Changes in soil carbon and nitrogen cycling along a 72-year wildfire chronosequence in Michigan jack pine forests

We investigated the changes in soil processes following wildfire in Michigan jack pine (Pinus banksiana) forests using a chronosequence of 11 wildfire-regenerated stands spanning 72 years. The objective of this study was to characterize patterns of soil nutrients, soil respiration and N mineralizati...

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Veröffentlicht in:Oecologia 2006-10, Vol.149 (4), p.690-700
Hauptverfasser: Yermakov, Z, Rothstein, D.E
Format: Artikel
Sprache:eng
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Zusammenfassung:We investigated the changes in soil processes following wildfire in Michigan jack pine (Pinus banksiana) forests using a chronosequence of 11 wildfire-regenerated stands spanning 72 years. The objective of this study was to characterize patterns of soil nutrients, soil respiration and N mineralization with stand development, as well as to determine the mechanisms driving those patterns. We measured in situ N mineralization and soil respiration monthly during the 2002 growing season and used multiple regression analysis to determine the important factors controlling these processes. Growing-season soil respiration rates ranged from a low of 156 g C/m² in the 7-year-old stand to a high of 254 g C/m² in the 22-year-old stand, but exhibited no clear pattern with stand age. In general, soil respiration rates peaked during the months of July and August when soil temperatures were highest. We used a modified gamma function to model a temporal trend in total N mineralization (total N mineralization = 1.853-0.276 x age x e -⁰.⁸¹⁴ x age; R ² = 0.381; P = 0.002). Total N mineralization decreased from 2.8 g N/m² in the 1-year-old stand to a minimum value of 0.5 g N/m² in the 14-year-old stand, and then increased to about 1.5 g N/m² in mature stands. Changes in total N mineralization were driven by a transient spike in N turnover in the mineral soil immediately after wildfire, followed by a gradual accrual of a slow-cycling pool of N in surface organic horizons as stands matured. Thus, in Michigan jack pine forests, the accumulation of surface organic matter appears to regulate N availability following stand-replacing wildfire.
ISSN:0029-8549
1432-1939
DOI:10.1007/s00442-006-0474-4