Abstract
Abstract. Plant functional traits have increasingly been studied as determinants of ecosystem properties, especially for soil biogeochemical processes. While the relationships between biological community structures and ecological functions are a central issue in ecological theory, these relationships remain poorly understood at the large scale. We selected nine forests along the North–South Transect of Eastern China (NSTEC) to determine how plant functional traits influence the latitudinal pattern of soil microbial functions and how soil microbial communities and functions are linked at the regional scale. We found that there was considerable latitudinal variation in the profiles of different substrate use along the NSTEC. Specifically, we found that the substrate use by microorganisms was highest in the temperate forest soils (soil microbial substrate use intensities of 10–12), followed by the subtropical forest soils (soil microbial substrate use intensities of 7–10), and was least in the coniferous forest soils (soil microbial substrate use intensities of 4–7). The latitudinal variation in soil microbial function was more closely related to plant functional traits (leaf dry matter content, leaf C concentrations, and leaf N concentrations, P=0.002) than climate (mean annual precipitation, P=0.022). The soil silt, leaf dry matter, and leaf C and N contents were the main controls on the biogeographical patterns of microbial substrate use in these forest soils. The soil microbial community structures and functions were significantly correlated along the NSTEC. Soil carbohydrate and polymer substrate use were mainly related to soil Gram-positive (G+) bacterial and actinomycic phospholipid fatty acids (PLFAs), while the use of amine and miscellaneous substrates were related to soil Gram-negative (G−) bacterial and fungal PLFAs. The enzyme production varied with changes in the soil microbial communities. The soil enzyme activities were positively correlated with the bacterial PLFAs but were not correlated with the fungal PLFAs. The soil organic matter (SOM) decomposition rates were significantly higher in the temperate forests than in the subtropical and tropical forests, emphasizing the rapid degradability of high-energy substrates such as soil microbial biomass carbon, carbohydrates, and amino acids. The SOM decomposition rates were significantly and negatively related to soil dissolved organic carbon concentrations, carboxylic acids, polymers, and miscellaneous substrate use. The relationships between soil PLFAs and microbial substrate use, enzyme activities, and SOM decomposition rate show that as the soil microbial community structure changes, soil biogeochemical processes also change.
Highlights
The catabolic diversity of soil microbial communities is a useful indicator of how microbial functions adapt to environmental stress
We examined the links between soil microbial community structure (PLFAs) and function (SOM decomposition rate, enzyme activities, and microbial substrate use)
Of the forests along the North–South Transect of Eastern China (NSTEC), the C metabolic intensity of soil microbes was lowest in HZ and LS; the C metabolic intensity of soil microbes differed significantly between JF and the other forests (Fig. 2), which indicates that the color development was significantly higher in the tropical forest soils than in the subtropical and temperate forest soils and is consistent with the variations in the average well color development (AWCD) (Fig. S1 in the Supplement)
Summary
The catabolic diversity of soil microbial communities is a useful indicator of how microbial functions adapt to environmental stress. Numerous studies have documented how environmental and anthropogenic perturbations impact on the structure, diversity (Tu et al, 2016; Zhou et al, 2016), and enzyme activities (Peng and Wang, 2016; Xu et al, 2017) of soil microbial communities and have reported that forests in the same climatic zone develop similar microbial communities. The soil microbial metabolic abilities are influenced by the dominant tree species, through the production of chemically unique litter and root exudates, and the soil physicochemical properties (Menyailo et al, 2002). Despite this and because of limitations in analytical methods, questions still remain about how soil microbial functions vary at the regional scale
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