Malozemelskaya and Bolshezemelskaya) tundra. The vegetation was classified using the Brown-Blanke approach. Communities were referred to 3 associations: Arctostaphylo alpini—Empetretum hermaphroditi (Zinserling 1935) Koroleva 1994, Elymo—Festucetum arenariae (Regel 1923) Nordhagen 1955 and Rumici graminifoliae—Festucetum sabulosae ass. nov. Five new variants were suggested within the first association and 2 subassociations and 4 variants within the last one. Syntaxon description and phytocoenological tables are presented. The vegetation on each sandy outcrops represents a complex of communities fragmentary located on the scars area. Subass. inops of ass. Rumici graminifoliae—Festucetum sabulosae is more common in the Ortina river basin and occurs at the bottom of blowing hollows. Syntaxa of ass. Elymo—Festucetum arenariae and var. Festuca rubra of ass. Rumici graminifoliae—Festucetum sabulosae are situated at the mobile sands in the central part, while var. Arctous alpina of ass. Rumici graminifoliae—Festucetum sabulosae occurs on a periphery of out­crops where substratum is stable. The variants inops and typicum of ass. Arctostaphylo alpini—Empetretum hermaphroditi occuring in the Sedujyakha river basin occur mostly in the centre of sandy outcrops, and the other ones can be met on their periphery. Ecological conditions determine poor diversity of syntaxa of the association level. Geographical position (the Sedujyakha river basin belongs to the northern hypoarctic tundras, the Ortina river basin — to the southern hypoarctic ones), geomorphology (in the first site — tops of hills and ridges, in the second one — watershed areas) and area of sandy outcrops (200—3000 m2 for the first and 61000—418000 m2 for the second site respectively) are the reasons for the less diverse communities found in each study site. A great number of variants is conditioned by succession stages of vegetation and instability of the substrates.