Woody stem and root litters influence soil carbon decomposition through enzyme activities in boreal peatland

Abstract

Under the context of climate warming, the increased abundance of woody plants in boreal peatlands introduces uncertainty to the peatland soil carbon balance. This study aimed to investigate the effect of the input and decomposition of woody litter on the CO₂ emissions of boreal peatland. Woody litters from two plant organs (stem and root) of four plant species, i.e., two shrub species (Vaccinium uliginosum and Chamaedaphne calyculata) and two tree species (Betula platyphylla and Larix gmelinii), were collected from a boreal peatland in northeast China and incorporated into the peat soil collected from northeast China for 100-day laboratory incubation experiments under various temperatures and soil moistures. The results showed that while the input and decomposition of woody litter increased CO₂ emissions by 130 %–210 %, the addition of woody litter had no significant effect on the temperature sensitivity of peat soil CO₂ emissions. Among the eight types of woody litters, the tree-type litters and root litters showed faster decomposition and higher accumulated CO₂ emissions compared to the shrub-type litters and corresponding stem litters, respectively, which could be attributed to low C/N ratios of tree-type litters and root litters. In addition, the temperature and soil moisture influenced the soil enzyme activities and thereby greatly impacted the woody litter decomposition and CO₂ emissions. The temperature increase and soil moisture decrease enhanced the woody litter decomposition and CO₂ emissions. The results of this study contribute to a better understanding of the effects of woody litter input and decomposition on CO₂ emissions from boreal peatlands, providing theoretical support for evaluating the impact of continuous climate warming on the carbon balance of boreal peatlands.