| Abstract: | Stable isotope ratios of terrestrial ecosystem nitrogen (N) pools reflect internal processes and input-output balances. Disturbance generally increases N cycling and loss, yet few studies have examined ecosystem ??15N over a disturbance-recovery sequence. We used a chronosequence approach to examine N distribution and ??15N during forest regrowth after agricultural abandonment. Site ages ranged from 10 to 115 years, with similar soils, climate, land-use history, and overstory vegetation (white pine Pinus strobus). Foliar N and ??15N decreased as stands aged, consistent with a progressive tightening of the N cycle during forest regrowth on agricultural lands. Over time, foliar ??15N became more negative, indicating increased fractionation along the mineralization- mycorrhizal-plant uptake pathway. Total ecosystem N was constant across the chronosequence, but substantial internal N redistribution occurred from the mineral soil to plants and litter over 115 years (>25% of ecosystem N or 1,610 kg ha-1). Temporal trends in soil ??15N generally reflected a redistribution of depleted N from the mineral soil to the developing O horizon. Although plants and soil ??15N are coupled over millennial time scales of ecosystem development, our observed divergence between plants and soil suggests that they can be uncoupled during the disturbance-regrowth sequence. The approximate 2??? decrease in ecosystem ??15N over the century scale suggests significant incorporation of atmospheric N, which was not detected by traditional ecosystem N accounting. Consideration of temporal trends and disturbance legacies can improve our understanding of the influence of broader factors such as climate or N deposition on ecosystem N balances and ??15N. ?? 2007 Springer Science+Business Media, LLC. |
| Genre: | Article |
| ProdID: | 70031420 |
| Citation Author: | Compton, J. E.; Hooker, T. D.; Perakis, S. S. |
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| Citation End Page: | 1208 |
| Citation Issue: | 7 |
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| Citation Language: | English |
| Citation Larger Work Title: | Ecosystems |
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| Citation Number Of Pages: | 12 |
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| Citation Search Results Text: | Ecosystem N distribution and ??15N during a century of forest regrowth after agricultural abandonment; 2007; Article; Journal; Ecosystems; Compton, J. E.; Hooker, T. D.; Perakis, S. S. |
| Citation Start Page: | 1197 |
| Citation Volume: | 10 |
| Citation Year: | 2007 |
| Type: | citation/reference |
| Text: | Ecosystem N distribution and ??15N during a century of forest regrowth after agricultural abandonment; 2007; Article; Journal; Ecosystems; Compton, J. E.; Hooker, T. D.; Perakis, S. S. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| URL (DIGITAL OBJECT IDENTIFIER): | http://dx.doi.org/10.1007/s10021-007-9087-y |
| Date Other: | Mon, 1 Jan 2007 00:00 -0600 |
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