Root order and initial moisture status influenced root decomposition in a subtropical tree species Liquidambar formosana

Abstract

Root decomposition plays an important role in biogeochemical cycles in terrestrial ecosystems. However, there is still controversy on whether low-order (finer) or high-order (coarser) roots decay faster. Previous studies on root decomposition often used dried root samples, and the dehydrating process may influence the results. In this study, we aimed to examine the decomposability of low- and high-order roots and whether initial moisture status would influence their decomposition. We carried out a one-year litterbag experiment for roots of a subtropical tree species Liquidambar formosana. Roots for the decomposition were divided into low- (1st and 2nd orders) and high-order (3rd and 4th orders) classes, and were dried or kept fresh before being buried into the soil. We found that low-order roots were decomposed slower (half the rate of high-order roots in terms of mass loss), and the content of soluble carbohydrates was the main influencing factor. We also found that drying prior to decomposition facilitated the decomposition of high-order roots during the early stage by 10%. Our study suggests that litter carbon quality, particularly soluble carbohydrate content, is the major driver for root decomposition, and that previous studies using dried root samples might have overestimated short-term root decomposition.