Study On The Spatial Heterogeneity Of Soil Ecological Environment Factors And The Relationship With Microbial Community Diversity In Castanopsis Kawakamii Natural Forest

Using the method of quantitative ecology,this paper discusses the litter enzyme activity,soil particle composition,carbon and nitrogen features,enzyme activity and soil microbial community structure and function diversity in three kinds phytocoenosium types(Castanopsis kawakamii-Pinus massoniana community(G1)?Castanopsis kawakamii-Schima superba community(G2)?Castanopsis kawakamii-Castanopsis carlesii community(G3))of Castanopsis kawakamii natural forest.We built the ecological environment factor evaluation system aimed to study the micro-heterogeneity,ecological environment factors and the relationship between microbial community diversity and its impact mechanism.The result provides the basis theory for forest management.The result showed that:(1)The soil particle composition in different commuty soil was significant.The soil particle composition in C.kawakamii-P.massoniana community(G1)is similar to C.kawakamii-S.superba community(G2)which the soil particle size more focused on 100?m to 500 ?m.The soil particle size in C.kawakamii-C.carlesii community(G3)was more concentrated in the 10 ?m to 250?m.The 0-10cm is greater than the 10-20cm in soil particle size.Other physical structure characteristics:Soil moisture content of three community types is between 31.67%±3.00 to 21.09%±0.00mm,and the 0-1Ocm soil moisture content is greater than the 10-20cm.Bulk density of the subsoil is greater than the 0-10cm.the first two types of community showed the characterized that 0-10cm soil is greater than the 10-20cm in porosity while the C.kawakamii-C.carlesii community(G3)soil showed no difference in porosity.(2)C.kawakamii-P.massoniana community(G1)occupy obvious advantage in carbon and nitrogen in litter and soil.The next is followed by C.kawakamii-S.superb.a community(G2),the last is C.kawakamii-C.carlesii community(G3).Vertical rules showed that 0-10cm layer is greater than the 10-20cm.Regression analysis of organic carbon and mechanical composition of soil particles(clay,coarse clay?silt and sand)showed that each component presents a significant linear correlation with soil organic carbon(P<0.05).Organic carbon content of different degree of litter decomposition reflects significant difference(P<0.05)and C.kawakamii-P.massoniana community(G1)organic carbon in litter is rather different than the others.(3)Litter and soil enzyme activity,acid phosphatase,catalase in litter and soil layer showed no significant.Urease activity in 10-20cm layer soil of C.kawakamii-S.superba community(G2)was bigger witch was 0.14 ± 0.12mg-g-d-1 while it was 10-20cm in Castanopsis kawakamii-Castanopsis carlesii community(G3).0-10cm soil urease activity is greater than the 10-20cm;C.kawakamii-P.massoniana community(G1)had a highest urease enzyme activity.To the different layers,the decomposition layer(H)had the largest urease activity,the not decomposition layers(L)second,decomposition layers(F)was the lowest.Invertase activity in 10-20cm layer soil of C.kawakamii-S.superba community(G2)was bigger witch was 67.4316.77mg·g·d-1 while it was lowest in C.kawakamii-C.carlesii community(G3),C.kawakamii-S.superba community(G2)reflect that 10-20cm soil invertase activity was higher than the 0-10cm,others were showed the opposite pattern.Litter invertase activity reflects the absolute advantage in the 0-10cm soil of C.kawakamii-P.massoniana community(G1),Vertical rules of C.kawakamii-P.massoniana community(G 1)and C.kawakamii-C.carlesii community(G3)were decomposition layer(F)>half decomposition layer(H)>not decomposition layers(L),the other community was half decomposition layer(H)>not decomposition layers(L)>decomposition layer(F).Cellulose enzyme activity was biggest in C.kawakamii-S.superba community(G2)10-20cm soil and smallest in C.kawakamii-C.carlesii community(G3)0-10cm soil.Cellulose enzyme activity of thesee 3 community soil are all showing the law that 10-20cm soil is higher than the 0-10m soil;Cellulose enzyme activity in litter layers showed no obvious regularity.Effect on sucrase,urease,community types were not significant(P<0.05),the degree of decomposition of litter decomposition enzyme activity and community types and the interaction were not significant(P>0.05).(4)Soil enzyme activity,soil environment various ecological factors had coupling relationship,soil enzyme activity and soil physical and chemical did not show obvious correlation.PCA sequencing analysis showed that litter enzyme activity contributed small in litter spatial variability except sucrase.(5)The soil microbial biomass carbon difference is small in three community of litter layers(F,H)and two layers of soil while vertical rules presents the rule of the amount of microbes reduced from top layer to the bottom.The relationship between microbial biomass carbon and environmental factors were significantly and most of the factors(community type,pH,natural moisture rate,etc.)present a strong positive correlation.(6)Using the Biolog EcoPlate micro plate technology,we studied the soil microbial community functional diversity characteristics in the three community types.The results show that the general trend of microbial carbon source utilization ability is:C.kawakamii-P.massoniana community(G 1)>C.kawakamii-S.superbacommunity(G2)>C.carlesii-C.kawakamii community(G3).the abilities to utilize the 31 kinds of carbon sources was also present a big difference,we classified the 31 kinds of carbon sources into 6 categories of chemical groups,C.kawakamii-P.massoniana community(Gl)and C.kawakamii-S.superba community(G2)had strong utilization of carbohydrates,amino acids and carboxylic acid.C.kawakamii-C.carlesii community(G3)had strong utilization of polymer and amine and low of the other four categories of carbon source.Significant difference was found in different communities of soil microbial diversity(p<0.05).Shannon diversity index and McIntosh richness index showed that C.kawakam ii-P.massoniana community(G 1)>C.kawakamii-S.superba community(G2)>C.carlesii-C.kawakamii community(G3).Dominance index showed that C.kawakamii-C.carlesii community(G3)>C.kawakamii-P.massoniana community(G 1)>C.kawakamii-S.superba community(G2).(7)PLFA method was used to study the microorganisms structure diversity in soil layers of three kinds of community,the results show that the dominant phospholipid fatty acid markers were 16:0,18:1w9c,24:0,a17:0,il8:0,26:0,i16:0.18:1w9c was the advantages of fatty acids in these three community.Total PLFA,fungi and bacteria PLFA had strong relationship with soil microbial biomass carbon and soil physical property but no obvious correlation with soil enzyme activity.Soil total PLFA,bacteria and fungi of each community type were showed 0-10cm soil are much higher than the 10-20cm.PCA two-dimensional sort showed that the composition of soil microbial structure in three kinds of community had a strong heterogeneity.(8)We select major micro ecological environment factors as specific index parameters to establish a micro-ecological environment health quality evaluation system.Results showed that C.kawakamii-P.massoniana community(G1)0-10cm soil environment had a highest score that was 0.65 while C.kwakmnii-C.carlesii community(G3)10-20cm soil had a lowest score which is-0.92.The total score were score were C.kawakamii-P.massoniana community(G 1)>C.kawakamii-S.superba community(G2)>C.arlesii-C.kawakamii community(G3),the environment of 0-10cm soil>the environment of 10-20cm soil.