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The present study describes the occurrence of a unique archaeal ammonia monooxygenase alpha subunit (amoA) gene in nitrifying acid-sulfate soil microcosms at pH 3.5. The soil was collected from an abandoned paddy field in Thailand. Microcosms were incubated in the dark at 30°C for 372 days with the following three treatments: addition of ammonium sulfate solution once a month (I) or once a week (II), and addition of only sterilized water (III). A quantitative PCR analysis revealed an increase in abundance of the archaeal amoA gene in microcosm soils in which nitrate concentrations increased after incubation. A phylogenetic analysis indicated a predominance of the novel gene, and a predominance of a betaproteobacterial amoA gene affiliated with the genus Nitrosospira. A 16S rRNA gene-based PCR assay revealed that crenarchaeotic Group I.1d was predominant among the Crenarchaeota in microcosms. These results suggest the presence of ammonia-oxidizing archaea corresponding to the unique amoA lineage in nitrifying acid-sulfate soil microcosms at pH 3.5.

To elucidate the mechanism of the high aluminum (Al) resistance of a Myrtaceae tree, Melaleuca cajuputi Powell, we investigated the responses of root tips to Al and compared them with those of an Al-sensitive species, M. bracteata F. Muell. Roots of seedlings of both species were treated with a calcium solution (pH 4.0) containing 0 or 1 mM AlCl3. After 3 h of Al treatment, inhibition of root elongation and deposition of callose and lignin in root tips, typical signs of Al injury, were induced in M. bracteata but not in M. cajuputi, yet Al accumulation in root tips was similar in both species. These results indicate that internal Al tolerance mechanisms, not Al exclusion mechanisms, are responsible for the Al resistance of M. cajuputi. After 3 h of Al treatment, amount of Al tightly bound to root tips, Al remaining after washing with a desorbing solution, was less in M. cajuputi than in M. bracteata. In M. bracteata, 6 h of Al treatment triggered the accumulation of hydrogen peroxide (H2O2) in root tips despite the upregulation of antioxidant mechanisms, activity of peroxidase and concentration of reduced glutathione. In M. cajuputi, 6 h of Al treatment did not affect the concentration of H2O2, but decreased activity of peroxidase, and increased concentration of reduced glutathione in root tips. These results suggest that the less Al tightly bound to root tips is involved in the suppressing the H2O2 accumulation and the internal Al tolerance in M. cajuputi, and that the H2O2 accumulation or changes in cellular environment that bring about H2O2 accumulation despite the upregulation of antioxidant mechanisms results in Al-induced inhibition of root elongation in M. bracteata.

We isolated four new ammonia-oxidizing bacterial strains from leucaena (Leucaena leucocephala) grown in fields of an acid sulfate soil (ASS) in Thailand; 17SS from the surface soil and 17RS from the rhizoplane of a non-limed plot; 9SS from the surface soil and 9RS from the rhizoplane in a limed plot. The cells of all strains had the typical lobate shape of the genus Nitrosospira (“Nitrosolobus”). The percentage similarity of the 16S rRNA genes of these strains to that of Nitrosospira (“Nitrosolobus”) multiformis ATCC25196T (ATCC25196T) was 99.52% (strains 17SS, 17RS and 9SS) and 99.66% (strain 9RS). These newly isolated bacteria were all identified as Nitrosospira sp. Each strain, especially 17SS isolated from ASS, had higher urease activity than that of ATCC25196T. The o-acetylserine(thiol)lyase activity of 17SS was the highest of all the isolates. At pH 6.0, every isolate and ATCC25196T were able to utilize urea as the sole nitrogen source, in particular, strain 17SS grew best. The isolates fro...

Recent trends in the world scientific circles including their influence to the environment and society were analyzed. In Japan, significant changes in forestry education and research occurred to adapt with these developments. For instance, the concept of “forestry” was changed to “forest science”, utilization of domestic wood becomes a trend, biomass and bioprocess are being promoted, effective absorption sources for carbon dioxide as remedy for global warming are being identified, and forest therapy is recognized. In addition, organization of national forestry universities and departments changed into a broader context and field science was broadly accepted. These changes in forestry education and research in Japan seeks to improve society and forest to suit the world progress.

To estimate the aboveground biomass of tropical secondary forests dominated by pioneer species, allometric equations to relate diameter at breast height with the dry mass of the aboveground organs of several pioneer species were developed. The aboveground biomass of secondary forests was estimated using four methods based on the allometric equations. Biomass estimated with an allometric equation for all species combined was equivalent to that estimated with species-specific allometric equations. However, the estimated biomass based on a general-purpose allometric equation was substantially higher than that using other allometric equations. The allometric equation for all species combined is suitable for estimating the biomass of a secondary forest from the view points of accuracy and labor.

The range of CO 2 emissions to the atmosphere from tropical land-use change has long been debated. A major source of uncertainty is attributable to the fluxes of CO 2 due to changes in tropical land use. For example, estimate is different depending on whether the biomass or carbon content of tropical forests is totally lost by burning or recovered by regrowth. To estimate CO 2 absorption by fallow forests after shifting cultivation, we investigated the floristic composition and measured the biomass of fallow forests in East Kalimantan, Indonesia. Above-ground biomass of fallow forests were 8–10 t/ha at one-year-old stands and 45–56 t/ha at 10–12-year-old stands, regardless of the floristic composition. It seems reasonable to suppose that 7.4% of carbon released to the atmosphere by tropical rain forest destruction is reabsorbed and stored by fallow forests in Indonesia. If this is a universal trend in other tropical forests, a significant amount of CO 2 is reabsorbed in fallow forests. We consider that fallow forests like the one studied here are substantial carbon sinks and help to offset the effects of anthropogenic CO 2 emissions.

The use of in vitro shoot cultures to evaluate osmotic and salt tolerance and the effects of salt and mannitol in the medium on proline and sugar accumulation were investigated in two poplar species, P. euphratica and P. alba cv. Pyramidalis × P. tomentosa. Shoot length, leaf number, whole plant dry weight, and the accumulation of proline and total soluble sugars in leaves were quantified after 2 weeks. All P. euphratica plantlets survived at all levels of mannitol and NaCl, while the mortality of P. alba cv. Pyramidalis × P. tomentosa increased both at the mannitol and the NaCl treatments. A significant increase in proline accumulation was observed in both young and mature P. euphratica leaves at 200 mM mannitol and above, and at 150 mM NaCl and above. The total soluble sugar content increased in young P. euphratica leaves at 250 mM NaCl; however, it decreased in the mature leaves. Similar increases of the total soluble sugar content were not seen in P. alba cv. Pyramidalis × P. tomentosa plants in response to either mannitol or NaCl treatment. Our results suggest that accumulated proline and sugars promote osmotic and salt tolerance. The effects of accumulated proline and total soluble sugars on leaves are discussed in relation to growth and osmotic adjustment.

Adaptability to light conditions was examined for seedlings of three species of Dipterocarpaceae, Shorea leprosula, S. ovalis and Dryobalanops lanceolata, possessing different ecological and silvicultural properties. S. leprosula and S. ovalis showed significant morphological adaptations to weak light conditions by changing leaf weight ratio, root weight ratio and leaf areal weight, as compared with D. lanceolata which is the most shade tolerant among the three species. When the shade-adapted leaves of each species were released from shading, they showed depression in photosynthetic activity, though the extent of depression differed with species. Only S. leprosula showed a recovery in photosynthetic rate 18 days after the release from shading. This result indicates that S. leprosula was more adaptable to increase in light intensity than the other two species. S. leprosula could be regarded as one of the adaptable species for reforestation in degraded open land.

Aesculus turbinata is a tree species with large seeds (6.2 g mean dry weight). We studied the demography of its seeds and seedlings in a temperate deciduous forest in northern Japan to elucidate the ecological significance of large seeds with special reference to herbivory and secondary dispersal. Both seed and seedling stages suffered greatly from herbivores. Seedling herbivory was important judged from experiments with shoot clipping and hypogeal cotyledon removal. However, some seedlings survived through re-sprouting after herbivory. Survival rate and percentage resprouting seedlings were lower than those with remaining cotyledons, though seedling size was not affected. This suggests that stored resources in hypogeal cotyledons are working as a kind of ‘risk hedge’ against severe aboveground shoot clipping experienced by A. turbinata. The spatial distribution of seedlings was expanded via seed scatter-hoarding by rodents. Seedling survival rate was higher within canopy gaps than under closed canopy, indicating that canopy gaps are safe sites for establishment, and was negatively correlated with seedling density. Therefore, secondary seed dispersal in this species seems to be effective in ‘finding’ safe sites and in ‘escaping’ density-dependent mortality. The large seeds and seedlings of A. turbinata are attractive to herbivores, but the high resistance of seedlings to herbivory due to large reserves and the effective secondary dispersal appear to mitigate these disadvantages.

植物は光合成によって, 有機物を生産すると同時に環境を形成する。人間を含め動物は光合成機能をもたないため, 植物の光合成産物を利用することによって, 生命を維持することができる。言い方を変えると, 植物を破壊し, 利用することが動物の宿命である。しかし, 植物資源が枯渇するほど, 利用することは動物の死を意味する。したがって, 地球上における植物の量と動物の量のバランスをとることが大切であり.生産活動も自然保護活動も, この根本的な摂理を考えていく必要がある。

Forest managers need new approaches for maintaining high stand volumes while keeping forests continuously productive and economically profitable. The Silvicultural Management System (SMS) accomplishes these objectives by increasing large-sized trees for periodic harvest, and continuously maintaining stand volumes at their highest possible levels. This system takes advantage of the diversity in growth, vigor, and longevity of dominant trees from a wide range of tree species found in natural forest ecosystems. Under the SMS developed at the Tokyo University Forest in Hokkaido, 13–17% of the stand volume is harvested at a cutting cycle of 8–10 years by removing the oldest mature trees. Residual stand volumes are maintained at about 70–80% of the levels found in natural old-growth stands. This removal of the oldest trees keeps the stands in a continuously healthy and productive state. The cutting level is planned to ensure a sufficient harvest to cover the construction costs of a necessary high-density forest road network that provides the great logging efficiency and limited maximum yarding distances. This form of selection cutting has proven to be highly productive, surpassing even the production realized under clear cutting. Well-managed cuttings under SMS improve the quality and quantity of the timber resource, with particular emphasis upon premium-quality hardwoods. Guidelines are given for individual tree selection cutting to produce premium-quality hardwoods, and based upon a high-density forest road network. The value of this high-quality timber makes such low-volume logging operations profitable. The SMS also maintains a favorable forest ecosystem for diverse wildlife and flora, and several endangered or threatened wildlife species that depend upon less dense mature forests occur in SMS forests. Managed forests with high-volume stocking also serve as an effective carbon dioxide sink.

A gene for chlorophyll a/b-binding protein (cab) of pine (Pinus thumbergii) was isolated and sequenced. The gene (cab-6) contains an intron at a position equivalent to the type II cab genes of angiosperms. Transcript mapping analyses show that the amount of the mRNA in the dark is about half of that in the light. The cab-6 gene is expressed in dark-grown seedlings at a very high level, differing from angiosperm cab genes which are induced by light. The cab-6 gene typifies the coniferous plant cab genes in light-independent gene expression.

「樹幹表面温度と気温との較差により求められる活力度値」を従来の活力度と区分するため「活性度」とし, 新しい活力指標としての可能性を検討した。樹木の幹の表面温度は気温と較差が生じ, その程度は樹液流量と対応していることをケヤキの切断幹中を異なる流速で水を人工的に流す実験により確認した。さらに, 植栽現場において, 樹幹表面温度と樹木への外部からの熱源である気温との較差, 科学技術庁による4ランク評価法で定義される活力度, 成育活動結果としての直径成長量について検討を行なったところ, 幹気温較差 (樹幹表面温度-気温) は, 活力度や直径成長量との関連が認められた。

The physiological characteristics of the dominant tree species in the tropical rain forest mainly belonging to dipterocarps as well as the environmental conditions especially for the light in the forest were studied to establish the silvicultural system for the forest regeneration in the tropical South Asia. The flowering patterns of the dipterocarp trees are usually irregular and unpredictable, which make difficult to collect sufficient seeds for raising the seedlings. The field survey revealed the diverged features of the so-called gregarious or simultaneous flowering of various species of this group. Appropriate conditions and methods for the storage of the seeds were established according to the detailed analyses of the morphological and physiological characteristics of the seeds such as the low temperature tolerance and the moisture contents. The intensity and spectra of the light in the forest primarily determine the growth and the morphological development of the seedlings under the canopy. Based on the measurements of the diffused light at the sites in the tropical forest in the varying sunlight, the parameters such as “the steady state of the diffuse light” and “the turning point” were defined, which were useful to evaluate the light conditions in the forest. To improve the survival of the transplanted seedlings, a planting method of “the bare-root seedlings”, the seedlings easy to be handled by removal of all leaves, soil and pots, was developed. Its marked efficiency was proved with various dipterocarps and other tropical trees by the field trial in the practical scale. Tolerance of the various species to the extreme environmental conditions such as fires, acid soils and drought were examined by the experiments and the field survey, which revealed marked adaptability of Shorea roxburghii as a potential species for regeneration of the tropical forests. (Contributed by Satohiko SASAKI, M.J.A.)

The ammonia-producing bacteria B55T, CA73, SA69 and SA72 were isolated from the waterweeds Ludwigia adscendens (B55T) and Eleocharis dulcis (CA73, SA69 and SA72) grown in highly acidic swamps (pH 2–4) in actual acid sulfate soil areas of Vietnam. The isolates were Gram-positive, irregular rod-shaped, non-spore-forming bacteria. On the basis of 16S rRNA gene sequence similarity, strain B55T was shown to belong to the genus Curtobacterium of the class Actinobacteria. Chemotaxonomic data (MK-9 as major isoprenoid quinone, d-ornithine as cell-wall diamino acid, acetyl as the acyl type of peptidoglycan) supported the affiliation of all four strains to this genus. Although their 16S rRNA gene sequence similarity was 99 % to species with validly published names within the genus, they formed a group that was distinct in the phylogenetic tree, and DNA–DNA relatedness values to these established species were less than 10 %. The results of physiological and biochemical tests and major fatty acids (cyclohexyl-C17 : 0, anteiso-C17 : 0 and cyclohexyl-C19 : 0) allowed phenotypic differentiation of these strains from the species of Curtobacterium with validly published names. Therefore, strains B55T, CA73, SA69 and SA72 represent a novel species, for which the name Curtobacterium ammoniigenes sp. nov. is proposed. The type strain is B55T (=NBRC 101786T=VTCC D6-11T=JCM 14609T).

A large forest fire occurred in East Kalimantan, Indonesia, from 1982 to 1983, and about 3.1 million ha of forest were lost. Degradation of the damaged forest was further accelerated by shifting cultivation and illegal felling. Various efforts have been made to find an effective and realistic remedy for the degradation (Adjjers et al. 1995; Palmiotto 1993; Nussbaum et al.l995; Ang and Maruyama 1995). One solution is to reforest the degraded forest, which has become an urgent matter in this area. Therefore, silvicultural techniques for reforestation and sustainable forest utilization must be developed. The 3,000 ha Sebulu Experimental Forest, located in Sebulu, East Kalimantan, was granted by the Indonesian Ministry of Forestry in 1991, with the aim of developing reforestation techniques and establishing a sustainable management system for the forest. We planted approximately 500,000 seedlings, mainly dipterocarps, on 300 ha of this forest from 1991 to 1997, in order to study and develop the most efficient and cost-effective planting technique. However, in February and March of 1998, the last big forest fire burned 80% of the plantation. In this report the results of various planting methods are described with consideration given to cost savings.

In vitro cultured shoots of three Chinese poplar species (Populus tomentosa, P. alba cv. Pyramidalis andP. euphratica) and an improved poplar (FS-51), as a control, were exposed to the stress of low osmotic potential, salinity and high pH, and the shoot growth was measured.P. tomentosa andP. euphratica could grow even under the high osmotic stress (0.5m mannitol; −1.7 MPa).P. euphratica shoots which were previously cultured on the medium containing 0.7m mannitol (−2.4 MPa) recovered its growth after being transplanted to the medium without mannitol. The shoot growth ofP. euphratica was not so reduced even on the medium containing 100 mM NaCl. However, growth of the other poplars markedly reduced with 10 mM NaCl. Medium pH (pH 5.8–10) also did not affect the shoot growth ofP. euphratica. These poplars have different tolerance to the stresses in cultured shootin vitro. P. euphratica was extremely tolerant to the stresses which are possible to damage plants in dry land.

Polysome formation in the embryos of Pinus thunbergii seeds was studied. Free ribosomes were dissociated to smaller subunits in a high salt buffer, but the complex ribosomes were not. The free ribosomes could be distinguished from monomer ribosomes derived from polysomes after RNase treatment. The monomer ribosomes present in the embryos of the dark-imbibed seeds were predominantly free ribosomes; very small quantities of polysomes could be detected in the embryos from dark-imbibed seeds. Such polysomes remained at a very low level during dark imbibition at least for a month. The level of polysomes increased 4 hours after a brief exposure to red light. The effect of red light on polysome formation was partially reversed when followed by far red light irradiation.

Dissociability of the monomer ribosomes prepared from dry and imbibed pine (Pinus thunbergii) seed embryos was analyzed in sucrose density gradient containing a high salt buffer. Abnormal dissociation into the subunits was observed with the ribosome preparation from dry seed embryos when compared with that from imbibed seed embryos, i.e. each subunit peak was broader and localized at a lower site in sucrose density gradient. This indicates some change(s) in ribosomes during imbibition of seeds. These ribosomal changes also progressedin vitro. That is, after incubation of ribosome preparation from dry seed embryos in a high salt buffer for 5 min at 30 C or in a low salt buffer for 15 hr at 0 C, complete dissociation into the normal subunits was observed. No difference was found between polyacrylamide gel electrophoresis patterns of ribosomal RNA from dry and imbibed seed embryos. These results suggest some alteration in the protein components of ribosome during imbibition of pine seeds.