Dynamics of soil inorganic phosphorus fractions at aggregate scales in a chronosequence of Chinese fir plantations

Successive cultivation of Chinese fir(Cunninghamia lanceolata) would markedly affect the distribution and accumulation of soil inorganic phosphorus(Pi).However,how different chronosequence phases of Chinese fir plantations exerting influences on the quality and quantity of soil Pi fractions in aggregate-scale remain poorly understood. This study researched the dynamic changes of aggregate-related Pi fractions encompassing occluded-P(O-P), aluminum-bound P(Al-P), iron-bound P(Fe-P), and calcium-bound P(Ca-P) in topsoil(0-20 cm) from different stand aged(9-, 17-, and 26-yr) Chinese fir plantations and one nearby abandoned land(CK) in Rongshui County,Guangxi, China. In this study, soil aggregates were classified into micro-aggregates(< 0.25 mm), small macro-aggregates(1-0.25 mm), medium macroaggregates(2-1 mm), and large macro-aggregates(> 2 mm) by one wet-sieving process. As the primary aggregate fractions correlated with better soil aggregate stability, the large macro-aggregates took the highest proportion in all aggregate sizes regardless of various stand ages of Chinese fir plantations. Besides, the 17-yr plantations of Chinese fir displayed the highest stability of aggregates structure. Compared with CK, all four soil Pi fractions from three different stand ages of Chinese fir plantations generally showed increasing trends.Irrespective of chronosequence phases, Al-P was mainly carried by small macro-aggregates. O-P showed the opposite tendency to Al-P, which had the lowest content in small macro-aggregates. Fe-P and Ca-P showed an even distribution in all aggregates.The contribution rates and stocks of each Pi fraction exhibited close relevance to the content of soil aggregates. As revealed from the results, planting of Chinese fir before 17-yr was beneficial to prompt the formation of large macro-aggregates and the level of soil P. But after 17-yr, successive monoculture planting of Chinese fir would reduce the stability of soil aggregates and render the losses of soil P. The dynamics of soil total phosphorous(TP) and Pi fractions contents were highly related to the stand ages of Chinese fir plantations, but less related to the distribution of soil aggregate sizes. As the major carriers for soil P stocks, the large macro-aggregates played a vital role in the cycles and reserves of soil P.

Effects of microwave post-treatments on leaching resistance of ACQ-D treated Chinese fir

In order to improve the leaching resistance of active ingredient-copper in ammoniacal copper quat-type D （ACQ-D） treated Chinese fir （Cunninghamia lanceolata Hook.）, microwave post-treatments were carried out. The percentages of leached copper from ACQ-D treated Chinese fir with different microwave post-treatments were obtained after leaching tests by analyzing the copper retention in treated wood. The fixation mechanism of copper in the treated wood was determined with the help of SEM and FTIR spectra, while the valence conversion of copper after microwave post-treatments was studied by UV spectroscopy. Our experimental results show that the percentage of leached copper was reduced significantly after microwave post-treatment over time. This development was reinforced by allowing even more time for the treatment as well as with an increase in the power of microwave post-treatment. The leaching resistance of copper in wrapped samples was better than that in unwrapped samples, which is attributed to the combined effects of temperature and moisture content. Compared with air-dried samples, the valence conversion in the samples with microwave post-treatments changed slightly, which demonstrates that microwave post-treatments cannot impair the natural decay resistance of ACQ-D treated wood. SEM and FTIR spectra showed the presence of crystal particles formed by chemical reactions between copper and wood ingredients in wood cell walls and wood pits. Only a small amount of copper reacted with cellulose, while lignin and hemicellulose were the major bonding sites for copper in wood. Given the experimental results of mechanical properties, microwave post-treatments had a slight effect on the compression strength parallel to the grain and on the erystallinity of ACQ-D treated Chinese fir.

模拟氮沉降对杉木人工林(Cunninghamia lanceolata)土壤酶活性及微生物群落功能多样性的影响

在杉木人工林中开展模拟氮沉降试验,设计N0(对照)、N1(N 60 kg/(hm2.a))、N2(N 120 kg/(hm2.a))和N3(N 240 kg/(hm2.a))等4个氮沉降水平。通过连续7年的处理后,研究了外加氮源对土壤酶活性及群落功能多样性的影响。相同氮沉降处理下,参与土壤碳循环的6种主要酶(蔗糖酶、纤维素酶、淀粉酶、β-葡糖苷酶、多酚氧化酶、过氧化物酶)活性、土壤微生物群落碳源利用能力和多样性指数与均匀度指数均随土层加深而降低。氮沉降对纤维素酶和多酚氧化酶具有促进作用,而对淀粉酶和过氧化物酶表现出一定的抑制作用;中?低氮沉降(N1、N2)对蔗糖酶无影响,而对β-葡糖苷酶具有促进作用,高氮沉降(N3)促进了蔗糖酶活性,但抑制了β-葡糖苷酶活性。各土层中,低氮处理(N1)促进了微生物群落碳源利用能力和多样性指数与均匀度指数的增加,而中?高氮处理(N2、N3)则呈抑制作用。主成分分析表明,土壤微生物群落利用的主要碳源为碳水化合物和羧酸,不同氮沉降处理碳源利用类型存在差异。因此,氮沉降促进了表层土壤纤维素酶、多酚氧化酶和蔗糖酶的活性,但在一定程度上抑制了淀粉酶、过氧化物酶和β-葡糖苷酶活性;氮沉降增加改变了杉木人工林土壤微生物群落的功能多样性。

氮沉降下杉木(Cunninghamia lanceolata)人工林凋落叶分解过程中C、N元素动态变化

在12年生的杉木(Cunninghamia lanceolata)人工林中开展模拟氮沉降试验,分N0(对照)、N1、N2、N3等4种处理,N沉降量依次为0、60、120、240kgNhm-2a-1,每处理重复3次。通过2a的监测和分析发现,经N0、N1、N2、N3处理后,凋落物分解过程中C平均含量分别为46.47%、46.35%、46.79%、46.6%,各处理之间无显著差异,但均随着分解时间的增加呈下降趋势。氮沉降明显增加了凋落物中的N含量,且随着沉降水平的增加而增加。各处理凋落物C的分解系数依次为0.739、0.744、0.936、0.708,周转期为4.26a、4.26a、3.46a、4.41a;而N的分解系数分别为0.458、0.543、0.776、0.565,周转期为6.26a、5.44a、3.91a、5.20a。N1处理表现出促进N释放的作用,但对C释放影响不明显;N2处理促进了凋落物C、N元素的释放,而N3处理则表现出一定的抑制作用。氮沉降处理也明显降低了凋落物的C/N比,N1、N2、N3处理使C/N比分别比N0下降8.59%、14.20%和17.54%。

杉木高世代杂交子代生长与木材性状遗传分析

为揭示杉木高世代杂交子代生长与材性性状的遗传效应,选择优良的杂交组合,利用设置在浙江省开化县林场的4×5双因素交叉设计的杉木高世代杂交子代测定林,研究8年生杉木的生长性状、木材基本密度和树干碳含量,估算各性状一般配合力(GCA)/特殊配合力(SCA)效应值及相对重要性,分析遗传控制方式及性状间的相关性。结果表明:杉木树高、胸径、单株材积、木材基本密度、树干碳含量在杂交组合间均差异显著(P<0.05),含碳率在组合间差异不显著。父母本配合力分析显示,树高、胸径、单株材积、树干碳含量的母本效应均大于父本效应,C25-3母本效应最大,B109-3父本效应最大;杂交组合各性状均以加性基因效应控制为主,杉木高世代育种工作仍需注重亲本的选配。性状间相关性分析表明,树干碳含量与生长性状呈显著正相关,按10%的入选率,联合选择出3211和3215两个速生高固碳的杂交组合,单株材积较对照(CK)增加30.91%以上,树干碳含量较CK增加26.95%以上,而木材基本密度与生长性状呈弱相关或负相关,筛选出3218和3216两个木材性状优良的杂交组合,木材基本密度较CK增加2.17%以上。

杉木林改造成阔叶林对根际和非根际土壤磷组分和转化的影响

磷(P)是维持亚热带森林生态系统生产力的关键因子。杉木主要分布于我国亚热带地区,杉木林的土壤酸化,P利用效率低,研究杉木林转化后对土壤P的影响、对生态系统的稳定和森林可持续经营具有重要意义。该研究以南亚热带杉木林采伐迹地上重新种植的杉木林、红锥林、米老排林和红锥/米老排混交林为研究对象,采集根际土和非根际土,重点探究南亚热带杉木人工林改造成阔叶林后土壤P组分及转化的影响。结果表明:(1)改造后的红锥林、米老排林和红锥/米老排混交林的根际和非根际土壤的微生物生物量P含量及酸性磷酸酶活性均显著高于杉木林,红锥林和红锥/米老排混交林的土壤全P比杉木林和米老排林更容易转化为速效P。(2)红锥林和红锥/米老排混交林的根际和非根际土壤中氯化钙提取P的含量均显著高于杉木林和米老排林,米老排林和红锥/米老排混交林根际和非根际土壤中酶提取P、盐酸提取P和柠檬酸提取P的含量显著高于杉木林和红锥林。(3)RDA结果显示,调控根际和非根际土壤P组分的关键因子分别是土壤含水量和微生物生物量碳。综上认为,将杉木林改造成阔叶林有利于森林土壤P的储存和供应,该研究结果为提高南亚热带人工林土壤P有效性的树种选择和经营管理策略等提供了重要科学依据。

抚育间伐强度对杉木林生长的影响

为探究不同间伐强度对杉木林生长的影响,以广西桂北地区为研究地点,以杉木的树高、胸径、材积和生物量为研究对象,考察不同间伐强度下杉木林树高、胸径、材积和生物量的生长情况。结果表明:20%、30%、40%3个间伐强度均对杉木树高、胸径、材积和生物量的增长有显著影响,30%间伐强度下杉木树高、胸径、材积和生物量的增长最明显,树高、胸径和材积较抚育前分别提高了6.50%、11.84%、23.34%,根部、叶部、枝部和整株的生物量较抚育前分别提高了19.53%、17.82%、16.54%、27.69%。指出了杉木林间伐抚育过程中,选择30%的间伐强度有利于杉木林的生长。本研究为杉木林的科学间伐抚育提供了理论依据。

基于机载激光雷达技术的山区针叶林单木分割方法研究

以杉木为研究对象,利用无人机激光雷达点云数据,结合地面实测样地数据,探索创新现有的森林资源调查模式,提升森林资源外业调查效率,更新资源调查数据,保证数据的现势性。考虑到研究区为山地林区,地面起伏较大,选取了一种基于改进加密三角网滤波算法进行滤波和分类,并对比分析了分水岭、点云分割、层堆叠种子点三种不同的单木分割方法,完成了研究区单木位置、树高、冠幅等林木参数的提取研究,优化了激光雷达林木参数反演的技术流程。从30个样地中抽取10个样地,对比样木实测值与单木分割的估测值,结果表明:层堆叠种子点算法分割效果最优,F评分在64.61%~85.29%之间;点云分割算法居中,F评分在56.00%~80.60%之间;分水岭算法分割效果最差,F评分在45.57%~69.45%之间。同一种方法中,不同样地分割效果也存在差异,这可能与样地地形、树木结构形态等因素有关;样地中林木分布存在树木遮挡或树木分布结构不规则时,一定程度会降低单木分割精度。因此,根据不同林分情况,建立适用性较强的无人机激光雷达森林参数反演模型是未来努力的方向。

保山杉木硫酸盐化学法制浆性能研究

通过测定保山杉木化学组分,并采用硫酸盐法蒸煮制浆,测定纸浆性能,全面评价杉木的制浆造纸性能。结果表明,杉木纤维长度与思茅松相当,细小纤维含量更低,杉木浆抄纸的耐破指数、二氯甲烷抽出物、抗张指数略高于思茅松,但撕裂指数、透气度较低。杉木树皮的成浆性能差,得率低,制浆的可行性低。综合分析,杉木的制浆性能略劣于思茅松,可作为造纸用材。

不同施肥方式对杉木木荷混交林的影响

为探究不同施肥方式对混交造林的影响,以江西省赣州市南康区大山脑国有林场作为杉木木荷混交林试验地,进行梯度施肥实验,分别设置复合肥梯度为100、200、300 g/株和不施肥对照(CK)。结果表明:各个梯度施肥方式均显著促进了杉木和木荷高度和地径的增长,造林8个月后,100 g/株施肥方式杉木高度最高为47.1 cm,地径最大为9.1 mm,相对对照(CK)分别增长33.4%、18.2%;200 g/株施肥方式木荷高度最高为99.6 cm,地径最大为13.1 mm,相对对照(CK)分别增长28.8%、21.3%。从培育成本考虑,以施肥量100 g/株为最佳。

Extraction Technology of Chinese-fir Heartwood by Supercritical Fluid Carbon Dioxide

Taking extraction rate as an indicator,the extraction technology of Chinese-fir heartwood by supercritical carbon dioxide treatment was studied, and the extraction rate of the SFE-CO2 method was compared to that of traditional extraction method. The results show that when extraction processing condition were:extraction pressure 30 MPa,extraction temperature 40℃,extraction time 120 m,and flow velocity 20 kg/h,the extraction rate of SFE-CO2 was 0.99%,0.20%more than that of the traditional extraction method.However,taking the cost into consideration,it is proposed that the traditional extraction is used unless there are specific requirements.

Clonal Variation in Growth and Wood Quality and the Multi-Trait Index Selection of Chinese Fir

Two clonal trial stands of Chinese Fir （Cunninghamia lanceolata） were used in this study, one was 19-year-old stand which included 38 clones, and the other was 17-year-old stand including 102 clones.The statistical analyses showed that there were very significant genetic variations in height, DBH,volume and ratio of heartwood(Rhw),wood basic density（ρb ） of the clones in the two stands. The repeatability of clones was in median to high level,and the genetic CV was different over the all five traits.There were very significant phenotypic and genetic correlations among height,DBH and volume,and negative correlations among growth, Rhw andρb.The selection method experiment indicated that index selection could improve volume, Rhw andρb,showing synthetically superior selection effects compared to any individual trait selection methods.

Comparison of Drying Rate and Energy Consumption between Vacuum and Ambient Pressure Drying for Chinese Fir

In this work, Chinese fir samples with a size of 400 mm (L) by 50 mm (W) 30 mm (H) weretaken as specimens, and drying rate and energy consumption were compared under the conditions, inwhich the absolute pressure was 0.02 , 0.04 , 0.06 and 0.10 MPa, respectively, and the temperature was80 oC. The results showed that, when the moisture content (MC) of the samples was above fibersaturation point (FSP), the vacuum drying rate was 0.96-1.24 times as high as the ambient pressuredrying rate. However, when it was below FSP, the vacuum drying rate was 1.26-1.32 times as high as theambient pressure drying rate. At the same time, when the MC was above FSP, the energy consumptionof vacuum drying was 81.1%-95.9% of that of ambient pressure drying; when the MC was below FSP,the energy consumption of vacuum drying was 62.40%-69.40% of that of ambient pressure drying.Therefore, the vacuum drying was superior to the ambient pressure drying in terms of drying rate andenergy consumption.

Rapid Estimation of Microfibril Angle of Increment Cores of Chinese Fir by Near Infrared Spectroscopy

Near infrared (NIR) spectroscope and X-ray diffractometry have been used for rapid prediction of the microfibril angle (MFA) which is one of the important factors affecting wood properties. Wood property evaluation in breeding and resource evaluation requires effective and rapid analysis methods for thousands of samples. In the experiment, all samples from increment cores with moisture content of 60% to 150% were used for measuring MFA by X-ray scanning diffractometry. Then, a partial least squares regression (PLS) model was built based on NIR data and MFA measured. As a result, a strong linear relationship was found between NIR spectroscope fitted and X-ray measured with coefficient of calibration 0.95 and prediction model rate 0.88. NIR estimating is in consist with X-ray determining closely, which indicates that NIR spectroscopy can be successfully used to estimate MFA of increment cores of Chinese fir.

Intratree Variability of Cleavage Resistance of Chinese Fir from Plantation

This paper studied the variation of cleavage resistance of Chinese fir wood from plantation. Six trees of 36 years old were investigated, and the cleavage resistance properties for 672 samples made of the trees were tested. The samples were cut from the sapwood and heartwood at different directions (south and north) and heights (1.3, 3.3, 5.3 and 7.3 m) of the trees. The result showed that: tangential cleavage resistance was higher than radial one, and cleavage resistance of sapwood was higher than that of heartwood, but there was no significant difference in cleavage resistances between sections of the north and the south of the trees. There was a little variation in cleavage resistance between the radial and tangential from butt to top log, which shows a little decrease with the height from 1.3 to 5.3 m , but a rise in the top of the trees.

Study on Volatile Organic Components from Chinese Fir Wood

The volatile organic compounds(VOCs) are emitted by a wide array of products, which include a variety of chemicals, some of them may have short- and long-term adverse health effects. Several analytical instrument including gas chromatograph, high preferment liquid chromatograph, mass spectrometry and solid phase microextraction (SPME) technique were used in this study. The results showed the aldehyde and ketone components of Chinese fir wood were little composed of formaldehyde, syn- acetaldehyde, anti-acetadehyde and acrolein, VOCs obtained by Tenax GR absorber consisted of the major component cedrene (42.92%) and another 28 components, and the major components of the VOCs from the sample by using solid phase microextraction (SPME) technique were cedrene and cedrol.

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.

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）.

氮沉降对杉木人工林土壤有机碳矿化和土壤酶活性的影响

为探讨氮沉降对亚热带森林土壤有机碳矿化及土壤酶活性的影响规律,在杉木人工林中开展了野外模拟N沉降试验。试验设计为4种处理,分别为N0(对照)、N1(60 kg N.hm-.2a-1)、N2(120 kg N.hm-.2a-1)和N3(240 kg N.hm-.2a-1),每处理重复3次。通过28 d的培养后发现,各土层有机碳日均矿化量随培养时间的延长呈下降趋势,而有机碳累计矿化量则逐步增加。不同氮沉降处理下各土层有机碳累计矿化量总体趋势表现为:随着氮沉降量的增加而降低,日均矿化量降低幅度以N1最大,其次是N0和N2,N3降幅最小。相同N沉降处理下,参与土壤碳循环的6种主要酶(蔗糖酶、纤维素酶、淀粉酶、β-葡糖苷酶、多酚氧化酶、过氧化物酶)活性、土壤有机碳日均矿化量和有机碳累计矿化量均随土层加深而降低。氮沉降对6种土壤酶活性的影响存在差异,对纤维素酶和多酚氧化酶具有促进作用,而对淀粉酶和过氧化物酶表现出一定的抑制作用;中-低氮沉降(N1、N2)对蔗糖酶无影响,而对β-葡糖苷酶具有促进作用,高氮沉降(N3)促进了蔗糖酶活性,但抑制了β-葡糖苷酶活性。表层土壤中,土壤有机碳累积矿化量与土壤纤维素酶、β-葡糖苷酶、过氧化物酶活性呈显著正相关。因此,氮沉降促进了表层土壤纤维素酶、多酚氧化酶和蔗糖酶的活性,但在一定程度上抑制了淀粉酶和过氧化物酶,对土壤有机碳矿化也表现出明显的抑制作用。