Bacterial community changes during fir needle litter decomposition in an alpine forest in eastern Tibetan Plateau

Abstract

Bacterial community plays an important role in litter decomposition. Although the changes of bacterial community as litter decomposition proceeding can be regulated by frozen temperature and changed litter quality in cold regimes, little information has been available on. Therefore, the structure and diversity of the bacterial community in Minjiang fir (Abies faxoniana) needle litter were measured in an alpine forest in eastern Tibetan Plateau. The litter samples were sampled at the onset of the freezing stage, the deep freezing stage, the thawing stage, the early growing season and the late growing season from December 2010 to November 2011. The methods of real-time polymerase chain reaction (qPCR) coupled with denaturing gradient gel electrophoresis (DGGE) were used. The copy numbers of bacterial 16S rDNA in the fir needle litter changed significantly as litter decomposition proceeding. The abundance of bacterial 16S rDNA was significantly lower at the deep freezing stage but highest at the thawing stage. A large number of bands were observed on the DGGE gel; the intensities and distances of the bands were significantly different among the samples at different stages; the indexes of bacterial diversity at the onset of the freezing and deep freezing stages were lower than them at the other stages. All of the bacterial sequences were affiliated with six distinct classes and an unknown group. Redundancy analysis indicated that moisture, mass loss and the release of litter elements (e.g., C, N, P) exerted obvious influences over the bacterial communities.