New Zealand Journal of Agricultural Research abstracts
Carbon dioxide emissions from mineral springs in Northland and the potential of
these sites for studying the effects of elevated carbon dioxide on pastures
P. C. D. NEWTON
C. C. BELL
H. CLARK
AgResearch Grasslands
Private Bag 11008
Palmerston North, New Zealand
Abstract Sites in Northland with mineral springs were
examined for their potential as experimental areas to study the effects of
elevated carbon dioxide (CO2) on grassland. A suitable site was defined as
having: (1) grassland species; (2) cold springs; (3) high levels of gas flow;
and (4) high concentrations of CO2. Two sites were selected for detailed
study--Hakanoa Springs near Kamo and Waiare Spring near Kaeo. At Hakanoa, the
vegetation was scrubby but at least 10 grassland species were present. Two
vents released large volumes of CO2 resulting in concentrations at 10 cm above
ground level that ranged from 5000 ul/litre near the vent to 400 ul/litre 10 m
downwind. At Waiare, the spring was situated in a grazed grass paddock that
contained 10 grass species as well as Trifolium repens and Lotus
spp. There was little enrichment of CO2 above the canopy but high
concentrations were measured at mid-canopy height with a maximum value
exceeding 2000 ul/litre. Because of the nature of the enrichment within, but
not above the canopy, it appeared that the enrichment was from the soil. This
was confirmed by measurements of soil CO2 efflux that were consistently very
high (greater than 9.9 g CO2/m2 per h in some instances). The
springs have existed for decades and the sites offer the potential to study
plant material that has been exposed to elevated CO2 for very long periods.
Keywords natural CO2 springs; elevated CO2; grassland
New Zealand Journal of Agricultural Research, 1996, Vol. 39: 33-40
0028-8233/96/3901-0033 $2.50/0 (c) The Royal Society of New Zealand
1996
PDF file of entire paper: medium quality (2047K); (scanned from paper original: notes about this process)
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