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Nghiên cứu này đã xem xét các ảnh hưởng của cây còn lại đến chiều cao của cây Cryptomeria japonica 18 và 19 tuổi được trồng trong các khoảng chọn nhóm khoảng 0,1 ha tại Yufuin, tỉnh Oita, miền nam Nhật Bản. Chúng tôi đã phát triển một mô hình tổng quát thể hiện sự biến đổi chiều cao của tất cả các cây trồng trong các khoảng từ các chỉ số cạnh tranh giữa các thế hệ (ảnh hưởng của cây còn lại) và cạnh tranh trong cùng một thế hệ (giữa các cây trồng cùng tuổi). Chỉ số cạnh tranh giữa các thế hệ được tính toán cả khi có và không tính đến hướng mà cây còn lại được đặt so với cây chủ. Hai mô hình đã gợi ý rằng các cây còn lại gần rìa phía bắc của khoảng không phải là đối thủ cạnh tranh hiệu quả về ánh sáng cho các cây trồng trong khoảng. Thêm vào đó, kết quả của chúng tôi cho thấy cả cạnh tranh giữa các thế hệ và cạnh tranh trong cùng một thế hệ đều quan trọng trong việc giải thích chiều cao cây trong các quần thể khép kín trong các khoảng chọn nhóm. Sử dụng mô hình tổng quát này, chúng tôi đã ước lượng tổn thất tiềm năng về sự phát triển chiều cao cho các cây chiếm ưu thế tại chỗ trong các khoảng mà chỉ có thể quy cho ảnh hưởng của cây còn lại. Các kết quả này cho thấy bên cạnh ảnh hưởng của kích thước khoảng mở, cả mức độ đông đúc và hướng của cây còn lại so với cây trồng là những yếu tố quan trọng ảnh hưởng đến chiều cao của từng cây trồng trong các khoảng chọn nhóm.

We used forest management records to estimate the annual supply potential and availability of timber and logging residue from profitable subcompartments for all the cities and towns in the Tochigi prefecture. Five log markets and three factories in the Tochigi prefecture were assumed to be the destination of timber and logging residue, and the forest operation systems were set on the basis of interviews with forestry cooperative officials. The results showed that the annual supply potential of timber and logging residue was 450,304 m3 and 549,957 tons, of which 6 % (26,304 m3) and 37 % (204,122 tons) were from precommercial thinning operations, 61 % (276,180 m3) and 50 % (276,276 tons) were from commercial thinning operations, and 33 % (147,820 m3) and 13 % (69,559 tons) were from final-felling operations, respectively. When the unit price of the logging residue was 10,000 yen/ton, the annual logging residue availability from profitable subcompartments could almost cover the annual demand of the three facilities that we considered in this study. Introduction of feed-in tariffs had a significant impact. However, the ratios of the availability to supply potential with unit prices of logging residue of 3,000, 6,000, and 10,000 yen/ton were estimated to be only 1.67, 2.06, and 4.09 %, respectively. Considering the subsidies, the ratios respectively increased to 5.79, 7.35, and 13.09 %. Furthermore, the annual logging residue availability with subsidy could meet 70 % of the annual woody biomass demand of the large-scale factory in Sano city, which is 100,000 tons.

Post-thinning stump sprout response was assessed in a coast redwood [Sequoia sempervirens (D. Don) Endl.] stand from 5 to 9 years after five treatments were initiated. Nine years after treatment, leaf area index (LAI) ranged from 5.9 to 14.1 and the percent above canopy light (PACL) ranged from 0.8 to 3.9. Sprout responses included rapid self-thinning in all treatments with complete sprout mortality at low light regimes. Self-thinning of clumps increased with greater overstory LAI and poorer light regimes. Leaf area of individual sprout clumps also declined in low light regimes. The probability of sprout survival declined rapidly below 10 PACL and coincided with declining leaf area in sprout clumps. A conceptual model is presented that shows the sensitivity of redwood sprouts to light regime. Results have implications for management of multiaged stands and indicate these redwood coppice systems require relatively severe overstory treatments to provide sufficient light for sprout vigor and growth.

To determine whether Monochamus alternatus can use the Japanese cedar (Cryptomeria japonica) as a host tree, experiments were conducted in a laboratory using three insect populations of different localities. Adult females chose Pinus densiflora bolts as oviposition substrate when supplied with cedar and pine bolts simultaneously, whereas some females from one locality oviposited on cedar bolts when supplied with them exclusively. Seventy-three percent of 40 eggs hatched in cedar bolts. When the first instar larvae were inoculated on cedar bolts, the development was stunted greatly and all died during the larval stage. Two of 20 larvae that were inoculated on cedar bolts at the third instar entered the diapause and one larva developed into an adult female, which produced viable eggs but was much smaller than those obtained from pine bolts. The results did not exclude the possibility that M. alternatus can use recently killed C. japonica trees as a host.

Mangroves play important roles in providing a range of ecosystem services, mitigation of strong waves, protection of coastlines against erosion, maintenance of water quality, and carbon sink in the context of global warming. For trees in mangrove forests in southern Ranong Province, Thailand, we investigated the allometric relationship between crown area derived from high-resolution satellite data and stem diameter and used the resulting model to estimate aboveground biomass. We used QuickBird panchromatic and multispectral data acquired for the study area on 15 October 2006 as the high-resolution satellite data. Individual tree crowns were extracted from the satellite image of panchromatic data by using the watershed method, and the species were identified by using the maximum-likelihood method for the multispectral data. Overall classification accuracy for species identification was 88.5 %. The biomass derived from our field survey was plotted against aboveground biomass in the sample plots, estimated from the QuickBird data. The regression line through the origin between the satellite-estimated biomass and biomass based on the field data had a slope of 1.26 (R 2 = 0.65). Stand aboveground biomass estimated from the high-resolution satellite data was underestimated because of a lack of data on the biomass of suppressed trees and inappropriate segmentation of crowns of large trees into two or more trees.

This review covers the heterogeneity in functions within the fine root architecture in order to clarify the multiple functions of fine roots. Many fine root characteristics, such as anatomy, physiology, morphology, and their consequences for the ecosystem, differ among root ages and ontogenetic branching hierarchies. Individual root age can be characterized by tissue development, with the main tissues developing from primary to secondary tissues. The physiological characteristics of individual roots, such as absorptivity and respiration rates, decrease with increasing branching order, mainly because of aging and tissue development. The C/N ratio and lignin and suberin contents also increase with branching order because of root aging. Morphological characteristics, such as diameter and specific root length, differ among root orders because of both aging and ontogenetic differences. The mortality of individual roots differs among branching orders and root diameters. The life cycles of roots in the fine root architecture, that is, ephemeral and perennial, indicate ontogenetic differences in functions and demographic traits, similar to those for leaves and branches in shoots. In addition, differences in individual root life cycles may affect the root chemical composition, in turn, affecting the decomposition rate. Future studies should seek to identify heterorhizic units in mortality related to anatomical, physiological, and morphological differences for various species. The decomposition processes of each mortality unit within the fine root architecture are also important in understanding the link between physiological and ecosystem functions.

Digital terrain modeling was used to evaluate landscape-level spatial variation of soil C and N storage and site productivity in Japanese cedar (Cryptomeria japonica D. Don) stands. Soil C and N storage were measured in samples from surface soils (0–25 cm depth) of 29 Japanese cedar stands in the 205-ha Myougodani watershed, Toyama Prefecture. The site index (C. japonica tree height at age 40 years) was used as a measure of forest productivity. Seven terrain attributes (elevation, slope gradient, aspect, profile curvature, plan curvature, openness, and wetness index) were calculated from a digital elevation model. Soil C and N storage were negatively correlated with slope gradient and positively correlated with openness. Variation in the site index was closely related to the wetness index. The prediction models using terrain attributes as explanatory variables explained 50% of the variability in soil C storage, 53% of the variability in soil N storage, and 75% of the variability in site index. This result demonstrated that this technique is useful for estimating the spatial distribution of soil properties and productivity in forest landscapes. On the other hand, there was no correlation between site index and soil C and N storage. Use of the prediction models in a geographic information system revealed that the spatial distribution of forest productivity differed considerably from those of soil C and N storage.

The diversity, vegetative and reproductive characteristics, and phenology of litter decomposing macrofungi (LDM) were compared between humus forms and climatic regions. Fruiting bodies of LDM were examined for the forest floor of subtropical (ST), cool temperate (CT), and subalpine (SA) forests in Japan. Field surveys during one growing season yielded 35, 32, and 18 species in ST, CT, and SA, respectively. Species richness was generally higher in mull than in moder humus and in a warmer than in a cooler climate. A total of ten fungal families were observed, and species in the Mycenaceae dominated in the LDM assemblages at all study sites. A larger number of species fruited on deeper F layers of the forest floor in SA than in ST, where 74 % of species fruited directly on leaf litter. This observation was consistent with the analysis of radiocarbon content in fruiting bodies, implying that LDM tended to utilize older carbon accumulated at deeper layers of the forest floor in cooler climates. Seasonal changes in the fruiting frequency over a growing season exhibited similar two-peak patterns for all the study sites, coinciding with the periods of rainfall and increasing and decreasing air temperatures in early summer and autumn, respectively, but the fruiting period extended longer in a warmer than in a cooler climate.

This study was designed to assess the mental aspect of the work load in operators of high proficient forestry machines. Workers engaged in the operation of harvesters, processors, tower-yarders, forwarders and an excavator were included in this study. Mental fatigue and stress generated by operating these five types of forestry machine were assessed. The stress intensity as a measure of mental strain was high in all types of work surveyed. In some types of work demanding a complicated operation of machine, complaints of both mental and physical strain were frequent. In the type of work such as undertaken on a contract basis, operators worked with a feeling of mental pressure to complete the work by the deadline in the contract. The results suggest that the work load needs to be assessed from the physical and mental aspects combined.