17:15 〜 19:15
[ACG46-P09] How do seasonal patterns in precipitation affect the productivity and forage quality of Mongolian grasslands with different livestock exclusion periods?
キーワード：降水量、乾燥地、草原生態系
Seasonal precipitation patterns are known to have a significant impact on the productivity of grasslands. However, there is a lack of research on the impact of such precipitation patterns on the productivity of grasslands under livestock grazing. The response of grassland productivity to precipitation patterns will be determined by changes in vegetation species composition with grazing intensity and the species-specific responses to precipitation patterns. In this study, we tested the response of grassland productivity to seasonal precipitation patterns in Mongolian grasslands with different livestock exclusion periods.
This study was conducted in a semi-arid grassland ecosystem in Bayan-Unjuul (47°02'32" N, 105°56'58"E) in central Mongolia. We conducted experiments in grasslands with three different grazing exclusions, 20-, 5-, and 1-year grazing exclusion periods. In May 2023, four water addition treatments (n = 6) were established at each site: control as no addition (C), spring addition (SP), summer addition (SU), and spring/summer addition (SS). In 2023, the water equivalent to 20 mm of precipitation was added in mid-May and early July to SP and SU, respectively. For SS, water equivalent to 10 mm of precipitation was added in mid-May and early July. In 2024, the amount of water was two times larger compared to 2023 which was applied to each water addition treatment at each site.
In 2023, no significant difference in aboveground biomass was observed among water treatments at each of the three sites. In 2024, the response of aboveground biomass to seasonal precipitation patterns varied with different grazing exclusion periods. While there was little difference between treatments at the 1-year site, it was observed that SS exhibited numerically higher biomass production values compared to both SP and SU at the 20- and 5-year sites. This discrepancy was attributed not to the grasses, but rather to variations in the biomass of semi-shrub species such as Artemisia adamsii and Artemisia frigida. Our results suggest that the response of grassland productivity to seasonal precipitation patterns would be larger in grasslands with lower grazing intensity. Furthermore, semi-shrub species exhibit more sensitivity to precipitation patterns, which can encourage the spread of species such as A. adamsii, which are less palatable to livestock, thus reducing pasture quality.
This study was conducted in a semi-arid grassland ecosystem in Bayan-Unjuul (47°02'32" N, 105°56'58"E) in central Mongolia. We conducted experiments in grasslands with three different grazing exclusions, 20-, 5-, and 1-year grazing exclusion periods. In May 2023, four water addition treatments (n = 6) were established at each site: control as no addition (C), spring addition (SP), summer addition (SU), and spring/summer addition (SS). In 2023, the water equivalent to 20 mm of precipitation was added in mid-May and early July to SP and SU, respectively. For SS, water equivalent to 10 mm of precipitation was added in mid-May and early July. In 2024, the amount of water was two times larger compared to 2023 which was applied to each water addition treatment at each site.
In 2023, no significant difference in aboveground biomass was observed among water treatments at each of the three sites. In 2024, the response of aboveground biomass to seasonal precipitation patterns varied with different grazing exclusion periods. While there was little difference between treatments at the 1-year site, it was observed that SS exhibited numerically higher biomass production values compared to both SP and SU at the 20- and 5-year sites. This discrepancy was attributed not to the grasses, but rather to variations in the biomass of semi-shrub species such as Artemisia adamsii and Artemisia frigida. Our results suggest that the response of grassland productivity to seasonal precipitation patterns would be larger in grasslands with lower grazing intensity. Furthermore, semi-shrub species exhibit more sensitivity to precipitation patterns, which can encourage the spread of species such as A. adamsii, which are less palatable to livestock, thus reducing pasture quality.