| Abstract: | High tissue nitrogen (N) accelerates decomposition of high-quality leaf litter in the early phases of mass loss, but the influence of initial tissue N variation on the decomposition of lignin-rich litter is less resolved. Because environmental changes such as atmospheric N deposition and elevated CO2 can alter tissue N levels within species more rapidly than they alter the species composition of ecosystems, it is important to consider how within-species variation in tissue N may shape litter decomposition and associated N dynamics. Douglas-fir (Pseudotsuga menziesii ) is a widespread lignin-rich conifer that dominates forests of high carbon (C) storage across western North America, and displays wide variation in tissue and litter N that reflects landscape variation in soil N. We collected eight unique Douglas-fir litter sources that spanned a two-fold range in initial N concentrations (0.67–1.31%) with a narrow range of lignin (29–35%), and examined relationships between initial litter chemistry, decomposition, and N dynamics in both ambient and N fertilized plots at four sites over 3 yr. High initial litter N slowed decomposition rates in both early (0.67 yr) and late (3 yr) stages in unfertilized plots. Applications of N fertilizer to litters accelerated early-stage decomposition, but slowed late-stage decomposition, and most strongly affected low-N litters, which equalized decomposition rates across litters regardless of initial N concentrations. Decomposition of N-fertilized litters correlated positively with initial litter manganese (Mn) concentrations, with litter Mn variation reflecting faster turnover of canopy foliage in high N sites, producing younger litterfall with high N and low Mn. Although both internal and external N inhibited decomposition at 3 yr, most litters exhibited net N immobilization, with strongest immobilization in low-N litter and in N-fertilized plots. Our observation for lignin-rich litter that high initial N can slow decomposition yet accelerate N release differs from findings where litter quality variation across species promotes coupled C and N release during decomposition. We suggest reevaluation of ecosystem models and projected global change effects to account for a potential decoupling of ecosystem C and N feedbacks through litter decomposition in lignin-rich conifer forests. |
| Genre: | Article |
| ProdID: | 70039003 |
| Citation Author: | Perakis, Steven S.; Matkins, Joselin J.; Hibbs, David E. |
| Citation Contributing Office: | Forest and Rangeland Ecosystem Science Center |
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| Citation Issue: | 6 |
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| Citation Language: | English |
| Citation Larger Work Title: | Ecosphere |
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| Citation Number Of Pages: | 12 |
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| Citation Phsyical Description: | 12 p.; Article 54 |
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| Citation Publisher: | ESA |
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| Citation Search Results Text: | Interactions of tissue and fertilizer nitrogen on decomposition dynamics of lignin-rich conifer litter; 2012; Article; Journal; Ecosphere; Perakis, Steven S.; Matkins, Joselin J.; Hibbs, David E. |
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| Citation Volume: | 3 |
| Citation Year: | 2012 |
| Type: | citation/reference |
| Text: | Interactions of tissue and fertilizer nitrogen on decomposition dynamics of lignin-rich conifer litter; 2012; Article; Journal; Ecosphere; Perakis, Steven S.; Matkins, Joselin J.; Hibbs, David E. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| URL (DIGITAL OBJECT IDENTIFIER): | http://dx.doi.org/10.1890/ES11-00340.1 |
| Date Other: | Wed, 11 Jul 2012 00:00 -0500 |
| Publisher: | ESA |
