What the Siberian forest is breathing

This was required by the scientists to be able to thoroughly investigate who or, more precisely, what is to answer for the greenhouse effect, from where oxygen, carbon dioxide and certain other gases are taken in the Earth’s atmosphere, what portion of the carbon dioxide can be absorbed by the Siberian bogs and forests and a mass of other questions which may at first sight appear to be trivial.

A truly amazing design is being constructed under a partner project between the International Science and Technology Centre and the Krasnoyarsk Sukachev Institute of the Forest SB RAS. The project is called “Response of Biogeochemical Cycles to Climate Change in Eurasia”and it will be accomplished by Russian researchers in cooperation with their German colleagues – specialists of the Institute of Biogeochemistry (Jena) and the Institute for Chemistry (Mainz). Both these institutes are a part of Europe’s largest scientific community, named after Max Planck.

However, the mast in itself is not unique. A twin-mast has been installed in Germany and it facilitates similar research, only not in forestland, like this Siberian one does, but in a region of exceptionally highly developed industry and agriculture. But together they will indeed provide a unique opportunity to compare the composition of the atmosphere in regions with fundamentally different anthropogenic load and ascertain how and due to what the composition changes. As a result, the atmospheric composition can be analyzed, or more precisely – the concentration within it of the most important gases (from the point of view of this research) at different altitudes, right up to 300 meters. Here it will be possible to study not simply the chemical but also the isotopic composition. And this will be the key to reveal the contribution of anthropogenic and natural components in the overall gaseous exchange flow in the atmosphere.

Project Manager Sergei Verkhovets explained in the most general terms why it was necessary to build a tower of such a height and how the isotopic composition of gases will help to determine their origin.

Measurements of CO2 concentrations at a height of 200 to 300 meters above the earth’s surface allow us to investigate the relatively homogeneous part of atmosphere, the so-called mixed layer. With that we can study the processes taking place over a vast territory, avoiding the “noise” caused by daily changes in the photosynthesis process close to the surface of the Earth.

As far as the isotope ratio in CO2, CH4, CO and N2O, and the ratio of O2/N2 are concerned, they make it possible to distinguish various carbon emission- and sink processes – photosynthesis and respiration of the ground-based biosphere, burning of fossil combustibles, and atmospheric-oceanic exchange and absorption.

For example, plants not only absorb ??2 in the course of photosynthesis; they also emit it while breathing. So, the carbonic acid gas “expired” by plants is enriched by a lighter isotope 12?. And above the ocean, where gaseous exchange processes obey to a greater extent physical rather than biochemical laws, the difference in isotopic composition is substantially equalized. Thus, if two air samples are taken and ??2 is isolated from them, and the isotopic composition is determined, its origin can be determined. The isotopic trace (signature) of a fossil combustible is also well-known. Carbon monoxide (CO), in its turn, bears information about anthropogenic emissions, because one of its main sources is the incomplete burning of fossil combustibles. A change in the correlation of 18O/16O in atmospheric CO2 helps to evaluate and isolate the respiratory flow from photosynthesis in Siberia. Continuous measurements of C16O18O on the continents are needed to reveal the climatic influence on carbon sink. Methane observations will help us better understand the connection between the climate and the ecosystem: from change in the concentration of “regular” and “heavy” methane 14CH4, researchers can track the respiration of peat bogs and, perhaps, of permafrost soils as well.

The data obtained in the course of observations will be the basic data for the construction of carbonic balance models both at regional and continental levels.

This task is especially topical for Russia. Owing to the adoption of the Framework Convention and the Kyoto Protocol, a situation has arisen whereby Russia can not only contribute to researching global climate change, but it can also gain significant economic benefits. The protocol stipulates that carbon dioxide removal from the atmosphere by natural absorbent ecosystems is rated as fulfillment of emission reduction ratings. The forests of Siberia constitute one fifth of the entire forests of the world, in terms of area at least. However, we need to know exactly what their capacity is in terms of an atmospheric carbon absorber. This project will make it possible to obtain data of this kind.