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An alternative explanation for the post‐disturbance NO 3 – flush in some forest ecosystems
Author(s) -
Bradley Robert L.
Publication year - 2001
Publication title -
ecology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.852
H-Index - 265
eISSN - 1461-0248
pISSN - 1461-023X
DOI - 10.1046/j.1461-0248.2001.00243.x
Subject(s) - nitrification , autotroph , heterotroph , assimilation (phonology) , primary production , ecology , environmental science , ecosystem , forest floor , environmental chemistry , forest ecology , chemistry , zoology , biology , nitrogen , linguistics , philosophy , organic chemistry , bacteria , genetics
The appearance of soil NO 3 – after forest disturbance is commonly ascribed to a higher availability of NH 4 + to autotrophic nitrifiers, or to a reduction in available‐C resulting in lower microbial assimilation of NO 3 – . Alternatively, it has been proposed that increasing NH 4 + pools following disturbance could increase net nitrification by reducing microbial assimilation of NO 3 – . Forest floor material was collected from shelterwood harvest plots which displayed both low available‐C and low NH 4 + pools, and where previous experiments had suggested the prevalence of heterotrophic nitrification. Subsamples were amended with incremental rates of glucose‐C or NH 4 + , and gross NO 3 – transformation rates were measured by isotope dilution. Glucose‐C additions had little effect on the net difference between gross NO 3 – production and consumption rates. On the other hand, NH 4 + additions caused gross NO 3 – consumption processes to decrease sharply, while gross NO 3 – production processes remained constant. The results suggest that NH 4 + can have an immediate positive effect on net nitrification rates by suppressing NO 3 – assimilation and uptake systems.