| Vegetation restoration project has an obvious effect on soil property improving and ecologicalenvironment restoration in the Loess Plateau. Nitrogen mineralization controling by soil microbial is thekey factor limiting the plant growth, however, the soil microbial species, characteristics and diversity in thisprocess was not clear yet. Therefore, in this study, typical soils from different vegetations restorationpatterns were selected in the hill area of southern Ningxia, numbers of three main microbial groups andnitrogen physiological groups, partial functions and characters of ammonifiers, and distributions of soilbacteria and fungi diversity were studied by culture isolation, MPN, DGGE and high-throughputsequencing techniques in the soil in-situ mineralization cultivation processes, to clarify the micobialresponses to in-situ mineralization process under different vegetation restoration patterns. The main resultsare as follows:(1) During soil in-situ mineralization cultivation process of different vegetation restoration patterns,bacteria population remained at a relatively high value(1.0×106CFU g-1dry soil~4.0×106CFU g-1dry soil)from60th day to180th day(June to October), fungi population showed the highest value(80CFU g-1drysoil~330CFU g-1dry soil) at120th day(August), and actinomycetes population remained high at240th dayand360th day(December and April in2013); after in-situ mineralization cultivation for360days(April in2013), bacteria population in all sample sites(except wild peach land) was significantly lower thanuncultivation land, fungi population in representative glassland(except abandoned land) was significantlylower than uncultivation land, little changed in the rest land, actinomycetes population in representativeglassland(except abandoned land) was significantly higher than uncultivation land, but representativeartificial forestland(except wild peach land) shows the opposite trend.(2) During soil in-situ mineralization cultivation process of different vegetation restoration patterns, allsample sites’ ammonifying bacteria population reached each highest value(1.3×104CFU g-1dry soil~3.0×105CFU g-1dry soil) in different cultivation periods, no consistent law exist among them; nitrite bacteriapopulation shows relative high value(90CFU g-1dry soil and1.15×103CFU g-1dry soil) at120th day and240th day(August and December) in the cultivation process; nitrate bacteria population reaches theirhighest value at60th day or120th day(June or August) in all sample sites; denitrifying bacteria populationshows highest value(3.0×102CFU g-1dry soil~4.0×103CFU g-1dry soil) in120th day(August); free-living nitrogen-fixing bacteria population in different sample sites reaches their relatively high value at60th day,120th day or240th day(June, August or December); after in-situ mineralization cultivation for360days(April in2013), ammonifying bacteria and denitrifying bacteria population in cultivation anduncultivation land soil of all sample sites show different value relationships, nitrate bacteria populationshows no significantly change; nitrite bacteria population in cultivation soil was a little higher thanuncultivation soil; free-living nitrogen-fixing bacteria population in cultivation soil significantly decreasedthan uncultivation soil(natural grassland and alfalfa land keep constant).(3) Soil microbial total DNA concentration shows highest in natural grassland while lowest in alfalfaland during the360days in-situ mineralization cultivation process. Total DNA concentration in all samplesites have the same trend along different cultivation periods,120th day and240th day(August andDecember) show high values and others remain low; after360days(April in2013) in-situ mineralizationcultivation, total DNA concentration of different vegetation restoration patterns soil decreased27.76%withcompared to uncultivation soil; according to bacterial DNA denaturing gradient gel electrophoresis modepattern, all sample sites can be divided into three categories:wild peach land, mixed land, alfalfa land andnatural grassland as one category, it has the highest bacterial diversity index, wild apricot land andabandoned land as one category, caragana microphylla land as one independent category and has thelowest diversity index.(4) High-throughput sequencing results showed that four sample sites’ bacteria belonging to68classes,121orders,198families,311genera and157species (Unclassified species contains manyunidentified species), Bacillus was the dominant genus, containing up to65%~80%; Chao index and Aceindex indicate that alfalfa land has the highest species richness and caragana microphylla land the lowest,the relative abundances of all kinds of bacteria are different in all sample sites, different sample sites has itsuniquebacterium; fungi belonging to10phyla,28classes,48orders,61families and69genera, nodominant fungi genus exists in four sample sites; Chao index and Ace index show some differences ofspecies richness in the four sample sites, the relative abundances of all kinds of fungi are different in allsample sites, different sample sites has its own fungus; bacterial OTU are much higher than fungi OTU infour sample sites, Chao index, Ace index and Simpson index of bacteria are higher than fungi’. |
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