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In order to clarify the eco-physiological mechanism of forest succession in eastern Siberia, water conducting function of the stem such as sap flow velocity and hydraulic conductivity of xylem and leaf gas exchange characteristics such as photosynthetic rate and stomatal conductance were investigated. In this study, ecological succession from Betula platyphylla (birch) dominated stage to Larix gmelinii (larch) dominated one was mainly discussed. Sap flow velocity was higher in larch than in birch. On the other hand, hydraulic conductivity of the stem xylem was much lower in larch than in birch. Both leaf photosynthetic rate and stomatal conductance were higher in birch than in larch. Relatively high sap flow rate in spite of low xylem conductivity in larch indicated its ability of water pump-up was strong. These results suggested suction force was greater in larch than in birch. Higher hydraulic conductivity and gas exchange rate in birch could have the advantage of rapid establishment in the fire-disturbed area and the occupation of the canopy layer. However, under the semi-arid conditions with low precipitation, when the competition with other individuals for soil water may be remarkable as the stand develops, larch may have the advantage of water absorption. Therefore, replacement of dominant tree species from birch to larch could be promoted. It was concluded that the difference in suction force of tree species was closely related to the mechanism of post-fire succession.

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Leaf physiological, morphological characteristics and light environment were examined in the canopy of Fagus crenata Blume at Naeba Mountain. The canopy was divided into several sectorial layers for vertical, radial direction and azimuth. Dependences of photosynthetic and transpiration rate on photosynthetic photon flux density (PPFD), and relative photosynthetic photon flux density (R-PPFD) were measured at each layers of north and south side. With increasing canopy depth for vertical direction, the R-PPFD decreased exponentially from 98 % to 16 %. With respect to radial direction, the R-PPFD at upper layer and middle layer decreased exponentially from 98 % to 25 % and from 78% to 16% respectively. The azimuthal difference in R-PPFD was found especially at middle inner layer. The R-PPFD at north middle layer exhibited 79 % decrease from that at south. Positive relationship between light saturated net assimilation rate (A_max) and R-PPFD was found (R²=0.854). However, A_max at north bottom or inner layers exhibited about 30 % decrease from that at south. Leaf dry mass per area (LMA) at north side layers was higher than that at south side. High LMA may be disadvantage for light capture at low light condition because LMA related to lamina thickness. Furthermore, thick leaf may exhibit a significant high diffusive resistance between sub-stomatal cavities and carboxylation sites in the chloroplasts. Therefore, spatial distribution of photosynthetic capacity may be associated with not only light environment but also morphological characteristics. Transpiration rate at high light (E; PPFD=1500 micro- mol/m²/s) increased with increasing R-PPFD. The variance of E to R-PPFD was considerably lower than that of A_max. Correlation coefficient of linear regression was also lower than that of A_max (R²=0.47). E would be associated with not only light environment at leaf surface but also hydraulic conductance or air temperature. Further detail studies were needed to explain spatial distribution of transpiration capacity.

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Diurnal changes in gas exchange and chlorophyll fluorescence were measured to evaluate physiological and environmental limitation to diurnal photosynthesis in canopy leaves of Fagus crenata Blume. Photosynthesis rate (P) and stomatal conductance (gs) reached maximum value at early morning and rapidly decreased with increasing photosynthetic photon flux density (PPFD), leaf temperature and leaf to air vapour pressure deficit (ALVPD). Leaf water potential remained stable throughout the day even in midday depression of P and gs.The maximum photochemical efficiency of Photosystem2(Fv/Fm) were constant around 0.8 throughout the day. This result suggested chronic photoinhibition did not occur. Maximum values of Electron transport rate (JT) were found at morning and then JT slightly decreased. P did not depend positively on JT. Electron flows used by the carboxylation (Jc) and oxygenation (Jo) of RuBP were calculated from P , JT and dark respiration(Rd). The Jo/JT ratio of midday was higher than that of morning. These results indicate photorespiration increased during midday depression of P and gs. Photosynthetic capacity , define as the rate of carbon assimilation measured with saturating CO2 and light, did not decline at midday.This result suggested that midday depression of P was ascribed to increasing rate of photorespiration. The increase in photorespiration rate was brought about by a decrease in leaf intercellular CO2 concentration (Ci) due to stomatal limitation. Thus, photorespiration possibly contributes to protecting the photosynthetic system from deleterious effects of high light and low Ci.Violaxanthin(V) was converted to antheraxanthin(A) and zeaxanthin(Z) with increasing PPFD. (Z+0.5A)/(Z+A+V) ratio depended positively on NPQ. Thus the increased capacity of non-photochemical quenching also contributes to avoiding photoinhibition under the low Ci condition which occur during the midday stomatal closure.To elucidate the impact of Tleaf and ALVPD on diurnal photosynthesis, Tleaf response curve and ALVPD response curve of photosynthesis rate were measured in detached leaves. P slightly decreased with increasing Tleaf > 30 C, because it resulted in slightly increased Rd and photorespiration rate. P was greatly decreased by experimentally increasing ALVPD. In conclusion, the effect of ALVPD on P was more important than that of Tleaf. We attribute the midday depression of photosynthesis to increased rate of photorespiration caused by stomatal closure. The increasing ALVPD induced the stomatal closure. Low Ci, induced by stomatal closure at high Tleaf and high PPFD, could enhance the photoinhibition. But in leaves of Fagus crenata, high capacities for photorespiration and non-photochemical quenching are essential to avoid chronic photoinhibition by excess light energy.

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Turnover rate of leaves and Photosynthetic rate of each leaf were examined in the culms of Phyllostachys bambusoides Sieb. et Zucc. Those were compared among the culms of different ages. The number of leaves per a meter of main branch was the highest in the culm of one-year old. Turnover rate of leaves in the branches decreased with an increase of the age of culms. Photosynthetic rates per a day and the photosynthetic rate at the light saturated point decreased with an increase of the age of culms.

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Geographic variation of chloroplast DNA in Picea jezoensis was studied in 118 individuals from 5 poulations (Jozankei, Akan, Nukabira, Otoineppu, Khabarovsk). Total genomic DNA of 6-7 individuals from each 5 populations were amplified by 4 universal primers (rbcL, trnK, psbD, trnC-trnD) and digested with 8 restriction enzymes (EcoRI, EcoRV, DraI, HaeIII, MspI, RsaI, StyI, TaqI). 3 primer/enzyme combinations (trnK/DraI and trnC-trnD/DraI, RsaI) showed polymorphisms. All the individuals were analyzed with these combinations. The detection of polymorphisms by restriction analysis of PCR-amplified cpDNA fragments allowed the identification of 8 haplotypes. Many individuals of 4 populations in Hokkaido had haplotypeII and many individuals of Khabarovsk had haplotypeIII. Haplotype variation was rich in Akan and Nukabira. Based on DNA fragment frequencies, average gene diversity (H) of Jozankei, Akan, Nukabira, Otoineppu, Khabarovsk was 0.33, 0.46, 0.37, 0.15, 0.32, respectively. High average gene diversity in Akan suggest the possibility that east Hokkaido was refugial area of P. jezoensis during last glacially. Low average gene diversity in Otoineppu suggest the possibility that distribution of P. jezoensis in north Hokkaido was declined during last glacially. Within population gene diversity (H_S) was 0.33, total gene diversity (H_T) was 0.44 and coefficient of gene differentiation (G_ST) was 0.26. Fairly high coefficient of gene differentiation may because of haploidy of chloroplast DNA. Based on standard genetic distance, neighbor joining phenogram was made by PHYLIP program. Low genetic identity of 4 populations in Hokkaido and Khabarovsk suggest the possibility that gene flow among these areas did not occur for long time.

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Inbreeding depression is important in the evolution of plant populations and mating systems. Most outcrossing species are inbred. High mortality occurred at several life stages. The occurrence of homozygotes at the alleles with deleterious mutations, such as lethal alleles, is believed to be responsible. In this study, we report the identification of the deleterious loci shared among the individuals within a local population of Fagus crenata, based on the segregation analysis. First, the effect of the pollen donors located in the vicinity of the female parent was examined. Second, constructing a linkage map of Fagus crenata. Next step, identification of deleterious loci based on a segregation analysis of the loci widely distributed on a linkage map.the female parent of the research area located in natural beech forest in Mt. Fuji, was pollinated with different types of pollens, self pollens, pollens collected from six single neighboring trees, pollens collected from the tree located in the different stand. The percentages of the nuts with sound seed produced from each types of pollination were examined. Most nuts produced from self-pollination were empty, demonstrating that beech has strong self-incompatibility. The percentages of the soundness were varied from 45% to 78% among the pollination types. These results suggested that the distance from female parent to pollen donor affects the nut production in beech. A total of 78 progeny was genotyped by AFLP and SSR. Using a pseudo-testcross strategy linkage map was constructed. A total of 309 markers (307 AFLP and 2 SSR) were distributed among 23 linkage groups. Resulting linkage map spread 1797.2 cM and average distance among markers was 5.8 cM.In order to identified the loci with deleterious mutations, we examined the segregation ratio with three F₁ populations (pollen donor located in the vicinity of the female parent) using 123 mapped markers. Fifteen markers with distorted segregation (P<0.05) were observed in 10 linkage groups. The main cause of the segregation distortions is probably linkage with deleterious or lethal alleles. Ten out of 15 distorted markers were commonly observed in two F₁ population, three of which were shared among all F₁ population. This showed the deleterious loci were shared among the individuals within a local population. That is, neighboring individuals has high proportion of genotype similarity and sharing deleterious loci. These results suggested that inbreeding depression is one of the important factors affecting regeneration of natural beech forest.

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In vitro culture conservation of many forest trees was successful. Cryptomeria japonica survived for 29 months without subculture. Chamaecyparis obtusa was for 24 months, Podocarpus macrophyllus was for 16 months, Pinus thunbergii was for 8 months, Cedrela odorata was for 24 months, Populus euphratica was for 18 months amd Paulownia tomentosa was for 16 months cultured surviving continuously at room temperature without any subculture. However, Quercus acutissima and Eucalyptus citriodora survived only 3 months without subculture at 25 degrees celsius. It is supposed that some extractives like tannin and kino had bad effect for long term storage of forest trees in vitro.Starvation condition of the medium might be effective for long time in vitro conservation of forest trees like in the case of Cedro and Cryptomeria.

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In order to develop the identifing method for Rhus succedanea cultivars, we evaluated fruit shapes of R. succedanea L. based on elliptic Fourier descripters. In this study, five cultivars planted at two places were used. In the result, we observed the following. First, the principal compornent analysis for elliptic Fourier descripters on fruit shape, the accumulating contribution rate of the first 6 components was 89 %. Second, we could almost identify each cultivars in the cluster analysis based on these principal component scores. These results suggested that fruit shapes were useful for identifing R. succedanea cultivars.

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We investigated the influences of volcanic ash covering pine twigs on the behavior and survivorship of adult Monochamus alternatus, as a potential inhibitory factor of the prevalence of pine wilt disease in Sakurajima Island, Kagoshima Prefecture. The adults fed on pine twigs covered with volcanic ash under the individually reared conditions, and their longevity was not shortened significantly compared with those fed on uncoverd twigs. The adults reared in the plastic cases containing a pine twig covered with volcanic ash and an uncoverd twig were not either attracted to nor repelled from both of the twigs. Thus it was not likely that the volcanic ash prevented pine wilt disease from prevailing thorough the effect on the insect vectors.

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This is the first report on Heterobasidion root rots distinguished by DNA sequence analysis of the ITS in Japan.

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