Root System Modifications in White Oak (Quercus alba L.) Saplings Grown Under CO2 Enrichment in the Field
Loading...
Authors
Nietch, Christopher
Issue Date
1992
Type
Thesis
Language
en_US
Keywords
Alternative Title
Abstract
The responses of white oak (Quercus alba L.) sapling root systems to C02
enrichment of the atmosphere were investigated after four seasons of growth
under field conditions. Seedlings were planted in the soil within open-top
chambers and exposed to a variable environment through four growing seasons
with atmospheric C02 concentrations of ambient + 0 (- 350 J.1mol mol-I),
ambient + 150 (- 500 µmol mol-l ) and ambient + 300 (- 650 µmol mol-I). Fine
root density, assessed by soil coring, was 29% and 138% higher in elevated C02
for saplings grown in +150 and +300, respectively, compared to ambient C02
controls. Soil respiration rates responded similarly, with a significant and
consistent increase in CO2 efflux from soils of C02-enriched chambers. On the
other hand, fine root specific respiration rate and nitrogen concentration tended
to decrease with increasing C02 concentration. These results suggest that an
increase in below-ground biomass will result in the face of a notable decrease in
specific metabolic activity under conditions of C02 enrichment. Thus, saplings
grown under elevated C02 may be presumed more efficient; able to maintain a
larger biomass at less cost energetically. This change in physiology may also be
supported by the observed increases in fine root density, which can lead to a
greater opportunity for soil exploration, and, therefore, nutrient acquisition and
symbiotic relations. With these modifications under elevated CO2 a sapling may
be able to reach an optimal adult biomass in a shorter amount of time and also be
in better condition for surviving times of environmental stress. Implications
that these physiological modifications may have for the global carbon cycle
depends on where the balance lies between carbon sequestered through
photosynthesis and carbon lost via cellular respiration.
Description
vi, 38 p.
Citation
Publisher
Kalamazoo College
License
U.S. copyright laws protect this material. Commercial use or distribution of this material is not permitted without prior written permission of the copyright holder.