Abstract:

To scientifically assess the impact of meteorological conditions on the growth, development and yield formation of natural forage grasses in the Hulun Buir grassland, this study used daily meteorological data from six meteorological stations and ten−days of natural forage observations data in the Hulun Buir grassland from 1991 to 2024. Methods such as correlation analysis, cluster analysis and principal component analysis were employed to classify the suitability grades of meteorological conditions during each growth period of natural forage grasses, determined their significance in the yield formation process, and thereby constructed annual yield harvest status assessment models for natural forage grasses in typical steppes and meadow steppes. The results showed that: (1) the yield of natural forage grasses during the regreening, jointing−heading, flowering and grain ripening periods were positive correlation with precipitation and the number of days with daily precipitation ≥5mm, while negative correlation with effective accumulated temperature ≥10℃, sunshine duration and daily temperature range in the Hulun Buir grassland. (2) The weights of the meteorological condition suitability grades for the four growth stages on yield formation differed between typical steppe and meadow steppe. For meadow steppe, the order was flowering period (0.49) > jointing−heading period (0.24) > regreening period (0.15) > grain ripening period (0.13). For typical steppe, the order was flowering period (0.39) > jointing−heading period (0.26) > regreening period (0.19) > grain ripening period (0.17). (3) The fitting test using historical samples from 2021 to 2024 for the annual forage yield harvest status assessment model showed that the coefficients of determination (R²) for the meadow steppe and typical steppe assessment models were 0.77 and 0.76, respectively. Root mean square error (RMSE) values were 0.45 and 0.76, respectively. Validation against 24 historical samples showed that the model's predictions were consistent with the observed data in 22 cases, achieving an accuracy of 91.7%. 

Key words: Hulun Buir grassland, Meteorological suitability grade, Annual yield harvest status, Natural forage, Meadow steppe, Typical steppe