Temporal variation in fine-root biomass, production, and mortality in a cool-temperate forest covered with understory Sasa senenensis

Abstract

The fine root production–mortality–decomposition process is crucial for carbon and nutrient cycling in forest ecosystems, however the process remain understudied. This is because quantifying temporal changes in fine root production and mortality or decomposition which occur simultaneously (fine root dynamics) has been quite limited even if fine root biomass can be evaluated, as fine roots are invisible belowground. The difference in fine root turnover rate which is expressed as the ratio of fine root production or mortality (decomposition) to fine root amount (biomass or density) is seen in the difference in fine root production or mortality in forest ecosystems. Thus, such dynamics must be evaluated accurately. Here, I reviewed our case study that investigated temporal changes in the fine root biomass using core method, and fine root density, production, and mortality using the non-destructive minirhizotron method in a cool-temperate forest covered with dense understory dwarf bamboo (Sasa senanensis) in northern Hokkaido. In this review, I considered the correlations of aboveground phenology of overstory trees and the dwarf bamboo with the temporal patterns of fine root production and mortality. In addition, to understand the contribution of fine roots to forest productivity, I compared fine root production with aboveground net primary production. Ultimately, I demonstrated the significance of fine root production in the productivity of the cool-temperate forest.