Analysis Of The Soil Enzyme Activity And Microbial Functional Diversity Of Cunninghamia Lanceolata Clones In Continuous Planting Obstacles Soil Of Cunninghamia Lanceolata

Continuous planting causing productivity decline as a global issue, has already generated a lot of long-term attention from scholars. Chinese fir as a unique fast-growing and high-yielding tree species, widely distributed in 16 provinces and regions in southern China. With the expansion of Chinese fir plantation area, pure forests of Chinese fir displace mixed forests, which resulted in continuous cropping in the same forest stand. Chinese fir plantation cultivation currently has the third generation, successive planting leading to productivity decline in Chinese fir plantation has become foresters and ecologists focused on. On the basis of the characteristics of soil physical and chemical、bacteria and fungi species variation in FCF、SCF、TCF、CK in Wangtai, Nanping city, through pot experiment method in soil of FCF、SCF、TCF、CK, Seedling height and ground diameter of patience and sensitive Chinese fir clones、seasonal variation of rhizosphere and non-rhizosphere soil enzyme activity and microbial functional diversity were analyzed. Study results illuminated the response of continuous planting in different Chinese fir clones from the perspective of rhizosphere and non-rhizosphere microbes, proving formation mechanism of Chinese fir continuous planting obstacles and forming theory basis of preventing Chinese fir plantation soil fertility decline. The results are as follows:(1) Through comparing the soil physical and chemical properties of Chinese fir plantation, soil moisture content, maximum water holding capacity and minimum water holding capacity, capillary water holding capacity, total porosity volume declined with the increasing successive rotation. Soil bulk density elevated with the increasing successive rotation. The pH、total C、total N of soil declined with the increasing successive rotation. It showed that soil acidification with the increasing successive rotation.(2) Bacterial samples were identified 18 phyla:including Acidobacteria; Proteobacter ia; Planctomycetes; Chloroflexi; Actinobacteria; Cyanobacteria; Gemmatimonadetes; Thermot ogae; Bacteroidetes; Nitrospirae; Firmicutes; Elusimicrobia; Chlorobi; Chlamydiae; TM6; T M7; WCHB1-60; Other. Percentage was more than 1% of FCF bacteria phyla including 8 kind from big to small order:Acidobacteria(56.08%); Proteobacteria(23.08%); Planctomycet es(7.14%); Chloroflexi(6.27%); Actinobacteria(1.76%); Cyanobacteria(1.57%); Gemmatimona detes(1.13%); Thermotogae(1.10%). Percentage was more than 1% of SCF bacteria phyla including 8 phyla from big to small order:Acidobacteria(51.76%); Proteobacteria(26.42%); Planctomycetes(8.67%); Chloroflexi(5.54%); Actinobacteria(2.12%); Thermotogae(1.25%); Fir micutes(1.18%); Gemmatimonadetes(1.07%). Percentage was more than 1% of TCF bacteria phyla including 6 phyla from big to small order:Acidobacteria(54.96%); Proteobacteria(2 6.49%); Planctomycetes(5.99%); Chloroflexi(5.79%); Actinobacteria(2.09%); Cyanobacteria(1. 57%).(3) Three different successive rotation plantation soil were identified five phyla, resp ectively:Ascomycota、Basidiomycota、Zygomycota、Rozellomycota、k_Fungi;Other、Unclass ified;Other. Fungi phyla of FCF was Ascomycota(50.94%); Fungi;Other(33.48%); Basidiom ycota(12.20%); Zygomycota(3.22%); Unclassified;Other(0.10%); Rozellomycota(0.06%). Fungi phyla of SCF was Ascomycota(67.07%); Fungi;Other(25.90%); Basidiomycota(6.71%); Zyg omycota(0.31%). Fungi phyla of TCF was Ascomycota(27.92%); Fungi;Other(66.33%); Basi diomycota(4.25%); Zygomycota(1.41%); Unclassified;Other(0.02%); Rozellomycota(0.08%).(4) Through the analysis of the RDA between the dominant soil bacteria、fungi cate gories and environmental factors, soil total K, capillary pore volume, water content, soil b ulk density had big effect on the relative abundance of eight kinds of bacteria. Soil bulk density, moisture content of soil total phosphorus, total carbon, pH had a greater influence on the distribution of fungus category. Through analysis of soil bacteria and fungi comm unity and correlation analysis of soil physical and chemical properties in different planting generations of Chinese fir plantation, Ace index of soil bacteria had correlation with soil moisture content, bulk density and total phosphorus. Chaol associated with bulk density, total phosphorus, Simpson was associated with total nitrogen and total carbon.(5) Through analyzing Chaol, Ace, Shannon and the Simpson index of soil bacteria and fungi in different planting generations of Chinese fir plantation, it was found that Chaol, Ace index order of bacteria was FCF>TCF>SCF from high to low. Shannon was highest in SCF, but lowest in Simpson. Chaol、Ace index of fungi was lowest in TCF. Shannon was lowest in TCF, but highest in Simpson.(6)Pot experiment showed that two allelopathy types of Chinese fir clones seedlings growth in seedling height, ground diameter showed that patience was higher than sensitive on the whole. Seedling height growth decreased with the increasing successive rotation, ground diameter largely declined with the increasing successive rotation.(7) Pot experiment showed that different stand types of soil had a significant impact on soil urease activity. Rhizosphere and non-rhizosphere of patience clones in urease activity showed that CK was significantly greater than the other three types. The change tendency was that summer elevated, autumn peak,, winter fall, the order is autumn>summer>spring>winter from high to low. Rhizosphere urease activity of sensitive clones, on the whole, also for CK was significantly higher than the other three types, the change tendency increased at first and then decreased. Different stand types of soil had a significant impact on soil sucrase activity. Rhizosphere and non-rhizosphere of patience clones in sucrose activity showed that CK was significantly greater than the others except autumn and winter, Change trend was that increase-decrease-increase. The change trend of sensitive was the same as patience. Different stand types of soil had a significant impact on soil cellulase activity. Rhizosphere and non-rhizosphere of patience clones in cellulase enzyme activity in highest value was TCF. Sensitive cellulose enzyme activity of rhizosphere was highest TCF(spring), SCF(summer), FCF(autumn) and CK(winter) respectively. The rhizosphere was highest(TCF) in spring and summer, was the largest(CK) in autumn, highest(SCF) in winter. Different stand types of soil had a significant impact on soil acid phosphatase activity. Patience rhizosphere and non-rhizosphere soil enzyme activity was SCF the largest, the trend increased, to reducing and then elevating process again. Sensitive rhizosphere and non-rhizosphere for SCF value was highest except winter. The trend of change was the same as sensitive.(8) Pot experiment showed that the change of soil microorganism overall activity AWCD value was "S" type, which fitted the characteristics of microbial cultures. Four types of soil AWCD value from high to low order was CK>FCF>SCF>TCF after cultivating 168h in spring, the AWCD value declined with the increasing successive rotation. In summer, the highest of AWCD value was TCF in rhizosphere and non-rhizosphere of patience, CK was highest in soil AWCD value of sensitive. Two types of Chinese fir rhizosphere soil AWCD value on the whole was greater than the rhizosphere. Comparing soil rhizosphere and non-rhizosphere showed patience was greater than the sensitivity. In autumn, rhizosphere and non-rhizosphere soil of patience in AWCD value:TCF>SCF>CK>FCF. Soil of rhizosphere was greater than the rhizosphere in AWCD. Generally sensitive rhizosphere was more than the non-rhizosphere. Comparing soil rhizosphere soil AWCD, patient type was greater than the sensitive type in the mass. In winter, rhizosphere and non-rhizosphere soil of patience in AWCD value: TCF>SCF>CK>FCF. Rhizosphere of soil was greater than the AWCD value of non-rhizosphere in the mass. Sensitive rhizosphere and non-rhizosphere soil AWCD maximum was TCF. Rhizosphere soil was greater than the value of rhizosphere soil microbial activity. In rhizosphere soil, sensitive was greater than patience, rhizosphere and non-rhizosphere soil of different successive rotation of Chinese fir clones had significant difference in Shannon and Simpson index.(9) Through the principal component analysis and change of soil microbial community 6 class carbon source utilization:In spring, utilization efficiency of microbes CK for polymer, phenolic acids was highest, FCF, SCF, TCF respectively for carbohydrates, amino acids and carboxylic acid, amine, was the largest. Soil microbial utilization of phenolic acids decreased, utilization of amine elevated with the increasing successive rotation.In summer, utilization efficiency of microbes for polymers, carbohydrates, phenolic acids, amino acids, amines elevated with the increasing successive rotation. Carbon source utilization efficiency of soil microorganisms for polymer, carbohydrates and phenolic acids:EC>SC, the same as amino acids, amines, carboxylic acid in rhizosphere soil. In non-rhizosphere soil, utilization efficiency of microbes for polymers and carbohydrates and carboxylic acids:EC>SC, the same as amino acid, amine and phenolic acids. In autumn, utilization efficiency of microbes SCF for polymers was highest. In rhizosphere soil, utilization efficiency of microbes for polymers, amines, carboxylic acid:EC>SC. In non-rhizosphere soil, the utilization efficiency of microbes for carbohydrates, phenolic acids, amino acids and carboxylic acid:SC>EC. In winter, the utilization efficiency of microbes for polymers, carbohydrates, phenolic acids, amino acid, amine, and carboxylic acid elevated with the increasing successive rotation. In rhizosphere soil, utilization of microbes for polymers, carboxylic acid:EC>SC, for carbohydrates, phenolic acids and amino acids:SC>EC. In non-rhizosphere soil, the utilization efficiency of microbes for carbohydrates, amino acids and carboxylic acid:EC>SC, for polymers:SC>EC.(10) Through correlation analysis of the function of soil microbial diversity index, AWCD value and soil enzyme activity:In spring, AWCD, Shannon index and urease reached significant level(p<0.05). In summer, AWCD and cellulose enzyme, invertase and acid phosphatase reached significant level(p<0.05). Shannon, Simpson index and invertase, acid phosphatase reached extremely significant level(p<0.01). In autumn, AWCD and invertase showed significant level(p<0.05). Simpson index and urease and sucrase presented significant level(p<0.05). In winter, AWCD, Shannon index and cellulose enzyme, sucrase reached significant level(p<0.05). Simpson index and cellulose enzyme, sucrase appeared significant level(p<0.05).