Наукові праці Лісівничої академії наук України (Dec 2020)
Matter and energy influence of forest vegetation on the environment
Abstract
Modern climate change is an important environmental problem of mankind. It is largely due to the powerful anthropogenic impact on the biosphere, in particular, deforestation. However, forests role in forming climate change in regions and the continents is still poorly understood. This primarily concerns the influence of forests on the gas composition of the surface layers of the atmosphere, their temperature, etc. The purpose of the study was an attempt to study theoretically the problem of assessing the matter and energy impact of the phytomass growth of Ukrainian forests on the surface atmosphere in comparison with other vegetation types. This applies to the carbon deposition, oxygen production, transpiration and the atmosphere enrichment with moisture, as well as the light and heat energy consumption from the environment. The theoretical concept is based on the known biochemical and physical laws. This is the substance and energy photosynthesis proportions and its accompanying transpiration, as well as the air cooling effect. The following axioms were taken as the basis of the study: – сlimate formation is largely connected with the energy and matter circulation in the biosphere; – at the local level near the earth's surface powerful matter and energy circulation is in progress between phytomass and the atmosphere; – the material and energy flow intensity is proportional to the increase of phytomass; – the phytomass increase occurs as the photosynthesis result and is accompanied by a powerful transpiration; – photosynthesis and transpiration require a large amount of energy consumption from the environment, which leads to its cooling. The calculation of the photosynthesis was performed balance on the basis of official materials as for productivity of forest, meadow vegetation and agriculture in Ukraine. Relevant final indicators of own experimental studies were also applied. The annual dry substance productivity of the total phytomass was taken as a basis. The substance and energy proportions of the generalized model of photosynthesis reaction are applied. Consumption: carbon dioxide – 3,668 tons, water – 1.5 tons and energy - approximately 11042 kWh. Production: oxygen – 2.67 tons and hexose - 2.5 tons, in which 1 ton of carbon is deposited. The volume of transpired moisture was calculated according to the phytomass dry substance productivity and the transpiration coefficient. Energy costs for transpiration were calculated according to the evaporation amount taking into account the specific vaporization heat. The cooling effect is calculated for the air surface layer 30 m height. This corresponds to average stand height at the age of 100. The calculation was performed on the basis of air energy consumption per 1 m2, that is from 30 m3 taking into account its specific heat capacity. The obtained analytical materials clearly testify the photosynthesis processes significant influence and the accompanying transpiration on the gas composition and energy potential of air surface layer. Generally, Ukraine's forests are able to deposit 3 t∙ha-1 of carbon during the year. This leads to the production of 8 t∙ha-1 oxygen and air enrichment with moisture in the amount of 3600 t∙ha-1. These processes require appropriate energy consumption, which leads to cooling 30-meter air surface layer by an average of 2.4 °C during the year. Meadow vegetation and agricultural crops also perform such ecological functions. However, this occurs only during a relatively short photosynthetic period. In terms of photosynthesis and transpiration intensity, forest ecological functions are three times higher than the corresponding properties of meadow vegetation. In the case of highly productive forests growing, the annual growth of which would reach 10 m3∙ha-1, the enrichment of the surface atmosphere with oxygen would be twice as much as with the current increase of 5 m3∙ha-1, and water vapor – three to four times more. Accordingly, the thermal energy consumption from the environment would be three to four times higher.
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