Litter chemical quality strongly affects forest floor microbial groups and ecoenzymatic stoichiometry in the subalpine forest
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Litter chemical quality regulates the distinct composition of the main microbial groups and ecoenzymatic stoichiometry. Microbes in spruce ( Picea asperata Mast.) and fir ( Abies faxoniana Rehd.) rather than birch ( Betula platyphylla Suk.) and rhododendron ( Rhododendron lapponicum (L.) Wahl.) can more easily adjust their physiological metabolism to acclimate to low N resources.
Litter decomposition is the main pathway of nutrient cycling that bridges aboveground and underground material circulation and energy flow. Microorganisms are essential for the regulation of organic carbon decomposition and nutrient cycling.
We sought to reveal whether litter chemical quality predominates forest floor microbial structure and function in different species and how their characteristics vary with litter decomposition stages.
We measured litter substrate quality, microbial community structure, microbial biomass carbon (MBC) and nitrogen (MBN), extracellular enzyme activities and stoichiometric homeostasis of fresh litter (L), and fermentative (F) and humus (H) layers for these tree species.
Overall, the enzyme activities and microbial biomass of birch and rhododendron were greater than those of spruce and fir. The microbial abundances of birch and rhododendron decreased with decomposition. Forest floor microbial nutrient limitation is generally restricted by N in subalpine forests, and ecoenzymatic stoichiometry is affected mainly by dissolved C/N/P stoichiometry. Stronger microbial C:N homeostasis (H′) was observed for spruce (5.56) and fir (4.17) than that for birch (1.82) and rhododendron (1.33).
We conclude that litter chemical quality led to the disparity in forest floor microbial groups and ecoenzymatic stoichiometry for different tree species.
KeywordsTree species Forest floor layers Litter chemical quality Microbial biomass Ecoenzymatic stoichiometry
We would like to thank Shuai Yang, Jing Deng, Jiaqi Shi, Shiyu Tang, and other graduate students at the Institute of Ecology and Forestry, Sichuan Agricultural University, for assistance with field sampling and laboratory analyses.
This study was financially supported by the National Natural Science Foundation of China (31570605), the National key Research Program of China (2017YFC0505003), the key project of Sichuan education department (18ZA0393), and Key Research Program of Sichuan Province (18ZDYF0307).
Compliance with ethical standards
Statement on ethical approval
Ethics Committee approval was obtained from the Institutional Ethics Committee of Miyaluo Nature Reserve to the commencement of this study.
Conflict of interest
The authors declare that they have no conflict of interest.
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