Relationship Between Plant Synthetic Community Structure And Productivity In Subalpine Meadow

In studies on the relationship between plant species richness and productivity,species richness is regarded primarily as an independent variable and productivity as a response variable,whereas other factors that may affect community productivity at the same species richness levels,such as species combination and composition,are largely ignored.This study,selected Festuca sinensis,Elymus nutans,Dactylis glomerata and Medicago sativa as the research objects,analyzed the effects of species richness,species combination,species composition and the interaction effects of species combination and composition on community productivity by pot experiment.This study aimed to explore the possible dominant factors that lead to the diversity of plant community productivity and the various relationships between species richness and productivity.The main results were as follows:（1）Community productivity increased with the increase of species richness,but had no significant difference in lower species richness.Community productivity was significantly different between high species richness and low species richness.（2）At the same species richness level,the productivity of different species was different based on the effect of individual plant resource utilization efficiency on plant growth,and the community species combination,species composition and their interaction had significant effects on community productivity（p<0.05）,with the mixed-seeding community containing Elymus nutans or Dactylis glomerata and community with a high proportion of Elymus nutans or Dactylis glomerata having higher productivity.（3）The Individual average productivity of Festuca sinensis,Elymus nutans,Medicago sativa and Dactylis glomerata had significant differences between low species richness and high species richness.For the same species,due to the interaction between neighboring individuals,individual average productivity had significant differences in different communities(p<0.05,Festuca sinensis,0.022-0.133g·per·plant^-1,Elymus nutans,0.053-0.127 g·per·plant^-1,Medicago sativa,0.149-0.389 g·per·plant^-1,Dactylis glomerata,0.021-0.046 g·per·plant^-1).Species combination and the interaction between species combination and composition had significant effects on the individual average productivity of four plant species.We concluded that there was positive relationship between species richness and productivity in subalpine meadow plant communities with the same environmental conditions.The presence,absence and individual amount of plant community species affected community productivity with differences in plant resource utilization efficiency,and then changed the relationship between species richness and productivity.Plant community productivity was more dependent on species combination and composition than on species richness.