Internal cycling of nitrate in soils of a mature coniferous forest
- University of California, Berkeley (United States)
Gross rates of N mineralization, immobilization, and nitrification were measured by [sup 15]N isotope dilution in a 10-yr-old conifer plantation and in a mature conifer forest. Gross rates revealed nutrient cycling characteristics that differ from expectations based on more common measures of net rates. Although net mineralization rates were somewhat higher in the young forest than in the old forest, gross mineralization rates in the old forest were 2-3 times as high as gross mineralization rates in the young forest, indicating more rapid turnover of inorganic-N pools in the old forest. Net mineralization rates were [lt]14% of gross mineralization rates. Smaller NO[sub 3][sup [minus]] pool size and lower net nitrification rates in the old forest than the young forest might lead to the conclusion that the old forest is a non-nitrifying ecosystem and that nitrate is important only in the N cycle of the young forest. However, gross nitrification rates were similar in both young and old forests. Microbial assimilation of NO[sub 3][sup [minus]] was also significant in both forests, indicating a rapid turnover of a small but important NO[sub 3][sup [minus]] pool. Microbial assimilation may be an important pathway for NO[sub 3][sup [minus]] retention in forest ecosystems.
- OSTI ID:
- 6914231
- Journal Information:
- Ecology; (United States), Journal Name: Ecology; (United States) Vol. 73:4; ISSN 0012-9658; ISSN ECOLAR
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
540220* -- Environment
Terrestrial-- Chemicals Monitoring & Transport-- (1990-)
560300 -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
CHEMICAL REACTIONS
CONIFERS
ECOLOGICAL CONCENTRATION
FORESTS
ISOTOPE APPLICATIONS
ISOTOPE DILUTION
ISOTOPES
LIGHT NUCLEI
MICROORGANISMS
MINERALIZATION
NITRATES
NITRIFICATION
NITROGEN 15
NITROGEN COMPOUNDS
NITROGEN CYCLE
NITROGEN ISOTOPES
NUCLEI
ODD-EVEN NUCLEI
OXYGEN COMPOUNDS
PINOPHYTA
PLANTS
SOILS
STABLE ISOTOPES
TRACER TECHNIQUES