| The development of clean,renewable energy has become the mainstream direction of energy development in the world today.Among other things,solar power is rapidly developing worldwide as an ideal form of new energy.In recent years,construction sites of photovoltaic(PV)power stations in China have gradually expanded from early desert areas to grassland areas.Currently,the distribution of PV power stations has become a "new landscape" on the Songnen Plain in northeastern China.Although PV power is a new form of renewable energy,the construction process and operation of PV power stations can also have a certain impact on the environment,for example,affecting vegetation and soil characteristics through the alteration of local microclimates by PV arrays.There are few reports on the effects of PV panel arrays on the composition and diversity of soil microbial communities in grassland ecosystems,especially in degraded grasslands.Therefore,studying the response of soil microbial communities in the Songnen grassland to PV panel arrays is important for scientifically assessing the impact of PV plants on grassland ecosystems.This study was carried out at the Honghua PV power station(44°18′52″N,123°57′27″E),which is located in the Songnen Grassland,Northeast China,and was constructed in 2018.The grassland around the power station was severely degraded before the construction of the station.A two-factor(i.e.,PV panel factor and plant community type factor)randomized block design was used.The first factor consisted of three treatment levels,the ambient zones outside the PV arrays,the gap zones between the PV panels,and the sheltered zones under the PV panels.The second factor consists of three levels: the Leymus chinensis community,the Artemisia scoparia community,and the Forb community.The PV power station and surrounding areas are fenced and free from grazing and other human interference.A vegetation survey and soil collection were conducted,and the components and diversities of soil microbes were determined by high-throughput sequencing methods.This study aims to answer the following questions:(1)What are the effects of PV panel arrays on the components and diversities of soil bacteria and fungi in different plant communities of the Songnen grassland?(2)What are the key plant community and soil physicochemical characteristics that influence the components and diversities of soil microbes under the influence of PV panel arrays?(3)Do PV panel arrays promote the restoration of soil microbial diversity in degraded grasslands? The main conclusions from this study are as follows:(1)A total of 29 phyla,82 classes,173 orders,274 families,473 genera and 521 species of bacteria were identified in the soil of three plant communities under the influence of the different PV panel treatments.Acidobacteria and Proteobacteria were the dominant bacterial phyla,and Actinobacteria,Alphaproteobacteria,Blastocatellia and Gammaproteobacteria were the dominant bacterial classes.Meanwhile,10 phyla,36 classes,86 orders,199 families,445 genera and 584 species of fungi were identified.Ascomycota and Basidiomycota are the dominant fungal phyla,and Sordariomycetes and Eurotiomycetes are the dominant fungal classes.(2)The PV panel arrays altered the composition and structure of soil bacterial and fungal communities in the Songnen grassland.The dominant bacterial classes whose relative abundance was significantly increased by the presence of PV panel arrays(the gap zones between the PV panels and the sheltered zones under the PV panels)included Bacteroidia,Clostridia,Acidobacteriia,Actinobacteria and Gammaproteobacteria.At the same time,the dominant fungal classes whose relative abundance was significantly increased by the PV panel arrays treatment,included Sordariomycetes,Eurotiomycetes,Tremellomycetes,Leotiomycetes,Dothideomycetes,and Neocallimastigomycetes.But the specific types of bacteria and fungi significantly affected by the PV panel arrays vary according to the type of plant communities.(3)The presence of the PV panel arrays significantly increased the α-diversities of soil bacteria and fungi and had greater effects on the diversities of soil bacteria and fungi in L.chinensis communities than in A.scoparia communities and Forb communities.Additionally,bacteria respond more sensitively to the PV panel arrays than fungi.(4)The main factors influencing the abundances of dominant soil bacterial taxa and bacterial α-diversities were soil p H,soil conductivity,plant community coverage and aboveground biomass.The main factors influencing the abundances and α-diversities of dominant soil fungal taxa were soil p H,soil conductivity,soil available nitrogen,plant community height,coverage,density,and belowground biomass.In summary,the PV panel arrays had impacts on the compositions and structures of the soil microbial communities in the Songnen Grassland,significantly increasing the relative abundances of some dominant taxa(class level)and actively restoring some soil microbial diversities.The main reason why the PV panel arrays affected soil microbial communities in the grassland was that the deployment of the PV panels changed local microclimatic conditions such as illumination,temperature and moisture;at the same time,the differences of the plant community types also changed soil microbial communities to some extent due to differences in the composition of plant species and the quantitative characteristics in plant communities.This study provides a preliminary assessment of the effects of PV power stations on the soil microbial communities in the Songnen Grassland and analyses the possible ecological mechanisms,which may provide a scientific reference for the planning of the PV power generation industry,the construction of PV power stations and their environmental assessments in the Songnen Plain.In addition,this study provided a theoretical reference for assessing the impact of PV power plant operation on the restoration of degraded grassland ecosystem functions. |
