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Volume 40 (1998)
- Issue 2 Pages 67-
- Issue 1 Pages 1-
Volume 40, Issue 1
Displaying 1-8 of 8 articles from this issue
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Hiromasa SHIMADA, Hiroto TODA, Kikuo HAIBARA, Takayoshi KOIKEArticle type: Article
1998 Volume 40 Issue 1 Pages 1-8
Published: June 30, 1998
Released on J-STAGE: April 03, 2017
JOURNAL FREE ACCESSSeasonal changes of CO_2 flux at the different slope sites and different depths were investigated in order to clarify CO_2 flux of forest soil. Experimental plots were established at a lower site (Japanese cedar, elevation 730m), a middle site (Japanese cypress, 760m) and an upper site (Japanese cypress, 800m) on a sequence of slope in the University Forest of Tokyo Univ. of Agric. and Technol., Gunma Prefecture. The stand age was 42-years-old and the soil parent material was phyllite of Paleozoic and Mesozoic strata. Gas diffusion coefficients in soil (D) were measured at each soil depth (0-5, 5-15, 15-25, 25-35, 35-50cm) at three slope positions using the improved gas diffusion instruments developed by Osozawa and Kubota (1987). The seasonal change of CO_2 flux from the soil surface at each depth was calculated using the CO_2 concentration and the CO_2 diffusion coefficient. The relative gas diffusion coefficient in the soil air (D/D_0) increased with increasing air porosity at the all soil depths in every slope position. Though, the linear relationships between the D/D_0 and the air porosity was seen at 0-5cm, it approximated exponentially below 5cm. In the same depth, there were no difference in D/D_0 among slopes. At the lower site in summer, the CO_2 flux from soil surface was 3 to 4 times as large as the flux in winter, and the flux at the other sites was showed several ten times. The maximum CO_2 flux from the surface soil was about 6×10^<-5>g・m^<-2>・s^<-1> at all sites. The CO_2 turnover time in 50cm of soil was about 10 hours in summer. There was an exponential relationship between soil temperature and CO_2 flux from the soil surface. Annual amounts of CO_2 flux from the surface soil measured by gas diffusion method was estimated as 13.4t・ha^<-1>・y^<-1> at the lower site, 6.5t・ha^<-1>・y^<-1> at the middle site and 9.9t・ha^<-1>・y^<-1> at the upper site.View full abstractDownload PDF (1221K) -
Masayuki ARAKIArticle type: Article
1998 Volume 40 Issue 1 Pages 9-16
Published: June 30, 1998
Released on J-STAGE: April 03, 2017
JOURNAL FREE ACCESSPropagation system of Pinus pumila was analyzed to clarify a relation between seed propagation and vegetative propagation, both have been considered for the species, with analyses of synchronization in pattern of annual shoot elongation (PYS) among main shoots. PYSs were measured in 1991 and '92 at 70 communities on 9 mountains. 45 correlation coefficients of PYS among 10 shoots in a plot were calculated. Similarity of PYSs among shoots in each plot was summarized by ratio of number of significant coefficients to the 45 coefficients (RSC). In the frequency distribution for number of plots to RSC, they were clarified that mode rank is 25〜35% of RSC, there are some plots showing higher RSC than 75%, and frequency decreases gradually from mode to higher RSC rank. Many RSCs in other species stands were calculated. Stands showed high RSC same to higher RSC in the pine were 6 stands made by clonal seedlings (60〜98%RSC) and a stand made by seedlings from seeds being in brother or semi-brother relation (73〜96%RSC). Stands showed low RSC near to the mode RSC of the pine were 5 stands made by seedlings from open pollinated seeds (39・24・7〜13・14・4%RSC). It was concluded that the vegetative propagation occures with high probability in a community locating in site where soil is deep. As the results, relation between seed propagation and vegetative propagation was clarified as follows. Namely, early development of community occures by seed propagation with synzoochory and development of community occures by both propagation systems. Especially, occurrence of vegetative propagation is affected by site condition as inclination of slope, depth of soil, and existence of rock in the ground.View full abstractDownload PDF (1102K) -
Yasuhiro OHNUKI, Hitoshi IKUZAWA, Ryuichi TERAZONOArticle type: Article
1998 Volume 40 Issue 1 Pages 17-25
Published: June 30, 1998
Released on J-STAGE: April 03, 2017
JOURNAL FREE ACCESSThe erosion of "reddish soil" caused by development projects has damaged the ecosystems of coral reefs around the main island of Okinawa, in southwestern Japan. To clarify the critical condition of soil erosion on hilly lands in Okinawa, we investigated the relationship between microtopographical units of zero-order basins and physical properties of the soils. The microtopographic units were divided into six units consisting four soil groups: 1) crest flats (red soils and surface gleyed red and yellow soils), 2) crest slopes (yellow soils and surface gleyed red and yellow soils) 3) upper sideslopes (yellow soils and surface gleyed red and yellow soils), 4) head hollows (yellow soils), 5) lower sideslopes (immature soils) and, 6) bottomlands (immature soils). From the clay ratio, dispersion ratio, porosity and saturated hydraulic conductivity of the soils, we concluded that the red soils and surface gleyed red and yellow soils in the higher areas have high erodibility, while yellow soils have low erodibility. This conclusion agrees with the observation that the thickness of the A horizon of the former soils decreased at crest slopes and upper side slopes after forest clearing. Therefore, areas of surface gleyed red and yellow soils are especially vulnerable to erosion after forest clearing, but there is little erosion of red soil after forest clearing because it is distributed in mainly flat areas.View full abstractDownload PDF (1101K) -
Yasuharu MURAMOTO, Satoshi ITO, Kangoro NOGAMIArticle type: Article
1998 Volume 40 Issue 1 Pages 27-32
Published: June 30, 1998
Released on J-STAGE: April 03, 2017
JOURNAL FREE ACCESSTree decline of hinoki (Chamaecyparis obtusa Endlicher) mature stands after typhoon (Typhoon13, 1993) damages was investigated in 1996 at the Miyazaki University Forests located in southern Kyushu. Our experiments indicated significant decline of trees facing large tree fall gaps. Most declined trees showed coloring and death of leaves in the lower crown. Frequency of tree decline was related to the exposure status of each tree in such a way that isolated trees have the largest decline followed by west-facing edge trees, south-facing edge trees, east-facing edge trees, north-facing edge trees and interior trees. Our experiments also showed that leaf water potential during the day time in autumn was significantly lower in the exposed lower part of crown of edge trees. Edge tree decline after the typhoon damages would be caused by increasing water stress in the lower crown induced by the environmental changes due to edge creation; larger water vapor demand, higher irradiance exposure and stronger wind environments.View full abstractDownload PDF (788K) -
Chihiro YAMAGUCHI, Masanori OKAZAKI, Abdul Halim HASSANArticle type: Article
1998 Volume 40 Issue 1 Pages 33-42
Published: June 30, 1998
Released on J-STAGE: April 03, 2017
JOURNAL FREE ACCESSThe annual nutrient fluxes in the tropical swamp and sago palm plantation ecosystems and their changes after harvesting were estimated. Open bulk precipitation, throughfall, and litterfall were monitored as inputs to the soil system, and drainage water, randomly selected trees and sago palms were collected to assess the nutrient output from this ecosystem. No significant differences were observed in the cation concentrations between the open bulk precipitation and in the secondary swamp forest throughfall in this study. The concentrations of elements (Na, K, Mg and Ca) in drainage water near the sago plantation were slightly higher than those in small streams near swamp forests, suggesting that nutrients are gradually leached from sago plantation ecosystems. The swamp forests have low phosphorus and high calcium concentrations in their total litterfall compared to most temperate forests. Substantial amounts of nutrients are returned via dead sago fronds to the ground of sago plantations. Annual input-output budgets indicated that swamp forest recycled the accumulated nutrients efficiently, whereas larger amounts of nutrients were lost from sago forests through streamflow. Sago cultivation accelerates total P, Na, K and Mg loss from this ecosystem via the withdrawal of vegetation. The net gain of swamp forests equals the net loss from sago palm plantations. For continuous sago palm production, swamp forests should be retained in the same watershed which act as the nutrient reservoir for sago plantation. Repeated harvests of sago palm would have detrimental effects on site productivity and soil fertility due to the depletion of nutrients. Nutrient management is essential.View full abstractDownload PDF (1072K) -
Teizou Maeda, Tokuzou Osada, Masayasu Kikuchi, Youiti Kanbe, Seigo Asa ...Article type: Report
1998 Volume 40 Issue 1 Pages 43-47
Published: June 30, 1998
Released on J-STAGE: April 03, 2017
JOURNAL FREE ACCESSDownload PDF (1369K) -
Hideaki HIRAIArticle type: Comment
1998 Volume 40 Issue 1 Pages 49-54
Published: June 30, 1998
Released on J-STAGE: April 03, 2017
JOURNAL FREE ACCESSDownload PDF (957K) -
Tatsuya TSURITAArticle type: Record
1998 Volume 40 Issue 1 Pages 55-57
Published: June 30, 1998
Released on J-STAGE: April 03, 2017
JOURNAL FREE ACCESS
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