土地整理对土壤微生物群落多样性的影响

土地整理保证了我国耕地总量的动态平衡和占补平衡,已成为实现国土资源集约利用的主要手段,但整治过程中的强度扰动会对土壤质量产生一定的影响.为了解土地整理对土壤微生物多样性的影响,采用PLFA法研究了土地整理1年(Z1a)、4年(Z4a)后土壤微生物群落多样性的变化.结果表明: 与未整理(Z0)相比,土地整理1年后,土壤pH值提高了14.6%,土壤有机碳质量分数降低了65.4%;各菌群磷脂脂肪酸PLFAs含量和相对丰度均显著下降(P<0.05),下降幅度达43.4%～63.7%和25.2%～53.9%;真菌/细菌(F/B)显著下降(P<0.05),降低了35.9%,而革兰氏阳性菌/革兰氏阴性菌(G⁺/G^-)升高明显,增加了56.1%,均与有机碳的降低和pH值的升高有显著相关关系;土壤微生物多样性Shannon指数和均匀度指数(E)均显著下降,Z0与Z1a、Z4a之间的差异达显著水平;土地整理4年后,表征土壤微生物群落多样性的各指标相比整理1年的样地有所提升,但与未整理样地仍有显著差异.综上,土地整理显著影响着土壤微生物群落的组成,降低了土壤生态系统的稳定性.

Effect of land consolidation on soil microbial community diversity.

Land consolidation has become a main means of achieving the intensive use of land resources, which ensures the dynamic equilibrium and requisition-compensation balance of the total cultivated land in China. However, the intensive disturbance during the land consolidation may affect the soil quality. In order to investigate the effect of land consolidation on soil microbial diversity, we studied the changes of soil microbial community diversity after 1-year and 4-year land conso-lidation by using PLFA method. The results indicated that compared with no consolidation (Z0), for land consolidation after 1a (Z1a), the soil pH value increased by 14.6%, the soil organic carbon content decreased by 65.4%, the phospholipid fatty acids content and relative abundance of all the microflora decreased significantly (P<0.05) by 43.4%-63.7% and 25.2%-53.9%, respectively, and the ratio of fungi/bacteria (F/B) decreased significantly by 35.9% (P<0.05), while the ratio of Gram-positive bacteria/Gram-negative bacteria (G⁺/G^-) increased significantly by 56.1%. These were significantly related to the increased pH value and the decrease of organic carbon content. The Shannon index and evenness index (E) of soil microbial diversity were significantly decreased, with significant differences observed among Z0 and Z1a, Z4a. After 4-year land consolidation, the indices characterizing soil microbial community diversity were improved compared with those after 1-year land consolidation. In summary, the land consolidation could significantly affect the composition of soil microbial communities, and decrease the stability of the soil ecosystem.