Title |
δ15N constraints on long-term nitrogen balances in temperate forests
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Published in |
Oecologia, May 2011
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DOI | 10.1007/s00442-011-2016-y |
Pubmed ID | |
Authors |
Steven S. Perakis, Emily R. Sinkhorn, Jana E. Compton |
Abstract |
Biogeochemical theory emphasizes nitrogen (N) limitation and the many factors that can restrict N accumulation in temperate forests, yet lacks a working model of conditions that can promote naturally high N accumulation. We used a dynamic simulation model of ecosystem N and δ(15)N to evaluate which combination of N input and loss pathways could produce a range of high ecosystem N contents characteristic of forests in the Oregon Coast Range. Total ecosystem N at nine study sites ranged from 8,788 to 22,667 kg ha(-1) and carbon (C) ranged from 188 to 460 Mg ha(-1), with highest values near the coast. Ecosystem δ(15)N displayed a curvilinear relationship with ecosystem N content, and largely reflected mineral soil, which accounted for 96-98% of total ecosystem N. Model simulations of ecosystem N balances parameterized with field rates of N leaching required long-term average N inputs that exceed atmospheric deposition and asymbiotic and epiphytic N(2)-fixation, and that were consistent with cycles of post-fire N(2)-fixation by early-successional red alder. Soil water δ(15)NO(3)(-) patterns suggested a shift in relative N losses from denitrification to nitrate leaching as N accumulated, and simulations identified nitrate leaching as the primary N loss pathway that constrains maximum N accumulation. Whereas current theory emphasizes constraints on biological N(2)-fixation and disturbance-mediated N losses as factors that limit N accumulation in temperate forests, our results suggest that wildfire can foster substantial long-term N accumulation in ecosystems that are colonized by symbiotic N(2)-fixing vegetation. |
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Brazil | 1 | <1% |
Argentina | 1 | <1% |
Mexico | 1 | <1% |
Japan | 1 | <1% |
Spain | 1 | <1% |
Unknown | 100 | 92% |
Demographic breakdown
Readers by professional status | Count | As % |
---|---|---|
Student > Ph. D. Student | 23 | 21% |
Researcher | 22 | 20% |
Student > Master | 18 | 17% |
Student > Doctoral Student | 6 | 6% |
Professor > Associate Professor | 6 | 6% |
Other | 19 | 17% |
Unknown | 15 | 14% |
Readers by discipline | Count | As % |
---|---|---|
Agricultural and Biological Sciences | 34 | 31% |
Environmental Science | 32 | 29% |
Earth and Planetary Sciences | 18 | 17% |
Social Sciences | 2 | 2% |
Psychology | 1 | <1% |
Other | 2 | 2% |
Unknown | 20 | 18% |