Study On Interspecific Competition Of Dominant Herbage In Artificial Grassland In Alpine Region Based On The Niche Theory

Planting artificial grassland is an important measure to develop intensive grassland animal husbandry,implement ecological restoration,reconstruction and implement sustainable development strategy.After mixed sowing,herbages occupy different niches and compete with environmental resources to varying degrees,which affects the stability of artificial grassland community.The study of herbage competition is of great significance for the construction of artificial grassland.Eight dominant grasses in alpine regions are represented by A-H and weeds by W.The grasses include top grass: Elymus breviaristatus ‘Tongde’(A),Elymus nutans(B),Elymus sibiricus ‘Tongde’(D)and Elymus sibiricus ‘Qingmu No1’(E);bottom grass:Puccinellia distans ‘Tongde’(C),Poa pratensis L.cv.‘Qinghai’(F),Poa crymophila‘Qinghai’(G),Poa pratensis var.anceps Gaud.cv.‘Qinghai’(H).8 varieties and 65 combinations were used for unicast and mixed sowing.Based on the field investigation and indoor experiment of herbage yield,the niche width,overlap and interspecific competitiveness of herbage are calculated,and the competition among the dominant species of artificial grassland in alpine areas is discussed.The results are as follows:Growth characteristics of herbage :The number of mixed sowing had no significant effect on the growth characteristics of herbage;There was a significant positive correlation between seed width and root length of 8 herbage species.Niche :With the increase of mixed sowing,the niche width of herbage decreased;After mixed sowing,the overlap degree of D-E and D-C was above 0.5,and the overlap degree of other herbages was below 0.5,and the weeds and dominant herbages used the same resources to a high degree.Biomass :The aboveground biomass was larger than the underground biomass under different number of mixed sowing;When SHM≥5,there was no significant difference in total community biomass,and when SHM≥4,there was no significant difference in the ratio of aboveground biomass to underground biomass of each combination.With the increase of mixed sowing number,the biomass of top grass decreased,but the biomass of bottom grass did not change significantly.Competitiveness :With the increase of mixed sowing number,the total relative yield in the community increased,and the competitiveness value of herbage became more concentrated.There were no more than 3 herbage species with competitiveness greater than 1 in the combination.The competitiveness of herbage changes with the change of resource species competing with it.According to the analysis of niche and interspecific competitiveness,Four or less herbages are suitable for mixed-sowing grassland.Herbages B,C,A and D are highly competitive vegetation.The combinations of B+E,B+D,E+H,A+C+D,B+C+D were the best herbage combinations in alpine mixed grassland,and C+D,D+E,F+G,F+H,F+G+H were the combinations to avoid because of weak competitiveness and low yield.