Belowground Spectroscopy — Novel Spectral Approach for Estimation of Vertical and Species-Specific Distributions of Forest Soil Characteristics and Heterotrophic Respiration

•Spectroscopic method was developed for monitoring heterotrophic respiration.•The respiration showed vertical and species specific differences in the forest.•Multiple regression model using N, moisture and cellulose explained the respiration.•PLSR using SWIR reflectance under varying moisture estimated explanatory variables.•Combined model demonstrated the variations of heterotrophic respiration in the field.