The History of Vegetation in Ulyanovsk and Its Environs

Abstract

The evolution of vegetation on the modern territory of Ulyanovsk and its surroundings, beginning from the late glacial period, can be presented as follows: 11 000–10 300 years ago, “tundra–steppe” with sagebrush–goosefoot, horsetail, fern, and undershrub–true-moss communities. 10 300–9500 years ago, sagebrush–goosefoot–grass cenoses and isolated islets of sparse pine forests. 9500–8500 years ago, sagebrush–goosefoot–grass and grass steppes and pine forests. 8500–8000 years ago, sod–grass and grass–herb meadow steppes and pine forests. 8000–6000 years ago, herb–grass, less often sod–grass meadow steppes, birch and birch–pine forests, the appearance of broad-leaved species. 6000–4500 years ago, pine–broad-leaved and broad-leaved forests, herb–grass meadow steppes, and maximum afforestation. 4500–3200 years ago, broad-leaved and pine–broad-leaved forests and the appearance of agrocenoses. 3200–2500 years ago, pine and pine–birch forests, reduction of broad-leaved species, expansion of sod–grass steppes and agrocenoses. 2500–700 years ago, appearance of secondary forests and meadow steppes (fescue and sagebrush–grass) and expansion of agrocenoses. 700–350 years ago, pine, pine–birch, and pine–broadleaf forests, reduction of agrocenoses. 350 years ago to the present time, a sharp forest decline, predomination of secondary pine, broad-leaved, small-leaved, and mixed forests and secondary meadow steppes, expansion of agrocenoses and residential areas. Thus, since the Late Ice Age period, the vegetation of the territory of Ulyanovsk and its environs has changed from steppe vegetation (11 000–8000 years ago) to the forest–steppe types (8000–700 years ago) and then back again to the steppe type (700 years ago–present time). The least afforestation of the territory was observed 11 000–9500 years ago (3–4%) and in the period from 350 years ago to the present time (6–7%). The greatest afforestation of the forest–steppe was observed 6000–3200 years ago, when the forest-to-steppe ratio was equal.