Partitioning of the net CO2 exchange using an automated chamber system reveals plant phenology as key control of production and respiration fluxes in a boreal peatland. (24th May 2018)

• Record Type: Journal Article
• Authors: Järveoja, Järvi; Nilsson, Mats B.; Gažovič, Michal; Crill, Patrick M.; Peichl, Matthias
• Is Part Of: Global change biology. Volume 24:Number 8(2018)
• Page Start: 3436
• Page End: 3451
• Publication Date: 2018-05-24
• Subjects: autotrophic and heterotrophic respiration -- biotic and abiotic controls -- boreal fen -- carbon dioxide -- climate change -- flux partitioning -- gross and net primary production -- vegetation phenology; Climatic changes -- Environmental aspects -- Periodicals; Troposphere -- Environmental aspects -- Periodicals; Biodiversity conservation -- Periodicals; Eutrophication -- Periodicals; 551.5
• DOI: 10.1111/gcb.14292
• Languages: English
• ISSNs: 1354-1013

Abstract

Abstract: The net ecosystem CO2 exchange (NEE) drives the carbon (C) sink–source strength of northern peatlands. Since NEE represents a balance between various production and respiration fluxes, accurate predictions of its response to global changes require an in depth understanding of these underlying processes. Currently, however, detailed information of the temporal dynamics as well as the separate biotic and abiotic controls of the NEE component fluxes is lacking in peatland ecosystems. In this study, we address this knowledge gap by using an automated chamber system established across natural and trenching/vegetation removal plots to partition NEE into its production (i.e., gross and net primary production; GPP and NPP) and respiration (i.e., ecosystem, heterotrophic and autotrophic respiration; ER, Rh and Ra) fluxes in a boreal peatland in northern Sweden. Our results showed that daily NEE patterns were driven by GPP while variations in ER were governed by Ra rather than Rh. Moreover, we observed pronounced seasonal shifts in the Ra/Rh and above/belowground NPP ratios throughout the main phenological phases. Generalized linear model analysis revealed that the greenness index derived from digital images (as a proxy for plant phenology) was the strongest control of NEE, GPP and NPP while explaining considerable fractions also in the variations of ER and Ra. In addition, our data exposed greater temperature sensitivity of NPP compared to Rh resulting in enhanced C sequestration with increasing temperature. Overall, our study suggests that the temporal patterns in NEE and its component fluxes are tightly coupled to vegetation dynamics in boreal peatlands and thus challenges previous studies that commonly identify abiotic factors as key drivers. These findings further emphasize the need for integrating detailed information on plant phenology into process‐based models to improve predictions of global change impacts on the peatland C cycle. Abstract : In this study, we used an automated chamber system established across natural and trenching/vegetation removal plots to partition the net CO2 exchange (NEE) into its production (i.e., gross and net primary production; GPP and NPP) and respiration (i.e., ecosystem, heterotrophic and autotrophic respiration; ER, Rh and Ra) fluxes in a boreal peatland in northern Sweden. We examined the temporal dynamics of these individual component fluxes and identified their separate biotic and abiotic controls (i.e., plant phenology, temperature, light, water). We show that the daily variations in NEE were regulated by GPP while the dynamics in ER were determined by Ra rather than Rh. Our results also revealed that the individual NEE component fluxes were tightly coupled to plant phenology in our boreal fen. These findings highlight the need for incorporating detailed information on the seasonal vegetation development into process‐based models to improve predictions of global change impacts on the peatland carbon cycle.