Effects of a high-severity wildfire and post-fire straw mulching on gross nitrogen dynamics in Mediterranean shrubland soil.
Little is known about the combined impacts of fire and straw mulching, a widely used post‐fire emergency measure, on the soil nitrogen (N) cycle. Unburnt (US) and severely‐burnt soils without (BS) and with straw mulching (BSM) were preincubated (3 and 6 months) in the laboratory before fire and mulc...
| Autores: | , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2017 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/160261 |
| Acceso en línea: | http://hdl.handle.net/10261/160261 |
| Access Level: | acceso abierto |
| Palabra clave: | Autotrophic nitrification emergency stabilisation techniques heterotrophic nitrification mineralisation-immobilisation turnover 15N tracing |
| Sumario: | Little is known about the combined impacts of fire and straw mulching, a widely used post‐fire emergency measure, on the soil nitrogen (N) cycle. Unburnt (US) and severely‐burnt soils without (BS) and with straw mulching (BSM) were preincubated (3 and 6 months) in the laboratory before fire and mulching effects on gross N transformations were investigated with a paired 15N‐labelling experiment. The ammonium‐to‐nitrate (NH4 +/NO3 ‐) ratio of burnt soils decreased with preincubation time from 21 to 1.3, consistent with a shift of the N cycle towards net nitrification. After 3 months of preincubation, gross mineralisation (MSON) and gross NH4 + immobilisation (INH4) in BS more than doubled compared to US, in the latter being MSON 4.82 mg N kg‐1 day‐1 and INH4 3.01 mg N kg‐1 day‐1. Mulching partly mitigated this stimulation in the mineralisation‐immobilisation turnover (MIT). After 6 months, MIT differences among treatments disappeared and gross rates approached those in US after 3 months. After three months, autotrophic nitrification (NH4 + oxidation) in all treatments was 0.41‐0.52 N kg‐1 day‐1, while after 6 months it remained similar in US but increased 8‐fold in burnt soils. Heterotrophic nitrification of organic N only occurred in burnt soils, and its importance was similar to autotrophic nitrification after 3 months, but around 4‐fold lower after 6 months. To conclude, burning opened up the N cycle and NO3 ‐ accumulated, increasing the potential for ecosystem N losses. In the short term, straw mulching slightly mitigates the effects of fire on the N cycle. |
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