Japanese Journal of Forest Environment

Dry evergreen forests in central flat lowland areas of Cambodia and site environment conditions

Makoto Araki, Eriko Ito

Article type: Review
2009 Volume 51 Issue 1 Pages 1-11
Published: June 25, 2009
Released on J-STAGE: April 03, 2017

DOIhttps://njjn-jsjc-gov-cn-s-1416.res.gxlib.org.cn:443/rwt/1416/https/MSYXTLUQPJUB/10.18922/jjfe.51.1_1

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Tropical forests of Southeast Asia are distributed in the tropical rain climate zone (tropical monsoon climate zone) or in the tropical savanna climate zone, according to Koppen's The climate of the world. The tropical savanna climate zone, which supports deciduous forests, has severe low-precipitation months in the dry season. The central low plains of Cambodia are located in a tropical savanna climate zone. The dry season there has months with no precipitation. In such climate conditions, deciduous forests would be expected. Although the area has a severe drying period each year, spectacular dry evergreen forests with large trees can be found in tropical rain forests and seasonal evergreen forests. To clarify why evergreen forests are able to grow there, soil profiles were examined, soil properties were analyzed, and soil moisture and groundwater levels were measured. Analyses of those investigated and measured data show that the soil retains more soil moisture contents than do soils of nearby dry deciduous forests and mixed forests. Even in the driest period (end of the dry season), soil moisture conditions of the dry evergreen forest are not an obstacle for trees to grow during the dry season there. Furthermore, those conditions are attributable to finely pored soil that retains water during the dry season. Moreover, the soil layer there is sufficiently thick to retain water during the dry season. Those site environment conditions support dry evergreen forest vegetation there.

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The effect of seed size variation and wind speed variation on dispersal efficiency in Japanese wing nut (Pterocarya rhoifolia)

Haruko Ochi, Hiromasa Koyama, Norio Takahashi

Article type: Article
2009 Volume 51 Issue 1 Pages 13-19
Published: June 25, 2009
Released on J-STAGE: April 03, 2017

DOIhttps://njjn-jsjc-gov-cn-s-1416.res.gxlib.org.cn:443/rwt/1416/https/MSYXTLUQPJUB/10.18922/jjfe.51.1_13

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Japanase wing nut (Pterocarya rhoifolia) produces wind dispersed seeds. In this study, we examined the effect of seed size variation on dispersal behavior under the field condition. Weight of each seed was positively correlated with square root of wing loading which was also positively correlated with its terminal velocity. Consequently small seeds seem to have advantageous dispersability. We conducted simulating experiment to test whether small seeds can be dispersed longer distance than large seeds. In the simulation, wind speed variation actually measured in the field condition was also incorporated. The mean sizes of seeds did not vary irrespective of dispersal distance with more than one seed per m^2. This result was almost identical to the result which was obtained by actual measurement of dispersal distance of seeds under the field condition. Since the effect of wind speed variation on dispersal distance was larger than seed size variation, the potential variation in dispersal efficiency of seeds was not reflected in the actual dispersal patterns in the field. Thus, the adaptive significance of seed size variation may exist in establishment stage, not in seed dispersal stage.

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Comparison of growth performance and leaf area index in Hinoki cypress (Chamaecyparis obtusa) plantations 5 years after thinning

Kazuki Miyamoto, Shiro Okuda, Yoshiyuki Inagaki, Eiji Kodani, Mahoko N ...

Article type: Article
2009 Volume 51 Issue 1 Pages 21-26
Published: June 25, 2009
Released on J-STAGE: April 03, 2017

DOIhttps://njjn-jsjc-gov-cn-s-1416.res.gxlib.org.cn:443/rwt/1416/https/MSYXTLUQPJUB/10.18922/jjfe.51.1_21

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We compared the growth performance and leaf area index (LAI) of Hinoki cypress (Chamaecyparis obtusa) stands in Shikoku 5 years after 30-50% of trees in the stands had been thinned. LAIs measured by the plant canopy analyzer (LAI-2000, Li-Cor Inc.) were similar in the 30 and 50% thinned stands in 2007, suggesting speedy recovery of the amount of leaves in the heavily thinned (50%) stands. There were no marked differences in 5-year basal area (BA) increment among the stands. On an individual tree basis, the median growth rate of trunk diameter at breast height (DBH) increased with increasing LAI per unit BA (LAI/BA) and LAI per tree (LAI/stand density) in the thinned stands. In our study sites, no negative effect on the remaining trees by heavy thinning such as severe growth reduction is recognized at this time, and there was little difference in BA-basis stand growth between conventional and heavy thinning. Our results suggest that the increase in the amount of leaves on each tree contributed to an increase in the growth rates of the remaining trees in the thinned stands.

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Climatic controls of the distribution and abundance of two evergreen Quercus species in Japan

Katsuhiro Nakao, Tetsuya Matsui, Nobuyuki Tanaka, Tukasa Hukusima

Article type: Article
2009 Volume 51 Issue 1 Pages 27-37
Published: June 25, 2009
Released on J-STAGE: April 03, 2017

DOIhttps://njjn-jsjc-gov-cn-s-1416.res.gxlib.org.cn:443/rwt/1416/https/MSYXTLUQPJUB/10.18922/jjfe.51.1_27

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We developed statistical distribution models for two evergreen Quercus species (Q. acuta and Q. salicina) by using classification tree analyses with phytosociological releve data, in Japan. Two different models were constructed for each of the two species: (1) species at least present (SP-model) and (2) species dominant in the canopy layer (DO-model). Four climate variables: warmth index (WI), temperature of the coldest month (TMC), summer precipitation (PRS) and winter precipitation (PRW), were used as predictor variables. WI and TMC were the most influential factors for each of the two species. The lower temperature range of each species was generally coincided with the averaged minimum temperature of the coldest month warmer than or equal to -1℃ The DO-models for the two species were mainly contributed by WI, and the predicted optimal habitats were narrower than those of the SP-models. The predicted distributions for the two species were similar to the geographical patterns of PRS. Specifically, Q. acuta was mainly predicted to occur under high precipitation conditions, such as on the western part of the Kanto region on the Pacific Ocean side. On the other hand, Q. salicina was predicted to occur both on the Pacific Ocean side and the Sea of Japan side. PRW was influential factors for the DO-models. Q. acuta was predicted to occur under low PRW conditions.

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Regeneration processes of natural Japanese beech (Fagus japonica Maxim.) forests under different canopy disturbances for 20 years in the Chichibu Mountains

Yota Kikuchi, Mikio Kaji, Haruo Sawada, Takeo Tanimoto, Mineaki Aizawa ...

Article type: Article
2009 Volume 51 Issue 1 Pages 39-48
Published: June 25, 2009
Released on J-STAGE: April 03, 2017

DOIhttps://njjn-jsjc-gov-cn-s-1416.res.gxlib.org.cn:443/rwt/1416/https/MSYXTLUQPJUB/10.18922/jjfe.51.1_39

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In order to clarify the regeneration processes of natural Japanese beech (Fagus japonica Maxim.) forest under different scales of canopy disturbances, we studied 20 years change of stand structure in secondary and natural Japanese beech forests in the Chichibu Mountain in the Pacific Ocean side of central Japan. Tree surveys were conducted in 40m×40m quadrat (CQ) in the secondary Japanese beech forest that was subjected to a large-scale canopy disturbance by clear-cutting 16 years ago, and 50m×70m quadrat (NQ) in the natural Japanese beech forest where a small-scale canopy disturbance by a few dead and fallen trees have occurred. In the clear cutting quadrat, the pioneer species such as Betula maximowicziana, Acer runiferve and B. grossa dominated in the canopy layer (H≧7m) and sprouts and a large number of seedlings (1,431 seedlings per ha) of Japanese beech dominated in lower layer (H<7m). Betula maximowicziana did not have any seedlings. In the natural forest quadrat, responding to canopy opening, Magnolia obovata, Cornus controversa, A. micranthum, which occurred in the lower layer before the gap formation, and C. controversa and Stewartia puseudo-camellia, which were recruited after the gap formation, grew rapidly than the sprouts of Japanese beech that occurred from their stools under the canopy gap. These results suggested that, under the large-scale canopy disturbance, the pioneer species reach the forest canopy in the early stage following the regeneration of canopy trees by the sprouts and seedlings of Japanese beech. In contrast, under the small-scale canopy disturbance, canopy trees in lower layer occurred before the gap formation and recruited trees after the gap formation reach the forest canopy in the early stage following the canopy closure by sprouts regeneration of Japanese beech.

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Application and improvement of the forecasting method of beech (Fagus crenata) crop in Yamagata prefecture

Taro Matsui, Hiromasa Koyama, Satoshi Ito, Norio Takahashi

Article type: Article
2009 Volume 51 Issue 1 Pages 49-55
Published: June 25, 2009
Released on J-STAGE: April 03, 2017

DOIhttps://njjn-jsjc-gov-cn-s-1416.res.gxlib.org.cn:443/rwt/1416/https/MSYXTLUQPJUB/10.18922/jjfe.51.1_49

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According to the forecasting method of beech (Fagus crenata) crop which has already been reported in Hokkaido, more than 500 of female flowers/m^2 are required for a stand to be good seed year. Further, percentage of predation is affected by annual increase rate of flower density between two consecutive years and insects are saturated when flower density is more than 20 times as much as those of previous year. However, whether those prerequisites would also have been applied to the other part of Japan had not been tested. In this study, we investigated flower and seed production at eleven beech stands in Yamagata, northern part of mainland of Japan during five years from 2003-2007. Seed trap data revealed that, in these study areas, only 350 female flowers/m^2 and 10 times annual increase rate in flower number are required to be a good seed crop. These values were lower than those of beech stands in Hokkaido. Presumably, eclosion from pupa of pseudopammene fagivora, a main predator of beech seeds, might be prevented due to the late snow disappearing in spring. Furthermore, mass flowering with over 350/m^2 female flowers always resulted in more than 10 times of flower production to those of previous year. Therefore, to predict the next year's seed crop, consideration might be required only for flower density of following year which could be estimated by the winter bud investigation. Prediction of beech seed crop for Tohoku district may contribute to solve the regional unique problems including forest management (promoting natural regeneration of beech at unsuccessful artificial plantations) and wildlife management.

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Stand structure and growth patterns of the Fraxinus longicuspis Sieb. et Zucc. Plantations

Tomomasa Suzaki, Tatsunori Hirano, Wajiro Suzuki

Article type: Article
2009 Volume 51 Issue 1 Pages 57-62
Published: June 25, 2009
Released on J-STAGE: April 03, 2017

DOIhttps://njjn-jsjc-gov-cn-s-1416.res.gxlib.org.cn:443/rwt/1416/https/MSYXTLUQPJUB/10.18922/jjfe.51.1_57

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The stand structure of two 93-year-old Fraxinus longicuspis plantations and the growth pattern of this species were studied for establishing a silviculutural system, with special attention paid to the practical history. Well developed stand of this species showed high tree density (617stems ha^<-1>) and large stem volumes (353m^3 ha^<-1>), which accounted for 27.0% and 81.7%, respectively, of the total. In contrast, the silviculturally unsuccessful stand showed only 220stems ha^<-1> in tree density, and 62m^3 ha^<-1> in stem volume. According to the stem analysis, F. longicuspis reached its diameter and height growth peaks at 40 years old, and then gradually decreased. This plantation has been subjected to weeding, vine cutting and selective cutting since planting, including the thinning of about 25% of the stem volume at 40 years old. Therefore, by selectively cutting this relatively slow-growing species, and reducing competition with other broad-leaved tree species, it may become possible to establish robust plantations of Fraxinus longicuspis.

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Mass loss and nitrogen release of wood debris remaining after thinning in Japanese cedar and hinoki cypress plantations

Yoshiyuki Inagaki, Shuichiro Yoshinaga, Tsuyoshi Yamada, Yoshiki Shino ...

Article type: Article
2009 Volume 51 Issue 1 Pages 63-67
Published: June 25, 2009
Released on J-STAGE: April 03, 2017

DOIhttps://njjn-jsjc-gov-cn-s-1416.res.gxlib.org.cn:443/rwt/1416/https/MSYXTLUQPJUB/10.18922/jjfe.51.1_63

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Mass loss and nitrogen release of wood debris remaining after thinning were measured in Japanese cedar (Cryptomeria japonica) and hinoki cypress (Chamaecyparis obtusa) plantations in Kochi prefecture. Wood density was measured for fallen logs of 4-8cm (D4-8 logs) or 8-16cm in diameter (D8-16 logs) and stumps of 8-16cm in diameter (D8-16 stumps) in forest plantations where thinning was conducted 0.5-18 years ago. Wood density during decomposition was determined by an exponential equation and the time for 50% mass loss was calculated. The time for 50% mass loss for D4-8 logs, D8-16 logs and D8-16 stumps was 10.1, 12.9, 44.6 years for Japanese cedar and 7.4, 8.1, 15.9 years for hinoki cypress, respectively. In both species, the mass loss of fallen logs was not different between D4-8 logs and D8-16 logs. By contrast, the mass loss of D8-16 logs was significantly faster than that of D8-16 stumps. The nitrogen content of wood excluding bark during decomposition did not change significantly. In the initial stage of decomposition little nitrogen was immobilized into wood. The results suggest that nitrogen remains in wood for longer time than in wood mass and can be a gradual and long-term source of available nitrogen.

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Effect of elevation on establishment of woody species at clear-cut sites of Cryptomeria japonica plantations at different elevations in heavy snow regions

Jiro Kodani

Article type: Article
2009 Volume 51 Issue 1 Pages 69-76
Published: June 25, 2009
Released on J-STAGE: April 03, 2017

DOIhttps://njjn-jsjc-gov-cn-s-1416.res.gxlib.org.cn:443/rwt/1416/https/MSYXTLUQPJUB/10.18922/jjfe.51.1_69

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Richness, stem density and composition of woody species were compared among the clear-cut sites (0.33-1.78ha) and adjacent sites (non-clear-cut site) of Cryptomeria japonica plantations, and surrounding broad-leaved forests at different elevations in heavy snow regions, on the Japan Sea side of central Japan. The richness and stem density of woody species tended to be higher in the surrounding broad-leaved stands than at the non-clear-cut sites or the clear-cut sites of plantations, except for some cases at a higher elevation. Some species originating from buried seeds occurred densely and frequently at the clear-cut sites at a low elevation. On the other hand, many woody species at the non-clear-cut sites were the same as those in broad-leaved forests at a higher elevation, although the frequency or density of these species tended to decrease at the clear-cut sites. The growth of C. japonica planted at a higher elevation is suppressed by heavy snow during the young seedling stage. This provides a favorable light condition for the advanced regeneration of woody species at the non-clear-cut sites. Species richness at the non-clear-cut sites tended to increase with the rise of elevation in all seed-dispersal types. Species richness of the clear-cut sites at a lower elevation, however, showed a tendency toward the frugivore-dispersed type and, that of the frugivore -and wind-dispersed types at a higher elevation is less at the clear-cut than at the non-clear-cut sites. Vegetation recovery at the clear-cut sites by advanced regeneration of seedlings may be clearer at a higher elevation than at a lower elevation, but moderate cutting or logging methods at plantations may be useful for rapid recovery of various species.

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Report on the field excursion of the Japanese Society of Forest Environment in 2009 : How to develop long, straight, and narrow woods

Rieko Urakawa

Article type: Record
2009 Volume 51 Issue 1 Pages 77-80
Published: June 25, 2009
Released on J-STAGE: April 03, 2017

DOIhttps://njjn-jsjc-gov-cn-s-1416.res.gxlib.org.cn:443/rwt/1416/https/MSYXTLUQPJUB/10.18922/jjfe.51.1_77

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