Seedling response of four birch species ot simulate nitrogen deposition: Ammonium vs. Nitrate

Journal Article · Sat May 01 04:00:00 EDT 1993 · Ecological Applications; (United States)

DOI:https://doi.org/10.2307/1941834· OSTI ID:5604804

Crabtree, R C; Bazzaz, F A ^[1]

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1. Harvard Univ., Cambridge, MA (United States)

Chronic nitrogen deposition, from air pollution with high concentrations of nitrogen, has the potential to alter seedling shade tolerance and growth in the temperate forest of northeastern United States, by affecting both the form and the quantity of available nitrogen. Simulated deposition treatments were applied to seedling of four birch species that co-occur at Harvard Forest (Betula lenta, B. alleghaniensis, B. populifolia, and B. papyrifera). Seedlings were individually potted in forest soil, and grown under light treatment representative of forest understory and treefall gap light levels. In a split-plot design, N was applied at 25 and 50 kg[center dot]ha[sup [minus]1][center dot]yr[sup [minus]1], as either nitrate, ammonium nitrate, or ammonium, within each light environment. While B, populifolia and B. papyrifera, and B. lenta all showed increased biomass allocation to leaves added, and this response was conditional on rate of N application and light environment. At low light, nitrate-fed B. lenta grew best, and also at low rate of supply, nitrate treatments out-performed ammonium treatment. Greater growth under these conditions is probably the result of higher biomass allocation to leaves, and greater specific leaf area, which increased the leaf area ratio, and improved the capacity for carbon gain. Under N deposition regimes that increase soil nitrate availability, the differences in response of B. lenta and B. alleghaniensis of nitrate at low light may potentially lead to changes in the species composition of the seedling communities in the understory. When a treefall occurs, a different species mix of seedling will be released, with potential consequences for sapling and tree species mix. 31 refs., 2 figs., 4 tabs.

• OSTI ID: 5604804
• Journal Information: Ecological Applications; (United States), Journal Name: Ecological Applications; (United States) Vol. 3:2; ISSN 1051-0761; ISSN ECAPE7
• Country of Publication: United States
• Language: English

Related Subjects

560300* -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BIRCHES
DEPOSITION
ECOLOGICAL CONCENTRATION
ELEMENTS
FORESTS
GROWTH
MAGNOLIOPHYTA
MAGNOLIOPSIDA
NITROGEN
NONMETALS
PLANT GROWTH
PLANTS
SPECIES DIVERSITY
TREES