Biological and ecological strusture and dynamics of meadow communities in the south of Sakhalin Island

The study of the species composition and productivity of meadows is important from a fundamental and applied point of view. On Sakhalin Island, meadows used as hayfields and pastures are often of secondary origin. The study of the dynamics of the species composition and productivity of meadows was carried out at four key sites (agricultural and natural meadows) in the southern part of Sakhalin Island in 2022–2024. Geobotanical descriptions, analysis of the biological and ecological structure, and selection of aboveground phytomass (green mass and mortmass, including mulch and dead grass) were performed. The hay harvest was air-dried and weighed; the results were analyzed taking into account the weather conditions of the respective years. It was found that the species composition is in constant dynamics, periodically there is a change of dominant species or there is an increase in the number of species due to an increase in the contamination of meadows. A low percentage of leguminous crops was recorded in the herbage of all key sites, which leads to an insufficient protein content in the feed. The absence of Carex sp. is also noted on agricultural meadows. Of the ecological groups represented, eumesophytes are the most common. Meadows are also represented by species of xeromesophytes, hydromesophytes, hemihydrophytes, and hypohydrophytes. The productivity of grassland communities is high (values of green mass vary from 281.14 to 721.89 g/m2, dead grass – from 116.28 to 645.88 g/m2, the maximum mulch value was 406.56 g/m2). However, the herbage is uneven, which leads to large values of standard deviation. The values of aboveground phytomass can vary significantly from year to year, which is confirmed by statistical methods.