Oleic acid and nonionic surfactants of oleic acid derivatives (Control, water; DGTO, diglycerol trioleate; GDO, Glycerol dioleate; GMO, Glycerol monooleate; PEDO, Pentaerythritol dioleate; STF, Sorbitan tri-fatty acid ester (16, 18, 18:1, 18:2, 18:3), STO: Sorbitan trioleate) were foliar-sprayed to Cryptomeria japonica and evaluated their browning effects on leaves and male flowers. All the tested surfactants exerted the selective effect on male flower browning, but that of Sorbitan trioleate was outstanding and thought to be promising for inhibition of pollen dispersal of Cryptomeria japonica. The male flower browning effect of these oleic acid derivatives was accompanied with inhibition of ethylene evolution and seemed to be closely related with their HLB values.

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Individual growth change of Pinus densiflora during 8 years after thinning prescription in a 94-year-old plantation was investigated comparing it with an unthinned plantation of the same age and a 140-year-old natural stand, to test whether growth of trees could be improved by thinning, what individual traits would affect growth improvement, and whether it would be possible or not to produce large sized timber in the plantations as found in the natural stand at 140 years. Trees in the plantations were characterized by smaller size (DBH=41 cm, H=25∼30 m) than old-growth natural stand (DBH=68 cm, H=30∼35 m). H/DBH ratio and proportion of crown length suggested that trees in the plantations were more vulnerable to external disturbance such as heavy snow and had less leaf mass than those in the natural stand. After thinning, about 40% of the trees showed an improved annual DBH increment (by ca. 0.1 cm yr⁻¹), whereas 80% of the trees in the unthinned plantation showed deceleration of DBH growth. Change in degree of competition with neighbors or individual variation in leaf mass did not explain inter-individual variation in growth improvement. Improved growth did not appear to be enough to reach equivalent size to trees in the natural stand at the age of 140 years.

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This study was conducted in a Quercus serrata forest in 2008 and in a Q. crispula forest in 2009. Each forest was divided into an equal number of non-sprayed and sprayed trees. The sprayed trees were sprayed with 1.6% fenitrothion on the trunk surface lower than 6 m above ground level just after the initial attack of Platypus quercivorus adults and again three weeks later. The number of attacks was not increased after the first spraying in infested trees. Therefore, the spraying just after the initial attack prevented subsequent attacks. Secondly, the percentage of newly infested trees among the non-sprayed trees was 81.1% and 95.7% in the Q. serrata and Q. crispula forests, respectively, but was controlled to 2.8% and 18.5%, respectively, by spraying. The attack density in the sprayed trees tended to drop. These results suggest that spraying of 1.6% fenitrothion twice has a high control effect on boring throughout the period of occurrence of P. quercivorus adults.

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Stand structure and growth dynamics were analyzed based on data from long-term monitoring (40 to 50 years) at experimental plots in three mixed coniferous/broad-leaved forests (one plot each in Esashi, Ikutora and Jozankei) in Hokkaido, northern Japan. In each plot, there was almost no change in stand volume and the gross growth and stand mortality remained roughly constant throughout the monitoring period. In each plot, the number of broad-leaved trees increased significantly and the stand type changed to multi-layered from single-layered. These results suggest that in these old-growth coniferous/broad-leaved forests, the species composition and stand type for each stand changed despite long-term stability in stand volume.

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To infer genetic lineages of Fagus crenata populations in Shizuoka Prefecture, we firstly investigated chloroplast DNA (cpDNA) haplotypes and their distribution in 55 populations throughout the entire range of the species within the prefecture. Three haplotypes, D, E and F, were found across the populations. Haplotypes D and E, which were widely distributed in the Pacific side of Chubu District, were dominant in the populations. Secondly, using a nuclear microsatellite (nSSR) we examined genetic diversity in six populations, which were selected based on the species’ range and the haplotype distribution revealed by this study. The unrooted neighbor-joining tree based on the between-population D_A distances calculated from allele frequencies at nSSR loci indicated that all the populations genetically belong to the Pacific side lineage in concordance with their geographic location. Although the allele frequencies at nSSR loci were almost homogeneous among the populations, there was geographic structure of cpDNA haplotypes. This difference most likely reflects the different rates of gene flow due to different modes of inheritance between chloroplast and nuclear DNA.

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We evaluated a combination of mechanized operations with a high-density road network and forestry machines in order to develop a new thinning operation system that keeps costs low and reduces damage to lower-story trees in thinning from above in multi-story forest management. We constructed temporary spur roads of 342.3 m/ha in a 1.58-ha multi-storied forest composed of 100-year-old upper-story trees and 40-year-old lower-story trees, and then implemented yarding with a grapple loader or swing yarder, and hauling with a forwarder. According to time studies, drawing with wire in felling operations and limbing in log-making operations take considerable amounts of time. The labor productivity was 5.97 m³/man-day, and is more than twice the national average in single storied Hinoki forests. Logging cost was held down to 7,516 yen/m³ through the use of rented forestry machinery. The damage to lower-story trees amounted to 16%, and was higher for thinner trees.

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The current status of a broadleaved forest after mass mortality caused by oak wilt disease was investigated in the Tango Peninsula in central Japan. Sasa palmata, a species of dwarf bamboo, dominated the forest floor and had been supposed to inhibit the regeneration of tree species, including Quercus crispula. Small stems and saplings of tree species were, in fact, not abundant. While the small stems whose diameter at breast height was less than 10 cm were very abundant, most were Clethra barbinervis, Viburnum furcatum, Benthamidia japonica, Lindera umbellata, Rhododendron lagopus var. niphophilum or Cephalotaxus harringtonia var. nana; all these species except B. japonica were subtree or shrub species. Tree species were not abundant in the layer below breast height. The stand structure suggested that the regeneration of tree species including Q. crispula was difficult, and that the current status would last at least until simultaneous death of S. palmata.

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Richard Varney’s article written in 1947 titled “The position of a forester in Japan” in the Journal of Forestry sharply described the problematic situation of the national forest management system in Japan at the time. This paper aims to discuss what we can learn from Varney’s article with its Japanese translation. He insisted that the bureaucracy dominated by senior members of the civil service was the biggest obstacle, and his warning still has plenty of meaning for the situation of forest administration in Japan today.

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