Effects of small-herbivore disturbance on the clonal growth of two perennial graminoids in alpine meadows

Graminoids are typically the dominant plants in certain grassland communities, and their clonal growth is considered an important method of evaluating their adaptation to environmental disturbances. Whether disturbances caused by small burrowing herbivores influence clonal growth in graminoids is not well documented. A field experiment was conducted to investigate the effects of disturbances by small burrowing herbivores, the plateau pika, on the clonal growth of the tussock-forming Kobresia pygmaea and the rhizomatous K. humilis across three sites. This study showed that disturbance by plateau pikas increased the shoot number, spacer number and tiller bud number per clonal fragment of both the tussock-forming K. pygmaea and the rhizomatous K. humilis across three sites. This study also showed that disturbance by plateau pikas increased the rhizome branch number, rhizome length, and rhizome bud number per clonal fragment of rhizomatous K. humilis at each site, while the effects of disturbance by plateau pikas on the rhizome branch number, rhizome length, and rhizome bud number per clonal fragment of the tussock-forming K. pygmaea were different among the three sites. These results suggested that disturbance by plateau pikas benefits for current and potential population recruitment in the tussock-forming K. pygmaea and the rhizomatous K. humilis due to the resulting higher shoot number and tiller bud number per clonal fragment.