中国杉王整枝复壮后新枝生长研究

生长在贵州省习水县太坪村的中国杉王，栽植于宋代，距今己800多年，其树高达44．8米，胸径达238厘米，冠幅达21米，主干立木蓄积达88．94立方米，由于多年管理工作未及时跟上，出现了严重的顶端部份腐烂、枝干干枯、树冠部份出现病虫危害、枝叶发黄，新枝萌发明显减少，呈现出严重的树体老化现象。在2007年至2008年期间，经过多方面的调查、分析，研究，编制了《中国杉王整枝复壮工程实施方案》，经过综合治理，中国杉王新发枝的生长情况特别明显，通过采枝取样检测与附近不同树龄与林木当年新枝检测数据表明：经过整枝复壮技术处理后，取得了非常明显的成效。

中国杉王整枝复壮技术研究

生长在贵州省习水县的中国杉王,栽植于宋代,距今己800余年。近年来,由于树龄较长,加之九十年代树梢被雷击燃烧,便出现大量枝叶枯黄,而呈现出严重的老化现象。若不及时进行预防和综合技术措施处理,那么,这棵享誉国内外的中国杉王,就会提前衰老甚至枯死。针对这一严峻现象,本文从该树的顶梢部份、树冠部份、地下根部进行了综合预防技术措施处理及其研究。

cDNA Cloning, Expression and Characterization of Taxadiene Synthase, a Diterpene Cyclase from Taxus chinensis

Taxadiene synthase, a diterpene cyclase, catalyzes the conversion of geranylgeranyl diphosphate (GGPP) to taxadiene, a key intermediate in Taxol biosynthesis in yew. A 2 151 bp cDNA fragment encoding taxadiene synthase of Taxus chinensis (Pilg.) Rehd. was cloned by homology-based PCR and cDNA library screening. The 5′-terminal 611 bp cDNA fragment of taxadiene synthase was isolated by PCR. The two fragments were ligated together and gave a 2*!712 bp cDNA fragment with a 2*!586 bp open reading frame (ORF), encoding 862 amino acid residues including a presumptive plastidial transit peptide. The taxadiene synthase of T. chinensis most closely resembles the one from T. brevifolia (97% identity). Heterologous overexpression of 2.5 kb cDNA fragment from T. chinensis was obtained using a fusion expression vector pET-32a and the Escherichia coli strain BL21trxB. The expressed proteins from E. coli BL21trxB were present as inclusion bodies. After the inclusion bodies were denatured, renatured and refolded, the recombinant enzyme was purified by a single step with a His-binding metal affinity column. The catalytic product of taxadiene synthase of T. chinensis was detected by capillary gas chromatography-mass spectrometry (GC-MS) and identified as taxa-4(5),11(12)-diene.

Biomass, litterfall and the nutrient fluxes in Chinese fir stands of different age in subtropical China

Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.), a fast-growing, ever-green conifer tree with high yield and excellent quality, is the most important tree species of timber plantations in subtropical China. We investigated the characteristics of biomass, litterfall and nutrient fluxes in the 8, 14 and 24 year-old stands, representing the young, middle-aged and mature stands. The results showed that Chinese fir plantations in central Fujian province had high productivity, and the proportion of stem mass in total biomass was between 50%-70%. Chinese fir was low nutrient-return tree species with litterfall. Nutrient withdrawal from senescing needles was a strong age-dependence for nitrogen, phosphorous and potassium in Chinese fir. With a management system of such short-rotation and continuously pure-crop planting, harvesting timber can lead to great nutrient loss, which may be one of the causes for site degradation.

Soil Biological Changes for a Natural Forest and Two Plantations in Subtropical China

Conversion of natural forests into pure plantation forests is a common management practice in subtropical China.To evaluate the effects of forest conversion on soil fertility, microbe numbers and enzyme activities in topsoils (0-10 cm)were quantified in two 33-year-old monoculture plantations of Castanopsis kawakamii Hayata (CK) and Cunninghamia lanceolata Lamb. (Chinese fir) (CF), and compared to a neighboring relict natural C. kawakamii forest (NF), in Sanming,Fujian. Five soil samples were collected once each in January, April, July, September and November in 2000 in each forest for laboratory analysis. Over the sampling year, there were significant differences for bacteria, fungi and actinomycetes between forests and between seasons (P ＜ 0.05). The largest bacteria and fungi populations were in NF, while CF contained the greatest number of actinomycetes. There were also significant differences (P ＜ 0.05) with microbial respiration for forests and seasons. Additionally, compared with NF, urease and acid phosphatase were significantly lower (P ＜ 0.05)in CK and CF. Also, the correlations of soil hydrolysable N and available P to soil microbial and enzymatic activities were highly significant (P ＜ 0.01). Thus, to alter the traditional Chinese fir monoculture so as to mimic the natural forest conditions, managing mixed stands of Chinese fir and broadleaf trees or conducting crop rotation of conifers and broadleaf trees as well as minimizing forest disturbances like clear-cutting, slash burning and soil preparing, could be utilized.

Effect of temperature on soil respiration in a Chinese fir forest

Soil samples collected from the surface soil （0-10 cm） in an 88-year-old Chinese fir （Cunninghamia lanceolata） forest in Nanping Fujian, China were incubated for 90 days at the temperatures of 15℃, 25℃ and 35℃ in laboratory. The soil CO2 evolution rates were measured at the incubation time of 2, 5, 10, 15, 20, 25, 30, 35, 40, 50, 60, 70, 80 and 90 days. The results showed that CO2 evolution rates of soil samples varied significantly with incubation time and temperature during the incubation period. Mean CO2 evolution rate and cumulative amount of CO2 evolution from soil were highest at 35℃, followed by those at 25℃, and 15℃. Substantial differences in CO2 evolution rate were found in Q10 values calculated for the 2nd and 90th day of incubation. The Q10 value for the average CO2 evolution rate was 2.0 at the temperature range of 15-25℃, but it decreased to 1.2 at 25 35℃. Soil CO2 evolution rates decreased with the incubation time. The cumulative mineralized C at the end of incubation period （on the 90th day） was less than 10% of the initial C amounts prior to incubation.

The efficacy and its related issues of combination of bevacizumab and taxanes-based regimens in Chinese patients with metastatic breast cancer

Objective: Bevacizumab has been challenging in the treatment of metastatic breast cancer. To investigate its efficacy, optimal partner to combine with and maintenance therapy, we performed a retrospective study based on Chinese patients with metastatic breast cancer (MBC). Methods: Patients with MBC treated with bevacizumab-contained regimens at the Sun Yat-sen University Cancer Center from 2006 to 2010 were recruited to the study. The primary endpoints were overall survival (OS), time to progression (TTP), objective response rate (ORR), and disease control rate (DCR). These endpoints were analyzed using the Kaplan-Meier and Chi-squared tests, respectively. Results: (1) A total of 229 cycles of bevacizumab with a median cycle of 7 (1-34) were administered among 25 patients. (2) In the whole group, ORR and DCR were 60% (15/25) and 76% (19/25), respectively. The mTTP was 5 months (1-21), mOS from diagnosis was 48 months (13-172), mOS from bevacizumab administration was 24 months (1-45). (3) Both ORR (73.7% vs. 16.7%, P = 0.023) and DCR (94.7% vs. 33.3%, P = 0.005) were significant higher once patients treated with the combination of taxanes-based regimen and bevacizamab when compared with the combination with non-taxanes-based regimens. (4) In the taxanes-based group, no matter bevacizumab used in first line or non-first line, the differences of ORR (P = 0.637) and DCR (P = 0.316) were insignificant. However, the maintenance therapy with bevacizumab will bring more longer TTP (P < 0.001) than those without maintenance therapy. Conclusion: Taxanes-based regimens were the optimal candidate to combine with bevacizumab regardless the timing in palliative setting, however, the maintenance therapy with bevacizumab should be considered once indicated.

Spatial pattern analysis and associations of different growth stages of populations of Abies georgei var.smithii in Southeast Tibet,China

Abies georgei var.smithii is an important plant species in Southeast Tibet,China.It has high ecological value in terms of biodiversity protection,as well as soil and water conservation.We analyzed the spatial pattern and associations of A.georgei var.smithii populations at different growth stages by using Ripley's L function for point pattern analysis.The diameter structure was a nearly reverse 'J' shape.The amount of saplings and medium-sized trees accounts for a large part of the entire population,suggesting a high regeneration rate and an expanding population.In the transition from saplings to medium trees or to large trees,saplings show a significant aggregation distribution at small scales,while medium trees and large trees show a random distribution.There are significant inverse associations between saplings and medium trees and large trees at small scales,while there are no obvious associations between medium trees and large trees.The natural regeneration was affected by interspecific competition,and it was also affected by intraspecific competition.The joint effects of biological characteristics and environmental factors contribute to the spatial distribution pattern and associations of this A.georgei var.sm ithii population.

Formation of Los Angeles's low density and high car dependence

As a typical car-dependent city, Los Angeles （LA） is extensively used as an example in research to illustrate car influences on city form. Focusing on the features of LA＇s geologic conditions and civil circumstances, we argued that the relationship between LA＇s low-density pattern and car dependence is more involved than previously deemed simple causality. The low density should be primarily credited to the spacious requirement of the mining industry, frequent earthquakes and multiethnic population of the city. Off reserves in LA fueled its economic boom and fast urbanization that coincided with the start of mass production of cheap cars, and cars became medium-priced consumables for average families. Politicians preference for short constrnction-period projects enabled fast establishment of LA＇s highway infrastructure. The popularity of car use in return faciliatated further development of the low-density pattern of the city. The low-density urban form and car dependence created environmental and social problems for LA. Looking at P. R. China＇s motorization and urban development, we found that the trajectory of Beijing＇s motorization between 197g and 2003 coincides with that of the U.S. in the 1910s and 1920s. Lessons from LA＇s urban and transportation development should be suggestive to China＇s urban and transportation planning.

NDVI Variation of Tree Rings between March and May since 1915 in the Eastern Part of the Qilian Mountains of China

[Objective] The aim was to analyze the correlation between tree-ring width of Picea crassifolia in the east of Qilian Mountains and the precipitation, temperature and the normalized difference vegetation index (NDVI). [Method] The correlation analysis and the regression analysis were used in this study. [Result] The tree-ring width was significantly correlated with the autumn precipitation and the spring average NDVI. The conversion equation between tree-ring width and spring NDVI (R2 = 48.5% , R2adj =46.2% , F =21.627, P <0.001) was developed and NDVI sequence was reconstructed during the period 1915 -2007. The drought in the 1920s was pronounced. Vegetation cover in the Qilian Mountains increased during the period 1922-1934, 1940-1957, 1965-1969, 1984-1988 and 1995-1997, but decreased during 1935 -1939, 1958 -1964, 1970 -1983, 1989 -1994 and 1998 -2005. [Conclusion] The reconstructed NDVI showed the drought evolution in the study area.

Use of Near Infrared Spectroscopy to Measure Mechanical Properties of Solid Wood

The visible and near infrared(NIR)(350-2500 nm)spectra and the MOE of 438 small clear wood samples from Chinese fir,eucalyptus and poplar 72 were measured.Using partial least-square(PLS)modeling,the NIR spectra could be used to predict MOE and MOR of the clear-wood samples from Chinese fir and eucalyptus solid wood.NIR spectra could only be used to predict MOE but not MOR of poplar clear-wood samples.With the exception of MOR of poplar clear-wood samples,the correlations between NIR and the mechanical properties are very strong,and the calibration and test correlation coefficients are both above 0.80.

Intratree Variability of Tensile Strength Parallel to Grain in Chinese Fir and I-214 Poplar from Plantation

The variation of tensile strength parallel to grain in Chinese fir and 1-214 poplar wood from plantations was studied in this paper. Aaccording to the national standards The Testing Methods for Physical and Mechanical Properties of Wood （GB 1927 to 1943 -- 1991）, the small clear wood samples were cut and tested, which represent the south and north of trees with heights of 1.3, 3.3, 5.3 and 7.3 m. The results showed： the tensile strength parallel to grain of the north wood was higher than that of south wood. ANOVA shows that the tensile strength parallel to the grain with height is of significant difference （at 0.05 level）.

Study on Chemical Components and Properties of Radial Chinese Fir

The variability of main chemical composition of radial Chinese fir was studied. Analysis of variance showed that variance was significant, especially for holocellulose and α-celluloSe; the hblocellulose content in heart wood was lower than that in sapwood; the lignin content decreased from Position t to Position 3, but increased gradually from Position 4 to Position 8; the a ~ cellulose content in heart wood was lower than that in sapwood; and the relative crystallinity was 59.97% in Position 1, 60i80% in Position 2, and about 42% in others.

Applicability of Visual Grading to Chinese Fir Structural Lumber

As one of the most important plantations,Chinese fir has drawn more and more attention from domestic wood researchers.And as the development and increasing of plantation resource of Chinese fir,research and development of the product will become a hot point.In this paper,we chose 1 571 pieces of structural lumbers from 4 areas to research grading.After sawing,drying and dressing,the lumbers were separated into 3 main grades by GB50005-2003 Code for Design of Timber Structures,namely SS,No.1 and No.2.The conclusions are that knot as the maximum strength reduced defect(MSRD)is a main character in the lumber,the visual quality of Fujian structural lumbers is polarized,and the applicability of visual grading to the lumber is poor,so we hold the point that we should adjust the grading rules to gain a better grading result.

Study on Variation Pattern of Microfibril Angle in Chinese Fir

Microfibril angle （MFA） in Chinese fir was tested by X-ray diffraction apparatus and calculated by computer software. The results were as follows： MFA was controlled strongly by inheritance, and there was no significant difference in MFA among interspecies, juvenile and mature wood. In the longitudinal, MFA reduces with the height rising from 0 to 5.5 m, especially in the heights from 0 to 1.5 m. The values of MFA are nearly consistence from 1.5 to 7.5 m. The variation range was between 10.82°and 12.57°from 1.5 to 7.5 m, R2 of power equation achieved 0.932 1, and analysis of variance indicated that the variation of MFA was not significant from 1.5 to 7.5 m, The age of the trees had an important influence on MFA, consequently, the difference in MFA was significant among annual rings in radial, which was maximal in near pith and reduced rapidly from the pith to sapwood, and its decline tendency was slow beyond the ninth annual ring. MFA reached minimum value at the 15th annual ring, and the difference reached more than 20° and R^2 of binomial equation achieved 0.755 6.

Properties of Wood/Montmorillonite Nanocomposites

With montmorillonite (MMT) organically modified as organophilic-MMT (OMMT) and water-soluble phenol formaldehyde resin (PF) as intermediate, the nanocomposites of Chinese fir (Cunninghamialanceolata) wood and MMT, i.e. WMNC, were prepared via nano intercalation compounding, some propertiesof WMNC were analyzed. Results show that, compared with Chinese fir wood and its PF-impreg, WMNChas lower humidity and water absorption, better dimension stability, higher longitudinal compressive strength,abrasive resistance, fire-resistance, and water-leaching resistance with a very low mass ratio about 3% ofMMT. The nano intercalation compounding of wood and exfoliated MMT nanolamellae is very promising.More studies should be carried out to fully reveal the nanosize effects and the special properties of WMNC.