Impact of a Low Severity Fire on Soil Organic Carbon and Nitrogen Characteristics in Japanese Cedar Soil, Yamagata Prefecture, Japan

Abstract

Slash and burn practices are widely used around the globe with different degrees of success which are mostly related to the impact of fire on soil properties. In Japan slash and burn practises, known as Yakihata, have a long history and are still used in Yamagata Prefecture today. The purpose of this study was to determine the impact of a low severity controlled fire underneath Japanese cedar (Cryptomeria japonica) on brown forest soil (Cambisol). Japanese Cedar is the dominant species among plantations in Japan. We measured organic carbon and nitrogen content as well as changes in carbon (δ 13 C) and nitrogen (δ 15 N) stable isotope composition in a steep west facing slope under heavy precipitation (~2600 mm/a) and heavy snowfall (~3 to 4 m/a). The accumulation of C total and N total at the bottom of the slopes was remarkably higher at the slash and burned site than in the control forest site. After slash and burn δ 15 N isotopes in the slope in general became significantly lighter than in the control forest while the δ 13 C did not show any significant difference between the two sites except at the bottom of the slopes where δ 13 C was heavier in the forest. The results show that C total and N total values as well as the isotopes ratios of C and N change with decreasing elevation in the forest as well as in the burned site being consistent with leaching and erosion. The changes in soil nitrogen and carbon isotopes at the bottom of the slope appear to be related to the transport of material with different isotopic composition from the upper slope. The effect of the low severity fire (as part of the slash and burn practice) on soil organic carbon and nitrogen movement was enhanced by the steepness of the slopes and the high precipitation of Shonai region.

Nitrogen resorption and fractionation during leaf senescence in typical tree species in Japan

“…The significant enrichment in larch, compared to the other non-leguminous tree species, may originate from the preferential type of N uptake from the soil, which is generally enriched in ammonium compared to nitrate. In this study, the main form of inorganic N is ammonium (Seidel et al 2017), which is also the preferred N type for larch (Malagoli et al 2000). Another influence on the δ 15 N value in the leaves could be mycorrhizal associations of the tree species; plants associated with ectomycorrhizal fungi (ECM) such as beech and larch have depleted δ 15 N compared to those with arbuscular mycorrhizal fungi (AM) (Michelsen et al 1996;Schmidt and Stewart 2003) such as cedar.…”

Soil temperature and soil moisture dynamics in winter and spring under heavy snowfall conditions in North‐Eastern Japan

“…Snow cover protects plants from frost damages and the length of coverage and snowmelt determine the rate of plant growth (Beniston, Keller, & Goyette, 2003;Wang, Li, Hu, & Wang, 2008). The dominant tree species in Japanese forests are beech (Fagus Crenata) and Japanese cedar (Cryptomeria japonica), which is the latter the main planted species in Japan (Seidel et al, 2019;Seidel, Lopez, Guggenberger, & Nobori, 2017). These tree species start transpiration when snow cover is still several meters high (Osonoi, 2018).…”