| Arbuscular mycorrhizal fungi(AMF)are the most widely distributed soil fungi in natural ecosystems,which can establish mutualistic symbiosis with the roots of most vascular plants.According to the different vegetation distribution types,the study area was divided into six areas: 1.Scirpus mariqueter area in the ecotone of Scirpus mariqueter and Spartina alterniflora,BC;2;2.Spartina alterniflora in the ecotone of Spartina alterniflora and Scirpus mariqueter,H;3.Single Spartina alterniflora area,DH;4.Spartina alterniflora in the ecotone of Phragmites australis and Spartina alterniflora,JH;5.Phragmites australis in the ecotone of Phragmites australis and Spartina alterniflora,JL;6.Single reed area,L.In November 2017,may 2018 and August 2018,samples were collected from the study site,and high-throughput sequencing technology was used to study the diversity of arbuscular mycorrhizal fungi in rhizosphere soil of different vegetation zones and their correlation with soil factors.The main conclusions are as follows:The plant height and density of Spartina alterniflora in different vegetation zones changed differently during the growth period,but tended to be the same at the end of the growth period.Spartina alterniflora had a certain inhibitory effect on plant height of Phragmites australis,but the inhibitory effect of Spartina alterniflora on plant density of Phragmites australis was not obvious;In the whole growth cycle,the changes of organic carbon content of Spartina alterniflora in different vegetation zones were different,but there was no significant difference at the end of the growth period.Spartina alterniflora inhibited the carbon fixation of Phragmites australis,and Spartina alterniflora had a longer growth cycle than Phragmites australis.At the end of the growth period,Spartina alterniflora had a stronger phosphorus absorption capacity than Phragmites australis.The results showed that there were significant differences in soil physical properties among different vegetation zones.The change of soil moisture content among different soil layers showed a trend of increasing with the deepening of soil layer,but there was no significant difference.The water content of ecotone was significantly lower than that of single vegetation zone,which indicated that the intraspecific competition of Spartina alterniflora and Phragmites australis was less than that of interspecific competition to a certain extent;The results showed that the soil p H was different in different months.In May,the soil p H in the single vegetation zone was significantly higher than that in the ecotone,and there was no significant difference in August.At the end of plant growth in November,the soil p H in the low tide zone was significantly lower than that in the high tide zone;The results show that the soil salinity in the low tide area is higher than that in the high tide area,and there are significant differences between different tide levels.Compared with different soil layers in the vegetation zone,the soil salinity increases with the increase of depth,but there is no significant difference between different soil layers;The average soil particle size in the low tide area was higher than that in the high tide area,and there was significant difference between the tide levels;The results showed that the soil median particle size was different in different months.The soil median particle size in May was the highest,and that in November was the lowest.The surface 0-10 cm soil and BC area located in the forefront were greatly disturbed by the tide and the change of river flow,and the seasonal variation was significantly different.The soil total organic carbon was higher in the high tide area than in the low tide area,which was different in different months.The soil organic carbon in August was significantly lower than that in May and November;There was no significant difference in soil total nitrogen content among single vegetation zones,but there was no significant difference in nitrogen and phosphorus absorption capacity among Scirpus mariqueter,Spartina alterniflora and Phragmites australis.There was a certain mutual inhibition between Spartina alterniflora and Phragmites australis,while Scirpus mariqueter had a certain promotion effect on nitrogen and phosphorus absorption of Spartina alterniflora.The soil of each vegetation zone in the study plot is silty,with good air permeability and water permeability,strong leaching,and strong nutrient transfer ability among different soil layers,so there is no significant difference between 0-30 cm soil layers.As a whole,the contents of easily extracted and total extracted glomus in soil decreased with the depth of soil layer.The results showed that there were significant differences among different vegetation zones,and the high tide zone was higher than the low tide zone,but there was no significant difference among different soil layers.There were significant differences in the content of easily extractable glomus in different seasons,and the content in May was significantly lower than that in August and November;There was no significant difference between JL and L.the content of glomus in Phragmites australis was significantly lower than that in Spartina alterniflora.The content of glomus in May was significantly higher than that in August and November.In general,the spore density in low tide area was higher than that in high tide area,but there was no significant difference.The colonization rate and colonization intensity in high tide area were higher than that in low tide area.The colonization rate and colonization intensity of Spartina alterniflora in H area and DH area were very low,Spartina alterniflora in the ecotone had a significant inhibitory effect on the colonization of arbuscular mycorrhizal fungi in Phragmites australis.During the three-month investigation,114 OTUs of AM fungi were found in 3 classes,4orders,8 families and 9 genera,belonging to Ambispora,Archaeospora,Acaulospora,Diversispora,Gigaspora,Scutellospora,Claroideoglomus,Glomus,Paraglomus.Fourteen OTU species were identified: Ambispora Hernandez-Hernandez17,Archaeospora HernandezHernandez17,Archaeospora Mueller15,Scutellospora LH-Sc01,Glomus clarum,Glomus Gl Ad2.4,Glomus Glo1,Glomus Glo-E,Glomus manihotis,Paraglomus Alguacil12 b,Paraglomus Alguacil14 b,Paraglomus Glom,Paraglomus occultum,Paraglomus Para2.The diversity of AM fungi in tidal flat wetland was significantly lower than that in land.Among all the identified AM fungi,only Glomus was distributed in three months and all the plots.There were 35 OTUs in Glomus,which was the most dominant among the tested samples.Paraglomus has 40 OTUs,and its relative abundance is the highest among the identified AM fungi,but its relative abundance is lower than Glomus.The species and diversity of AM fungi were different from each other.There were 7 genera of AM fungi in H and BC,and 8 genera in JH,JL and L.The results showed that the intertidal zone occupied by H,DH,JH and JL was more suitable for AM fungi growth.Ambispora and Gigaspora are only distributed in JH,JL and l vegetation belts in high tide area.Diversispora,Glomus and Paraglomus had the highest relative abundance in H area,Archaeospora had the highest relative abundance in DH area,Acaulospora and Scutellospora had the highest relative abundance in JH area,Ambispora and Gigaspora had the highest relative abundance in JL area.The dominant and endemic genera of AM fungi were different in different months.In May,the dominant genus was Archaeospora,but there was no endemic genus;The dominant genus in August is Archaeospora,and the endemic genera are Diversispora and Gigasporaceae;The dominant species in November is Glomus,and the endemic genera are Acaulospora and Scutellospora,which are distributed in all vegetation belts in November.There was a significant positive correlation between total glomus and ACE index,OTU(p< 0.05);Soil total nitrogen was significantly positively correlated with Simpson index(p <0.01),and negatively correlated with Shannon index(p < 0.05). |
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