| Disturbance is an important factor affecting forest ecological environment,which can affect forest structure,function and ecological process by changing stand structure and habitat environment.Ectomycorrhizal fungi(EMF)are mutually beneficial symbionts formed by specific fungi in soil and vegetative roots of plants.As an important biological component of forest ecosystem,EMF plays an important role in succession and diversity maintenance of forest ecosystem.Pinus massoniana Lamb is the dominant tree species for local afforestation in south China,and also the pioneer tree species for greening barren mountains,which has important utilization value and economic benefits.This study selected the P.massoniana forest under different disturbance types(resin tapping,litter removal and fire)as the research object,using morphological and molecular biology identification method combined to explore the impact of different interference types on P.massoniana EMF community,and further analyze the difference of the impact of different disturbance types on P.massoniana EMF community.In order to provide some scientific basis for the restoration and sustainable management of P.massoniana forest after disturbance.The main research results are as follows:The effects of soil properties and enzyme activities in P.massoniana forest were mainly reflected in the nutrient content in the surface soil(0-20 cm)was significantly higher than that in the bottom soil(20-40 cm and 40-60 cm),indicating that the soil chemical properties had a "surface aggregation" effect.Soil urease activity decreased and catalase activity increased with increasing soil depth,and the significant difference was consistent with soil chemical properties.There were significant differences in soil properties among different disturbance types.After resin tapping,soil p H increased and nutrient content increased significantly at 0-20 cm.Soil p H,organic carbon and total nitrogen contents in P.massoniana forest decreased significantly after litter removal,while the contents of total phosphorus,available nitrogen and available phosphorus had no significant difference.The content of p H and available potassium increased,while the content of other nutrients decreased significantly.The content of available phosphorus showed no obvious regularity in different soil layers and different disturbance.The correlation between soil enzyme activities and chemical properties of P.massoniana forests with different disturbance types was different.Effects of resin tapping on EMF community of P.massoniana: A total of 49 OTUs were identified based on mycorrhizal samples of resin tapping and non-resin tapping P.massoniana forests,belonging to 2 phyla,4 classes,11 orders,15 families,18 genera.The quantity ratios of Ascomycota and Basidiomycota in EMF community of P.massoniana forest were about 1:4 and1:6.The species richness of Ascomycota in EMF community of P.massoniana forest showed an increasing trend,but the species richness of Basidiomycota still dominated;The dominant genera of the resin tapping P.massoniana community were Lactarius and Tomentella,while the dominant genera of non-resin tapping P.massoniana forest community were Russula,Unc.Thelephoraceae,and Tomentella;The species richness and diversity index of EMF community in P.massoniana forest of resin tapping was lower than that of non-resin tapping,and the similarity index of EMF community between the two was low,indicating that the composition and diversity of P.massoniana EMF community could be changed by resin tapping.AK and AP were the main environmental factors affecting EMF community in P.massoniana forest.Effects of litter removal on the EMF community of P.massoniana: A total of 58 OTUs were identified based on mycorrhizal samples from P.massoniana forest with and without litter removal,belonging to 2 phyla,6 classes,14 orders,15 families and 22 genera.The quantity ratios of Basidiomycota and Ascomycota in P.massoniana forest were 3:1 and 5:1 of litter removal and nonlitter removal,among which Tomentella,Russula and Cenococcum were the dominant genera in P.massoniana forest.and Tomentella,Lactarius,and Russula were the dominant genera in the EMF community in the non-litter removal P.massoniana forest,The diversity of EMF community in P.massoniana forest of litter removal was lower than that in non-litter removal;TP and p H were the main environmental factors affecting EMF community in P.massoniana forest.Removal of litter had a significant effect on the composition and structure of the EMF community of P.massoniana,and decreased the diversity of the EMF community of P.massoniana.Effects of fire on EMF community of P.massoniana: Based on the mycorrhizal samples of P.massoniana forest in fire and non-fire,a total of 69 OTUs were identified,belonging to 2 phyla,7classes,15 orders,18 families,23 genera,and the EMF community species richness of Basidiomycota was significantly higher than that of Ascomycota.The composition and structure of EMF community in P.massoniana were significantly changed by fire.The dominant genera of EMF community in fire P.massoniana forest were Laccaria,Russula and Tomentella.The dominant genera of EMF communities in non-fire P.massoniana forests were Lactarius,Tomentella,and Cenococcum.The ratio of Basidiomycota and Ascomycota in the EMF community of fire and nonfire P.massoniana forests was about 2:1 and 5:1,the number of Basidiomycota was significantly higher than that of Ascomycota,the diversity index and abundance index of EMF community in in fire P.massoniana forest showed a downward trend.RDA analysis showed that p H and TP were important environmental factors affecting EMF community in P.massoniana forest.There were significant differences in the species composition of EMF communities with different disturbance types in P.massoniana forests.(1)The dominant genera that resin tapping with the EMF community in the P.massoniana forest were Lactarius and Tomentella;(2)The dominant genera of EMF community disturbed by litter removal were Tomentella and Russula.(3)The dominant genera of EMF community disturbed by fire were Laccaria and Russula.There were also some differences in the species composition of EMF communities in undisturbed P.massoniana forests in different sites.Among them,The dominant genus of P.massoniana EMF community in Longli Forest farm was Russula;(2)The dominant genera of the P.massoniana EMF communities in Mengguan Forest And Guli Village were Tomentella and Lactarius,and the differences in species composition may be related to distance.An indicator species analysis of different EMF communities indicated that the P.massoniana EMF community was Lactarius under resin tapping,Cenococcum under litter removal,and Laccaria under fire disturbance.AK,AP and p H were the main environmental factors affecting the composition and structure of EMF community in P.massoniana forest with different disturbance types.Therefore,it shows that there are significant differences in the effects of different disturbance types on the EMF community of P.massoniana forests. |
