Increased soil temperature stimulates changes in carbon, nitrogen, and mass loss in the fine roots of Pinus koraiensis under experimental warming and drought

Abstract

The effects of warming (+3 °C) and drought (–30% precipitation) on the fine root decomposition of Pinus koraiensis seedlingswere examined using a litter bag method. The study site included a full factorial design with two temperature and two precipitationlevels, with three replicates. Litter bags containing fine root litter of 2-year-old P. koraiensis seedlings were retrieved after 3, 6, and 12months of decomposition. After 12 months, the mass loss of fine roots was significantly increased in response to warming (control =31.1%, warming = 35.9%, drought = 29.2%, and warming plus drought = 35.5%); no change was observed until 6 months. Mass losswas not influenced by drought or by the interaction between warming and drought. Warming increased the nitrogen concentration offine root litter but decreased the carbon concentration and carbon/nitrogen ratio after 6 and 12 months. This may be because warmingstimulated nitrogen immobilization, which reduced the carbon/nitrogen ratio. Therefore, the carbon/nitrogen ratio may be affected bywarming prior to changes in the mass loss of fine roots because roots with a low carbon/nitrogen ratio are generally characterized byhigh available nitrogen for decomposers. These results suggest that climate change (especially warming) may cause rapid decompositionof organic matter.