Effects of different rest grazing periods on the reproduction and root characteristics of Carex capillifolia in subalpine meadow

Abstract

Carex capillifolia is a dominant subalpine meadow plant species with considerable ecological and economic value. We studied the effects of different springtime rest grazing periods on C. capillifolia reproduction and the root characteristics. The rest grazing periods were established according to the soil thawing depth, plant regreening, and the local traditional rest grazing period. We set up five plots from the critical period of soil thawing (T1), the late period of soil thawing (T2), the early period of grass reviving (T3), the late period of grass growing (T4), and the local traditional rest grazing period (T5) to the start of the rest grazing. The end of the rest grazing in each plot was the plant withering period. Results showed that the sexual reproduction effort of T1 was 64.3% higher than that of T5. The root biomass of T5 was significantly lower than that of all the other treatments. The plant height, ear length, number of seeds per ear, reproductive branch density, and the seed yield of T1 were significantly higher than those of all the other plots. The reproductive branch density was significantly positively correlated with the seed yield. The seed yield of T1 was 200.0%, 349.1%, and 340.4% higher than those of T3, T4, and T5, respectively. The root length, surface area, and volume were the highest for T3. The root phenotypic traits and the nutrient storage content indirectly affected each other and jointly formed part of risk diversification strategies. A grey correlation analysis demonstrated that rest grazing during the critical soil thawing period (T1) was conducive to the growth of C. capillifolia. Therefore, springtime rest grazing should start from the critical soil thawing period in subalpine meadows.