Effects of Exogenous Organic Acids on Phosphorus Availability of Dark Brown Forest Soils and Phosphorus Absorption and Accumulation of Larix olgensis Seedlings with Nutrient Deficiency

Different proportions of A1 and B horizons dark brown forest soils （A1∶B=1∶2） were utilized to set the soil nutrient deficient conditions, and Larix olgensis seedlings were cultivated. By simulating organic acids concentrations in forest litter leachates of northeast China, the effects and mechanism of different concentrations of organic acid solutions on phosphorus （P） availability of dark brown forest soils and P absorption of Larix olgensis seedlings with nutrient deficiency were studied. The results showed that, compared with A1 horizon soils, available P contents of mixed soils in A1 and B horizons decreased, and P accumulation and efficiency of P uptake in root and leaves of Larix olgensis seedlings also decreased, but efficiency of P utilization increased. After treatments of exogenous organic acids, available P contents of mixed soils increased and the impact sequence of different organic acids were succinic acid 〉 citric acid 〉 oxalic acid; the concentration of 5.0 mmol/L had the best function, and the best effect of organic acids was at 20 d. Organic acids also increased P accumulation and efficiency of P uptake in roots and leaves of Larix olgensis seedlings, but decreased efficiency of P utilization. The impact strength of organic acids on P accumulation and efficiency of P uptake varied with treatment time, type and concentration of organic acids. The results of 20 d and 30 d in roots were higher than those of 10 d, however, the results of 10 d and 20 d in leaves were higher than those of 30 d, thus, at the earlier stage of organic acids treatments, more P absorbed were transferred to leaves, and at the later stage, more P would be accumulated in roots. The concentration of 10.0 mmol/L had the best function, and the impact sequence of different organic acids was succinic acid 〉 citric acid 〉 oxalic acid. Therefore, organic acids might contribute to P absorption and accumulation by Larix olgensis seedlings, final y increasing the adaptability and endurance of Larix olgensis seedlings to nutrient deficient soils.

Studies on the Secretion of Organic Acids from Roots of Two-year-old Larix olgensis under Nutrient and Water Stress

[Objective] This study aimed to investigate the effects of nutrient and water stress on the secretion of organic acids from roots of two-year-old Larix olgensis. [Method] Different nutrient and water stress conditions were designed to investi- gate the types and quantities of organic acids secreted from roots of two-year-old L. olgensis. [Result] Under nutrient and water stress, the types of organic acids secreted from roots of two-year-old L. olgensis increased, which varied with different stress levels. In addition, nutrient and water stress also increased the secretory vol- ume of organic acids from roots of two-year-old L. olgensis. The increment in total amount of organic acids reached the maximum under Level 1 （high stress）. Among different types of organic acids, the increment in secretory volume of citric acid reached the maximum, followed by malic acid, while oxalic acid presented relatively small increment. Furthermore, the increment in secretory volume of these three organic acids all reached the maximum under Level 1. [Conclusion] The proportion of the secretory volume of each organic acid accounting for the total amount of organic acids varied slightly, but the overall order was unchanged.

Larix olgensis growth-climate response between lower and upper elevation limits:an intensive study along the eastern slope of the Changbai Mountains,northeastern China

Larix olgensis is a dominant tree species in the forest ecosystems of the Changbai Mountains of northeast China.To assess the growth response of this species to global climate change,we developed three tree-ring width and biomass chronologies across a range of elevations in the subalpine forests on the eastern slope of the Changbai Mountains.We used dendroclimatic analyses to study key factors limiting radial growth in L.olgensis and its variation with elevation.The statistical characteristics of chronologies suggested that elevation is a determinant of tree growth patterns in the study area.Response function analysis of chronologies with climate factors indicated that climate–growth relationships changed with increasing elevation:tree growth at high elevation was strongly limited by June temperatures of the previous year,and as elevation decreases,the importance of temperature decreased;tree radial growth at mid-elevation was mainly controlled by precipitation towards the end of the growing season of the current year.Biomass chronologies reflected a stronger climatic signal than tree-ring width chronologies.Spatial correlation with gridded climate data revealed that our chronologies contained a strong regional temperature signal for northeast China.Trees growing below timberline appeared to be more sensitive to climate,thus optimal sites for examining growth trends as a function of climate variation are considered to be just below timberline.Our study objective was to provide information for more accurate prediction of the growth response of L.olgensis to future climate change on the eastern slope of the Changbai Mountains,and to provide information for future climate reconstructions using this tree species in humid and semi humid regions.

Variation analyses of growth and wood properties of Larix olgensis clones in China

The growth traits (tree height, diameter at breast height, and stem straightness degree) and wood properties [wood density (WD), fiber length, fiber width, ash content (AC), lignin content, cellulose content, hemicellulose content (HEC), and holocellulose content] of 208 26-year-old Larix olgensis clones were analyzed. Except for WD and AC, there were significant differences (p < 0.01) for all traits among clones. The phenotypic coefficient of variation and repeatability of all traits were 9.34-35.33% and 0.218-0.930, respectively. Tree height and diameter at breast height showed significant positive correlation; however, the correlation coefficients among growth characteristics and wood properties were mostly not significant. Ten clones (L70, L56, L82, L90, L59, L91, L61, L92, L86, and L64) were selected as excellent clones under a selection rate of 5%, using tree height, diameter at breast height, and stem straightness degree as evaluation indexes, providing genetic gains of 28.69, 17.96, and 0.67%, respectively. Ten clones (L88, L305, L59, L66, L253, L304, L277, L298, L248, and L293) were selected as excellent clones using wood properties as an evaluation index, with a selection rate of 5%, providing genetic gains in WD, fiber length, fiber width, cellulose content, and HEC of 4.14, 3.64, 9.28, 6.77, and 9.61%, respectively. This study provides a theoretical basis for selecting excellent L. olgensis clones.

Effects of thinning on microsites and natural regeneration in a Larix olgensis plantation in mountainous regions of eastern Liaoning Province, China

In order to understand the effects of thinning on microsite conditions and natural regeneration in the larch plantation, thinning experiment was conducted in a 40-year-old Larix olgensis plantation in Qingyuan County in eastern Liaoning Province, China in 2003-2004 Five thinning treatments （0%, 10.2%, 19.8%, 29.7% and 40.3% thinned） were designed on the same site. After thinning, canopy openness and the microsite conditions such as photosynthetic photon flux density （PPFD）, soil moisture content, and soil temperature were measured in one growing season. Meanwhile, the investigation of natural regeneration was conducted at the end of the growing season. The results showed that the canopy openness increased with the increase of thinning intensities. PPFD and soil temperature and soil moisture content in different soil layers were positively relative with canopy openness after thinning. The richness of regenerating tree species did not significantly increase （p=0.30） after one growing season since thinning, but the regeneration density and frequency of tree species increased significantly （p〈0.05）. In addition, the number of regenerating tree species increased, and the increment was correlated with the characteristics of iudividual tree species. The increasing percentage of regenerating seedlings of the shade-intolerant tree species was more than that of shade-tolerant tree species. Among the investigated regeneration species, the biggest response of seedling emergency to the canopy openness was Phellodendron amurense. This paper confirmed the following conclusions： after thinning, the variety of regenerating tree species was correlative with the characteristics of regenerating tree species, and the distribution of unthinned trees and the site conditions in the investigated larch plantation were the additional factors influencing, the regeneration.

Screening and verification of the factors influencing somatic embryo maturation of Larix olgensis

With embryogenic callus of Larix olgensisis, we investigated the effects of inositol, glutamine, casein hydrolysate, carbohydrate, abscisic acid and silver nitrate concentration on the maturation of the somatic embryo.Three dominant factors emerged, and we developed a response surface model based on the Box-Behnken design.We defined the optimal conditions for the maturation of somatic embryos. The contents of abscisic acid, silver nitrate, sucrose and casein hydrolysis significantly affected the amount of maturing embryos, but inositol, maltose and glutamine had no effect. By establishing a response surface model with multiple factors, we predicted that the optimal number of L. olgensis somatic embryos was 204 ± 4 gon basal medium, containing 18.28 mg Labscisic acid,5.46 mg Lsilver nitrate and 82.67 g Lsucrose. In the verification experiments, the addition of 20 mg Labscisic acid, 5 mg Lsilver nitrate and 80 g Lsucrose to BM yielded an average of 202.06 somatic embryos per gram. These results should guide large-scale breeding of L. olgensis.

Nutrient retranslocation from the fine roots of Fraxinus mandshurica and Larix olgensis in northeastern China

Nutrient retranslocation in trees is important in nutrient budgets and energy flows in forest ecosystems. We investigated nutrient retranslocation in the fine roots of a Manchurian Ash （Fraxinus mandshurica） and a Larch （Larix olgensis） plantation in northeastern China. Nutrient retranslocation in the fine roots was investigated using three methods, specifically, nutrient concentration, the ratio of Ca to other elements （Ca/other elements ratio） and nutrient content. The method based on nutrient content proved most suitable when investigating nutrient retranslocation from fine roots of the two species. The nutrient-content-based method showed that there were retranslocations of N, P, K and Mg from the fine roots of Manchurian Ash, with retranslocation efficiencies of 13, 25, 65, and 38 %, respectively, whereas there were no Ca retranslocations. There were retranslocations of N, P, K, Ca and Mg from the fine roots of Larch, with retranslocation efficiencies of 31, 40, 52, 23 and 25 %, respectively.

COMPARATIVE STUDY ON DROUGHT RESISTANCE OF LARIX OLGENSIS HENRY AND PINUS SYLVESTRIS VAR.MONGOLICA(Ⅰ)──THE INFLUENCE OF SOIL WATER CONTENT ON SEEDLINGS PLANTING IN FLOWERPOT

Water potential (φ w .) and net photosynthetic rate (Pn) of Larix olgensis and Pinns.sylvestris var. mongolica deercased with the deerease of soil water content φw and Pn of L.olgensis changed hardly during the first 9 davs after stopping watering, then deereased sharply at the 10th dav Pn of P sylvestris var mongolica deereased slightly during the lirst 8 days, then deereased sharply at the 9th day Their respiration rate, chlorophyll content and their a/b ratio changed hardly. The tollowing 3 conclusions were obtained and discussed exhaustively . (Ⅰ) φ w can be used to direct watering as a sensitive index of judging whether L. olgensis and P.sylvestris var. mongolica lacking water (2 )The deereasc of Pn of L. olgensis and P. sylvestris var. mongolica when drought had nothing to do with chlorophyll. (3) P. sylvestris var. mongolica had morphological drought resistance . while L,olgensis had physiological drought resistance, and their drought resistance was discnssed comparatively first time.

Exogenous application of succinic acid enhances tolerance of Larix olgensis seedling to lead stress

Larix olgensis A. Henry(Changbai larch) is a productive commercial species and good candidate for afforestation in northeast China. It is widely planted in lead-stressed soils which can induce oxidative damage in this plant. Increasing tolerance to lead(Pb) stress is therefore of keen interest. A greenhouse experiment was conducted to identify the biomass, physiological responses and Pb accumulation of L. olgensis seedlings to Pb stress under succinic acid(SA) application and to explore the interaction of exogenous SA applications and stress resistance. L. olgensis seedlings were planted in Pb-stressed or unstressed haplic cambisols in pots. In Pb-contaminated soils the seedlings were treated daily with concentrations of SA solutions at a rate approximately equivalent to 0, 0.04,0.2, 1.0, or 2.0 mmol kg-1of soil for 10, 20, and 30 days,respectively. Pb treatment induced damage in the seedlings and led to the inhibition of biomass accumulation in roots,stems and leaves, and a rise in Pb accumulation in fine roots and leaves. Malondialdehyde(MDA) content and electrolyte leakage in leaves significantly increased while peroxidase(POD) activities, soluble protein and photosynthetic pigment contents in leaves were all reduced.Physiological toxicity was promoted with increasing Pb treatment times. When Pb-stressed seedlings were exposed to SA(especially 10.0 mmol L-1 over 20 days), the physiological responses for Pb-only were reversed and the biomass of roots, stems, and leaves dramatically increased.SA facilitated Pb uptake in fine roots and leaves but more Pb accumulated in fine roots. The results demonstrate that exogenous SA alleviates Pb-induced oxidative injuries and improves the tolerance of L. olgensis seedlings to Pb stress.

Aboveground biomass and nutrient allocation in an age-sequence of Larix olgensis plantations

Biomass and nutrient （N, P, K, Ca, Mg） stock in various aboveground tree components （stemwood, stembark, branches and leaves） were quantified in an age sequence of pure Larix olgensis plantations （20, 35, 53 and 69 years old） in Northeast China. The results show that the aboveground biomass allocation in various tree components was in the order of stemwood （62%-83%）, branches （9%-21%）, stembark （7%-11%） and leaves （1%-6%） for all stands. The proportion of stemwood biomass to total aboveground biomass increased whereas that of other tree components decreased consistently with stand age from 20 to 53 years old, but kept relatively constant with stand age from 53 and 69 years old. The nutrient allocation in various tree components generally followed the same pattern as the biomass allocation （i.e. stemwood 〉 branches 〉 stembark 〉 leaves）. The proportion of nutrient stock in leaves to total aboveground nutrient stock decreased consistently with increasing stand age, while that in stemwood increased with stand age from 20 to 53 years old but then decreased from 53 to 69 years old. The rate of nutrient removal for stands was estimated at different stand ages under different logging schemes, showing that the rate of nutrient removal would be unchanged when the rotation length was shortened to 20 years by the harvest of stem only, but greatly increased by the harvest of total aboveground biomass. The rate of nutrient removal would be a considerable reduction for all elements by debarking, especially for Ca.

A STUDY ON THE GEOGRAPHIC VARIATION ANDSELECTIONOFTHEBEST PROVENANCE OF LARIX OLGENSIS

On the basis of the results from the geographic provenance test of nine years old /arix olgensis in Liangshui Natural Reserve of our university, a study on the geographic varition and the primary selection of the best provenance of torix oIgensis was carried out. The main results are as follows: 1. The different provenances of Larix olgensis have rich and wide genetic variation, and exist a linear correlation with latitude and longitude in collection area. General trends are enumerated below: Provenances at lower latitude and more west longitude have lighter thousand seed weight. short growth period, higher increment, wide branches, rich leaves and crown as well as worst adaptabi llity. It is a dual-way variation along with two directions of latitude and longitude, and also embodies a change gradually in climate condition from south to north. The temperat ures in seed production site, especially the mean temperature in January and≥10℃ accumulated temperature, are important factors that produce geographic variation for larix olgensis. 2. The variation of different provenances in periodic biological phenomena and growth rhythm trends are that: ① both of the provenances from Changbai Mt. (Ⅲ) and Dashitou(Ⅳ) at low latitude belong to the centralized growth type, and have shout growth period, the difference between these two provenances is that the provenance from Changbai Mt. grows well in all time, Dashitou provennce is well only in later period; ②the provenance from Baidao Mt. (Ⅱ) at middle latitude belongs to even growth type and has longer grpwth period, this provenance has higher increment in early and later periods relatively; ③ Xiaobeihu provenance at high latitude is a growth type among Ⅱ Ⅲ and Ⅳ provenances and has a general growth period, the provenance grows better in middle time and worse in later time. 3. The best provenance in Liangshui Natural Reserve and its meighbourhood is Dashitou Procenance. which growth in height. diameter and volume has exceeded 16. 28%, 46. 27%, 30. 58%, 78. 20, 82. 00% as well as 392. 00% by comparison with the mean value of the contrast and the worst provenance respectively, The result from the height growth of three, five. seven and nine years old Larix olgensis by using the method of order correlation analysis demonstrates that it is possible to make early selection of the provenance. Meanwhile. data from juvenile and mature of larix olgensis plantation also prove the reliability of the early selection. 4. The provenance heritabilities of nine years old larix olgensis in Liangshui Natural Reserve are follows:The heritability of the height growth (h2)is 0. 79; The heritability of the diameter breast height (h2) is 0. 791; The geretic gain is 24. 5%and 40. 36% respectively.

A New Labdane Diterpenoid from the Bark of Larix olgensis Henry var. koreana Nakai

A new diterpenoid was isolated from the bark of Larix olgensis Henry var. koreana Nakai. Its structure was elucidated as 5S, 9S, 10R-labda-8 (17), 13-diene-6a, 15-diol l by spectroscopic methods.

Nitrogen retranslocation, allocation, and utilization in bare root Larix olgensis seedlings

We quantified biomass accumulation and nitrogen （N） re- translocation, allocation, and utilization of Changbai larch （Larix olgen- sis） seedlings subjected to four fertilization treatments （24, 59, 81, 117 kg.ha-1 N） with an unfertilized control during summer and autumn 2009. Ammonium phosphate （18-46-0） was the fertilizer used in all treatments. On both sampling dates, the needles had greater biomass and N content than new （2009） stems and old （2008） stems, and coarse, medium and fine roots （diameters of 〉5, 2-5 mm, and 0-2 mm, respectively）. Higher N concentration was observed in old stems and coarse roots than that in new stems and medium roots. In mid-summer, fine roots had higher N concentration than coarse roots. The treatment with 24 kg.ha1 N had the greatest biomass and N content in needles and old stems, and highest net N retranslocation （NRA） and amount of N derived from soil. On Sep- tember 21, no N translocation was observed, while the treatment with 24 kg.ha^-1 N had the highest N utilization efficiency and fertilizer efficiency. Vector analysis revealed that all four fertilization treatments induced Nexcess relative to the control. The treatments with 59, 81, 117 kg.ha^-1 N induce N excess compared with treatments at 24 kg.ha-1 N. We conclude that the traditional local fertilizer application rates exceeded N require- ments and N uptake ability for Changbai larch seedlings. The application rate of 24 kg.ha^-1 N is recommended.

Genetic variation and superior provenances selection for wood properties of Larix olgensis at four trials

Larix olgensis,one of the most important timber species in northeastern China,is used for paper making and construction.In this study,10 wood properties(wood density,fiber length,fiber width,fiber length-to width ratio,hemicellulose content,cellulose content,holocellulose content,lignin content,ash content,and carbon content)of 10 provenances of L.olgensis planted at sites of CuoHai(CH),JiaGeDaQi(JGDQ),LiangShui(LS),and Mao'erShan(MES)were analyzed.The results of ANOVA showed that almost traits differed significantly among locations and provenances,with a significant interaction effect.Each trait also differed significant among provenances within sites.The phenotypic and genetic coefficient of variation(PCV and GCV)and provenance heritability(H 2)for wood properties ranged from 1.122 to 27.365%,from 0.564%to 21.113%and from 0.332 to 0.996,respectively.A correlation analysis showed that wood density was significantly negatively correlated with cellulose content and holocellulose content at sites CH,JGDQ,and LS,but were significantly positively correlated at site MES.Wood density was significantly negatively correlated with lignin content at CH and JGDQ,but not at LS and MES.Fiber width(FW)was negatively correlated with the ratio of fiber length(FL)to width across sites,and FW and FL/W were all positively correlated with FL.Lignin content was significantly positively correlated with hemicellulose content at site JGDQ and significantly negatively correlated with cellulose content and with holocellulose content at site MES.Interestingly,carbon content was positively correlated with cellulose content and holocellulose content at CH,but negatively correlated with these two traits at site MES.In a correlation analysis of wood properties with geographic,soil and climatic characteristics at the four sites,wood properties were mainly correlated with latitude and altitude of the site and affected by the average annual precipitation and temperature simultaneously.To select superior pulpwood provenances and high carbon storage provenances,we selected the two best provenances with excellent wood properties for each location based on a multi-trait comprehensive evaluation,which can be used as the preferred materials for the establishment of large-scale plantations in specific locations.

THE EFFECT OF LOW TEMPERATURE ADVERSITY ON MALE FLOWERS AND POLLEN IN LARIX OLGENSIS

The electrie conductivity of pollen life-force and male flowers of Larix olgensis on condition of low temperature adversity has been respectively measured by means of fluorescent dying method and conductivity method in 1992 and 1994. The results indicate that:(1 ) If the same clonal pollen is treated at equal time at different low temperatures, there are significant differences in pollen life-force, the pollen life-force is the largest between O℃aild -3℃, in higher or lower temperature range, the pollen life-force will decrease. The measurement of electric conductivity of male flowers provcs that the low temperature of below -3℃ is the inain reason that the cell membrane is damaged and the pollen.life-force decreases. (2) The same clonal pollen life-force at the saine low temperature will gradually decrease with the increasing of frozen time. Its main reason is that suffocation and losing body fluid result in the damage of cell membrane, the measurement of electric conductivity of male flowers call prove that. (3) If pollen is treated with the same low temperature, the humidity will be the main factor of affecting pollen life-force. (4) There are significant differences in Larix olgensis's resistance against low temperature in its different growth stage, the male flower's resistance of near pollen spreading period is low. (5) The resistance is different within clones. (6) The resistance against low temperature of Larix call be incrcased by means of chemical treatment.

Preliminary analysis of two NAC transcription factor expression patterns in Larix olgensis

The NAC transcription factor family is plant-specific with various biological functions.However,there are few studies on the NAC gene involving coniferous species.Bioinformatics research and expression analysis of NAC genes in Larix olgensis can be used to analyse the function of the NAC gene in the future.Screening of excellent genetic materials and molecular breeding have been utilized to cultivate high-quality,stress-resistant larches.According to the transcriptome data for L.olgensis,the genes Uni-gene81490 and Unigene70699 with complete ORFs(open reading frames)were obtained by conserved domain analy-sis and named LoNAC1 and LoNAC2,respectively.The cDNAs of LoNAC1 and LoNAC2 were 1971 bp and 1095 bp in length,encoding 656 and 364 amino acids,respectively.The molecular weights of the proteins encoded by the two genes were predicted to be 72.61 kDa and 41.13 kDa,and subcellular localization analysis indicated that the proteins were concentrated in the nucleus.The results of real-time quantitative PCR analysis showed that at different growth stages and in different tissues of L.olgensis,the relative expression levels of the two NAC genes were highest in the stem,and the expression differences were more obvious in non-lignified tissues.After drought,salt and alkali stress and hormone treatment,expression was induced to different degrees.The expression levels of LoNAC1 and LoNAC2 in semi-lignified L.olgensis were higher than in the other two periods(non-lignified and lignified),and expression levels significantly increased under drought and salt stress.Relative expression levels changed under hormone treatment.It is speculated that these two genes may not only be related to drought and salt stress and secondary growth but may also be induced by hormones such as abscisic acid.Overall,LoNAC1 and LoNAC2 are genetic materials that can be used for molecular breeding of larch.

Mining Myb transcription factors related to wood development in Larix olgensis

Larix olgensis A.Henry is a fast-growing tree used for aff orestation in northeastern China and has great ecological and economic value.For studying developmental genes in the xylem of this species,we investigated the Myb transcription factor family,one of the largest families of transcription factors in plants,which plays an important role in the regulation of lignifi cation in plant secondary walls.By sequencing a L.olgensis cDNA library using the Illumina HiSeq2500 high-throughput sequencing platform,we obtained 58,683 unigene sequences,of which 16,554 unigenes were longer than 1000 bp,accounting for 28.2%of the total database.The alignment of these genes with the GO,COG,KEGG,Swiss-Prot and NR databases resulted in annotated 29,350 unigenes.We obtained a total of 1460 differentially expressed genes,of which 453 were upregulated and 1007 were downregulated at the two developmental stages analyzed.The gene annotations showed a wide range of biological functions and metabolic pathways.The 10 Myb transcription factors that were obtained from the diff erentially expressed genes were analyzed by real-time quantitative PCR(qRT-PCR).The results showed that four Myb transcription factors may be associated with xylem development in L.olgensis.Due to the large genome size of conifers,genomics research on these species has lagged behind that for other plant groups.Our data provide the basis for further studies on xylem development in L.olgensis.

THE OCCURRENCE AND DEVELOPMENT OF THE ADVENTITIOUS ROOTS FORMING GREEN SHOOT CUTTING OF LARIX OLGENSIS

The experiment with the green shoot cutting propagation of Larix olgensis was made in the Maoer Mountain Forestry Farm on July 5, 1990. After the callus formed of the cutting base before adventitious roots came out the materials were collected from the cutting base and fixed in FAA solution. By the paraffin sections and anatomical observatio-n. the results indicted that it needed 40 days from the cutting to the rooting. The induced primordium of the cutting was endogenous in origin, which came from : (1) vascular cambium of the callus, and became roots; (2) meristematic cell population in the intersect between the cambium and xylem ray of the cutting base. There were extruding, crushing process and enzymolysis when the adventitious roots broke through the outer layers in two rooting types.

EFFECT OF LOW TEMPERATURE ON POLLEN VITALITY OF LARIX OLGENSIS

After the treatment of pollen of larix olgensis at the different low temperature, the pollen vitality was observed by using fluorescent staining method. Several conclusions were obtained: 1) 0℃-3℃ is the best temperature range for storing pollen of Larix olgensis. 2) At the same temperature, humidity is the key factor influencing the pollen vitality. 3) Different clones shows different resistance to low temperature. Among the ten clones 2# clone shows the highest resistance.

Dendrochronology-based stand growth estimation of Larix olgensis forest in relation with climate on the eastern slope of Changbai Mountain, NE China

The eastern slope of Changbai Mountain is characterized by pure larch forest （Larix olgensis） with little human disturbance. Response of tree growth to climate in this area remains unknown. Meanwhile, little is known about how climate variations affect the biomass increase which could be recognized as a three-dimensional tree growth index. The objective of this study is to investigate the climate effects on the radial and biomass growth of larch on eastem slope of Changbai Mountain. Tree-ring width chronologies and mean annual biomass increment were established using tree-ring data. We used correlation analysis and multiple regression analysis to explore the relationship between larch growth and climatic factors from 1957 to 2009. Results show that tree-ring growth and mean annual biomass increment were primarily and significantly affected by previous year climatic variables with slight difference among months. Temperatures were more consistently and strongly corre- lated to the chronologies and mean annual biomass increment than was precipitation. Temperature is the main factor limiting larch growth on Changbai Mountain and the ongoing climate warming may accelerate the growth of the species. The current stand biomass of the area was 240.72Mg.ha-1 and the annual stand biomass increment in 2009 was 2.91 Mg.ha-1. In conclusion, the old-growth forest in the study area is still accumulating carbon efficiently.