Research On Response Of Alpine Seed Bank To Warming And Precipitation Change On The Tibetan Plateau

The Tibetan plateau is the highest plateau,and it is also considered as the third pole in the world.In recent decades,global warming has a huge influence on the alpine ecosystems of the Tibetan Plateau.Meanwhile,the precipitation pattern of Tibetan plateau has also changed.For example,some places became wetter while others became drier.Alpine meadow vegetation and ecosystems are inherently vulnerable,global climate change has had a profound impact on them.At present,much research has been done about the effect of global climate change on above-ground vegetation systems.However,few studies research the effect of climate change(e.g.temperature and precipitation)on above-ground potential vegetation—soil seed banks.For many species,soil seed bank is a "spreading risk strategy" when they face to the disturbance;for vegetation,seed bank is a "buffer" when they suffered disturbances,and it is also an important resource for degraded vegetation restoration.Recently,some research showed that the ‘spreading risk strategy' that some species used in soil seed bank would be destroyed by future global climate change.Hence,the changes in the dynamics of soil seed banks increase the risk of local extinctions of these species.However,we still unknown how climate change(warming and precipitation change)influence on soil seed bank,especially in the alpine meadow ecosystem on the Tibetan plateau.In our research,we chose ten common species,which have persistent soil seed bank,as experimental materials,and then we used buried method to research the effects of warming,precipitation changes,and fungicide on seed germination,survival,inactivation and the impact of pathogenic fungi on alpine meadow soil seed bank.We used the following two experiments in our research,1)warming and precipitation change experimental platform(four treatment,control,warming,increase and decrease 40% ambient precipitation)at the Research Station of Alpine Meadow and Wetland Ecosystems of Lanzhou University.2)Fungicide experiment(eight treatments,control,20% 40%,60% increase in ambient precipitation,and half these four treatments added fungicide).After the entire growing season burial experiment,the germination rate,survival rate,inactivation rate and mortality rate of each species has no significant difference among four treatments(p>0.05).There was also no significant difference in seed germination rate and survivalrate(p>0.05)at the community level(the sum of 10 species);The results of burial + fungicide experiment showed that whether used fungicide or not,with the precipitation increase of 20%,40% and 60%,the seed germination rate and survival rate of each species(9 species)had no significant difference among different treatments(p>0.05),and there also no significant difference at the community level(p>0.05).Independent sample t-test was used to test the significant difference of the same species which used fungicide or not.Whatever at the species(9 species)and community level,the results showed that the germination rate,survival rate,inactivation rate and mortality rate of burial seeds have no significant difference(p>0.05).In summary,the response of soil seed banks was not positive in our experiment warming and precipitation change experiment systems.During the whole growing season,most of the buried seeds can survival in the alpine meadow soil with warming,increasing/decreasing precipitation and fungicide addition experiments.Only a small percent of seeds changed their germination rate,mould rate and mortality rate due to warming and precipitation change.Our results indicated that soil seed bank can effectively resist external disturbance within a certain range,and could be as a basic potential resource for reconstruction of vegetation.Moreover,the alpine meadow soil seed bank is an important part of alpine meadow ecosystem resilience,especially when they face to the effects of global climate change.