Структура, разнообразие и продукция леймусовых сообществ (Leymus chinensis ((Trin.) Tzvel.) южной части Восточного Забайкалья

Abstract

The study of the steppe gramineous communities with Leymus chinensis (Trin.) Tzvel as a monodominant that vegetate on different soil types of meadow and haloxerophytic steppe and steppe floodplain grasslands within the southern part of Eastern Transbaikalia was performed for the first time. Species composition of Leymus communities is represented by 21 families, 45 genera and 62 species, accounted for 11,3% halophytes, 29% – halotolerant, and 59,7% – glycophytes. Multispecies families are Asteraceae (19), Poaceae (11), and Rosaceae (5). Artemisia (9) and Potentilla (4) are multispecies genera, each of Heteropappus, Poa, and Carex genera had 2 species, and the rest are single-species.L. chinensis as edificator mainly formed the projective cover of communities (40- 80%) that is determined by the soil and ecological conditions of its growth. The community dominant has been established to belong to the forest-steppe group, to be a xeromesophyte, of Central Asian type of areal and represented by long-rhizome biomorphs. It is the positive feature for the effective use of mineral fertilizers. The similarity between communities is in the range of weak to medium due to the significant part of single-species families and genera. Leymus communities are attributed mainly to steppe complex with different variants of xerophytes of Asian type of areal. The main part of biomorphs is represented by rhizomatous species, and the share of perennials is also significant. The similarity between communities was evaluated as weak – medium due to a large number of single-species families and genera. Primary production of L. chinensis communities was estimated to be high (2105-3189 g/m2 per year). The contribution of L. chinensis and each of its components (stems, leaves, ears) separately to the above-ground mass, as well as the role of other species (cereals, sedges, legumes, forbs), united in the group of forbs, was determined first. An assessment of the seasonal rag accumulation, depending on the soil and ecological conditions is given. The largest part of ears in aboveground phytomass was noted only in two communities (4 and 5). The coefficient of seed productivity had the maximum value (52-58%) in descriptions 3 and 4, in the rest – 7,5-14%, caused by adaptation of the species to the long-term climate change, due to increased reserves of nutrients that provide energy for vegetative growth and reproduction, reducing the generative. The underground phytomass consist of 84-94% of the total productivity. Depending on the soil-ecological conditions, the excess of underground phytomass over above-ground varies within 1:5-15. In perspective, the development of a system of rational use and mineral fertilizers application of that increase and improve the productive process in the soil-plant system is required to increase and preserve the productive longevity of Leymus communities in Eastern Transbaikalia.