| The project takes the common Leymus chinensis,Stipa grandis,Cleistogen,and Silver ash flower as the target plants in the typical steppe of Inner Mongolia.By excluding the above-mentioned plant species from the native vegetation,different species combinations are formed,the effects of different species communities on soil environment and plant growth were explored by measuring plant height,coverage,density and soil physical and chemical properties,the aim is to further explore the response of plants and soils to species loss in the short term,and this will provide a theoretical basis for the protection of biodiversity in typical grasslands,the reconstruction of degraded ecosystem functions and the restoration of degraded grasslands.The main findings are as follows:(1)After species were removed,the plant height,total coverage,grass cover and density were significantly affected.During the measurement period,on September 7,the plant height of Leymus chinensis community(A)was significantly different from that of the untreated community(F)(p<0.05);the C.sylvestris community(E)and in the untreated community(F),the plant height of C.serrata and the Leymus chinensis+C.serrata community(C)showed significant differences in the height of the plants(p<0.05),indicating the existence of species competition in the community.And the species grow vigorously in the absence of nutrient competition.Among the total coverage results,the growth rate of Stipa community(B),Stipa grandis+C.sylvestris(D),and Cryptopsis community(E)was significantly higher than that of other treatment communities,and on August 25 Both day and September 7 showed significant differences(p<0.05),indicating that the removal of Leymus chinensis promoted the growth of the retained species Stipa grandis and C.serrata in a short period of time.After species were removed,the density of Leymus chinensis in the untreated community(F)and the Cryptium chinensis+Leymus chinensis community(C)and the Leymus chinensis community(A)was significantly lower and showed a significant difference on September 7(p<0.01);on August 25,the coverage of Leymus chinensis in Leymus chinensis community(A)was significantly higher than that in C.serrata+Leymus chinensis community(C)and untreated community(F),and the performance Significant differences(p<0.01),the presence of Leymus chinensis hindered the growth of other grass species in the community.On September 7th,the coverage of C.serrata in the C.glabra community(E)was significantly higher than that of Leymus chinensis+C.serrata(C)and Stipa breviflora+C.sylvestris(D)and untreated communities(F),and showed significant difference(p<0.01).The presence of C.serrata inhibited the growth of other grasses in the community.In summary,in this rejection experiment,the competition between species is reflected by the growth of retained species.(2)After species were removed,the soil water content of Leymus chinensis community was significantly lower than that of the untreated community at 5 cm(p<0.01).After removing the species,it may affect the soil water content and affect the growth of grass species.development.The soil temperature values of the treated communities are dynamically changing,which may be due to the time lag of the soil environment in response to species loss in the short term.(3)After the species were removed,the pH of the soil and the nitrate nitrogen of the soil were significantly affected.The experimental results showed that the pH of the Leymus chinensis community was significantly lower than that of the untreated community(p<0.05),indicating that species removal significantly changed the pH value of the soil and affected the growth and development of the plants.After species were removed,the soil nitrate nitrogen in the C.serrata community reached the maximum value in each treatment community(p<0.05),indicating that the species competition between the communities affected the nutrient cycling in the soil and further affected the vegetation growth. |
