Abstract
Miscanthus-dominated semi-natural grasslands in Japan appear to store considerable amounts of soil C. To estimate the long-term effect of Miscanthus vegetation on the accumulation of soil carbon by soil biota degradation in its native range, we measured total soil C from the surface to a 1.2 m depth along a catena toposequence in three annually burned grasslands in Japan: Kawatabi, Soni, and Aso. Soil C stock was estimated using a radiocarbon age and depth model, resulting in a net soil C accumulation rate in the soil. C4-plant contribution to soil C accumulation was further estimated by δ13C of soil C. The range of total soil C varied among the sites (i.e., Kawatabi: 379–638 Mg, Soni: 249–484, and Aso: 372–408 Mg C ha−1). Catena position was a significant factor at Kawatabi and Soni, where the toe slope soil C accumulation exceeded that of the summit. The soil C accumulation rate of the whole horizon in the grasslands, derived C mainly from C4 plant species, was 0.05 ± 0.02 (Average ± SE), 0.04 ± 0.00, and 0.24 ± 0.04 Mg C ha−1 yr−1 in Kawatabi, Soni, and Aso, respectively. Potential exists for long-term sequestration of C under M. sinensis, but the difference in the C accumulation rate can be influenced by the catena position and the amount of vegetation.
Highlights
Miscanthus, a cold-tolerant perennial grass C4 native to East and Southeast Asia, exhibits potential as a feedstock for the production of biofuels and bio-based products [1,2,3,4]
Semi-natural Miscanthus sinensis grasslands in Japan, some of which have been managed for hundreds of years [4], offer an opportunity to assess the effects of centuries of Miscanthus growth and management on soil C resources [10,11,12,13,14,15]
The site is dominated by M. sinensis, which is maintained by annual mechanical cutting in the fall with the grass left in place after cutting
Summary
Miscanthus, a cold-tolerant perennial grass C4 native to East and Southeast Asia, exhibits potential as a feedstock for the production of biofuels and bio-based products [1,2,3,4]. In order to estimate the potential effects on edaphic resources, several researchers have considered the impact this genus has on soil carbon, mostly in cultivated or fallow fields [5,6,7,8,9] Observations, from these studies have been limited to less than 20 years. Soils previously investigated in the same biome contained high C content and demonstrated highly correlated age-to-depth models (R2 = 0.98–0.99) [11]. Using these age-to-depth models, Howlett et al (2013) estimated Miscanthus-derived soil C accumulation at 0.62–0.85 Mg C ha−1 yr−1 down to a 1.5 m depth in a Miscanthus-dominated semi-natural grassland in southern Japan
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