Formation of Aboveground Phytomass of Deciduous Tree Species on Post-Agrogenic Lands

Abstract

The withdrawal of lands from active agricultural use and their overgrowth with woody vegetation have a steady trend in Russia, especially in the boreal zone. Studying the plantations developed on fallow lands of agricultural territories enables estimation of their resource potential for further use. The aboveground phytomass of vegetation is the most reliable indicator of habitat productivity. It is possible to determine the volume of carbon storage by assessing the phytomass of tree and shrub vegetation, which is relevant in the context of global climate change. The study object was a field out of active agricultural use in the Gatchina district of the Leningrad region. A trial area was laid out on the test site, where a complete enumeration of native hardwoods (birch, aspen, tree and shrub willows) with the determination of the basic inventory indicators was carried out. In order to find out the volume of phytomass, from 6 to 8 model trees of each species were cut down. Allometric equations for calculating the fractional composition of phytomass with a high determination coefficient were derived based on the data obtained on the values of individual fractions of the trunk ground part. The accuracy of the derived equations is reduced due to the high variability of crown characteristics in dense deciduous young growth. The highest phytomass is in the trunk part, and the lowest in the assimilation apparatus for all species of woody vegetation. Calculation of aboveground phytomass on the test site according to the obtained equations showed that the highest value per 1 ha at this successional stage is typical for downy birch. Currently, the participation of woody vegetation growing on post-agrogenic lands in carbon sequestration has no reliable full assessment for the study region. Wood that was grown on lands out of active agricultural use can serve as a biofuel source and be harvested in the form of technological chips.