南九州テフラ断面土壌のδ^<13>C値とδ^<15>N値に基づく古植生推定の試み

概要

論文の詳細を見る
Organic carbon and nitrogen contents in soils and the natural abundance of carbon and nitrogen isotopes (δ^<13>C, δ^<15>N) were analyzed to estimate old vegetation at three sites (Takarabe, Ooiwata,Yamada) in southern Kyushu. The soil samples were obtained from each layer of tephra profiles developed at the sites. C and N contents were relatively high in the kuroniga (buried humic ash) layer, while low in the Miike pumice layer, akahoya (highly glassy ash) layer and shirasu (pyroclastic flow deposit) layer. Theδ^<13>C of soil organic C ranged from -26.1‰ (which means the old vegetation largely originated from C_3 plants) to -19.2‰ (around 56% C_4 plant origin). Regarding the δ^<13>C of the lower kuroniga layers at the three sites, lower parts of the Miike pumice layer and kuroboku (highly humic ash) layer at Yamada were less than -24‰ (more than 79% C_3 plant origin). In other soil layers, larger in put of C_4 plant carbon was suggested from their higher δ^<13>C values. The δ^<15>N values ranged from +1.2‰ (which suggests large N in put by N_2 fixation) to +10.7‰ (which indicates δ^<15>N was enriched by N metabolism such as ammonia volatilization and denitrification). The δ^<13>C and δ^<15>N values were well correlated(R^2=0.4751, P<0.0001).
社団法人日本土壌肥料学会の論文
2000-12-05