Long-term nitrogen deposition linked to reduced water use efficiency in forests with low phosphorus availability
1. The impact of long-term nitrogen (N) deposition is under-studied in phosphorus (P)-limited subtropical forests. We exploited historically collected herbarium specimens to investigate potential physiological responses of trees in three subtropical forests representing an urban-to-rural gradient, a...
| Autores: | , , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2016 |
| País: | España |
| Institución: | Universitat Autònoma de Barcelona |
| Repositorio: | Dipòsit Digital de Documents de la UAB |
| Idioma: | inglés |
| OAI Identifier: | oai:ddd.uab.cat:147629 |
| Acceso en línea: | https://ddd.uab.cat/record/147629 https://dx.doi.org/urn:doi:10.1111/nph.13785 |
| Access Level: | acceso abierto |
| Palabra clave: | Herbarium specimens Nitrogen : phosphorus (N : P) P-limited soils δ¹³C δ¹⁵N |
| Sumario: | 1. The impact of long-term nitrogen (N) deposition is under-studied in phosphorus (P)-limited subtropical forests. We exploited historically collected herbarium specimens to investigate potential physiological responses of trees in three subtropical forests representing an urban-to-rural gradient, across which N deposition has probably varied over the past six decades. We measured foliar [N] and [P] and stable carbon (δ¹³C), oxygen (δ¹⁸O) and nitrogen (δ¹⁵N) isotopic compositions in tissue from herbarium specimens of plant species collected from 1947 to 2014. - 2. Foliar [N] and N : P increased, and (δ¹⁵N and [P] decreased in the two forests close to urban centers. Consistent with recent studies demonstrating that N deposition in the region is 15N-depleted, these data suggest that the increased foliar [N] and N : P, and decreased [P], may be attributable to atmospheric deposition and associated enhancement of P limitation. - 3. Estimates of intrinsic water use efficiency calculated from foliar (δ¹³C decreased by c. 30% from the 1950s to 2014, contrasting with multiple studies investigating similar parameters in N-limited forests. This effect may reflect decreased photosynthesis, as suggested by a conceptual model of foliar (δ¹³C and δ¹⁸O. - 4.Long-term N deposition may exacerbate P limitation and mitigate projected increases in carbon stocks driven by elevated CO₂ in forests on P-limited soils. |
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