Effects of water extracts from litter of alpine meadows and grasslands in Northern Tibet on seed germination

Alpine grasslands and meadows are important grassland types in northern Tibet. Fencing is an important restoration method for alpine grasslands and has been widely used in grassland restoration in recent years. Long-term enclosure can lead to litter accumulation and affect vegetation renewal. This study used different concentrations of litter water extracts to simulate rainwater leaching and explore their effects on the germination characteristics of local dominant and associated species to investigate the specific effects of alpine grasslands and meadows on seed germination. The results showed that the alpine meadow litter water extract had a more significant effect on seed germination. The alpine grassland litter water extract had the highest inhibition on seed germination rate, germination potential, average germination time, and germination index, which were 75%, 75%, 79%, and 64% of the control group, respectively. However, in the alpine meadow litter treatment, four indicators reached 52%, 53%, 66%, and 64% of the control group. Compared with other species, the inhibitory effect of water extract from litter on the germination index of Leontopodium nanum is more significant, while the germination rate of Potentilla saunderiana improved under all treatments. In addition, Stipa purpurea was more tolerant to the effects of litter allelopathy. The allelopathic effect of litter had a promoting effect on the germination of Potentilla saundersiana Therefore, S. purpurea and P. saundersiana can be selected as reseeding in the restoration of incompletely degraded grassland. When fencing is used as a restoration method for degraded grassland, litter removal can effectively improve seed germination, thereby increasing community density, which is conducive to restoring degraded grassland.