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Meintien mountain in the Yangmingshan National Park was
formed from andesitic volcanic lavas erupted 0.41 million years
ago. Three soil pedons were selected from different landscape
positions including summit, backslope, and toeslope to study
the soil characterestics, pedogenesis, and classification of
volcanic rock-derived soils. Soil properties of these Andisols
are characterized with andic soil properties including low bulk
density, high phosphate retention, and high oxalate-extractable
aluminum and iron.
The climate conditions in the study area are characterized
with moderate temperature (16.6 ℃) and high precipitation (4800
mm/yr). Soil chemical propertiees are characterized with strong
acidity (pH<5), very low bases saturation, and high exchangeable
aluminum. Umbric epipedon with high organic carbon content and
cambic horizon can be developed in study area. Soil properties
can''t be affected by different vegetation types. Black color and
porous soil structure with high organic carbon can be found by
soil micromorphology.
Clay mineralogy can be semi-quantitatively identified by
X-ray diffractometer (XRD), transmission electromicroscope (TEM)
, or selective chemical extraction methods. The results indicate
that (1) the similar clay mineral compositions in three pedons
are major with kaolinite and gibbsite, and minor with 2:1 type
clay minerals including illite, chlorite, and/or hydroxyinter-
layered vermiculite by XRD, (2) Al-humus complexes are main
sources for active aluminum, and little allophane and imogolite
can be found in the lower part or R horizon of the soil pedons
by TEM, and (3) laminar opaline silica can''t be found in these
Andisols by TEM.
No recurrent landslides or slip actions in this stable con-
ditions, soil characteristics and clay mineralogy are not sig-
nificantly related to soil slope and landscape positions.
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