A₀layer (fallen leaves)

A₀ layer is consisted of fallen leaves, branches and decomposed organic matters. The color is gray and black. It is also called “deposited organic layer” or “deposited humic layer”.

A₀layer is subdivided into L layer, F layer and H layer by the degree of degradation.

• L layer
  The closest layer to ground surface, consisted of fresh or merely decomposed fallen leaves and branches. Also called “Oi layer”.
• F layer
  Locating under the L layer. Fallen leaves and branches are well decomposed but original tissues are visually recognized. Also called “Oe layer”.
• H layer
  Organic matters are almost degraded and original tissues are visually not recognized. Also called “Oa layer”.

A layer

A layer locates under A₀ layer. Fumus rich, swelling, soft and low density. Plant rootlet is rich and the activity of microorganism and soil animals is high. The color is almost dark brown. Soil particles aggregates. The surface layer of the mineral soil.

B layer

B layer locates under A layer. The mineral soil of bright color and low fumus. Some soils accumulated iron and fumus eluviated from A layer. In the case of brown forest soil, the color is bright brown.

C layer

C layer contains much gravel and remains status of basement rock. Soils in C layer is merely affected of soil genesis.

---

Reference

1. 森林土壌学概論(博友社、1989年)
2. 土壌調査ハンドブック改訂版(博友社、1997)
3. Earth Surface Processes, Landforms and Sediment Deposits(Cambridge University Press、2008年)
4. 森のバランス(東海大学出版会、2012年)
5. 造林学第四版(朝倉書店、2016年)