关键词: 积雪, 丛枝菌根真菌, 尖喙牻牛儿苗(Erodium oxyrrhynchum), 真菌菌丝, 短命植物, 古尔班通古特沙漠

Abstract: Compared to other desert ecosystem,snow cover in winter in the Gurbantunggut Desert is relatively stable and thick.Moisturizing and warming effects of snow cover provide the good conditions for the growth of desert ephemeral plants.However,the desert ephemeral plants can make use of favorable conditions in early spring of two months to complete the whole process of their rapid growth.They have an important role in the formation and succession of plant community as well as sand-fixation.The well-developed herbaceous layer in the Gurbantunggut Desert is mainly related to the existence of stable snow cover in winter.A comprehensive understanding that the ephemeral plant-arbuscular mycorrhizal fungi (AMF) how to respond to the changes of snowfall and snow cover in winter is the key to reveal the stability and maintenance mechanism of desert ecosystem under the climatic and environmental changes.However,it is not clear whether there is an interaction between AM fungi and snow cover change,and how about the growth and reproductive characteristics of ephemeral plants response to the interaction. Erodium oxyrrhynchum is a typical dominant desert ephemeral plant species growing in deserts in the Junggar Basin in north Xinjiang.Our research was carried out at the ecosystem in the Gurbantunggut Desert on the basis of long-term monitoring of plots.A dual influence of physical factor (snow cover) and biological factor (AMF) on the seedling growth of dominant desert ephemeral plants was verified based on the altered treatments of field snow cover (snow cover removal,snow cover addition and natural snow cover left in place),on-site mycorrhizal treatments (PVC tube rotated and static) and analysis in laboratory.A dual influence of snow cover removal-PVC rotated treatment on the seedling growth of E.oxyrrhynchum was detected.The results are as follows: ① In non-mycorrhizal treatment (rotated PVC tubes),the leaf traits of E.oxyrrhynchum were lower than that under the mycorrhizal treatment (static PVC tubes).The snow cover removal (-S) treatment exacerbated the above difference.Compared to the snow cover addition (+S) treatment,the leaf area and leaf perimeter under the -S treatment were reduced by 70.92% and 37.26% respectively; ② Other surveys echoed the conclusions that the non-mycorrhizal treatment restricted the plant growth.In non-mycorrhizal treatment,the plant height and root length of E.oxyrrhynchum were also lower than that under the mycorrhizal treatments.Plant height was decreased by 40.45% under the (+S) treatment and by 39.47% under the (-S) treatment.Root length was also decreased by 47.75% under the (-S) treatment; ③ The non-mycorrhizal treatment was also suggested to impede the biomass accumulation.In non-mycorrhizal treatment,both aboveground and underground biomasses were lower than that under mycorrhizal treatments.The snow cover removal (-S) treatment exacerbated the above difference.Under the-S treatment,the aboveground and underground biomasses were decreased by 80.32% and 65.74% respectively.In conclusion,the dual ecological influence of non-mycorrhizal treatment and-S treatment was found to impede the seedling growth of desert ephemeral plants of E.oxyrrhynchum.Our results could provide the scientific data for speculating the adaptation mechanism of desert ephemeral plants under winter precipitation change.

Key words: snow cover, arbuscular mycorrhizal fungi (AMF), Erodium oxyrrhynchum, fungal hyphae, ephemeral plant, Gurbantunggut Desert