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本研究以温带森林土壤为研究对象,设置野外模拟氮沉降实验,分析不同施氮形态和施氮水平对微生物群落结构的影响。试验设置对照(Control,0 kg N·hm~(-2)·a~(-1))、混合态低氮(NH_4NO_3,50 kg N·hm~(-2)·a~(-1))、混合态高氮(NH_4NO_3,150 kg N·hm~(-2)·a~(-1))、铵态氮低氮((NH_4)_2SO_4,50 kg N·hm~(-2)·a~(-1))、铵态氮高氮((NH_4)_2SO_4,150 kg N·hm~(-2)·a~(-1))、硝态氮低氮(NaNO_3,50 kg N·hm~(-2)·a~(-1))、硝态氮高氮(NaNO_3,150 kg N·hm~(-2)·a~(-1))7种氮处理,持续施氮3年后,运用磷脂脂肪酸(PLFA)法对土壤微生物群落结构进行测定。结果表明:在不同水平的氮添加下,土壤微生物总量、细菌、土壤革兰阳性细菌(G+细菌)、土壤革兰阴性细菌(G-细菌)和真菌的PLFA含量均随施氮水平的增加而升高;在不同形态的氮添加下,混合态氮添加提高了微生物总量、细菌、真菌和放线菌的PLFA含量。主成分分析(PCA)表明,除铵态氮低氮添加样地外,其他氮添加处理样地中的土壤微生物结构都发生了改变。这些结果表明,模拟大气氮沉降初期,氮添加会增加温带森林土壤微生物生物量,达到一定水平后会改变土壤微生物群落结构。
In this study, temperate forest soils were selected as the research object to set up a field simulated nitrogen deposition experiment to analyze the effects of different nitrogen forms and nitrogen application rates on the microbial community structure. The experiment set up control (0 kg N · hm -2 a -1), low nitrogen (NH 4 NO 3, 50 kg N · hm -2 · a -1) (NH_4NO_3, 150 kg N · hm -2 · a -1), low nitrogen (NH_4) _2SO_4, 50 kg N · hm -2 · a ~ (-1)), high nitrogen (NH_4) _2SO_4,150 kg N · hm -2 · a -1, low nitrogen (NaNO_3, 50 kg N · hm ~ (-2) · a ~ (-1)) and high nitrogen (NaNO_3, 150 kg N · hm ~ (-2) · a ~ After the phospholipid fatty acid (PLFA) method was used to determine the soil microbial community structure. The results showed that the PLFA contents of total soil microbes, bacteria, soil gram-positive bacteria (G + bacteria), soil gram-negative bacteria (G- bacteria) and fungi at different nitrogen levels increased with the increase of nitrogen application rate But increased with different forms of nitrogen. The addition of mixed nitrogen increased the total amount of microorganisms, PLFA content of bacteria, fungi and actinomycetes. The principal component analysis (PCA) showed that the soil microbial structure in all other nitrogen-added treatments changed with the exception of ammonium nitrogen additions. These results indicate that nitrogen addition increases soil microbial biomass in temperate forests at the initial stage of simulated atmospheric nitrogen deposition, and changes the soil microbial community structure after reaching a certain level.