Characteristics and pedogenesis of podzolic forest soils along a toposequence near a subalpine lake in northern Taiwan

Podzolic soils are commonly found under cypress forests in the subalpine region of northern
Taiwan where the climatic conditions are cold and humid. Toposequential change from summit to lake shore
along a subalpine lake (Lake Jialo) was selected to evaluate the influence of high soil moisture conditions on
vegetation and pedogenic processes, and to clarify the mechanism of podzolization. Along this toposequence,
the podzolization process occurs at all landscape sites except for the one at the lakeshore. Organicallycomplexed
Fe and Al are the dominant forms in the Bs horizons at summit and footslope sites. The fulvic
acids complex Fe and Al and translocate the latter downwards into the Bs horizons. The placic horizon in
soils at the footslope is dominated by amorphous Fe oxides. Formation of placic horizons is mainly attributed
to perched water, which is caused by heavy rainfall and seasonally high lake water level between the AE and
Bs horizons. This situation causes Fe reduction and translocation to lower parts of the soil profile, resulting in
formation of a placic horizon between E and Bs horizons. The soils towards the lakeshore are characterized
by increasing dominance of hydromorphic process over podzolization. However, although the podzolization
process occurs, the studied soils cannot be classified as Spodosols. High clay and crystalline Fe oxide contents
derived from parent materials retard the mobility of organically-complexed metal cations and thus slow down
the podzolization process and formation of spodic horizons in this area.