Effects Of Warming And Precipitation Changes On Plant Communities And Soil Physical And Chemical Factors In Alpine Meadow

At present,the alpine ecosystem of the Tibetan Plateau is suffering from the profound impact of global climate change,and the precipitation pattern has undergone significant changes.Alpine meadow ecosystems are sensitive to global climate change.However,to date,studies on the response of alpine meadow plant communities and soil physical and chemical factors to global climate change are still lacking.Therefore,this thesis explore the effects of temperature and precipitation patterns on the alpine plant community and soil physical and chemical environment through long-term ecological control experiments.Through two years of research,the species composition and characteristics of plant communities and the changes of soil physical and chemical factors under different experimental treatments were revealed.The current research results can provide direct evidence for the impact of future temperature rise and precipitation pattern changes on alpine ecosystems,and provide a scientific basis for the protection and restoration of alpine meadow ecosystems in the Tibetan Plateau.This paper adopts the following two field long-term ecological control experiments: 1)Warming,precipitation increase or decrease experiment(6 treatments: including warming,increasing precipitation,reducing precipitation,warming + reducing precipitation,warming + increasing precipitation,and control);2)Warming and precipitation variation experiment(In the first year,the rain-increasing treatment became rain-reducing treatment in the second year,while the first year rain-reduction treatment became rain-increasing treatment in the second year,while the rest of the treatment remained unchanged).Plant community was monitored and analyzed(Composition,diversity,productivity,etc.).Soil environment factors including soil physical(soil moisture)and chemical factors(pH,organic matter,nitrogen,phosphorus,etc.)were analyzed under different experimental treatments.Our findings were listed in the follow:1.There was no significant difference in plant species composition between the two experimental treatments,indicating that the species composition of plant communities did not change under warming and precipitation treatments;In the experiments of warming and precipitation increase or decrease,the species richness of plant communities decreased significantly under the conditions of warming and precipitation reducing,and the biomass of forb(community level)increased significantly under the warming treatment;in the experiment of warming and precipitation variation,only the biomass of forb was increased significantly after changes in precipitation reduction treatment.2.In the experiment of warming and precipitation increase and decrease,the soil moisture content decreased significantly under the warming treatment,and the soil pH decreased significantly under the precipitation reduction treatment;in the experiment of warming and precipitation variation,there was no significant difference in all physical and chemical factors among different treatment.3.In the experiment of warming and precipitation increase or decrease,oil water content,organic matter,total nitrogen and nitrate nitrogen are the main environmental factors affecting the species composition of plant communities in the first year.Ammonium nitrogen is the main environmental factor affecting the total biomass of plant communities.However,Soil pH and total phosphorus are the main environmental factors affecting plant species composition in the second year.Total phosphorus is the main environmental factor affecting plant community biomass.In the experiment of warming and precipitation variation,ammonium nitrogen,nitrate nitrogen,organic matter and total nitrogen are the main environmental factors affecting the species composition of plant communities.