Livestock grazing ingestion suppressed the dominant species population (Stipa aliena) germination: a laboratory experiment

Abstract

Grazing has an important effect on population dynamics in grassland vegetation. This paper aims at providing information on the impact of livestock ingestion on seed germination in a Tibetan meadow. We conducted a laboratory germination experiment in which Stipa aliena seeds were treated by yak and Tibetan sheep rumen fluids and yak dung extract with undiluted, 1-fold and 10-fold diluted solutions. The results showed that seed germinability was restrained in all these treatments. In the control treatment, 66.2% of the seeds germinated, while there was almost no S. aliena germination in the undiluted and 1-fold diluted solutions of both yak and Tibetan sheep rumen fluids. Yak dung extract had relatively less effect on seed germination. Additionally, the primary effect of rumen fluid seems to be that it kills part of the seeds rather than delaying germination. Seed death may be due to the acidity of the fluid or/and due to the effect of microorganisms in the fluid. The negative effects of livestock digestive juices on S. aliena germination may constitute a mechanism explaining the population dynamics in alpine meadows of the Qinghai-Tibetan Plateau.

Ensiling, In Vitro Rumen Digestion and Soaking in Slurry Altered the Germination Capacity of Rumex obtusifolius Seeds

“…Several authors found in similar experiments that the seeds of Stipa aliena [30], Saussurea japonica and Saussurea iodostegia [31] and Vicia angustifolia [29] exposed to microbial digestion in the rumen did not germinate or that seed germination was significantly reduced, whereas in the present experiment, only the germination of R. obtusifolius was studied. Even if the rumen juice in the present Experiment I had a stimulating effect on seed germination (the microbes thin the cell wall of the seeds with their microbial activity and thus accelerate germination), the discrepancies between the studies are most likely due to the fact that different plant species react differently to microbial digestion.…”

“…This value is statistically the lowest compared to the other germination energies achieved by R. obtusifolius. Similarly, many studies [29,30] have confirmed that the seed germination capacity generally decreases with the time spent in the digestive tract and that microorganisms in the rumen significantly reduce seed germination.…”