Root decomposition of four temperate species in the Republic of Korea: associations of root traits and microbial community with root decay

Abstract

Background and aims

Despite the importance of root litter decomposition on biogeochemical processes in forest ecosystems, the factors controlling its variability with diameter sizes and species remain uncertain. We aimed to investigate the decomposition rates of roots with varying diameters from four temperate species (Quercus mongolica, Pinus koraiensis, Pinus densiflora, and Larix kaempferi) and the influence of root traits and microbial community on root decomposition.

Methods

We conducted a 359-day litterbag decomposition experiment from December 5, 2022 to November 29, 2023 with roots sorted into four diameter classes (0–0.5 mm, 0.5–1 mm, 1–2 mm, and 2–5 mm). Initial root chemical (C, N, C:N, P, K, Mg, Ca, hemicellulose, cellulose, and lignin) and morphological traits (specific area and length) were determined. Mineral soil was sampled to analyze the microbial community.

Results

Decomposition rates across species were higher for P. densiflora (0–0.5 and 2–5 mm roots) and P. koraiensis (0.5–1 and 1–2 mm roots). Roots with 0.5–1 mm decomposed more rapidly for P. koraiensis and L. kaempferi; however, the decay of Q. mongolica and P. densiflora did not differ among root diameters. Decomposition was positively related to initial Mg, P, N, K, specific root length and area, and fungal Shannon index, and negatively related to C:N and C.

Conclusion

Chemical traits and microbial diversity are key drivers controlling species-based decomposition patterns. Additionally, our data showed that diameter-based decomposition patterns are species-specific, and diameter is not always a determinant factor for predicting decomposition. This study offers insights into the root decomposition processes in temperate forests, highlighting the complexity surrounding root decomposition patterns.