Soil organic matter quality influences mineralization and GHG emissions in cryosols: a field‐based study of sub‐ to high Arctic

• Published in: Global Change Biology
• Main Authors: Paré, Maxime C., Bedard‐Haughn, Angela
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2013
• Subjects: Arctic
• Online Access: http://dx.doi.org/10.1111/gcb.12125; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fgcb.12125; https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.12125

Abstract Arctic soils store large amounts of labile soil organic matter ( SOM ) and several studies have suggested that SOM characteristics may explain variations in SOM cycling rates across Arctic landscapes and A rctic ecosystems. The objective of this study was to investigate the influence of routinely measured soil properties and SOM characteristics on soil gross N mineralization and soil GHG emissions at the landscape scale. This study was carried out in three C anadian A rctic ecosystems: Sub‐ A rctic ( C hurchill, MB ), Low‐ A rctic ( D aring L ake, NWT ), and High‐ A rctic ( T ruelove L owlands, NU ). The landscapes were divided into five landform units: (1) upper slope, (2) back slope, (3) lower slope, (4) hummock, and (5) interhummock, which represented a great diversity of S tatic and T urbic C ryosolic soils including B runisolic, G leysolic, and O rganic subgroups. Soil gross N mineralization was measured using the 15 N dilution technique, whereas soil GHG emissions ( N 2 O , CH 4 , and CO 2 ) were measured using a multicomponent Fourier transform infrared gas analyzer. Soil organic matter characteristics were determined by (1) water‐extractable organic matter, (2) density fractionation of SOM , and (3) solid‐state CPMAS 13 C nuclear magnetic resonance ( NMR ) spectroscopy. Results showed that gross N mineralization, N 2 O , and CO 2 emissions were affected by SOM quantity and SOM characteristics. Soil moisture, soil organic carbon ( SOC ), light fraction ( LF ) of SOM , and O ‐Alkyl‐C to Aromatic‐C ratio positively influenced gross N mineralization, N 2 O and CO 2 emissions, whereas the relative proportion of Aromatic‐C negatively influenced those N and C cycling processes. Relationships between SOM characteristics and CH 4 emissions were not significant throughout all Arctic ecosystems. Furthermore, results showed that lower slope and interhummock areas store relatively more labile C than upper and back slope locations. These results are particularly important because they can be used to produce ...