土地利用方式对豫西黄土丘陵区土壤团聚体微生物生物量及群落组成的影响

采用熏蒸浸提和磷脂脂肪酸(PLFA)法研究了豫西黄土丘陵区不同土地利用方式下土壤团聚体中微生物生物量及其群落组成。结果表明,0.25~2 mm粒级团聚体微生物生物量碳(MBC)和微生物生物量氮(MBN)含量最高,0.053~0.25mm粒级团聚体MBC和MBN含量最低;阔杂林、刺槐林和灌草地5、2~5和0.25~2mm 3个粒级团聚体的MBC和MBN含量较耕地显著提高(P0.05),果园与耕地之间无显著差异(P0.05)。不同利用方式下,细菌PLFA含量及其占团聚体总PLFA的比例分别以0.25~2和0.053~0.25mm粒级团聚体最高;真菌PLFA含量及其占比为5mm粒级团聚体最高,且随团聚体粒径的减小而降低。MBC和MBN含量与PLFA总量、表征细菌和真菌PLFA含量均显著或极显著正相关(P0.05或P0.01)。与耕地和果园土壤相比较,阔杂林地、刺槐林地和灌草地中5、2~5和0.25~2mm粒级团聚体中表征真菌PLFA的含量显著增加。综上,阔杂林、刺槐林和灌草地较耕地和果园显著提高了0.25mm粒级团聚中微生物生物量及真菌含量。

Effect of different land use types on soil aggregates microbial biomass and community composition in the loess hilly region of west Henan

Microbial biomass and community composition in aggregates of different land use types in the loess hill region of west Henan were analyzed by fumigation extraction method and phospholipids fatty acids (PLFA) biomarkers.Microbial biomass carbon (MBC)and microbial biomass nitrogen (MBN)contents were the high-est in aggregate of 0.25~2.00 mm and lowest in 0.053~0.250 mm.Compared with the farmland,the MBC and MBN contents in >5 mm,2~5 mm and 0.25~2.00 mm aggregates of broad-leaved mixed forestland,Robinia pseudoacacia plantation forestland and shrub-grass land were significantly increased(P<0.05),which in or-chard and farmland were no significant difference(P>0.05).The PLFA contents of bacteria were the highest in the 0.25~2.00 mm aggregates,however,the highest proportion of bacteria to total PLFA were found in 0.053~0.250 mm aggregates in all different land use types.The PLFA contents of fungi and its proportion to total PLFA in the >5 mm aggregates were the highest and induced with the decrease of the aggregates size. The contents of MBC and MBN present a notable positive correlation with the PLFA contents of the bacteria and fungi(P<0.05 or P<0.01).Compared with the farmland and orchard soil,the contents of fungi in>5 mm,2~5 mm and 0.25~2.00 mm aggregates of broad-leaved mixed forestland,R.pseudoacacia plantation forestland and shrub-grass land increased significantly.To sum up,soil microbial biomass and fungi PLFA con-tents in >0.25 mm aggregates of broad-leaved mixed forestland,R.pseudoacacia plantation forestland and shrub-grass land were significantly increased compared with farmland and orchard.