Production potential of photosynthesis in forest ecosystems of the low mountain Pokuttya (Ukrainian Carpathians)
Authors: Milevskaya S. Y. 
Published: May 2016

The aim of the study was testing on the example of a model region a method of estimation of the production potential of forest ecosystems and the consequences of anthropogenic changes there. The object of study is a typical Carpathian lower mountain forest in the basin of the river Lyuchka, an area of 14,806 ha. It has long undergone considerable agricultural transformations. Studies were based on cartographic modeling of modern anthropogenically transformed biogeocenotic cover using large scale satellite images. The main types of biogeocenotical cover were defined according to the altitudinal zonation of vegetation of the parts of the mountain terrain and the prevailing types of soil and hydrological conditions. For analytical procedures a database of materials describing the biometric features of the forests was created. It is possible to perform calculations of average and potential biometrical parameters of stands growing in different climatic, soil and hydrological conditions. The structure and the biological diversity of different vegetation types was determined by construction of mapping models of spatial structures of the basic types of biogeocenotic cover. The biological productivity of the main types of forest ecosystems was determined on base of the volume of timber stands. The mass of dry wood was determined taking into account its size and standard density of wood of different tree species. Calculation of the total volume of forest biomass was performed using the conversion factors of weight relative to the trunk timber volume. The mass of carbon deposited accounted for 50% of the total biomass. The average annual growth of biomass and carbon deposited was determined by dividing the volume of the stands by their average age. Calculation of phytocenosis consumed as a result of photosynthesis reaction of CO2, H2O and light energy was performed taking into account corresponding material and energy ratios. In general, in the course of one year the biogeocenotic cover of the model lowland area could deposit as a result of photosynthesis for the restoration of potential vegetation cover 43.3 ths. tons of carbon, while consuming 159 ths. t of CO2 and 65.2 ths. t of H2O and 1,724 ∙ 103 GJ of light energy, which is equivalent to 479 GW ∙ hour. During this process O2 – 115.7 ths. t would be emitted into the atmosphere. In terms of 1 hectare, this is equal to C – 2.92 t ∙ ha–1, CO2 – 10.7 t ∙ ha–1, H20 – 4.4 t ∙ha–1, O2 – 7.8 t ∙ ha–1, E – 116.4 GJ ∙ ha–1, which is equivalent to 32.3 MW ∙ h ∙ ha–1. The total production capacity of photosynthesis of the modern biogeocenotic cover model area is 38% of the potential. As a result, the energy loss is 20 MW ∙ h–1 ∙ ha–1 light energy to 1.9 t ∙ ha–1 less than the deposited carbon 6.7 t ∙ ha–1 less carbon dioxide used, 2.8 t ∙ ha–1 water is not used, 3.9 t ha–1 oxygen is not returned to the atmosphere. The large specific amount of unused resources of productivity of biogeocenotic cover, carbon dioxide, light energy, untranspired moisture in the air and unemitted oxygen can cause a significant impact on local climatic conditions.