Effect Of Light Environment Heterogeneity On The Characteristics Of Microbial Community At Small-Scale

The heterogeneity of light environment has important influence on the structure and function of plant tissue,individual,community and ecosystem.At different spatial scales,the large-scale zonal distribution of latitude and the small-scale change of life form of plant communities are formed.Microbial communities have a wide array of biodiversity,making them one of the important parts on the earth's biodiversity.Microorganisms play crucial role in the biogeochemical cycle and energy flow in the ecosystem.However,there is no systematic report on how light environment affects microbial community diversities,distribution patterns,structures and functions.In this paper,the diversity and distribution patterns of microbial community under two kinds of small-scale heterogeneous light environment were studied.One is the microbial communities on the shading and non-shading bark surface of Larix principis-rupprechtii in subalpine,and the other is the plant-soil-microbial system in shading and non-shading conditions of photovoltaic power station.Based on the high-throughput sequencing,nonmetric multidimensional scale analysis?NMDS?,redundancy analysis?RDA?,zero model,co-occurrence network and structural equation model?SEM?were used to explore the maintenance mechanisms of microbial community diversities and structures in different light environments.The main results are as follows:1.Effects of light on microbial community characteristics on bark surface of Larix principis-rupprechtii.?1?There were no significant differences in physical and chemical factors?TN,TC,C/N and p H?on the bark surface between non-shading?NS?and shading?S?.?2?The?diversity of bacterial community in S and NS conditions was significantly different,and the?diversity in shading condition was higher than that in non-shading one.There was no significant difference in the?diversity of fungal community between shading and non-shadying surface of the bark.?3?The bacterial community structure was significantly different between shading and non-shading surface of the bark,and light intensity is the main driving factor.There was no significant difference in fungal community structure.?4?A closer connection between bacteria and fungi community on non-shading environment were finded,and the coexistence of microbial communities was greater than exclusion.2.Effects of light environment heterogeneity on soil-plant-microbe system?1?There were significant differences in photosynthetically active radiation?PAR?and soil temperature?Tm?between shading?S?and non-shading condition?P<0.05?.The soil has higher PAR and Tm in NS condition.The PAR in NS condition was about 744?mol·m^-2·S^-2,which in S condition was about 98?mol·m^-2·S^-2.The Tm in S condition was significantly lower than that of NS condition?P<0.05?.?2?The plant community in non-shading condition?NS?had significantly higher?diversity and aboveground biomass than those in shading condition?S??P<0.05?.The results showed that plant?diversity was influenced by total nitrogen?TN?and nitrate nitrogen?NO₃^--N?,while aboveground biomass was most significantly affected by PAR.The diversity of fungi in S condition was significantly higher than that in NS condition?P<0.05?,while the?diversity of soil bacterial and protistan communities have no significant change?P>0.05?.The?diversity of plant was significant correlation with that of fungi,rather than significant correlation with bacteria and protists?P>0.05?.?3?The composition of plant and soil microbial communities?bacteria,fungi and protist?was significantly changes in different light conditions?P<0.05?.PAR is a main driving factor for assembly of above and belowground communities,which can influence soil microbial communities through direct and indirect effects,among which the indirect effect is mainly through the plant community to regulate microorganisms.The distribution patterns of the soil microbial community were mainly affected by environmental filtration.The?diversity of plant community can predict the trend of soil microbial community composition?P<0.05?.?4?The soil bacteria-fungi-protist communities were more closely connected in shading conditions,and the coexistence of microbial communities was greater than the exclusion.Taken together.In this study,the deterministic process dominated by environmental factors is the main factor in driving the process of microbial community assembly at small-scale.The distribution of microbial community diversities in different habitats is directly and indirectly affected by the intensity of light,and the heterogeneity of light is an important factor to maintain the diversities of microbial community.