Correlation between perennial grass productivity and landscape and climatic conditions

The yield monitoring (1998–2023) of cloverothymothy grass stands of 1 year of use within the moraine hill was carried out in order to find patterns in the influence of weather conditions on it. The grass stands were operated in the conditions of the Tver region without fertilizers in a single-cut mode on a field divided into 120 plots. Using regression analysis, we determined the influence of temporal variability of average monthly values: average daily temperatures, their amplitude, amount of precipitation and hydrothermal coefficient on the hay yield of perennial grasses. It was revealed that in total these parameters determine about 43% of the variability in grass productivity, but fluctuations in temperature amplitudes are responsible for 32% of the temporal variability of the yield. The yield of herbs is affected by the variability of growing conditions not only in time, but also in space. The negative impact on the yield of air temperature changes is observed in all parts of the landscape, except for the flat top, where productivity responds positively to the growth of the hydrothermal coefficient and negatively to the increase in air temperatures in the pre-harvest period. The following have a negative impact on product yield: temperature changes in late summer and early autumn, especially on southern slopes, which can make it difficult for plants to overwinter; thaws in March, causing the formation of an ice crust on the soil surface and damaging the tillering nodes of plants; hot days in the pre-harvest period, accelerating the ripening of grasses and reducing the intensity of biomass accumulation. February thaws, promoting the accumulation of moisture in the soil, lead to an increase in grass yield. Measures that reduce the negative impact of temperature changes on the grass harvest include: autumn mowing of young grass, snow retention in meadows, and sprinkling of grass on the hottest days of the pre-harvest period.