Effects Of Species Loss On Plant-pollinator Interaction And Arthropod Diversity In Alpine Meadow

In the past decade,the relationship between biodiversity and ecosystem functions has attracted much attention in the study of community ecology.Based on field investigation and artificial construction experiments,it is concluded that biodiversity plays an important role in ecosystem functions and services.However,at present,more studies have focused on single index,such as the relationtship between plant species diversity and ecosystem functions in a community,but single index often can not reflect well the relationship between species diversity and ecosystem functions.If we want to have a deeper understanding of the relationship between biodiversity and ecosystems,it is necessary to consider comprehensively from more dimensions(i.e.plant species diversity,and biodiversity based on plant-pollinator and/or plant functional traits).As the largest natural grassland in China,the Tibetan alpine meadow has high species diversity,including monocotyledons and dicotyledons.As the most diverse and adaptable group of plants in the grassland,how the existence of dicotyledons affects the grassland ecosystem requires further discussion.Based on the above background,we carried out a two-year eliminated experiment.Our purpose is to explore the effcets of loss of dicotyledons on pollinators,plant-pollintor networks,and the diversity of arthropod communities.We hope to provide a scientific basis for the conservation and utilization of the Tibetan alpine meadow and similar natural grasslands.The perliminary results are as follows:(1)When dicotyledons decrease,the number of pollinating insect species significantly decreases.It is indicated that pollinators are strongly dependent on flower diversity due to specialization.When plant diversity decrease in the community,some specialized pollinators may be particularly vulnerable,and even extinction.In paticular,most flower visitors in pollination network are Hymenoptera,Coleoptera and Diptera,and Hymenoptera(flies)are the most.When dicotyledons exist,the whole pollination network shows higher species diversity,nesting,high asymmetry and higher generalization of the whole network,indicating that the plant-pollinator interaction network can make the community have greater functional redundancy,higher community diversity and lower interdependence,and make the community more stable.(2)When dicotyledons decrease,the diversity of arthropod community are affected.And when dicotyledonous plants decrease,the functional groups of herbivorous arthropods in their communities descend.Most arthropods use suiface vegetation as main source,and different plants in the community provide different types of nutrients to arthropods.Therefore,when some plants are lost,it will affect the life and fecundity of arthropods,further cause the vatiation of their individual numbers and composition.In addition,soil factors(such as physical and chemical factors)will also have an impact on the diversity of arthropod community.(3)The elimination of dicotyledons has no great effect on the productivity of monocotyledons,but has significant impact on plant functional traits.In the control group,monocotyledons diversity and Shannon Weiner index were positively correlated with productivity.In the treatment with only three dominant species(dicotyledons:Geranium pylzowianum,Potentilla potaninii,Euphrasia regelii)and monocotyledons(treatment2),there is a positive correlation between richness and productivity.It is proved that the higher the species diversity in the community,the higher the productivity of the plant.