# Effects of different combinations of pre‐ and post‐grazing heights on herbage mass and nutrient reserves of Leymus chinensis in Northeast China

## TL;DR

This study finds that preserving the growing tip of Leymus chinensis plants improves grassland health and productivity compared to removing it.

## Contribution

The study identifies an optimal grazing management strategy for Leymus chinensis by preserving the apical meristem at specific pre- and post-grazing heights.

## Key findings

- Preserving the apical meristem at 35 cm pre-grazing and 17 cm post-grazing height maintains biomass without significant loss.
- Apical meristem removal increases nutritive value but reduces carbohydrate reserves and herbage mass.
- Preservation treatments yielded higher crude protein over two years compared to removal treatments.

## Abstract

The preservation or removal of apical meristem in Leymus chinensis is contingent upon grazing intensity and has a significant impact on above‐ and belowground biomass, nutritive value, and sustainability of L. chinensis grassland. However, this topic remains understudied. Therefore, a manipulative trial was conducted to induce grazing defoliation through mowing, where two post‐grazing heights (preservation or removal of the apical meristem) and four pre‐grazing plant heights (i.e., 18, 24, 31, and 35 cm) are combined factorially to create gradients of grazing intensities, resulting in a total of eight treatments. Additionally, two identical control treatments are also incorporated. Our results showed that apical meristem removal at various pre‐grazing heights resulted in varying degrees of increased grazing intensities, thereby enhancing the nutritive value of L. chinensis. However, this practice also led to detrimental effects on the plant's carbohydrates reserve as well as herbage mass. The results indicated that although defoliation in treatments involving apical meristem removal resulted in the highest number of frequent cuttings, it did not confer any advantages in terms of herbage mass and nutrient preserves, except for herbage nutritive values when compared to treatments involving apical meristem preservation. The apical meristem preservation treatments demonstrated the highest CP yield over a 2‐year period compared to the apical meristem removal treatments. Furthermore, within these apical meristem preservation treatments, only when the pre‐grazing height is 35 cm and post‐grazing height is 17 cm, there is no significant decrease in above‐ and belowground biomass. This establishes this specific defoliation regime as an optimal and effective management strategy for L. chinensis grassland.

The apical meristem plays a crucial role in the growth of L. chinensis, as its removal leads to death and reproduction through tillers, while its preservation ensures survival and continued growth via regenerative properties. Our findings suggest that preserving the apical meristem of L. chinensis leads to increased herbage mass and greater persistence of L. chinensis grassland, in contrast to removing it.