In order to clarify the potential range of deer browsing height on Sugi cuttings, as well as the effects of slope gradient on this range, we plantedlarge Sugi cuttings (＞160 cm; n＝300) on slopes with different gradients (0 to 50°) and measured the height of browsing activity over the course of one year. The slope gradient at each site was measured at 5° intervals. The findings showed that the browsing rate and the number of browsed shoots tended to decrease as the gradient became steeper. When the Sugi cuttings were planted on almost level ground (≤5°), 67.4％ of the shoots from 75 to 110 cm were browsed (median height: 96 cm). As the slope gradient exceeded 35°, the median height of the browsing range increased by more than 40 cm. On slopes ＞30°, 81-100％ of the browsed shoots were on the uphill-side of the Sugi crown. The observed range in browsing height (75 to 110 cm) shows that cuttings shorter than this would be at highest risk from deer due to damage to the terminal leader. It is therefore necessary to use Sugi cuttings ＞110 cm on gentle slopes and at least 140 cm on slopes with gradients ＞35°.
To improve the shipping operation of multi-cavity container seedlings, it is necessary to select seedlings with appropriate root balls. The aim of this study was to develop indices and measurement methods evaluating the physical properties of the root ball, and to clarify the effects of the cavity type of container on the indices and the relationship between the indices and the above-ground morphological characteristics of seedlings. Seedlings of Japanese cedar (Cryptomeria japonica D. Don) cultivated in rib and slit types of multi-cavity containers were used for measurements before (June) and after (November) the second growing season of the seedlings. Root ball hardness (hardness index obtained by a Yamanaka-type soil hardness scale), root ball collapsibility (detached soil amount after dropping of a root ball), and difficulty of extracting a root ball (pull-out force of extracting a root ball from a cavity) were measured. Height, root-collar diameter and root biomass of the seedlings were also measured. As root biomass increased, the detached soil decreased whereas the hardness index and the pull-out force increased. These results suggest that the indices are easily understandable owing to simple measurements and have close relationships with root growth. In addition, the root balls of the seedlings in slit-type containers are easier to collapse, and easier to extract from the containers than those of the seedlings with the same root biomass in rib-type containers. Moreover, the physical properties of the root ball have closer relationships with root-collar diameter, than with the height, of the seedlings.
We report the development of two types of simple DNA markers that can be used to easily identify genotypes of both the male-sterile and wild-type individuals at a locus, which is tightly linked to the causative gene of male sterility in the “Sosyun” clone of Cryptomeria japonica. Both the allele-specific primer (ASP) PCR marker and cleaved amplified polymorphic sequence (CAPS) marker were designed using previously reported single nucleotide polymorphism (SNP) information. The cDNA and genomic DNA of the EST reCj19250, which is linked to the ms-1 locus, were sequenced for both the “Sosyun” and wild-type plus-tree “Usui2” clones. Primers were designed for detecting both the sterile and wild-type SNPs using the genomic DNA sequences. For the ASP-PCR marker, homozygous recessive male-sterile individuals yielded a single 157-bp fragment, whereas the homozygous wild-type individuals yielded a single 345-bp fragment, and heterozygotes yielded both fragments. Similarly, for the CAPS marker, male-sterile individuals yielded a single 101-bp fragment after digestion, whereas wild-type ones yielded an intact single 125-bp fragment, and heterozygotes yielded fragments of both sizes. These markers could be utilized for identifying male-sterile individuals during seedling production and for identifying heterozygous trees for future tree breeding.
An old picture map named “Yakushima kozu” which covered Yakushima Island was drawn around 1660. This old map was drawn in detail; therefore, we can distinguish the names of villages, mountain tops, rivers, famous points, the existence of dominant tree species in the forest (e.g. Japanese cedar (Cryptomeria japonica) and pine trees), and mountain trails. In this study, we geo-referenced this old map to match a present map on GIS, and estimated the distribution of Cryptomeria japonica at that time. Furtermore, we compared the distribution of Cryptomeria japonica at that time and the present, and considered the factors of change. We also considered the possibility of using this old picture map for academic research. In summary, we succeeded in geo-referencing an old picture map. The distribution of Cryptomeria japonica at that time was biased to the east of the island, especially to the basin of the Anbo River. In the basin of the Anbo River, the distribution of Cryptomeria japonica was down to 200 meters a.s.l. The currently lost distribution area of Cryptomeria japonica compared to that of around 1660 is concentrated in the lower elevation zone and the location near the rivers. In conclusion, this old picture map named “Yakushima zennzu” is worth using as valuable data describing the forest conditions of Yakushima Island around 1655.
We conducted a root pull-out test using wind-fallen Cinnamomum camphora and Morella rubra trees located on a pebble beach. The effects of root diameter and sand-pebble particle size composition on the pull-out resistance were examined. The root pull-out resistance (kN) was expressed as a power function of the root basal diameter (mm). The sand-pebble particle size composition at the locations of 14 trees subjected to the test was classified into two types by cluster analysis. The root pull-out resistance had lower values at locations with a higher proportion of pebbles sized ＞5.6 mm. There was no difference between the two species in root pull-out resistance or in root tensile strength. The parameter in the power function of root diameter and pull-out resistance in this study was smaller than those observed in previous studies conducted in a montane forest and a sand beach. This suggests a smaller pull-out resistance of tree root in coastal forests on pebble beaches with rounded gravel than in other terrains.
To clarify whether adult Monochamus alternatus, the vector of pine wilt disease, are attracted to slight damage to branches of the host tree, a sheaf of fresh or dead cut branches were attached to four healthy Pinus densiflora in late June 2017, and egg-laying scars and feeding wounds on the stems and branches of the trees caused by the beetles were counted. Egg-laying scars and feeding wounds were found first on all of the trees in mid-July, and their numbers increased until mid-September. The final number of egg-laying scars ranged from 26 to 101 per tree and that of feeding wounds from 10 to 27, while there were no egg-laying scars on the stems of 10 healthy control trees without cut branches. Two of the four trees with cut branches died showing symptoms of pine wilt disease. These results suggest that that cut branches attracted the beetles and caused them to oviposit on healthy host trees. Therefore, slight damage to host trees, such as recently broken branches caused by snowfall or wind, can attract adult M. alternatus and influence their occurrence and expansion, as seen in the historical effects of diseased trees with pine wilt disease.