Arthropod communities in a Japanese cedar (Cryptomeria japonica D. Don) plantation: Abundance,biomass and some properties

Arboreal arthropod communities were censused by insecticidal knockdown in a plantation of Japanese cedar,Cryptomeria japonica, in central Japan from April 1983 to February 1985 at intervals of two months. All arthropods sampled were allocated to higher taxonomic groups or guilds and the composition of the communities was analyzed with respect to abundance, biomass and their seasonal trends. The total densities fluctuated seasonally from 200 to 3500 m⁻²; corresponding biomass values ranged from 7 to 600 mg fresh weight m⁻². Maximum density and biomass generally occurred in summer and were minimum in winter. The consistently dominant guild in terms of abundance were the detritivores, mostly comprising Collembola and oribatid mites, accounting for 36–93% of all arthropods; phytophages, predators and detritivores were major guilds in terms of biomass, showing average proportions of 27%, 23% and 20%, respectively. Biomass ratios of predators to prey were generally high in some canopy communities, suggesting the importance of predation pressure in regulating the population levels of arthropods in forests. Average individual size of predators was approximately proportional to that of prey, irrespective of tree locality. Soil arthropod communities maintained densities approximately 10²–10³ times as large as the corresponding canopy communities throughout the year. The seasonal variations in abundance were much greater in canopy than in soil communities.     

Contribution of root respiration to total soil respiration in a Japanese cedar (Cryptomeria japonica D. Don) artificial forest

Soil respiration was measured for 2 years in an artificial gap and in an undisturbed area in a Japanese cedar (Cryptomeria japonica D. Don) forest to estimate the contribution of root respiration to total soil respiration. Measurement plots were set up at the center of the gap, the edge of the gap, the edge of the surrounding stand and within the stand. Using a small gap (2.5 m × 2.5 m) enabled us to maintain the same soil temperature and soil moisture as found in the stand. Seasonal fluctuations in soil respiration, increasing in summer and decreasing in winter, corresponded to changes in the soil surface temperature. Soil respiration in the gap site did not differ significantly from those in the stand in the first year of gap formation. However, in the second year, the minimum CO₂ flux was observed at the center of the gap and the maximum at the edge of the surrounding stand. Assuming that the differences between soil respiration in the center of the gap and that in the stand were equal to the root respiration, the root respiration rate was calculated from the relationship between the root respiration rates (Rr) and the soil surface temperature (Ts) by Ln(Rr) = 0.07Ts + 3.48. The average contribution of root respiration to total soil respiration, as estimated from the soil surface temperature in the stand by using the above equation, was 49%. After taking root decomposition into consideration, the contribution of root respiration to soil respiration increased from 49 to 57%.     

Germination inhibitor from the Japanese cedar Cryptomeria japonica

(1S,6R)-2,7(14),10-Bisabolatrien-1-ol-4-one was identified as a germination inhibitor from the methanol extract of Japanese cedar wood, Cryptomeria japonica. The occurrence of this compound in 1 g fresh wood was 2.0 mg, and showed a maximum of 60% germination inhibition at the dose of 20 mg/filter paper (157 microg/cm(2)) against both of lettuce and rice seeds for 4 d. A selective activity between Dicotyledoneae and Monocotyledoneae seeds was not observed.     

Antifeedants against Acusta despesta from the Japanese cedar, Cryptomeria japonica

During our studies on the components in Japanese cedar, Cryptomeria japonica, we found that the crude methanol extract of C. japonica showed intense antifeeding activity against one snail species, Acusta despesta, which is well-known as a pest of many vegetables and crops. The active components in the extract were separated into the hexane and ethyl acetate soluble fractions. From the active ethyl acetate soluble fraction, two norlignans, sequirin-C and agatharesinol, were isolated and identified as the active compounds. Both compounds inhibited feeding behavior of A. despesta at 30 microg/cm2 and 40 microg/cm2 concentrations, respectively, when applied by an eggplant leaf or filter paper containing 20 microl of 5% sucrose solution.     

Seasonal changes of humoral and cellular immune responses to Japanese cedar (Cryptomeria japonica) pollen allergens in Japanese monkeys (Macaca fuscata) with pollinosis

The natural occurrence of Japanese cedar [Cryptomeria japonica (CJ)] pollinosis has been reported in Japanese monkeys (Macaca fuscata). The present study was designed to investigate seasonal changes in immunological reactions to CJ pollen allergens in monkeys with CJ pollinosis. Blood samples were collected from six monkeys with CJ pollinosis before and after CJ pollen season. Seasonal changes in specific IgE and IgG to major allergens (Cry j 1 and Cry j 2) were observed before and after CJ pollen season. The humoral responses decreased significantly before CJ pollen and increased after CJ pollen season. Similar seasonal changes in peripheral blood mononuclear cells proliferative responses to CJ allergens were observed before and after CJ pollen season. These humoral and cellular immune responses might serve as a biomarker for assessing new immunotherapies for monkeys with pollinosis.     

Antifeedants against Acusta despesta from the Japanese cedar, Cryptomeria japonica II

Cryptomeria japonica against Acusta despesta. This hexane soluble-fraction was used to isolate and identify two sesquiterpenols, (-)-cubebol and (+)-2,7(14),10-bisabolatrien-1-ol-4-one, as the active compounds. Both compounds strongly inhibited the feeding behavior of A. despesta at 120 microg/cm2 and 80 microg/cm2 concentrations, respectively.     

Shoots grafted into the upper crowns of tall Japanese cedar (Cryptomeria japonica D. Don) show foliar gas exchange characteristics similar to those of intact shoots

The lower foliar photosynthetic rates seen in shoots in the upper crowns of tall trees than those in seedlings could be caused by extrinsic factors, such as hydraulic conductance, for shoots or by irreversible intrinsic change in the meristems during tree development. To clarify which is most significant, we compared foliar gas exchange characteristics and water relations among scions of Japanese cedar (Cryptomeria japonica D. Don) grafted into the upper crowns of tall trees, rooted cuttings developed from scions of the same clones, and intact shoots in the upper crowns of the tall trees. Grafted shoots had the same water regime as intact shoots, as confirmed by their similar water potentials at the turgor loss point, which were more negative than those of the rooted cuttings. No significant difference was observed between the grafted and intact shoots in their light-saturated photosynthetic rate (P_max), stomatal conductance (g_s), photosynthetic capacity, carboxylation efficiency, ratio of intercellular to ambient CO₂ concentration (C_i/C_a), and carbon isotope composition (¹³C). Compared with the rooted cuttings, the grafted shoots showed significantly lower P_max, g_s, photosynthetic capacity, and carboxylation efficiency (to 49%, 31%, 68%, and 65%, respectively). The C_i/C_a and ¹³C indicated significantly stronger instantaneous and long-term stomatal limitation in the grafted shoots than in the rooted cuttings. These indicate that changes in extrinsic factors can reduce foliar photosynthetic rates in shoots in the upper crowns of tall trees as a result of stronger stomatal limitation and reduced photosynthetic activity, without irreversible intrinsic changes in the meristems.     

Repellents in the Japanese cedar,Cryptomeria japonica,against the pill-bug,Armadillidium vulgare

Sandaracopimarinol and (1S,6R)-2,7(14),10-bisabolatrien-1-ol-4-one were isolated and identified from Cryptomeria japonica as repellents against Armadillidium vulgare which is well known as an unpleasant pest in the house and as vegetable pest in Japan. These compounds strongly repelled A. vulgare when they were combined, although each compound alone did not show any activity.     

Development and characterization of microsatellite markers for Cryptomeria japonica D.Don

Thirty four microsatellite markers for Cryptomeria japonica D. Don were developed by searching three types of library: a database of C. japonica cDNA sequences, a standard non-enriched genomic DNA library and a microsatellite-enriched library using magnetic particles. The enrichment of microsatellite sequences using magnetic particles is very efficient compared to the other two methods both in terms of the numbers of markers generated, and in the polymorphism they detect. The microsatellites developed from the genomic DNA library generally have longer repeat sequences and are more polymorphic than those from cDNA. All the developed microsatellite markers in this study showed polymorphism among 28 plus trees selected from locations scattered throughout Japan. The mean number of alleles per locus (MNA) detected in the 28 plus trees ranged from 2 to 21 with an average of 7.5. The Polymorphism Information Content (PIC) ranged from 0.160 to 0.936 with an average of 0.666. Co-dominant segregation of alleles in a three-generation pedigree of C. japonica was demonstrated at 34 microsatellite loci, and the segregation was not distorted from Mendelian expectation for all loci. In 12 out of 34 loci, a null allele was detected. Key relationships between polymorphic parameters, such as MNA and PIC, and the characteristics of microsatellite sequences, such as the longest repeat number, total repeat number and total number of nucleotides, were investigated using rank correlation coefficients, Kendall's tau. A positive correlation was found between repeat lengths and polymorphisms. The markers provide sufficient resolution for investigating gene flow within forests and seed orchards, and for genome mapping.     

Seasonal prevalence of arthropods after line thinning of overstocked Japanese cedar (<Emphasis Type=Italic>Cryptomeria japonica</Emphasis> D. Don) plantations in central Japan

We investigated the seasonal changes in the abundance of coleopteran and hymenopteran functional groups to evaluate the ecological suitability of line thinning in overstocked Japanese cedar plantations in central Japan. In line thinning, 3- to 5-m-wide sections of the stand are harvested parallel to the mountain slope and perpendicular to the forest roads. The thinning intensity varies from 25 to 35% of the total number of trees. We compared the seasonal abundance between the thinned stand and the unthinned (control) stand in two plantation forests: a low-elevation Sugi site (4 years since thinning) and a high-elevation Kuchiotani site (6 years since thinning). Most coleopteran and hymenopteran functional groups were consistently more abundant in the thinned stand than in the unthinned stand. The differences in arthropod abundance between the thinned and unthinned stands were mainly caused by marked differences in the abundance of seasonally strongly changing functional groups during their peak seasons. The predators and parasitoids of insects as well as the plant and pollen feeders (plant-dependent functional groups) responded to seasonal changes in the vegetation (food and microhabitats) and microclimate. The ants were less affected by line thinning. Our results indicate that line thinning is an ecologically suitable silvicultural treatment for the improvement of biodiversity conditions in the overstocked plantation forests.     

Spatiotemporal variation in N2O flux within a slope in a Japanese cedar (Cryptomeria japonica) forest

Topographic factors affect nitrogen cycling in forest soils, including nitrous oxide (N₂O) emissions, which contribute to the greenhouse effect. We measured the N₂O flux at 14 chambers placed along a 65-m transect on a slope for 1 year at 2- to 3-week intervals. We applied a hierarchical Bayesian model with a conditional autoregressive (CAR) model to assess the spatiotemporal N₂O flux along a slope and quantify the effects of environmental factors on N₂O emissions. N₂O fluxes at chambers located at lower positions along the slope were relatively greater than those at higher positions. During the non-soil-freezing period, N₂O fluxes fluctuated seasonally depending on soil temperature. The soil temperature dependency of N₂O fluxes at each chamber increased with descending slope position (the median of the Q₁₀ equivalent simulated from posterior distribution ranged from 1.18 to 3.64). According to the Bayesian hierarchical model, this trend could be partially explained by the C/N ratio at each chamber position. During the soil-freezing period, relatively high N₂O fluxes were observed at lower positions along the slope.     

Photosynthesis-nitrogen relationship in a Hinoki cypress (Chamaecyparis obtusa) canopy: a comparison with Japanese cedar (Cryptomeria japonica)

The relationship between light-saturated photosynthetic capacity (P _max) and leaf nitrogen (N) content was investigated for one year in a 15-year-old Chamaecyparis obtusa canopy and was compared with a Cryptomeria japonica canopy previously described. The linear regression between P _max and leaf N content tended to converge toward a single line segment from July to January and in May for C. obtusa. The slope of the linear regression between P _max and leaf N content of C. obtusa was gentler than that of C. japonica. The smaller regression coefficient of C. obtusa may reflect species differences in nitrogen nutrition requirements between C. obtusa and C. japonica. A pronounced decrease in the slope of the linear regression lines due to low temperature was observed in February and March. During this period, P _max of C. obtusa declined more than that of C. japonica suggesting that C. obtusa is less tolerant to low temperatures than C. japonica.     

Development and characterization of chloroplast microsatellite markers for Cryptomeria japonica D. Don

We developed 17 chloroplast microsatellite markers, which consisted of seven mononucleotide microsatellites with a minimum repeat number of 10 and 10 dinucleotide microsatellites with a minimum repeat number of six, from the complete chloroplast genomic sequence of Cryptomeria japonica. A survey of 45 C. japonica individuals showed the number of alleles ranging from two to 11 alleles and a diversity index ranging from 0.085 to 0.895. Consequently, the 45 C. japonica individuals were divided into 39 haplotypes. These markers will be useful genetic markers in the gene flow analysis and population genetics of C. japonica.     

Formation and vertical distribution of sapwood and heartwood in Cryptomeria japonica D. Don

The formation and vertical distribution of sapwood and heartwood were studied with a 45-year-old Cryptomeria japonica D. Don. The tree was grown at a plantation with 1.5 m × 3.0 m spacing near Miao-Li, Taiwan and was felled on 27 February 1992. The thickness of sapwood and heartwood was expressed by a ring count and a linear measurement. The east-west (E-W) wood strips were collected from 0.3 m above ground upwards to the top of the tree at 2.5 m intervals. The sapwood thicknesses from the base to the 10.3 m tree level height are around 20–22 growth rings and 42±2 mm. At the top of the tree, the sapwood thickness is narrower. The heartwood, which decreases in thickness with increasing tree level heights is not found at the top of the tree. The heartwood appears as a conical shape in the tree trunk. There is no statistical difference in sapwood/heartwood thickness between E-W aspects. Tree level heights and the tree level age were found to be important parameters in determining the thickness of sapwood/heartwood.     

Live crown tops of Japanese cedar (Cryptomeria japonica) approach one another in height at urban forest sites

Since the 1980s, we have found Japanese cedar, Cryptomeria japonica (L. f.) D. Don, trees with crown tops affected by dieback in isolated urban forests on the low altitude plain. To clarify future growth of C. japonica in these forests, we investigated their growth, decline levels and water status. The live crown-top heights from the ground (LCTHs) per diameter at breast height (dbh) were lower in forests with C. japonica top dieback than in forests with no top dieback. Furthermore, in a forest with C. japonica top dieback, the LCTHs were similar between trees although dbh and decline levels were different. Moreover, water status near the top of the live foliage was very similar although decline levels were different, suggesting that in urban forests, where C. japonica top dieback is observed, the LCTH is subject of restriction. A sudden increase in temperatures since the 1980s may be restricting the LCTHs of C. japonica in urban forests. We conclude that LCTHs of C. japonica in urban forests are becoming lower and more equal in each forest. If temperature continues to increase, height restriction will become more severe and LCTHs of C. japonica in urban forests will become even lower.     

Regeneration of transgenic Cryptomeria japonica D. Don after Agrobacterium tumefaciens-mediated transformation of embryogenic tissue

A genetic transformation procedure for Cryptomeria japonica was developed after co-cultivation of embryogenic tissues with the disarmed Agrobacterium tumefaciens strain C58/pMP90, which harbours the visual reporter gene sgfp and two selectable marker genes, hpt and nptII. We were able to generate eight and three independent transgenic lines per gram of embryogenic tissue after selection on hygromycin and kanamycin medium, respectively. Transgenic plants were regenerated through somatic embryogenesis in 4 lines out of these 11 lines. Green fluorescent protein fluorescence was observed under fluorescent microscopy. Integration of the genes into the genome was confirmed by polymerase chain reaction analysis of embryogenic tissues and Southern blot analysis of regenerated plantlets.     

A sesquiterpene hydrocarbon from the bogwoods of Cryptomeria japonica D. Don, presumably formed by diagenetic hydrogenation

Structure of an hitherto unknown component of the essential oils from two bogwoods of Cryptomeria japonica D. Don was determined by mass spectrometry and NMR analyses. It was identified as cadina-1(10)-ene, a new cadinane-type sesquiterpene hydrocarbon with a single double bond.     

Effect of the water status within a tree on tracheid morphogenesis in Cryptomeria japonica D. Don

Three-year-old cloned trees of Cryptomeria japonica D. Don growing in a growth cabinet, in which the temperature, relative humidity and light conditions could be controlled automatically, were irrigated every day or every 3 days. The xylem pressure potential of the leaves was measured using a pressure chamber. The tangential strain of each stem was monitored with a strain gauge. After about 1 month the trees were cut, and the anatomical features of tracheids and cambial cells were observed. In trees irrigated every day, the tangential strain of the stems increased gradually with a regular diurnal pattern. On the other hand, in trees irrigated every 3 days, both the maximum and the minimum tangential strains within a stem increased every 3 days. In both irrigation conditions, the tangential strain showed a minimum value immediately before irrigation, and a maximum value around the onset of light within a day. The fluctuation of xylem pressure potential was similar to that of the tangential strain in both irrigation conditions. Stems of trees irrigated every 3 days shrank and swelled more than those irrigated every day with the same water potential change. The diameter of tracheids produced during the experimental period was larger in trees irrigated every day and smaller in trees irrigated every 3 days than that before the experiment. The number of cell layers of cells in the cell expanding zone and the cambial zone, and the tracheid diameter in the cell expanding zone were smaller in trees irrigated every 3 days than in trees irrigated every day. Received: 1 February 1999 / Accepted: 17 June 1999     

Ancestral MADS box genes in Sugi, Cryptomeria japonica D. Don (Taxodiaceae), homologous to the B function genes in angiosperms.

In flowering plants, flower organ identity is controlled by the ABC genes, including several MADS box genes. We present two MADS box genes of a conifer, Cryptomeria japonica D. Don. The genes, CjMADS1 and CjMADS2, were related to the angiosperm B function genes which determine the identities of petals and stamens. A phylogenetic analysis showed that these genes form a new clade outside the angiosperm B group, that is, PISTILLATA (PI) and APETALA3 (AP3) lineages. CjMADS1 had a PI-group specific motif and CjMADS2 had AP3-group specific motifs at the C terminal end, respectively. CjMADS1 was expressed in male strobili (or cones) throughout its development, while CjMADS2 was transiently expressed during male strobilus development. The specific expression in the male reproductive organ indicated that the B function is maintained in gymnosperms. Our cladistic analysis suggests that the gene duplication event which generated B function gene lineages predates the divergence of angiosperms and gymnosperms and that the gene duplication which produced the two genes of C. japonica occurred in an ancestral conifer species.     

Cleaved amplified polymorphic sequence markers in sugi, Cryptomeria japonica D. Don, and their locations on a linkage map

Sugi, Cryptomeria japonica D. Don, is one of the most important forestry species in Japan. We here report the development of 217 CAPS markers derived from sugi cDNA libraries. More than half of a set of STS markers produced could be converted into CAPS markers using restriction endonuclease analysis. Of the 217 markers, 71 showed different patterns of polymorphism when they were digested with a range of endonucleases and, in total, 347 polymorphisms were found in the various combinations of STSs and endonucleases. When the polymorphisms gave co-dominant patterns in a screening program, the polymorphic information content (PIC) used to evaluate the value of the polymorphisms was relatively high (0.33, on average) compared to the information yielded by commonly used markers, like isozymes. The results of a segregation analysis suggest that approximately 80% of the CAPS markers developed here will show co-dominant inheritance. From logistic regression analysis, the polymorphisms were found to be associated more strongly with intron than with exon regions. Sixty two markers were subsequently mapped on the previously reported linkage map, 15 of which showed abnormal segregation, presumably caused by linkage with lethal factors. Received: 7 December 2000 / Accepted: 23 January 2001