COS 29-9 - Soil nitrogen determines greenhouse gas emissions from northern peatlands under concurrent warming and vegetation shifting

Tuesday, August 8, 2017: 10:50 AM
B117, Oregon Convention Center


Junwei Luan, International Centre for Bamboo and Rattan; Jianghua Wu, Grenfell Campus, Memorial University of Newfoundland; Shirong Liu, Chinese Academy of Forestry; Nigel Roulet, McGill University; Mei Wang, Grenfell Campus, Memorial University of Newfoundland


Boreal peatlands contain an enormous pool of stored soil carbon that is dependent upon – and vulnerable to changes in – climate, as well as other interacting factors, such as nitrogen availability and plant community composition. However, how nutrient availability affect the direct and interactive effects between concurrent changes in both the abiotic and biotic variables environment interact to drive changes in ecosystem processes in these nutrient-poor ecosystems is unclear . In this study, we manipulated the temperature, plant community composition, nitrogen content, and N contentvegetation composition of boreal peatland plots to determine how these factors affect ecosystem processes and greenhouse gas emissions


While methane (CH4) and nitrous oxide (N2O) levels responded significantly to manipulation, ecosystem respiration might respond in an insignificant fashion. Strikingly, although warming was associated with higher CH4 emissions, the concurrent addition of N counteracted most (79%) of this effect, perhaps due to nitrogenous oxidation of CH4 triggered by warming. The presence or absence of grass-like plants had a stronger impact on warming-induced CH4 emissions than the presence or absence of shrubs, due to the positive effect on dissolved organic carbon (DOC) quality as a consequence of the presence of grass-like plants. Warming alone did not increase N2O emissions, but did interactively accelerate N2O emissions with the addition of N, and this interaction was modulated by the plant community composition. Our study is the first to reveal these complex interactions under a N-unlimited condition, and suggests that the responses of GHG emissions to future warming and shifting in plant community composition are largely depend on the N availability.

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