Nitrogen use by <Emphasis Type="Italic">Pinus densiflora</Emphasis> trees growing on a Mt. Fuji lava flow

To quantify the nitrogen (N) use by Pinus densiflora trees growing on an infertile lava surface, N pools, N requirement and N uptake through fine roots and N deposition from the atmosphere were estimated. The N requirement and the N uptake of fine roots were 55.5kgNha^–1year^–1 and 39.7kgNha^–1, respectively. Thus, the ratio of N uptake to N requirement of the fine roots was 71.5%. Including fine-root contribution, the total N requirement of the P. densiflora trees was 98.6kgNha^–1year^–1, and the total N uptake was 64.2kgNha^–1year^–1. Thus, the N uptake of the P. densiflora trees was 64.1% of the N requirement, indicating that P. densiflora trees growing on an infertile lava surface obtain some of their N from below-ground organic material layers every year and the contribution of N storage in trees for their growth is not any higher than indicated in previous reports that excluded fine-roots contribution. The wet N deposition of our research forest was only 5.8% of the N requirement of the P. densiflora trees and only 8.9% of the N uptake. Movement of the below-ground organic material layer N concentrations in the F- and L-layers coincides with needle development and fine-root growth, suggesting the possibility that P. densiflora trees extract N from the organic N of those layers for growth.     

Fine root biomass and morphology of <Emphasis Type="Italic">Pinus densiflora</Emphasis> under competitive stress by <Emphasis Type="Italic">Chamaecyparis obtusa</Emphasis>

The fine root (diameter ≤2.0 mm) biomass and morphology of Japanese red pines (Pinus densiflora) grown under different aboveground conditions (i.e., high and low competitive environments) were examined in a pine–cypress mixed forest. All P. densiflora subject trees were about 40 years old, and the aboveground condition (i.e., size) of red pines appeared to be influenced by the surrounding Japanese cypress (Chamaecyparis obtusa). Smaller P. densiflora exhibited lower fine root biomasses, shorter root lengths, and lower root tip densities, but longer specific root lengths and higher specific root tip densities relative to larger pines. These results suggest that P. densiflora may adjust the morphological traits of fine roots to the different conditions in biomass allocation to fine roots of individuals with different aboveground growth.     

Allometric model of the Reineke equation for Japanese cypress (<Emphasis Type="Italic">Chamaecyparis obtusa</Emphasis>) and red pine (<Emphasis Type="Italic">Pinus densiflora</Emphasis>) stands

An allometric model that explains the mechanism of the difference in the slope of the Reineke equation (A) among species was proposed based on the allometric relationships of mean tree height (H) to quadratic mean diameter D (H ∝ D ^θ ) and stand density N (H ∝ N ^δ ), i.e., A = θ/δ. The proposed model was fitted to Japanese cypress (Chamaecyparis obtusa Endl.) and red pine (Pinus densiflora) stands. The allometric exponents θ and δ were, respectively, 0.8995 and −0.5000 for cypress and 0.8612 and −0.6619 for pine. The difference between cypress and pine was significant for δ but not for θ. Inserting the exponents into the model resulted in predicted slopes of −1.7991 for cypress and −1.3011 for pine. The difference in the slope of the Reineke equation between the two species was produced by characteristics related to the tree crown, rather than characteristics related to stem slenderness. The proposed model enables us to estimate the slope of the Reineke equation from commonly measured stand attributes, such as mean tree height and quadratic mean diameter. Therefore, the proposed model is expected to be practical and convenient for estimating the slope of the Reineke equation and for explaining the mechanism of its variation among species. The model should be also accepted as a generalized model of the stand density versus quadratic mean diameter relationship, whereas the original Reineke equation should be seen as a specific case of this model.     

Effects of urea treatment on litter decomposition in <Emphasis Type="Italic">Pasania edulis</Emphasis> forest soil

Five kinds of ammonia fungi were observed in a Pasania edulis forest after treatment with 1600g·m^–2 of urea. The number of fungal fruiting bodies decreased with time, and disappeared completely within 6 weeks. The population of cellulose decomposing bacteria also decreased after urea treatment. Urea treatment brought about marked changes in soil pH, redox potential (Eh), and nitrogen content, but no significant changes were observed in carbon content. In this experiment, urea treatment promoted decomposition of branches, but inhibited decomposition of leaves. In urea-treated plots, the decomposition rate of leaves was lower than that of branches, and the decomposition rate of large branches was greater than that of small branches. However, in the control plots, the decomposition rate of leaves was greater than that of branches, and the decomposition rate of large branches was lower than that of small branches. This experiment indicated that litter (branch and leaf) decomposition was dependent on the texture and size of the litter components, and that ammonia fungi and cellulose decomposing bacteria were not closely related to the litter decomposition.     

Recessive inheritance of morphological characteristics of utsukushimatsu,<Emphasis Type="Italic">Pinus densiflora</Emphasis> f.<Emphasis Type="Italic">umbraculifera</Emphasis>

Pinus densiflora f.umbraculifera, commonly known as utsukushimatsu, is a distinctively shaped form of Japanese red pine whose growth is restricted to a forest stand in Shiga Prefecture, Japan. The inheritance mode of morphological characteristics of utsukushimatsu was studied to preserve the genetic resource of this pine. As previously reported, F₁ trees grown from open-pollinated seeds harvested from trees inhabiting the native stand showed two phenotypes: one resembling utsukushimatsu, which produces multiple trunks, and the other resembling normalP. densiflora, which produces one or a few trunks. In the present study, controlled pollination was carried out using F₁ and normalP. densiflora trees. Segregation ratios of the two phenotypes observed in the F₂ population showed that the morphological characteristics of utsukushimatsu are inherited recessively. This suggests that the mutation of one gene or a few closely linked genes controls the morphological characteristics of utsukushimatsu. Since multiple trunk formation of utsukushimatsu might be related to a loss of lateral bud inhibition, it follows that a simple gene mutation breaks apical dominance inP. densiflora.     

An inoculation experiment of Japanese <Emphasis Type="Italic">Bursaphelenchus</Emphasis> nematodes on Japanese black and red pine, <Emphasis Type="Italic">Pinus thunbergii</Emphasis> and <Emphasis Type="Italic">P. densiflora</Emphasis>

The pinewood nematode (PWN) Bursaphelenchus xylophilus is an invasive pathogen that was introduced from North America to Asian countries and Portugal and is devastating native pine forests. Some native European and Asian Bursaphelenchus nematodes also have weak to moderate pathogenicity to native pine species. To evaluate the potential risk of native Bursaphelenchus species, we inoculated ten Japanese Bursaphelenchus species into native pine species (the dominant forest species) in Japan, and evaluated their pathogenicity using mortality and tracheal tissue damage as indices. Inoculation was conducted on August 3, 2007, and the symptoms were observed every 2 weeks until February 1, 2008. None of the inoculated trees, excluding the pathogenic PWN inoculated control, showed external disease symptoms; however, four species [a less pathogenic PWN isolate, B. luxuriosae, Bursaphelenchus sp. NK215 (undescribed), and NK224 (undescribed)] caused tracheal tissue damage in inoculated seedlings and showed weak pathogenicity. Therefore, we conclude that there are some potentially pathogenic native species of nematodes distributed in Japan. Interestingly, two of these weakly pathogenic species, B. luxuriosae and NK215, are not associated with Pinaceae trees, suggesting that nematode pathogenicity may be a pre-adaptive character. More experimental studies under different conditions are necessary to accurately evaluate the potential risk of these pathogens.     

Estimating the production and mortality of fine roots using minirhizotrons in a <Emphasis Type="Italic">Pinus densiflora</Emphasis> forest in Gwangneung,Korea

The aim of this study was to estimate fine root production (FP) and fine root mortality (FM) at 0–10, 10–20, and 20–30 cm soil depths using minirhizotrons in a 75-year-old Pinus densiflora Sieb. et Zucc. forest located in Gwangneung, Korea. We developed the conversion factors (frame cm^?2) of three soil depths (0.158 for 0–10 cm, 0.120 for 10–20 cm, and 0.131 for 20–30 cm) based on soil coring and minirhizotron data. FP and FM were estimated using conversion factors from March 26, 2013 to March 2, 2014. The annual FP and FM values at the 0–30 cm soil depth were 3200.2 and 2271.5 kg ha^?1 yr ^?1, respectively. The FP estimate accounted for approximately 17 % of the total net primary production at the study site. FP was highest in summer (July 31–September 26), and FM was highest in autumn (September 27–November 29). FP was positively correlated with seasonal change in soil temperature, while FM was not related to that change. The seasonality of FP and FM might be linked to above-ground photosynthetic activity. Both FP and FM at the 0–10 cm depth were significantly higher than at 10–20 and 20–30 cm depths, and this resulted from the decrease in nutrient availability with increasing soil depth. The minirhizotron approach and conversion factors developed in this study will enable fast and accurate estimation of the fine root dynamics in P. densiflora forest ecosystems.     

Field trap test for bioassay of synthetic (1<Emphasis Type="Italic">S</Emphasis>,4<Emphasis Type="Italic">R</Emphasis>)-4-isopropyl-1-methyl-2-cyclohexen-1-ol as an aggregation pheromone of <Emphasis Type="Italic">Platypus quercivorus</Emphasis> (Coleoptera: Platipodidae)

An ambrosia beetle, Platypus quercivorus, is a vector of Japanese oak wilt, which causes massive mortality of oak trees in Japan. Previous studies have identified (1S,4R)-4-isopropyl-1-methyl-2-cyclohexen-1-ol ((−)-IMCH) as the major component of the aggregation pheromone of P. quercivorus. We tested the ability of synthetic (−)-IMCH to attract P. quercivorus adults. The synthetic compound attracted 14.4 times as many P. quercivorus, of both sexes, as control traps. Control and (−)-IMCH-baited traps both captured 3.32 times as many males as females, probably because of the nature of Lindgren funnel traps and of male-biased emergence sex ratio early in the season of adult flights. (−)-IMCH was proved to be a major component of the aggregation pheromone of P. quercivorus.     

Time-trajectory of mean component weight and density in self-thinning <Emphasis Type="Italic">Pinus densiflora</Emphasis> stands

The allometric relationships between mean weights of components, such as stems, branches and leaves and tree weight as well as their time-trajectories, were studied with data of self-thinning Pinus densiflora stands with different densities. The allometric relationships existed between the weights of stems, branches and leaves and the tree weight during the course of self-thinning. The stem weight ratio increased with increasing tree weight because the allometric coefficient in stem was higher than unity, whereas the branch weight ratio and the leaf weight ratio decreased because the allometric coefficients in branches and leaves were less than unity. An allometric power relationship existed between mean component weight and mean tree weight during the course of self-thinning. The time-trajectory of mean component weight (w _o) and density (ρ) in the early growth stage was expressed as a mathematical model which incorporates the allometric power relationship into the Tadaki’s model, whereas the model for describing w _o-ρ trajectory in the later growth stage was derived by combining the allometric power relationship with 3/2 power law. The two models, Tadaki’s model and 3/2 power law, showed a good fit to data from P. densiflora stands. The time-trajectories of mean tree weight (w)-density (ρ) or w _o-ρ initially almost moves nearly vertically in the low-density stand, moves along a steep curve and an inclined curve in the medium- and high-density stands, respectively, and gradually approaches self-thinning line in the early stage of stand development, whereas they reached and moved along the self-thinning line in the later stage of stand development. The self-thinning exponents were determined to be 1.71, 1.19 and 1.13 for the trees, 2.38, 1.33 and 1.20 for the stem, 3.16, 1.55 and 1.46 for the branches, 2.66, 1.39 and 1.35 for the leaves in the low-, medium- and high-density stands, respectively. The 3/2 power law of self-thinning is derived on the basis of simple geometric model of space occupation by growing trees, but allometric growth of tree and components can make the slope of the self-thinning line being different from −3/2. The reasons that the self-thinning exponents of components in the low-density stand were greater than those in the medium- and high-density stands were discussed.     

Comparison of postfire mortality in endemic Corsican black pine (<Emphasis Type="Italic">Pinus nigra</Emphasis> ssp. <Emphasis Type="Italic">laricio</Emphasis>) and its direct competitor (<Emphasis Type="Italic">Pinus pinaster</Emphasis>)

• Introduction   

Laricio pine (Pinus nigra J.F. Arn. ssp. laricio (Poiret) Maire var Corsicana Hyl.) is a form of black pine endemic to Corsica, that may now be under threat due to current fire regimes and competition with maritime pine (Pinus pinaster Aiton).     

Successful <Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated transformation of <Emphasis Type="Italic">Populus tomentosa</Emphasis> with apple <Emphasis Type="Italic">SPDS</Emphasis> gene

The problem of salinized soils has become one of the most serious constraints to agricultural and forest productivity. With the purpose of enhancing salt stress tolerance of Populus tomentosa, we transformed this tree species with spermidine synthase （SPDS） genes derived from an apple by an Agrobacterium-mediated method. Four transgenic clones were confu＇med by PCR and Southern blot analysis. As well, the expression of introduced SPDS genes was analyzed by real-time quantitative PCR.     

Relationships of stem surface area to other stem dimensions for Japanese cedar (<Emphasis Type="Italic">Cryptomeria japonica</Emphasis> D. Don) and Japanese cypress (<Emphasis Type="Italic">Chamaecyparis obtusa</Emphasis> Endl.) trees

I investigated the relationships between stem surface area outside bark and other stem dimensions for Japanese cedar (Cryptomeria japonica D. Don) and Japanese cypress (Chamaecyparis obtusa Endl.) trees. The stem dimensions used here were the basal area and the product of diameter at breast height (dbh) and total tree height. The regression equation of the stem surface area s against basal area g was s = 184.216g for the cedar trees and s = 156.878g for the cypress trees. The slope of the equation was significantly different between the two species. For the same dbh, the cedar trees tended to have a higher total tree height than the cypress trees. The cedar trees also had a larger surface area of relative stem form than the cypress trees. These results indicated that the difference in the slope was produced by the differences in both the stem slenderness and tapering between the two species. On the other hand, the regression equation between the stem surface area and the product of dbh and total tree height dh was s = 1.937dh for the cedar trees and s = 1.921dh for the cypress trees, whereas no significant difference in the slope was found. The obtained slopes for the cedar and cypress trees seemed to be in accord with that for other coniferous species reported in earlier studies, suggesting that the variation in the slope among coniferous species would be small. The estimation from the basal area would provide a simpler means for estimating the stem surface area and would be useful in obtaining an approximation of the surface area. By contrast, the estimation from the product of dbh and total tree height would provide a more accurate and precise estimate as well as a wider applicable range, i.e., a parameter for physiological growth models. In conclusion, it could not be judged which regression equation examined in the present study was superior to the other, and thus it was important to select an appropriate equation depending both on the purpose and on the time and labor available.     

Modelling stemflow production by juvenile lodgepole pine (<Emphasis Type="Italic">Pinus contorta</Emphasis> var. <Emphasis Type="Italic">latifolia</Emphasis>) trees

Stemflow is a focused point source input of precipitation and nutrients at the base of a tree or plant and can have a significant impact on site hydrology. To date, no known studies have modelled stemflow production for juvenile lodgepole pine (Pinus contorta var. latifolia). Meteorological conditions, tree characteristics, and stemflow were sampled for two juvenile lodgepole pine stands over the course of the 2009 growing season. Step-wise multiple regression was used to assess which meteorological and tree architecture variables influenced stemflow production for each research plot. Once predictor variables were identified, models were produced for each stand and a generic model was produced that applied to both plots. A model employing precipitation depth and crown projection area successfully explained 71.3% of the variation in stemflow production from sampled trees. Stemflow was found to represent 1.8% of the study period rainfall and, although not a large component of the plot-scale canopy water balance, it is an order of magnitude greater than the fractioning of stemflow from mature lodgepole and lodgepole pine dominated forest. Additionally, stemflow funnelling ratios were found to average 22.2 and 24.3 from the two sample plots over the study period with a single tree, single event maximum of 111.7 recorded for a tree with a 3.3 cm bole diameter and a rain depth of 17.4 mm.     

Aboveground biomass equations for individual trees of <Emphasis Type="Italic">Cryptomeria japonica</Emphasis>, <Emphasis Type="Italic">Chamaecyparis obtusa</Emphasis> and <Emphasis Type="Italic">Larix kaempferi</Emphasis> in Japan

Generic equations are proposed for stem, branch and foliage biomass of individual trees in even-aged pure stands of Cryptomeria japonica, Chamaecyparis obtusa and Larix kaempferi. Biomass data was collected from a total of 1,016 individual trees from 247 stands throughout Japan, and five regression models were assessed by root mean square error, mean bias, fit index (FI), and AIC. The results show that a power equation using diameter at breast height (dbh) and height is the most suitable for all species and components. This equation is more accurate than the familiar power equation that uses ‘dbh² height’, and it expresses the greater volume of branch and foliage mass of trees with a lower height/diameter ratio. A power equation using dbh is more reasonable for models with dbh as the only independent variable and more accurate than a power equation using ‘dbh² height’ for estimating branch and foliage mass. Estimating error for branch and foliage mass is larger than that for stem mass, but the entire aboveground biomass can be estimated with an error of less than 19%, except in the case of small trees with dbh less than 10 cm.     

Enzymatic saccharification and ethanol production of <Emphasis Type="Italic">Acacia mangium</Emphasis> and <Emphasis Type="Italic">Paraserianthes falcataria</Emphasis> wood,and <Emphasis Type="Italic">Elaeis guineensis</Emphasis> trunk

We examined the saccharification and fermentation of meals from Acacia mangium wood, Paraserianthes falcataria wood, and Elaeis guineensis trunk. The levels of enzymatic hydrolysis of cellulose and ethanol production were highest for P. falcataria wood and lowest for A. mangium wood. Ultrasonication pretreatment of meal further increased the rates of hydrolysis and ethanol production in meal from P. falcataria wood. Through this pretreatment, hemicelluloses (xylan and xyloglucan) and cellulose were released in the meal from P. falcataria wood. Loosening of hemicellulose associations can be expected to make P. falcataria wood more useful for bioethanol production.     

Molecular cytogenetics and flow cytometry reveal conserved genome organization in <Emphasis Type="Italic">Pinus mugo</Emphasis> and <Emphasis Type="Italic">P. uncinata</Emphasis>

• Introduction   

The most common representatives of the European mountain pine complex (Pinus mugo s.l.) are P. mugo s.s. and Pinus uncinata.     

Suggestions on management measures of pine forest ecosystems invaded by <Emphasis Type="Italic">Bursaphelenchus xylophilus</Emphasis>

Pine wood nematode （PWN）, Bursaphelenchus xylophilus （Steiner et Buhrer） Nickle is an important invasive alien species in forests of China and has become one of the most destructive forest diseases. In order to improve the resistance and resilience of pine forest ecosystems against B. xylophilus invasion and make the pine forest ecosystem more timely responsive to PWN invasion, we made some recommendations based on five years of intensive observations. We advocate a set of management measures with the theme “Prevention is priority, but integrated with curative techniques and ecological resilience” on the pine forest ecosystem invaded by B. xylophilus; details of accurate measures are proposed. The aim is to discover the underlying problems of present pine forest ecosys-tems and to take, correspondingly, administrative measures and strategies, which will encourage the pine forest ecosystem to develop in a benign way.     

Insecticidal properties of <Emphasis Type="Italic">Thymus persicus</Emphasis> essential oil against <Emphasis Type="Italic">Tribolium castaneum</Emphasis> and <Emphasis Type="Italic">Sitophilus oryzae</Emphasis>

Red flour beetle Tribolium castaneum (Herbst) and rice weevil Sitophilus oryzae (L.) are considered to be the major insect pests in storage. Essential oils from aromatic plants are recognized as proper alternatives to fumigants. Thymus persicus (Ronniger ex Rech. f.) is one of these plants that have medicinal properties and is indigenous to Iran. The essential oil was obtained from aerial parts of the plant and analyzed by GC and GC–MS. Carvacrol (44.69%) and thymol (11.05%) were the major constituents of the oil extracted. In this experiment, fumigant toxicity of the essential oil was studied against T. castaneum, S. oryzae at 27 ± 1°C and 60 ± 5% RH in dark condition. The adult insects were exposed to the concentrations of 51.9, 111.1, 207.4 and 370.4 μl/l air to estimate median lethal time (LT₅₀) values. The fumigant toxicity was increased in response to increased essential oil concentrations. The LT₅₀ values at the lowest and the highest concentrations tested were ranged from 28.09 to 13.47 h for T. castaneum, and 3.86 to 2.30 h for S. oryzae. It was found that S. oryzae adults were much more susceptible to the oil than T. castaneum. After 24 h of exposure, the LC₅₀ values (95% fiducial limit) for T. castaneum and S. oryzae were estimated to be 236.9 (186.27–292.81) and 3.34 (2.62–4.28) μl/l air, respectively. These results suggest that T. persicus essential oil merits further study as potential fumigant for the management of these stored-product insects.     

<Emphasis Type="Italic">Bursaphelenchus mucronatus</Emphasis> (Nematoda: Aphelenchoididae) vectored by <Emphasis Type="Italic">Monochamus </Emphasis><Emphasis Type="Italic">urussovi</Emphasis> (Coleoptera: Cerambycidae) in Hokkaido,Japan

Bursaphelenchus mucronatus Mamiya et Enda has been recovered for the first time from adults of the cerambycid beetle, Monochamus urussovi (Fischer), in Hokkaido, Japan. The nematode was also recovered from the inner bark of Picea jezoensis (Siebold et Zuccarini) Carrière and Abies sachalinensis (Fr Schmidt) Masters infested with M. urussovi larvae. PCR–RFLP analysis indicated that B. mucronatus in Hokkaido is the European type.