Response Of Alpine Meadow Soil Seed Bank To Warming,Precipitation Change And Nitrogen Addition

The impact of climate change(temperature,precipitation)and increased nitrogen deposition on ecosystems is a hot spot point in the field of ecology.Continuous changes of climate can change soil temperature,moisture and eutrophication,which will have unfavorable impact on the terrestrial ecosystem.The alpine meadow ecosystem on the Tibet Plateau is an important part of the terrestrial ecosystem,it is particularly affected by climate change factors,due to its own sensitivity and vulnerability.At present,most of the studies explore the impact of climate change on the alpine ecosystem of the Tibetan Plateau have focused on aboveground vegetation,while there has been little research on the potential vegetation buried in the soil-soil seed bank.Soil seed bank is an important potential resource for vegetation restoration,and plays an important role in maintaining species diversity and restoring degraded ecosystems.Thus,there is a great scientific significance to explore the response of soil seed banks to climate change and nitrogen addition.Based on this,this paper uses the long-term experimental platform of climate change and nitrogen addition on the alpine meadows of the Tibetan Plateau to explore the effects of climate change and nitrogen addition on the soil seed bank through the seed burial-retrieval experimental method.In the climate change experiment,seeds of nineteen representative species on alpine meadow were buried and we retrieved them after 4 or16 months of burial respectively.In the nitrogen addition experiment,seeds of thirty-one main species on alpine meadow plant community were buried and we retrieved them after 4 months of burial.We measured the indices of seed loss and vitality under different experimental treatments.The results are mainly as follows.(1)The results of climate change and nitrogen addition experiments show that seeds loss and viability at the community level are not affected by the experimental treatment.(2)In climate change and nitrogen addition experiments,cluster analysis results show that seeds loss and viability are not related to the families and genus and seed size.(3)At the individual level,there was no significant difference between the 13 species(68.4% of the total species)in seed loss and viability compared with the control between climate change treatments.The experimental treatment had a significant impact on the seed loss of 5 species(Taraxacum mongolicum,Erodium stephanianum,Descurainia Sophia,Trollius farreri and Halenia elliptica)and a significant impact on the viability of 4 species(Angelica wulsiniana,Descurainia sophia,Taraxacum mongolicum and Halenia elliptica),accounting for 31.6% of the total species.(4)In the climate change experiment,the burial time has a significant effect on seeds loss and viability of 13 species,accounting for 68.4% of the total species.(5)In the nitrogen addition experiment,there was no significant difference in seeds loss and viability of 28 species(accounting for 90.3% of the species)between different fertilization concentrations.The experimental treatment had a significant effect on the seeds loss of two species(Silene aprica and Stipa bungeana),and the experimental treatment had a significant effect on the seeds viability of Agrostis trinii.Soil seed bank,as a component of ecosystem resilience,can maintain high seed viability under warming,rainfall change and nitrogen addition except few species.These indicate that the soil seed bank is stable in the alpine meadow ecosystem,and it will be an important resource for vegetation restoration and reconstruction under the interference of climate change and eutrophication in the future.