Abstract
Central Yakutia is in one of the most northern agricultural centers of the world. In this territory a notable area of arable land was made by removing the boreal Taiga with the primary purpose of crop cultivation. Such a method of cultivation significantly changes soil total carbon (STC, soil organic carbon + soil carbonate carbon) balance, because of the destroyed upper humus horizon. Soil organic carbon (SOC) of cultivated arable lands is almost a half of that in forest. In abandoned arable lands with grass vegetation, the recovery of SOC has increased to 30% in comparison with cultivated arable lands. On arable lands recovering with new growth of trees, the SOC is related to the abandonment period. Soil carbonates carbon (SCC) content was significantly lower than SOC and showed significant difference among abandoned and other types of arable lands. Objectives of this study are to identify how STC stocks change in response to conversion of the forests to agricultural land and to analyze the arable land system’s recovery process after abandonment. Furthermore, after transformation of forest to arable land, a significant decrease of STC was observed, primarily due to mechanical loss after plant residue removal. It was also identified that the restoration and self-recovery of STC in abandoned arable lands of Central Yakutia continuously and slightly increase. Grass vegetation regenerates STC for 20 years. While the difference of average STC of forests and cultivated arable lands reached 41%, a new growth of forest on some abandoned arable land follows the tendency of STC decrease due to a low productivity level and suppressing effect on grass vegetation.
Highlights
Soil organic carbon (SOC), the largest carbon pool on land, plays an important role in the global carbon cycle [1,2]
It has been reported that boreal forest soils keep more C than above-ground biomass of forest [5,6,7,8]
The objective of this study is to show how soil C stocks change in response to the conversion of forests to arable land and to show how the arable land system is recovering after the abandonment
Summary
Soil organic carbon (SOC), the largest carbon pool on land, plays an important role in the global carbon cycle [1,2]. Small changes in the SOC stock may significantly impact atmospheric CO2 concentration. Forest soil stores about 40% of the total organic carbon (C) [3]. Boreal forest occupies 33% of the circumpolar region’s total area and soils here are the reservoir for long-term C stock which takes a significant part of global C storage [4]. It has been reported that boreal forest soils keep more C than above-ground biomass of forest [5,6,7,8].
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