Carbon dioxide exchange of arboreal plants in urban ecosystems

Research on all factors that contribute to the carbon balance in the biosphere is of paramount importance, owing to the current increase in air carbon dioxide content. This work presents data on the carbon dioxide exchange of the needles of the common spruce (Picea abies L.) and the douglas-fir (Pseudotsuga menziesii L.) in an urban environment as exemplified by Moscow. It was established that a warm spell in autumn contributed to the prolongation of the period of carbon dioxide uptake by coniferous trees. Our analysis of the impact of environmental factors on needle photosynthetic activity revealed that photosynthesis intensity only depends on the illumination level. The midday increase in air temperature failed to affect photosynthesis intensity, probably because the plants were adapted to low night and morning air temperatures According to the regression analysis data obtained, the dependence of СО₂ assimilation on illumination represented a logarithmic curve; the approximation validity coefficient (R²) being 0.8. The impact of environmental conditions on conifer photosynthesis in autumn proved to be species-specific. The common spruce exhibited the maximum resistance to environmental factors, and its photosynthetic activity was 1,4 fold higher than that of the douglas-fir. Calculations revealed that the СО₂ assimilation level in the common spruce and the douglas-fur exceeded the light respiration level 3,6- and 2,7-fold, respectively, which points to a positive carbon dioxide exchange “balance sheet” and highlights the important role of coniferous trees in regulating the carbon balance of an urban ecosystem.

1. Endreny T., Santagata R., Perna A., De Stefano C, Rallo R.F., Ulgiati S. Implementing and managing urban forests: A much needed conservation strategy to increase ecosystem services and urban wellbeing // Ecol. Model. 2017. Vol. 360. Р. 328-335.

2. Hamada S, Ohta T. Seasonal variations in the cooling effect of urban green areas on surrounding urban areas // Urban For. Urban Green. 2010. Vol.9. N 1. Р. 15-24.

3. Baro F, Chaparro L, Gomez-Baggethun E, Langemeyer J, Nowak D.J., Terradas J. Contribution of ecosystem services to air quality and climate change mitigation policies: the case of urban forests in Barcelona, Spain // Ambio. 2014. Vol. 43. N 4. Р. 466-479.

4. Na H.R., Heisler G.M., Nowak D.J., Grant R.H. Modeling of urban trees’ effects on reducing human exposure to UV radiation in Seoul, Korea // Urban For. Urban Green. 2014. Vol. 13. N 4. Р. 785-792.

5. Long S.P., Ainsworth E.A., Rogers A., Ort D.R. Rising atmospheric carbon dioxide: plants FACE the future // Annu. Rev. Plant Biol. 2004. Vol. 55. Р. 591-628.

6. Nowak D.J., Stevens J.C., Sisinni S.M., Luley C.J. Effects of urban tree management and species selection on atmospheric carbon dioxide // J. Arboric. 2002. Vol. 28. N 3. Р. 113-122.

7. Yang J., McBride J., Zhou J., Sun Z. The urban forest in Beijing and its role in air pollution reduction // Urban For. Urban Green. 2005. Vol. 3. N 2. P. 65-78.

8. Yuzbekov A.K., Zamolodchikov D.G., Ivashchenko A.I. Spruce fir photosynthesis in the forest ecosystems of the Log Tayezhnyi test area // Moscow Univ. Biol. Sci. Bull. 2014. Vol. 69. N 4. P. 169-172.

9. Chang C.Y., Frechette E., Unda F., Mansfield S.D., Ensminger I. Elevated temperature and CO2 stimulate late-season photosynthesis but impair cold hardening in Pine // Plant Physiol. 2016. Vol. 172. N 2. Р. 802-818.

10. Lundmark T., Bergh J., Strand M., Koppel A. Seasonal variation of maximum photochemical efficiency in boreal Norway spruce stands // Trees. 1998. Vol. 13. N 2. P. 63-67.

11. Hadley J.L. Effect of daily minimum temperature on photosynthesis in Eastern hemlock (Tsuga canadensis L.) in autumn and winter // Arct. Antarct. Alp. Res. 2000. Vol. 32. N 4. Р. 368-374.

12. Stinziano J.R., Huner N.P.А., Way D.A. Warming delays autumn declines in photosynthetic capacity in a boreal conifer, Norway spruce (Picea abies) // Tree Physiol. 2015. Vol. 35. N 12. P. 1303-1313.