I studied the comparison of juvenile growth characteristics of cuttings and seedlings of sugi (Cryptomeria japonica) in heavy snowfall region. I selected three pairs of a seedling-trial and a cutting-trial that are closely located with similar environmental conditions. Only seedlings and only cuttings are planted in seedling-trial and cutting-trial, respectively. Data for each cuttings and seedlings from identical varieties in a pair of trials was defined as a dataset. Three datasets were used to compare. Survival rates of cuttings and seedlings at 5 years were almost the same; however, the survival rates of cuttings at 10 years were clearly less than those of seedlings. The main cause of tree death was broken stems or roots. Basal bending and the height of the cuttings were less than those of the seedlings. From these results, I conclude that cuttings can resist basal bending caused by snow pressure better than seedlings; however, the survival rate of cuttings is lower than that of seedlings because of the greater incidence of broken stems in cuttings as they grow. The cuttings' inferior height growth causes them to be buried in the snow for long periods during winter. Therefore, I conclude that afforestation using cuttings in heavy snowfall region has a high risk of poor survival because of stem breakage caused by snow pressure.

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Instructional textbooks can help educators to promote better forest education programs. We analyzed and compared ten forest education textbooks to find a policy of developing texts to facilitate better understandings of the multiple functions of forest by examining how the textbook contents addressed these multiple functions. We found that about half of all programs have already been developed to encompass the multiple functions of forest, and are suitable for use in forest-education programs. The ten textbooks were classified into four contextual groups, according to the relationship between a particular topic related to an education program and its interpretation in the textbook, as follows. Group a: textbooks that contained no interpretation; group b: textbooks that contained several interpretations, and each interpretation corresponded to a particular program; group c: textbooks that contained several interpretations and each interpretation bound several programs; and group d: textbooks in which all programs were accounted for under one interpretation. Textbooks with several interpretations (groups b and c) contained more programs that were well-linked to forest functions than the other textbooks. To promote the multiple functions of forest in forest education, textbooks should contain separate interpretations that address forest functions, and clear links should be established between each program and its interpretation.

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We investigated past growth of trees within a natural stand of Cryptomeria japonica in Sado Forest Reserve, Akita Prefecture, northeastern Japan, relating to temporal changes in environmental conditions. We cut 43 disc sections through the trunks of wind fallen trees selected from 3 locations within the reserve (area: ca. 25 ha). The wood samples were taken at 30∼200 cm height above ground. Average disc diameter was 62 cm. Mean number of annual rings per discs was 235, from which we calculated the average date of emergence at AD 1705 (after applying a correction taking into account the estimated number of extra years in the trunk wood below the cutting height). In order to evaluate historical conditions that may have affected growth performance of trees (e.g., canopy condition), we developed a discriminant function composed of trunk diameter and growth rate, which was estimated from the diameters and growth rates of current trees (height >130 cm, dbh <30 cm) within the same stands. Using this discriminant function, saplings which emerged in the early 18 th century were estimated to experience good growing conditions that soon deteriorated. However, for most trees, growth rate improved at around AD 1790. Estimated dates derived from these calculations were not significantly different among locations within the forest reserve. We conclude that this stand experienced two large disturbances in the 18 th century within about 85 yr. The first enhanced emergence of new trees and the second lead to improved growth. The most likely disturbance at that period of human history was likely felling of trees.

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We measured leaf loss caused by typhoons in four Hinoki (Chamaecyparis obtusa) plantations in northern Kagoshima Prefecture. In 2004, five typhoons passed through Kagoshima Prefecture and over nearby seas, Typhoon 18 was strongest; easterly and southwesterly winds impacted the forests with storm velocities of >40 m/s. The fallen branches lengths were mostly <10 cm; tree debris of ≥20 cm dimension was relatively rare in four stands. The amounts of fallen leaves were 1.0 and 0.8 t/ha in stands P1 and P2 (located on slopes with southwestern exposure), respectively, and 0.7 and 0.2 t/ha in stands P3 and P4 (located on north-facing slopes), respectively. The mass of fallen branches in these stands amounted to only 7∼15% of the mass of fallen leaves. The difference in the amount of fallen leaves among stands were putatively attributed to factors that influenced wind velocity, such as slope direction and presence or absence sheltering mountains on the windward sides. The leaf biomasses before the typhoon impact were estimated to be 13.8 and 15.5 t/ha in stands P1 and P2, respectively. The ratios of fallen leaf amount to leaf biomass before the typhoon were 7.5 and 5.1% in stands P1 and P2, respectively. Thus, defoliating damage by typhoon impact in Hinoki stands can occur, even in the absence of conspicuous damage such as trunk breakage.

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To examine the conversion of conifer plantations to mixed forests comprising coniferous and broad-leaved trees, we investigated responses of understory vegetation to variable-intensity thinning in 39-year-old Todo fir (Abies sachalinensis) stands 8 and 11 years after thinning, with 28-year-old unthinned stand for comparison. The following three operational thinning levels were used: one-row thinning and four-rows leaving (Th1), two-rows thinning and three-rows leaving (Th2), and three-rows thinning and two-rows leaving (Th3). Understory relative Photosynthetic Photon Flux Density increased with thinning intensity. Species richness and density of broad-leaved trees were positively influenced by thinning. However, in thinned stands, tree density decreased with thinning intensity. The maximum height and cover of both shrubs and herbs were positively affected by thinning, with the highest thinning level resulting in the highest maximum height and cover. The maximum height of herbs was higher than the mean height of trees under the Th2 and Th3, which may have hindered tree growth. However, 2,500∼3,750 seedlings/ha of ≥100 cm in height occurred under the Th2 and Th3 regimes, which may be sufficient for regeneration. Therefore, it may be feasible to apply thinning to convert conifer plantations to mixed forests.

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We tested for induced resistance, a phenomenon by which pine trees inhibit symptoms of pine wilt disease after pre-inoculation with avirulent isolates from pine wood nematodes (Bursaphelenchus xylophilus), in Japanese black pine (Pinus thunbergii). One-year-old seedlings from five families were pre-inoculated with avirulent isolates (OKD-1 or C14-5) or sterilized distilled water (control), and then post-inoculated with virulent isolates (Ka-4 or Shimabara) after the prescribed incubation period following pre-inoculation. Seventeen weeks after post-inoculation with virulent isolates, morbidity and mortality rates significantly depended on seedling family, pine wood nematode isolate used for post-inoculation, and seedling height, but not on pre-inoculation with avirulent isolates. In experiments using 2- to 3-year-old clonal ramets, which have uniform genetic composition, there was no significant difference in symptom development between individuals pre-inoculated with avirulent OKD-1 and controls. These results suggest that induced resistance is not a general phenomenon in pine trees pre-inoculated with avirulent isolates.

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To select suitable sites for restoring plantations to natural Abies firma and Tsuga sieboldii forests in the Kirishima mountain region, the likelihood of the existence of Abies seedlings was predicted using logistic regression analysis. Using information on natural forest patches and individual mature trees as seed sources, the results of the model selection procedure showed that the existence of seedlings was best predicted when the distance from a mature tree and the basal area of the mature tree in a natural forest were considered. In other words, Abies seedlings tend to exist near large mature trees in a plantation. Moreover, to select a suitable site for restoration, information on individual mature trees is indispensable for predicting the likelihood of seedling existence with high accuracy.

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From our examination which used the published data observed in the Tatsunokuchi-yama Experimental Watershed, it was concluded that May 1 is the most suitable day for the first day of the water-year in the discharge-duration analysis focused on low flow. The water-year beginning on May 1 could produce a smooth discharge duration curve and high contribution ratios of the regression lines from the discharge-duration curves between Kitatani and Minamitani, as compared with those obtained by the practical water year beginning on January 1. And the contribution ratios obviously increased in low flow range of discharge-duration curve. Hence importance of the definition of water-year period is confirmed.

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I reviewed the effects on forest birds of replacing broadleaved forests at the patch and landscape levels, with emphasis on replacement by plantations. I proposed methods mitigating such effects. Reduction in patch area of broadleaved forests, loss and fragmentation of broadleaved forests caused by plantations reduce bird species richness and densities. The effects of loss and fragmentation of broadleaved forests operate strongly in landscapes where most broadleaved forests have been lost. Plantations have been treated as homogenous non-habitats (matrix), and ignored in biodiversity conservation. However, because structurally and compositionally complex plantations function as habitats for many forest birds, such negative effects would be mitigated by increasing the complexity of the structure and composition of surrounding plantations through extended rotation, strong thinning, and planting trees further apart, retention of green trees, deciduous trees, and coarse woody debris in clearcuts. Future challenges facing the development of forest management to conserve biodiversity are discussed.

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