摘要
Biological soil crusts(BSCs) are the important components of alpine meadow ecosystems.The extent and morphology of BSCs vary greatly with alpine meadow retrogressive succession due to grazing pressure.There is significant interest in impacts of crust composition on plant seed germination,especial l y in(semi-) arid environments.However,little is known about the influences of BSCs,and their associations with alpine meadow succession,on germination of typical alpine meadow vascular plant species.In a full factorial common-gardenexperiment,we studied effects of:(1) crust type,(2) seed position,and(3) surface texture on seed germination.We chose three typical alpine meadow plant species(i.e.Poa pratensis,Tibetia himalaica and Potentillen nivea),which belonged to different functional groups(graminoids,legumes,and forbs) and play important roles in all alpine meadow succession stages.Crust type and seed position influenced seed germination,and the inhibitory effects of BSCs depended on the crust type and seed species tested.The major factors influencing seed germination were BSC type,seed position,soil texture,and the interactions between BSC type and seed position; species and seed position; species andsurface texture; and species,crust type,and surface texture.Cyanobacteria crust significantly inhibited germination of all seeds.Seed position also had a significant effect on seed germination(p < 0.001).Fewer seedlings germinated on the surface than below the surface,this was especially true for P.nivea.seeds within cyanobacteria and lichen crusts.Only germination rates of T.himalaica on the soil surface were significantly correlated with plant occurrence frequency within the alpine meadow community.The poor correlation for the other two species is possibly that they are perennials.Our results clearly demonstrated that BSCs can be biological filters during seed germination,depending on the BSC succession stage.Through their influences on seed germination,BSCs can strongly influence community assemblages throughout alpine meadow retrogressive succession.
Biological soil crusts （BSCs） are the important components of alpine meadow ecosystems. The extent and morphology of BSCs vary greatly with alpine meadow retrogressive succession due to grazing pressure. There is significant interest in impacts of crust composition on plant seed germination, especially in （semi-） arid environments. However, little is known about the influences of BSCs, and their associations with alpine meadow succession, on germination of typical alpine meadow vascular plant species. In a full factorial common-garden experiment, we studied effects of： （1） crust type, （2） seed position, and （3） surface texture on seed germination. We chose three typical alpine meadow plant species （i.e. Poa pratensis, Tibetia himalaica and Potentillen nivea）, which belonged to different functional groups （graminoids, legumes, and forbs） and play important roles in all alpine meadow succession stages. Crust type and seed position influenced seed germination, and the inhibitory effects of BSCs depended on the crust type and seed species tested. The major factors influencing seed germination were BSC type, seed position, soil texture, and the interactions between BSC type and seed position; species and seed position; species and surface texture; and species, crust type, and surface texture. Cyanobacteria crust significantly inhibited germination of all seeds. Seed position also had a significant effect on seed germination （p 〈 0.001）. Fewer seedlings germinated on the surface than below the surface, this was especially true for P. nivea. seeds within cyanobacteria and lichen crusts. Only germination rates of T. himalaica on the soil surface were significantly correlated with plant occurrence frequency within the alpine meadow community. The poor correlation for the other two species is possibly that they are perennials. Our results clearly demonstrated that BSCs can be biological filters during seed germination, depending on the BSC succession stage. Through their influences on seed germination, BSCs can strongly influence community assemblages throughout alpine meadow retrogressive succession.
作者
LI Yi-kang
OUYANG Jing-zheng
LIN Li
XU Xing-liang
ZHANG Fa-wei
DU Yan-gong
LIU Shu-li
CAO Guang-min
HAN Fa
LI Yi-kang OUYANG Jing-zheng LIN Li XU Xing-liang ZHANG Fa-wei DU Yan-gong LIU Shu-li CAO Guang-min HAN Fa(Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810001, China University of Chinese Academy of Sciences, Beijing 100049, China Institute of Geographic Sciences ＆ Natural Resources Research, the Chinese Academy of Sciences, Beijing 100101, China Liancheng National Nature Reserve of Gansu Province, Yongdeng Country 730000, China)
基金
funded by the Chinese National Natural Scientific Foundation(Grant No.31270576)
by the grant(Grant No.2016-ZJ-710)from Qinghai Province and Key laboratory of crop molecular breeding of Qinghai Province
