施氮肥对东北帽儿山云杉人工林土壤微生物生物量和群落结构的影响1）

采用磷脂脂肪酸（ PLFA）方法，研究了施氮肥对东北帽儿山地区云杉人工林的土壤微生物生物量和群落结构的影响。结果表明：与对照相比，施肥使土壤微生物总生物量在表层（0～10 cm）和亚表层（＞10～20 cm）分别下降了28．5％和11．5％。施肥也使细菌、真菌、革兰氏阳性菌生物量比对照显著降低，但是革兰氏阴性菌比对照组显著增加，而对放线菌无显著影响。施肥导致土壤部分理化因子也发生了显著改变，特别是施肥处理下硝态氮质量分数在表层和亚表层分别提高了10倍和6倍，而pH值在表层和亚表层显著下降。因此，施氮肥可以显著改变云杉人工林土壤的理化性质，导致土壤微生物生物量下降和土壤微生物群落结构的改变。

Effect of Nitrogen Fertilization on Soil Microbial Biomass and Community Structure of Picea koraiensis Planat tion in Maoershan Mountains of Northeastern China

We studied the effect of nitrogen ( N) fertilization on soil microbial community structure in Picea koraiensis plantation by using phospholipids fatty acids ( PLFA) in Maoershan Mounntains of Northeastern China .The total microbial biomass in surface and subsurface soil was decreased by 28.5%and 11.5%, respectively, under the N fertilization treatment .The bio-mass of bacteria , fungi , Gram-positive bacteria ( G+) was decreased significantly in the treatment plots than that in the control, while the Gram-negative bacteria (G-) was increased significantly.However, N fertilization did not change the bi-omass of actinomycete .Compared with the control , N fertilization changed soil chemical characteristics , particularly with NO-3-N concentration increasing by 10-and 6-fold in surface and subsurface soil , respectively , and with soil pH decrea-sing.Therefore, N fertilization could change soil chemical properties in P.koraiensis plantation, leading to the decrease of soil microbial biomass and the shift of microbial community structure .