Effects Of Grazing And Disturbance Of Plateau Zokors On Reproductive Characteristics Of Potentilla Anserine

Reproduction is the basic process by which organisms continue their offspring.It is the key to the renewal of plant populations and the completion of individual life history.Plants respond to changes in their habitats by changing their reproduction methods to improve their adaptability.In the alpine meadows of the Qinghai-Tibet Plateau,grazing and other factors cause grassland degradation.Degraded grassland provides a basis for the increase in the number of plateau zokors(Eospalax baileyi)and accelerates grassland degradation.Potentilla anserina is one of the dominant species in degraded grassland,and it is also the most popular plant for plateau zokors.Therefore,it is of great significance to understand the influence mechanism of ground livestock grazing and underground plateau zokors interference on the reproduction of P.anserina to optimize the management of alpine meadows.In this study,four alpine meadow plots disturbed by 4 different grazing systems(Continuous grazing(CG),Growing season grazing(GSG),Traditional grazing(TG),and Prohibition grazing(PG))and 3 different plateau zokors population densities(high,medium,and low density)were selected,taking P.anserina as the research object,analyzing the changes in the growth and reproduction characteristics of P.anserina under the disturbance of grazing and zokors,and discussing its relationship between soil and vegetation characteristics,the results are as follows:1)Grazing and plateau zokors disturbance significantly affected the microhabitat of P.anserina.The soil compactness under the grazing system was Continuous grazing > Traditional grazing > Growing season grazing > Prohibition grazing in the growing system.Soil moisture content and bulk density under Continuous grazing increased by 41.66%,6%;30.56%,2%;13.89%,14%;respectively,compared with Growing season grazing,Traditional grazing and Prohibition grazing,the total nitrogen and total potassium content of the soil was the largest under Growing season grazing,but the total phosphorus content was the largest in Traditional grazing.The order of soil organic matter content was: Continuous grazing > Growing season grazing > Traditional grazing > Prohibition grazing,indicating that continuous grazing had a greater impact on the physical and chemical properties of the soil.With the increase of plateau zokors population density,soil compactness decreased,soil water content,total nitrogen(except 0 ～ 10 cm),and organic matter all increased,while total potassium content gradually decreased.2)Grazing and plateau zokors disturbance significantly affected the growth characteristics of P.anserina.The above-ground biomass and underground biomass of P.anserina in the turing-green period were the largest under the Growing season grazing,the above-ground biomass,underground biomass,and root-to-shoot ratio in its peak period,the aboveground biomass and underground biomass of P.anserina during the turning-green period increased by 6.57%,67.89%;7.21%,14.70%;29.65%,36.08%;respectively,compared with Prohibition grazing,Continuous grazing and Traditional grazing in the growing system,and the underground biomass and root-to-shoot ratio in the yellowing period were the largest under Prohibition grazing,the plant height,relative content of chlorophyll,leaf area,leaf circumference,leaf length in the peak period,and root length of P.anserine in the yellowing period were the largest under grazing prohibition,its root length,root diameter,root surface area,root volume and root length during the turing-green period,and root surface area and root volume at peak stage were the largest under Growing season grazing;When the plateau zokors population density was high,the SPAD value,leaf area,leaf circumference and leaf length,root length,root diameter,root surface area and root volume in the peak period of P.anserine were the largest,medium density increased its above-ground biomass,underground biomass and coverage,indicating that medium density had the greatest impact on its biomass and coverage,root length,root surface area,root volume at the turning green stage,and root length,root diameter,root surface area and root volume at the yellowing stage had the greatest influence at low density.The root length and root diameter of P.anserine showed a decreasing trend with the growth period.3)Grazing and plateau zokors disturbance significantly affected the reproduction pattern of P.anserine.Under Continuous grazing,the number of flowers,females and stamens of P.anserina were the largest,and under Continuous grazing,the number of flowers,females and stamens of P.anserina were the largest,and the number of flowers under Continuous grazing was 60.61%,61.61%,and 62.81% higher than Traditional grazing,Prohibition grazing and Growing season grazing,respectively.When the population density of plateau zokors was high,the length and number of stolons and spacers of P.anserina were the largest and the number of pistils and stamens per plant was the smallest.It showed that the selection of sexual reproduction mode of P.anserina under grazing disturbance was the most beneficial to its population reproduction,while under the disturbance of plateau zokors,the number of stolons and spacers increased.Choosing asexual reproduction mode had a positive effect on rapidly increasing its population.4)Correlation analysis found that the vegetation coverage,richness index,and evenness index under the grazing system had a significant impact on the sexual reproduction indexes(number of flowers,number of stamens,dry weight of flowers,and fresh weight of flowers)of P.anserina(P<0.05);Under the disturbance of plateau zokors,soil moisture,bulk density,total nitrogen content and organic matter significantly affected the asexual reproduction characteristics(number of spacers,stolon length,spacer length)of P.anserina(P<0.05).In summary,the grass degraded microhabitats under the disturbance of grazing and plateau zokors had undergone significant changes,affected the growth characteristics of P.anserine,the transformation and different responses of asexual reproduction and sexual reproduction of P.anserine were the results of adapting to environmental changes.The research provides a reference for optimizing management strategies for alpine meadows.