proposed by Honna et al. (1988) and Yamamoto et al. (2000). The colorimetric
properties of free HA extracted with 1 M NaOH were measured by using a UV
spectrophotometer (UV 2400, Shimadzu Corp.). Absorbance values were measured
at 450, 520, 600, and 610 nm, and K450/K520 and K610/KA600 were calculated to
obtain the MI and PI, respectively. A lower MI value indicates a higher degree of
humification, and a higher PI value indicates a higher content of “Pg.” Using these
indices, the HA type can be classified into the following five categories: P+ to +++;
PÆ and Rp(1); B and P 0 ; Rp(2); and A (Yamamoto et al. 2000).
For sclerotia collection, 500 mL of distilled water was added to 10–30 g air-dried
soil samples and then the floated sclerotia were collected using tweezers. Sclerotia
were classified by diameter: 0.2–0.5 mm, 0.6–1.0 mm, 1.1–1.5 mm, 1.6–2.0 mm,
2.1–2.5 mm, and 2.6–3.0 mm. Sclerotia content was determined by weight (SGw:
mg g
À1 ) and count (SGc: count g
À1 ) of sclerotia per gram of oven-dried soil.
Air-dried sclerotia were sliced in half using a sterilized knife to observe the morphological features and chemical composition of the transverse wall. For this
analysis, large grains were selected from three sites (B-5, C-5, and E-8) that differed
in soil pH (KCl) and Al Ex content. The chemical composition of these samples was
determined using SEM-EDS analysis system (JSM-6490LA, JEOL Ltd., Tokyo,
Japan), accelerating voltage of 15 eV.
10.2.2 Results and Discussion
Figures 10.6 and 10.7 show the distribution of sclerotia (SGw and SGc) along the
transects at sites A–C and D–E, respectively. The overall averages of SGw and SGc
were 0.54 mg g
À1 and 1.3 count g
À1 , respectively. Sites A and B are a side slope and
a crest slope, respectively. At site A, sclerotia were most abundant at point A-2
(2.0 mg g
À1 and 2.1 count g
À1 ). At site B, sclerotia were most abundant at point B-2,
near the bottom of the crest slope (1.1 mg g
À1 and 3.0 count g
À1 ). No sclerotia were
detected at the bottom of the opposite side slope at site B, at point B-12. This point
lacked P. abies but had grass coverage. Site C is a transverse section of the lower
side slope and bottomland, encompassing a river. Sclerotia were evenly distributed
across the bottomland. At site D, we established three transects (D1–D3), three
parallel transverse lines that crossed the watercourse at the head of the channel
hollow. Point D2-7 showed the maximum SGc and D3-9 had the maximum SGw, at
7.8 count g
À1 and 2.8 mg g
À1 , respectively. Five points at site D contained no
sclerotia. These points were relatively flat and had high levels of crude organics. Site
E is a channel hollow tangential to the side-slope line. At site E, sclerotia were most
abundant at point E-2 (5.4 mg g
À1 and 5.8 count g
À1 ). Point E-9, near the edge of a
cliff, showed a higher content of sclerotia than adjacent points. The small peak in
sclerotia at point E-14 might have been caused by transportation of sclerotia down
the cliff wall. Exceptionally, no sclerotia were present at the top of the cliff at point
E-17, but sclerotia were present on the cliff wall (E-15).
10 Spatial Distribution of Sclerotia Grains in Low-pH Forest Soils, Central Germany
185
properties of free HA extracted with 1 M NaOH were measured by using a UV
spectrophotometer (UV 2400, Shimadzu Corp.). Absorbance values were measured
at 450, 520, 600, and 610 nm, and K450/K520 and K610/KA600 were calculated to
obtain the MI and PI, respectively. A lower MI value indicates a higher degree of
humification, and a higher PI value indicates a higher content of “Pg.” Using these
indices, the HA type can be classified into the following five categories: P+ to +++;
PÆ and Rp(1); B and P 0 ; Rp(2); and A (Yamamoto et al. 2000).
For sclerotia collection, 500 mL of distilled water was added to 10–30 g air-dried
soil samples and then the floated sclerotia were collected using tweezers. Sclerotia
were classified by diameter: 0.2–0.5 mm, 0.6–1.0 mm, 1.1–1.5 mm, 1.6–2.0 mm,
2.1–2.5 mm, and 2.6–3.0 mm. Sclerotia content was determined by weight (SGw:
mg g
À1 ) and count (SGc: count g
À1 ) of sclerotia per gram of oven-dried soil.
Air-dried sclerotia were sliced in half using a sterilized knife to observe the morphological features and chemical composition of the transverse wall. For this
analysis, large grains were selected from three sites (B-5, C-5, and E-8) that differed
in soil pH (KCl) and Al Ex content. The chemical composition of these samples was
determined using SEM-EDS analysis system (JSM-6490LA, JEOL Ltd., Tokyo,
Japan), accelerating voltage of 15 eV.
10.2.2 Results and Discussion
Figures 10.6 and 10.7 show the distribution of sclerotia (SGw and SGc) along the
transects at sites A–C and D–E, respectively. The overall averages of SGw and SGc
were 0.54 mg g
À1 and 1.3 count g
À1 , respectively. Sites A and B are a side slope and
a crest slope, respectively. At site A, sclerotia were most abundant at point A-2
(2.0 mg g
À1 and 2.1 count g
À1 ). At site B, sclerotia were most abundant at point B-2,
near the bottom of the crest slope (1.1 mg g
À1 and 3.0 count g
À1 ). No sclerotia were
detected at the bottom of the opposite side slope at site B, at point B-12. This point
lacked P. abies but had grass coverage. Site C is a transverse section of the lower
side slope and bottomland, encompassing a river. Sclerotia were evenly distributed
across the bottomland. At site D, we established three transects (D1–D3), three
parallel transverse lines that crossed the watercourse at the head of the channel
hollow. Point D2-7 showed the maximum SGc and D3-9 had the maximum SGw, at
7.8 count g
À1 and 2.8 mg g
À1 , respectively. Five points at site D contained no
sclerotia. These points were relatively flat and had high levels of crude organics. Site
E is a channel hollow tangential to the side-slope line. At site E, sclerotia were most
abundant at point E-2 (5.4 mg g
À1 and 5.8 count g
À1 ). Point E-9, near the edge of a
cliff, showed a higher content of sclerotia than adjacent points. The small peak in
sclerotia at point E-14 might have been caused by transportation of sclerotia down
the cliff wall. Exceptionally, no sclerotia were present at the top of the cliff at point
E-17, but sclerotia were present on the cliff wall (E-15).
10 Spatial Distribution of Sclerotia Grains in Low-pH Forest Soils, Central Germany
185