Physiological profiling of the soil microbe community using the EcoPlate and assessment of soil properties at 74 planted forest sites across Japan

Due to policies supporting large-scale expansion of plantation forestry, about 40% of the forests in Japan are planted forests, such as Japanese cedar (Cryptomeria japonica) and hinoki cypress (Chamaecyparis obtusa). We present the largest freely available EcoPlate dataset for planted forests in Japan, comprising data collected from a network of 74 planted forest sites (114 plots) in regions ranging from cool-temperate to subtropical. The EcoPlate is a 96-well microplate that contains three sets of 31 “response wells” with different carbon substrates. The utilization of each carbon substrate by the microbial community is quantified based on the color development of the well during incubation, providing a multifunctional index of the soil microbial community. Soil properties (water content, carbon, nitrogen, the carbon/nitrogen (C/N) ratio, and pH) essential for interpreting the EcoPlate results were also analyzed. Using a standardized protocol, soil was sampled between July and November 2021. A preliminary principal coordinate analysis (PCoA) was performed on the temporal integration of color density using the 31 substrates. PCo1 explained 36.5% of the variance of the overall absorbance of all substrates. A model of environmental factors, including elevation, and a model of soil properties, including pH, water content, and carbon, were the best-fit models. EcoPlate data allow us to test hypotheses related to community ecology and the ecosystem functions of the soil microbial community in planted forests on a regional scale.