Nitrogen limitation and growth response to CO{sub 2} in ponderosa pine
- Desert Research Institute, Reno, NV (United States)
- Univ. of Nevada, Reno, NV (United States); and others
Ponderosa pine (Pinus ponderosa) was grown from seed and subjected to three levels of CO{sub 2} (370,525, and 700 {mu}l/ l{sup {minus}1}) and three levels of N (0, 10, and 20 g N m{sup {minus}2} yr{sup {minus}1}) for three years in open top chambers. Both N and CO{sub 2} produced a positive growth response, and there was a growth response to CO{sub 2} without fertilization. This growth increase was accompanied by increased N uptake with elevated CO{sub 2}; the commonly-observed reduction in tissue N concentration was insufficient to allow a significant growth response without additional N uptake. Detailed and exhaustive analyses of both bulk soil and rhizosphere soil revealed no growth response without additional N uptake. Detailed and exhaustive analyses of both bulk soil and rhizosphere soil revealed no effect of elevated CO{sub 2} on soil N mineralization rate. Thus, the growth response to elevated CO{sub 2} with suboptimal N was facilitated by greater root biomass and exploration of the soil for available N supplies. Root biomass was disproportionately greater in trees treated with elevated CO{sub 2}. Results of this in combination with previous pot studies show that N limitation is a continuum rather than an on/off situation, and thus N limitation constraints upon CO{sub 2} response varies continuously from complete limitation at very low N to no limitation at high N.
- OSTI ID:
- 107108
- Report Number(s):
- CONF-9507129-; ISSN 0012-9623; TRN: 95:006512-0024
- Journal Information:
- Bulletin of the Ecological Society of America, Vol. 76, Issue 3; Conference: 80. anniversary of the transdisciplinary nature of ecology, Snowbird, UT (United States), 30 Jul - 3 Aug 1995; Other Information: PBD: Sep 1995
- Country of Publication:
- United States
- Language:
- English
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