Twelve fragments of fossil shells were sampled from the Ma8, MalO, and Ma 12 marine clay beds
of the May a-Wharf boring cores in Hyogo Prefecture, western Japan, and dated by ESR. Total doses
of the fossil samples were determined by an additive dose method with exponential fitting .Annual
dose rates were calculated based on the contents of 238U, 232Th, and 40K in the sediments around the
fossils. Because of disequilibrium between 238U and 226Rn and excess of 210Pb, annual dose rates
were recalculated for individual samples considering 222Rn-loss and contribution of the 210Pb excess,
in addition to correction of water content of the sediments and of thickness of the fossil shells.
The ESR dates thus obtained were 92 ± 15 to 127 ± 20 ka for the Mai2, 216 ± 45 to 322 ± 79 ka
for the MalO, and 227 ± 65 to 246 ± 41 ka for the Ma8. The former two dates are consistent with
the previously estimated ages of the Ma 12 and MalO, while the latter dates are much younger than
ages of the Ma8 estimated based on the fission-track age of an intercalated tuff and correlation with
marine oxygen isotope stages.
The younger ESR dates for the Ma8 are considered to arise from the following reasons:
underestimations of total doses due to extension of ESR-signals by the higher-rate radioisotope
addition to the saturated fossil shell samples, and overestimation of annual doses based on limited
sediment samples. Although such problems remain, our results suggest the possibility of systematic
ESR dating of fossil shells in long boring core sediments.
Genotype polymorphism in agamospermous Taraxacum officinale Weber was investigated among
9 populations in the southeastern area of Hyogo Prefecture. Seven clone types were distinguished
by 8 polymorphic enzyme loci. Each population has a dominant clone type. Sanda clone type is
dominant among populations in the North of Rokko mountains, while Rokko l'and Rokko 2 are so
in the South. Based on multivariate statistica lanalysis of frequencies of clones, three clusters were
recognized: populations of cluster 1 distribute in the North of Rokko mountains, and cluster 2 and 3
in the South of Rokko mountains.
The distribution of dominant forest types, their community structures and soil conditions were
investigated in the fragmented secondary forest on a hill slope in Flower Town, Sanda City, Hyogo
The dominant tree species in the fragmented secondary forest were Pinus densiflora at the top
and upper part of slope, and Quercus serrata at the lower part of slope. Pinus densiflora was distributed
on the thin and hard soil. On the other hand, Quercus serrata was distributed on the thick and soft
The forest vegetation of the fragmented secondary forest was classified into the following three
forest types on the basis of their physiognomy and vegetation height: 1. Medium-tree Pinus forest
(height 10-13m ; younger), 2. Tall-tree Pinus forest (height 16-18m), 3. Quercus forest. Surface soil
moisture status (measured by tensiometric method) was compared among the three forest types.
The soil moisture status of vegetation types in heavy-rainfall term maintained a lower level of under
pF value 1.8. In light-rainfal lterm, it maintained a higher level of more than pF value 1.8, in the order of Plot No.l (Medium-tree Pinus forest), Plot No.2 (Tall-tree Pinus forest), Plot No.3 (Quercus forest).
Recently, range expansion of bamboo forests has been observed in various parts of western and
eastern Japan, and this phenomena has become a very important problem for conservation of local
ecosystems. It seems that the most certain method to prevent range expansion of bamboo forests is
to convert the forests into other vegetation. Therefore, we studied the vegetation dynamics of the
Phyllostachys pubescens forest after clear-cutting in Flower Town, Sanda, Hyogo Prefecture, in
order to examine the effectiveness of clear-cutting for converting bamboo forests into other vegetation.
Clear-cutting of the Phyllostachys pubescens forest was carried out on June and July, 1997. From
September, 1997 to May, 1999, floristic composition and layer structure of the vegetation formed
after clear-cutting was surveyed using the phytosociological method. The results showed that
Phyllostachys pubescens declined remarkably due to clear-cutting. Zanthoxylum ailanthoides, Albizia
julibrissin, Rhus javanica, Mallotus japonicus and so on, which were not found in the Phyllostachys
pubescens forest ,appeared after clear-cutting .The vegetation formed after clear-cutting was identified
as Rubo-Aralietum elatae Miyawaki et al. 1971. From the results, it is considered that clear-cutting is
very effective in converting Phyllostachys pubescens forest into other vegetation.
Nuphar oguraense Miki (Nymphaeaceae) is endemic to southwestern Japan and one of the
endangered water plant species .The habitat of this species in Sanda distric tis usually irrigation
ponds. We surveyed 230 irrigatio nponds in Sanda City and found N. oguraense populations at 25
ponds. Other Nuphar species (AT .japonicum DC. and N. subintegerrimum (Casp. )Makino) were found in 19 ponds. N. oguraense was found to prefer oligotrophic ponds with low conductivity whose embankment is constructed by natural materials such as clay and rock.
Bryophyte flora of Isl. Kii-Oshima (Wakayama Pref., Japan) was reported on the basis of 300
specimens collected in 1998. A total of 45 families, 82 genera, and 139 species was found on this
island; they include 28 families, 57 genera, and 91 species in mosses, 16 families, 24 genera, and 47
species in liverworts, and one species in hornworts.
In a series of papers, we will lis tthe species of vascular plants collected in Hyogo Prefecture. Most
of the specimens are being preserved in herbaria at Shoei Junior College (SHO) and the Museum of
Nature and Human Activities, Hyogo (HYO), the others at the indicated herbaria. Many different
investigators have identified the taxa. Their names will be indicated with the appropriate taxa. This
is the first paper and concerns all the families of Ptericiophyta.