The height growth process of the trees in unsuccessful plantations of Cryptomeria japonica with broad-leaved trees and shrubs were analyzed in the snowy region of Gifu Prefecture, central Japan. The broad-leaved species grew after weeding or improvement cutting. The Cryptomeria appeared at a canopy layer in the all of stands, and also existed at understory in many stands. On the whole, the height of the broad-leaved trees was same or lower as the height of the canopy Cryptomeria. The growth rate was large in Betula platyphylla var. japonica and B. maximowicziana, medium in B. grossa and Magnolia obovata, small in the canopy Cryptomeria, Quercus mongolica var. grosseserata and Fagus crenata, and specially small in the understory Cryptomeria and shrubs. The growth rate of each species and the tending after planting were factors affecting the future forest type. The improvement cutting especially had great effect on the development of forest. Based on this examination, the following was proposed. The result of the afforestation is evaluated from density and average tree height of the Cryptomeria, and in the unsuccessful plantation, the improvement cutting is stopped. In the unsuccessful plantation with enough merchantable broad-leaved trees, trees suppressing crop trees may be removed.

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Seasonal changes in leaf number and elongation pattern of shoot and leaves of fifty-three broad-leaved woody species were investigated in a Cryptomeria japonica plantation in the lower part of the cool temperate region in Japan. The elongation patterns of the woody species studied were classified into succeeding and flash types. Juvenile trees (Juglans mandshurica var. sachalinensis and Magnolia obovata) and shrubs (Sambucus racemosa subsp. sieboldiana and Ligustrum obtusifolium) belonged to the succeeding type with many leaves and short leaf longevity per shoot, and long elongation period. This type shows an elongation pattern advantageous for maximizing light acquisition in gaps. In contrast, other tree species (Acer amoenum var. matsumurae and Quercus crispula) and shrubs (Daphniphyllum macropodum var. humile and Euonymous oxyphyllus) belonged to the flash type with few leaves and long leaf longevity per shoot, and short elongation period. This type shows tolerant quality to the shading stress. Evergreen species belonged to the flash type, except for Aucuba japonica var. borealis that showed the succeeding type of elongation. Heteroptosis species belonged to the succeeding type, except for Euonymus alatus sieb. f. striatus that showed the flash type of elongation. Consequently, it was considered that the two typical phenological pattern reflected the degree of dependency on gaps in a C. japonica plantation.

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We investigated the responses of growth and dry matter partitioning of seedlings of Cedrela odorata (west Indian cedar), Swietenia macrophylla (Honduras mahogany) and Schizolobium parahybum (quamwood) to different soil water regimes: water deficit, wet and moderate. All species showed the maximum growths in height, diameter at root collar, leaf area, and total dry weight in the moderate condition. Relative growth rate (RGR) in the water deficit and the wet conditions for all species declined compared to those in the moderate condition. For S. macrophylla and S. parahybum, the degree of decline was greater in the water deficit condition. Decreases in the net assimilation rate (NAR) in the water dificit and the wet conditions were same level. Leaf area ratio (LAR) decreased in the water dificit condition for S. Macrophylla, and increased in the wet condition for S. parahybum. Thus, larger decline of dry matter allocation to leaves in the water deficit condition compared to those in the wet condition might relate to the severer dicline of RGRs. For C. odorata, the decline of RGR was severer in the wet condition in contrast to other two species. NAR slightly increased in the wet condition, and slightly decreased in the water deficit condition. LAR decreased in both wet and water deficit conditions, with a larger decline in the wet. The severe decline of RGR in the wet condition compared to those in the water deficit condition might result from the largely declined dry matter allocation to leaves.

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In order to study the effects of the supply of broad-leaved litter to the forest floor of a Japanese cypress (Chamaecyparis obtusa) forest on soil fertility, we investigated (i) the amounts and nutrition contents of the forest floor, (ii) the soil chemical characteristics (0-30cm depth) and (iii) the characteristics of N mineralization (0-10cm depth) in the Japanese cypress forest and a natural deciduous broad-leaved forest. Investigation was carried out using pure Japanese cypress forest soil with (JCB) and without (JC) deciduous broad-leaved litter supplied to its forest floor from an adjacent natural deciduous broad-leaved forest and from a natural deciduous broad-leaved forest (NBL) soil at varying depths. Results show that the K, Ca, Mg, contents of the forest floor in the NBL were approximately 20-70% larger than those of the JCB, and were 3-9 times larger than those of the JC. The C and N concentrations and pH (H_2O) at a depth of 0-10cm decreased in the order of NBL≧JCB&gt;JC. The amounts of N mineralization at the depth of 0-10cm in the NBL, JC and JCB were 100, 77 and 67mg kg^<-1>, respectively. The ratio of NH^+_4-N to N mineralization was approximately 40% in the NBL and JCB and approximately 10% in the JC. From those results, it was considered that the supply of broad-leaved litter to the forest floor of the Japanese cypress forest was effective in improving soil fertility.

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In order to modify of regular root sampling and sorting techniques for simultaneous analysis of root and arbuscular mycorrhiza dynamics, three kinds of root sampling were conducted in several Japanese cedar (Cryptomeria japonica D. Don) stands from 1988 to 1992. The results of root mass analysis indicated that, compared to other tree species, great sampling variation in Japanese cedar posed the most serious problem to detecting subtle fluctuations in active root tips that are capable of forming mycorrhiza. In place of direct root mass comparison, several indices calculated from root parameters (e.g., number of living root tips per gram of living fine roots) can be applied to reduce the influence of sample variation.

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