| With the interference of climate change and human activities,the phenomenon of grassland degradation in China is becoming more and more serious.The vegetation on the temperate desert steppe is sparse,and the nitrogen and phosphorus elements in the soil are greatly lost.The ecosystem is fragile and extremely sensitive to climate change.It is of great strategic significance to study the changes of desert grassland ecology.Fertilization and reseeding are the main measures to improve degraded grassland in northern China.In order to explore the changes of soil physical and chemical characteristics and plant communities under the new compound fertilizer-biochar-based phosphate fertilizer,foliar fertilizer and reseeding measures,as well as the relationship between them,it is of great significance to explore the changes of vegetation and soil characteristics in desert grassland and understand the changes of each component to reveal community characteristics and stability,protect grassland biodiversity,maintain grassland ecosystem function and sustainable grassland management.This thesis is divided into two experiments : The first experiment consists of four treatments: control(CK),reseeding(CP),biochar-based phosphate fertilizer(CB)and biochar-based phosphate fertilizer + reseeding(CPB).The quantitative characteristics of plant communities,plant community diversity and soil physical and chemical characteristics were analyzed.In the second experiment,four treatments were set up:spraying water(CKY),spraying excellent sea protection fertilizer(ES),spraying Hailiangsu fertilizer(HL),spraying Pranica alginate fertilizer(PA).The community characteristics of plant functional groups were measured in the growing season.The main results are as follows:(1)Through the study of experiment 1,it was found that under the first year treatment,the total density,average height,total coverage and proportion of dominant species of plant communities treated with CB were the highest,and the total aboveground biomass treated with CP was the highest.In the second year,the total density and average height of plant communities in CB treatment were the highest,and the total coverage and the proportion of dominant species in CP treatment were the highest(P<0.05).Compared with CK treatment,after 1 year of vegetation restoration,the plant community characteristics of different fertilization and reseeding treatments have been greatly improved.CB treatment can increase soil organic carbon,total nitrogen,total phosphorus and available phosphorus content.(2)Among the plant diversity indexes under different treatments,the Simpson dominance index,Shannon-Wiener index and species richness under CK treatment in2021 were higher,and the Pielou evenness index under CP treatment was higher.In 2022,Simpson dominance index and Pielou evenness index were the highest under CB treatment,Shannon-Wiener index was the highest under CK treatment,and species richness was the highest under CP treatment.After one year of treatment,the plant diversity index under CB and CP treatment was improved.(3)The relationship between plant species diversity and soil physical and chemical properties was as follows: soil temperature,soil water content,p H value and soil total nitrogen were significantly positively correlated with Simpson dominance index,and soil water content,p H value and soil total nitrogen were significantly positively correlated with Pielou evenness index(P<0.05).There was a significant negative correlation between soil temperature,soil water content,p H value,soil total nitrogen and Shannon-Wiener index.There was a significant negative correlation between soil organic carbon and Simpson dominance index,Pielou evenness index and species richness(P<0.05).(4)The soil environment mainly carries the information of soil temperature and soil water content,and soil nutrients mainly provide the information of organic carbon and carbon-phosphorus ratio.Reseeding had a greater impact on plant community density and biomass.(5)Through experiment 2,it was found that ES treatment could significantly increase the density of one and biennials functional group and the aboveground biomass of shrub and semi-shrub functional groups,HL and PA treatments significantly reduced the density of perennial grasses and increased the importance value of perennial weeds(P<0.05).Under HL and PA treatments,the plant community was in a relatively stable state,while under CKY and ES treatments,the plant community was in a relatively unstable state.In summary,in the temperate desert steppe,the application of biochar-based phosphate fertilizer and reseeding treatment can increase the number of plant characteristics and soil physical and chemical characteristics.The plant community and soil indicators are interrelated and interact with each other.The application effect of foliar fertilizer in desert steppe has not shown obvious advantages. |
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