Contrasting effects of increased carbon input on boreal SOM decomposition with and without presence of living root system of Pinus sylvestris L
2014
Lindén, Aki | Heinonsalo, Jussi | Buchmann, Nina | Oinonen, Markku | Sonninen, Eloni | Hilasvuori, Emmi | Pumpanen, Jukka
AIMS: We studied how the availability of carbon affects the decomposition of soil organic matter (SOM) in the presence of living root system compared to bare SOM treatments without roots. METHODS: We measured the effect of living Pinus sylvestris L. root systems on SOM C and N budgets, on the age of carbon in CO₂ efflux, and on SOM protease enzyme activity. We examined the possible explanatory factors for increased SOM mineralization such as plant biomass, photosynthesis, microbial C, and protease enzyme activity in the soil. RESULTS: The age of carbon respired during the decomposition of soil organic matter was significantly older in the presence of living root systems than in treatments lacking roots. If plants were present, glucose added directly in the SOM accelerated the C and N loss from the bulk material and decreased the rate of photosynthesis. CONCLUSIONS: We conclude that the priming effect of SOM decomposition was affected by the presence of living root system. Our results stress the importance of including the plant–soil interactions in the SOM decomposition models used in climate change studies.
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