Sakai A.,Japan International Research Center for Agricultural science |
Sakai A.,Shikoku Research Center |
Visaratana T.,Forest Research and Management Bureau |
Vacharangkura T.,Forest Research and Management Bureau |
And 2 more authors.
Japan Agricultural Research Quarterly | Year: 2011
With the aim of establishing silvicultural techniques for tree species indigenous to monsoon tropical areas, we examined the survivorship and growth performance of three tree species under different light conditions. A 23-year-old Acacia mangium plantation was thinned in different ways: group selection thinning (gap creation, 50 m by 60 m in size), 2/3 random selection thinning based on basal area, 1/3 random selection thinning, and no thinning (control). The seedlings of Hopea odorata, H. ferrea, and Xylia xylocarpa var. kerrii were planted in each treatment area with three replications. At 30 months after planting, all species achieved a high survival rate (>90%) in all treatments, perhaps owing to intensive tending in the experimental plots. Both stem thickening and height growth were promoted as light conditions improved: most in the gap plot and least in the control plot for all species. H. ferrea grew to a large height even in dark conditions, suggesting that this species is considerably shade-tolerant. In contrast, X. xylocarpa var. kerrii was light-demanding owing to vigorous growth in the gap plot. The growth of the seedlings seemed to be associated with regeneration patterns in their natural habitats. The group selection thinning seemed to be most suitable for the growth of indigenous tree species. © 2011 JIRCAS.
Ohnuki Y.,Japan Forestry and Forest Products Research Institute |
Ohnuki Y.,Kyushu Research Center |
Nik A.R.,Malaysian Forest Research Institute |
Noguchi S.,Japan International Research Center for Agricultural science |
And 3 more authors.
Japan Agricultural Research Quarterly | Year: 2010
To prevent soil runoff from logging roads and skid trails, buffer zones are commonly established along both sides of streams. These buffers range in width from 10 to 100 m from the center of the stream, depending on stream width, (from 1 to > 40 m) as dictated by the Reduced-Impact Logging Guidelines for Lowland and Hill Dipterocarp Forests in Indonesia. In the Bukit Tarek Experimental Watershed in Malaysia, sediment accumulations were observed along narrow streams after logging despite the presence of 20-m-wide buffer zones, double the width set out in the guidelines. Thus, we examined erosion-accumulation depths on different slopes in 20-m-wide buffer zones to clarify the spatial effects on sediment discharge, particularly as it relates to the microtopography and the vegetation cover, including fallen trees. Some of the accumulation depths at lower elevations and along streams were small, whereas on steep concave slopes and hollows that extend to streams, large accumulations were observed 1 year after logging. These findings indicated that, although a 20-m-wide buffer zone may be partly effective at preventing sediment discharge, it is not adequate on concave slopes (lower side-hollows and channel walls) where surface flows often converge. We compared several physical properties of the surface soil in accumulated areas relative to undisturbed areas and demonstrated that bulk density was larger and total porosity and coarse porosity were smaller in the accumulated soils, especially on lower side-hollows. These results indicate that soils accumulated on concave slopes would accelerate the occurrence of surface flow. Tree distribution was not dense in the buffer zones, but fallen trees and the relatively dense understory vegetation including rattans and palms partly prevented the discharge of sediment into streams. Our findings suggested that 20-mwide buffer zones with dense fallen trees and understory vegetation are partly sufficient to prevent sediment discharge; however, along steep concave slopes and hollows where rain water converges, wider and thicker buffer zones are needed.
Morishita T.,Japan Forestry and Forest Products Research Institute |
Aizawa S.,Soil Plant Ecosystem Group |
Yoshinaga S.,Kyushu Research Center |
Journal of Forest Research | Year: 2011
Temperate forest soils are one source of nitrous oxide (N2O), which is an important greenhouse gas and the most important ozone-depleting substance. To clarify N2O flux mechanisms in relation to soil temperature, moisture, and nitrification activity, we measured N2O fluxes and net nitrification rates over 3 years at the lower (Japanese cedar) and upper (deciduous broad-leaved trees) parts of a hill slope in a small forest catchment in the northern Kanto region of Japan. The N2O flux was measured by the closed-chamber technique every month, along with soil temperature and water-filled pore space (WFPS). At the lower slope, the N2O flux increased with increasing soil temperature (r2 = 0.383, P < 0.01) owing to an increase in the nitrification rate. At the upper slope, no positive linear correlation of N2O flux with soil temperature, WFPS, or nitrification rate was observed. The low N2O flux at the upper slope during summer was caused by the low summertime WFPS there. We attributed the higher mean N2O fluxes observed at the lower slope (median 2.36 μg N m-2 h-1) than at the upper slope (median 1.10 μg N m-2 h-1) to a high soil moisture during summer season in the surface soil of the lower slope. © 2011 The Japanese Forest Society and Springer.
Sueyoshi M.,Kyushu Research Center
Zootaxa | Year: 2013
Morphological features of a Japanese fly that developes in orchids, Orchidophaga gastrodiacola Kato, 2006, assigned to the family Scathophagidae, are reviewed and this species is proposed as a junior synonym of Chyliza vittata Meigen, 1826, of the family Psilidae. Morphological features of specimens from Japan correspond well with those from European. Japanese specimens of this transpalaearctic species utilize buds and stems of the achlorophyllous mycoheterotrophic Gastrodia elata Blume. This association is an exceptional habitat in comparisons to other congeners and European specimens of the same species. Copyright © 2013 Magnolia Press.
Toriyama J.,Japan Forestry and Forest Products Research Institute |
Takahashi T.,Kyushu Research Center |
Nishimura S.,Japan Forestry and Forest Products Research Institute |
Sato T.,Japan Forestry and Forest Products Research Institute |
And 8 more authors.
Forest Ecology and Management | Year: 2014
Tropical swamp forests growing on peatlands are exposed to various risks of deforestation. To assess the greenhouse gases (GHG) emission from the deforested tropical peatlands, the amount of carbon released during a forest fire needs to be accounted for. The establishment of a fuel mass data set based on a field-based approach is essential to reduce the uncertainty in estimating GHG emissions during forest fires. We estimated the fuel mass (both living and deadwood) in tropical peat swamp forests and its loss during the fire event in 2009 in Central Kalimantan, Indonesia. We also examined the relationship between the forest structure and the burning process by comparing the distribution of stem diameter in burnt and unburnt areas using a fallen wood simulation. We selected two types of peat swamp forests, mature forest and regenerated forest following a fire in 1997/98, and their neighboring burnt areas. The mean fuel mass values in mature and regenerated forest were 319.7 and 131.5Mgha-1, respectively. In burnt areas of mature and regenerated forest, the mean fuel mass values were 235.8 and 89.0Mgha-1, respectively, which corresponded to 73.8% and 67.7% of the values of unburnt areas, respectively. The fuel mass in burnt area comprised mainly solid deadwood. Due to the large amount of deadwood left on the ground, the estimated GHG emissions after the forest fire were larger than those during the forest fire in both forest types. The regenerated forest, which was dominated by small trees and contained a small stock of deadwood, was considered to produce a large amount of solid deadwood during the forest fire. In contrast, the mature forest, which contained many large standing trees and large amounts of deadwood, experienced a high-intensity fire over a long duration time, resulting in surface or deeply burnt deadwood. The development of a simple method to tally the surviving large trees in the burnt area (i.e., designing a study plot with a nested structure for different-sized trees) might reduce uncertainties in the estimation of fuel mass and GHG emissions in future forest fires. © 2013 Elsevier B.V.