| Objective:Field artificial simulation experiments and traditional cultivation methods were used to explore the changes and driving factors of the temperature and ash on the soil nematode-trapping fungi community,which are important components of forest fires,and provide a theoretical basis for the restoration of ecosystems after fire and forest fire management.data support.Methods:1.Plot design and fire treatment: the forest soil was laid on the sample square of the practical teaching base of Dali University,and was divided into temperature groups(group 1,2,3),ash group(group 4),temperature plus ash group(group 5)and control group(group 6)with heat-resistant ceramic tiles.Both groups 1 and 2 use a mid-range torch to continue to act on the soil,the time for group 1 is 1 h,and the time for group 2 is 20 min;group 3: put the iron box containing red charcoal on the soil and continue heating for 1 h;group 4: 260 g pine needles were burned and the ashes after cooling were placed on the soil;group 5: burns the pine needles directly on the soil;group 6: no treatment.In addition,the temperature of 0-15 cm soil depth was measured by thermocouple thermometer alone.2.Soil sample collection: before treatment,5 microbial samples and 1 Physical and chemical sample were collected;the sampling time after the fire treatment was on the first day,and every 10 days thereafter,and ended at 100 days,a total of 11 times;The group collected 5 samples each time and collected 335 microbial samples.The sampling time of soil physical and chemical properties was 1th,50 th,and 100 th after fire treatment;One sample was collected for each group,and a total of 19 physical and chemical samples were collected.3.Detection of nematode-trapping fungi and determination of physicochemical properties: the nematode-trapping fungi were isolated and purified by traditional culture method,and species wer e identified by combining morphology and molecular biology.Refer to forestry standards to determine soil moisture,p H,total nitrogen,organic matter,and total phosphorus,while collecting rainfall from Dali City through the Central Meteorological Networ k.4.Data processing and statistical analysis: Excel,SPSS 20.0,Venny,canoco 5.0 and graphpad prism software were used to calculate,analyze and plot the number,diversity index,species distribution,community structure and the correlation of physical and chemical properties of nematode-trapping fungi.Results:(1)Physical and chemical properties of soil: c ompared with the control group,both temperature groups and the temperature plus ash group,p H and total phosphorus were increased,in temperature groups,soil moisture,organic matter and total nitrogen were decreased,in temperature plus ash group,soil moisture was decreased,organic matter and total nitrogen the were increased temporarily;in ash group,p H,soil moisture,organic matter,total phosphorus and total nitrogen were increased.(2)Temperature treatment group: the maximum temperature and average temperature of soil layer 0-10 cm are in order of 1 group> 2 groups> 3 groups;the total number of nematode-trapping fungi were decreased by all temperature treatments,for reduction of strain number,group 1 > group 3 > group 2(F=38.61,P<0.001),among these,the strains number of Arthrobotrys musiformis,Arthrobotrys thaumasia and Dactylella parvicolla were lower than the control group significantly(P<0.05);all temperature treatments can result in the increase of species diversity index,the index of group 1,group 2 and group 3 were 2.23,1.89,2.02,respectively,the control group was 1.80;c ompared with the control group,the structure of the community of nematode-trapping fungi changed significantly,and the number of endemic species increased in all treatment groups,especially in group 1,then in group 3,group 2;the community dynamic change analysis after temperature treatment was found,in group 1,the total strain detection number and community structure fluctuated greatly over time,in gr oup 2 and group 3,these fluctuated greatly in the early stage and were more stable in the later stage.(3)Ash group: compared with the control group,the total strains number of nematode-trapping fungi decreased,but the difference between the two groups di d not reach significance(P>0.05),and the strain number of Arthrobotrys oligospora are increased significantly;the species diversity index and species distribution were not significantly different from the control group,and the community structure was significantly changed,with the most obvious change in the community structure at 30-80 d.(4)Temperature plus ash group;c ompared with the control group,the total strains number of nematode-trapping fungi decreased significantly(P<0.05),and the strains number of A.musiformis,A.thaumasia and Dac.parvicolla were decreased significantly(P<0.05),which of A.oligospora was increased slightly,but the difference between the two groups did not reach significance(P>0.05);the species diversity index increased to 1.96,the number of endemic species increased and the community structure changed significantly,with the most obvious change in the community structure at 1 d,40 d,60 d,90 d.(5)Comparison of different treatment groups: reduce the degree of the total strains number of nematode-trapping fungi and the strains number of the dominant species(A.musiformis,A.thaumasia and Dac.parvicolla)of temperature plus ash group were less than that of temperature groups,the increase of strain number of A.oligospora was less than that of ash group;the species diversity index and temporal variation trend of community structure of temperature plus ash group were similar to the temperature group;the effect of temperature on organic matter and total nitrogen was greater than that of ash,the influence of ash on p H and soil moisture is greater than that of temperature.(6)Redundancy analysis and correlation analysis : the change of community structure in different treatments was mainly related to the change of soil moisture and total nitrogen caused by the treatment and the rainfall during the experiment.Conclusion:Both Temperature and ash have an impact on the community structure of nematode-trapping fungi,and the higher the temperature,the greater the impact;temperature,organic matter and total nitrogen are the main reasons driving the change of community structure of nematode-trapping fungi.In addition,the sensitivity of nematode-trapping fungi to temperature was different among species.Temperature and ash had an effect on the community structure of nematode-trapping fungi,and the effect of temperature was more significant.The degree of temperature affected nematode-trapping fungi was related to the temperature,duration and mode of combustion,In addition,the s ensitivity of nematode-trapping fungi to temperature was different among species.Organic matter and total nitrogen were the main environmental factors driving the community structure change of nematode-trapping fungi. |
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