The effect of three atmospheric CO2 concentrations (ambient –
400 ppm, doubled – 800 ppm and tripled – 1200 ppm) has been studied (1) on the
productivity of cottonwood tree (Populus
deltoides Barr.), (2) on the activity of soil microbial biomass in rooting
zone. It has been shown, that the total biomass of cottonwood trees increase under
elevated CO2 (2.61, 5.59 and 4 kg/tree for 400, 800 and 1200 ppm
respectively). The highest production had the stem and coarse roots at 800 ppm (in
3 and 2 times higher as compared to ambient CO2). Under 1200 ppm CO2
we observed increased the roots biomass, but the biomass of leaves and branches
was insignificant or didn’t changed at all. The shoot/root ratio changed as
following: 400 ppm – 1.8, 800 ppm – 2.3, 1200 ppm – 1.4. The rate of С-СО2
flux from soil samples being incubated for 70 days increased in the row 1200>800>400
ppm CO2, the average values of CO2 emission were 2.76, 2.33,
2.02 mg 100g-1·day-1, respectively. The largest amount of
C microbial biomass (Cmb) was in the variant with triple CO2
concentration (75.1 mg 100g-1), and the lowest – under ambient
concentration (53.7 mg 100g-1).
Author: V.N.Kudeyarov, K.Biel, S.A.Blagodatsky, V.M.Semenov, et al (kudeyarov at issp dot serpukhov dot su)
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