کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
81895 158357 2012 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Trenching reduces soil heterotrophic activity in a loblolly pine (Pinus taeda) forest exposed to elevated atmospheric [CO2] and N fertilization
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات علم هواشناسی
پیش نمایش صفحه اول مقاله
Trenching reduces soil heterotrophic activity in a loblolly pine (Pinus taeda) forest exposed to elevated atmospheric [CO2] and N fertilization
چکیده انگلیسی

Forests return large quantities of C to the atmosphere through soil respiration (Rsoil), which is often conceptually separated into autotrophic C respired by living roots (Rroot) and heterotrophic decomposition (Rhet) of soil organic matter (SOM). Live roots provide C sources for microbial metabolism via exudation, allocation to fungal associates, sloughed-off cells, and secretions such as mucilage production, suggesting a coupling between the activity of roots and heterotrophs. We addressed the strength of root effects on the activity of microbes and exo-enzymes by removing live-root-C inputs to areas of soil with a trenching experiment. We examined the extent to which trenching affected metrics of soil heterotrophic activity (proteolytic enzyme activity, microbial respiration, potential net N mineralization and nitrification, and exo-enzyme activities) in a forest exposed to elevated atmospheric [CO2] and N fertilization, and used automated measurements of Rsoil in trenched and un-trenched plots to estimate Rroot and Rhet components. Trenching decreased many metrics of heterotrophic activity and increased net N mineralization and nitrification, suggesting that the removal of root-C inputs reduced Rhet by exacerbating microbial C limitation and stimulating waste-N excretion. This trenching effect was muted by N fertilization alone but not when N fertilization was combined with elevated CO2, consistent with known patterns of belowground C allocation at this site. Live-root-C inputs to soils and heterotrophic activity are tightly coupled, so root severing techniques like trenching are not likely to achieve robust quantitative estimates of Rroot or Rhet.


► The coupling between live-root-C inputs to soils and microbial activity was explored.
► Removing roots exacerbates microbial C limitation and increases N excretion.
► Techniques that sever roots are unlikely to eliminate Rroot without affecting Rhet.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Agricultural and Forest Meteorology - Volume 165, 15 November 2012, Pages 43–52
نویسندگان
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