关键词: 凋落物, 埋深, 狼毒, 种苗定居, 微环境

Abstract: Seed germination and seedling settlement are the most fragile two stages in life history of plants. To clarify habitat selection of Stellera chamaejasme in seedling settlement, both the effect of litter covering on micro-environment factors and the seedling settlement performance (i.e. emergence and survival) under different microhabitat conditions were investigated through artificial control experiments in the original habitat in alpine grassland. The results showed that litter mulching, on the whole, could decrease soil temperature, increase soil moisture, and significantly reduce the daily amplitudes of both factors especially in surface soil of grassland. Compared with the control (without litter), the treatment of litter covering significantly reduced the rate of emergence and seedlings settlement, but had little effect on overwintering survival rate of the seedings. The soil burial depth had significant effects on the emergence and overwintering survival of seeds, and both the indicators for the seeds in surface soil (< 0.5 cm) were significantly higher than those in deeper soil (2 cm and 4 cm). In conclusion, litter mulching and burying seeds in deep layer was not conducive to and the settlement of S. chamaejasme seedings in alpine grassland. Therefore, both soil bareness and seed superficialization may contribute to the establishment of S.chamaejasme population, which should be the main ecological factors leading to the spread of S.chamaejasme population in degraded grassland.

Key words: Litter, Burial depth, Stellera chamaejasme, Seeding settlement, Micro-environment