Effect of Ferric Citrate on Microstructure and Corrosion Resistance of Micro-arc Oxidation Black Film on Mg-alloy AZ40M

利用二次微弧氧化法在AZ40M镁合金表面成功制备了黑色的氧化膜层,通过SEM、EDS和XRD表征了膜层的微观形貌和成分组成。结果表明,柠檬酸铁添; 加剂浓度可显著影响镁合金表面氧化膜的形貌、组成和厚度,添加剂浓度越高,膜层中的铁氧化物含量也越高,而对膜层厚度的影响则没有呈现出明显规律。同时,; 测试了0.1 mol/L; NaCl溶液中的电化学阻抗谱和动电位极化曲线,结果显示镁合金表面黑色膜层具有较好的耐蚀性,且膜层越厚,铁含量越少,膜层的耐蚀性越好。Black oxide films on Mg-alloy AZ40M were prepared by means of a two-step; micro-arc oxidation process in electrolytes of 15 g/L Na_3PO_4+ 3 g/L; NaF+5.6 g/L KOH and 20 g/L Na_3PO_4+5 g/L NaF with different additions; of ferric citrate respectively. The microstructure and composition of; the films were characterized by scanning electron microscope (SEM),; energy dispersive spectrometer (EDS) and X-Ray diffractometer (XRD). The; electrochemical corrosion property of the films was assessed by using; electrochemical impedance spectroscopy (EIS) and potentiodynamic; polarization curves in 0.1 mol/L NaCl solution. Results showed that the; concentration of ferric citrate strongly affects the surface morphology,; composition and thickness of the formed oxide films. The oxide films; have good corrosion resistance. The thicker oxide film with less iron; content presents better corrosion resistance.国家自然科学基

Effects of fertilization on Casuarina equisetifolia seedlings total phenolics and extractable condensed tannin contents.

研究了施用氮肥和磷肥对短枝木麻黄幼苗总酚(TOTAl PHEnOlICS,TP)和可溶性缩合单宁(EXTrACTAblE COndEnSEd TAnnIn,ECT)含量的影响,探讨短枝木麻黄单宁形成的养分效应.结果表明:施加氮肥使短枝木麻黄幼苗小枝的TP和ECT含量显著降低,支持碳氮平衡假说和生长分化平衡假说,但对氮含量没有显著影响,从而导致TP/n和ECT/n降低;施加磷肥对TP和ECT含量没有显著影响;随着处理时间的延长,短枝木麻黄幼苗小枝TP含量升高了9.91%~14.32%,而ECT含量降低了14.32%~298.88%;TP或ECT与有机物质含量的关系则相反,表明不同类型单宁的合成途径不同,但由于TP和ECT均与氮含量无显著相关性,故不支持蛋白质竞争模型;在贫瘠土壤条件下,TP/n和ECT/n的水平较高,有利于提高短枝木麻黄的防御水平,降低凋落物的分解率,减少养分损失,从而保持较高的生产力.This paper studied the effects of nitrogen-and phosphorus fertilization on the total phenolics(TP) and extractable condensed tannin(ECT) contents in the branchlets of Casuarina equisetifolia seedlings,aimed to approach the nutrient effect on tannin production.Under nitrogen fertilization,the TP and ECT contents decreased significantly,which supported the hypotheses of carbon-nitrogen balance(CNB) and growth-differentiation balance(GDB),but the plant nitrogen content had less change,resulting in the decrease of TP/N and ECT/N ratios.Phosphorus fertilization had no significant effects on the TP and ECT production.With prolonged treatment time,the TP content in the branchlets of C.equisetifolia seedlings increased by 9.91%-14.32%,but the ECT content decreased by 14.32%-298.88%.The TP and ECT had opposite relationships with organic matters content,showing that different types of tannin had different biosynthetic pathways.However,both TP and ECT had no significant correlation with nitrogen content,and thus,the protein competition model(PCM) was not supported.Under nutrient-poor condition,the TP/N and ECT/N ratios were relatively high,which would be beneficial for the improvement of defense ability,the decrease of litter decomposition ratio and nutrient loss,and the maintenance of high productivity of C.equisetifolia plantations.国家“十一五”科技支撑计划项目(2006BAD03A14-01);国家林业局南方山地用材林培育重点实验室和福建省森林培育与林产品加工利用重点实验室项目资

Rhizosphere soil nutrient and enzyme activity of Casuarina equisetifolia clone plantation and seedling plantation

木麻黄无性系林根际土壤有机质、全氮、水解氮、全磷、全钾、速效钾、钙和镁离子含量均大于木麻黄实生林,有效磷含量则相反。与实生林相比,木麻黄无性系林根际和非根际土壤pH值均有所下降,CEC值增加。木麻黄无性系林根际土壤脲酶、磷酸酶、过氧化物酶及多酚氧化酶活性均高于木麻黄实生林。脲酶除外,其余3种酶活性均是根际大于非根际。与木麻黄实生林相比,木麻黄无性系林根际环境得到改善,林地土壤营养贮量和养分供应能力提高,生长效果亦优于本地实生苗造林。The results showed that the contents of organic matter,total N,Hydrolytic N,total P,total K,available K,Ca2+ and Mg2+ in rhizosphere soil of clone plantation were higher than those of seedling plantation,except for available P.Compared to seedling C.equisetifolia,pH value of soil declined in clone plantation but CEC value increased.Uresese,phosphataese,peroxidase and polyphenol oxidase of rhizosphere soil were more active in clone plantation than those in seedling plantation.Environment in rhizosphere soil of C.equisetifolia clone plantation was improved and nutrient-holding and providing capacities were enhanced,therefore,growth status was better than seedling C.equisetifolia.国家“十一五”科技支撑计划项目(2006BAD03A14-01,2006BAD01A16);; 福建省重大专项和福建省林木种苗攻关项

Dynamics of tannin concentration and nutrient resorption for branchlets of Casuarina equisetifolia plantations at different ages

通过对福建省惠安县不同林龄短枝木麻黄人工林不同发育阶段小枝单宁含量及氮磷再吸收率的研究,探讨了短枝木麻黄林分发育过程中的营养保存策略。结果表明,幼龄林(5年生)成熟小枝中的总酚(TP)、可溶性缩合单宁(ECT)总缩合单宁(TCT)含量及蛋白质结合能力(PPC)显著高于成熟林(21年生)和衰老林(38年生)。随着林分发育,成熟小枝中n含量显著升高,而P含量呈降低趋势。不同发育阶段林分成熟小枝中n∶P比均大于20,且随着林龄的增加而升高。磷再吸收率(PrE)显著高于氮再吸收率(nrE),均以成熟林分最高。这表明短枝木麻黄小枝单宁含量与养分再吸收受林龄影响,其养分保存机制会随着林分生长发育的变化而进行调节。Casuarina equisetifolia is characterised by high primary productivity in coastal sandy soils,which are generally low in nutrient contents.High tannin production and nutrient resorption may be important strategies for C.equisetifolia in coastal environments.Despite the widespread planting and known ecological and physiological properties of C.equisetifolia,there is scant information about the nutrient resorption patterns and tannin concentrations for branchlets of C.equisetifolia plantations during stand development.Since plant ecophysological traits are associated with ageing,tannin content and nutrient resorption efficiency could change with stand development.Therefore,tannin level and nutrient resorption of C.equisetifolia at different developmental phases(juvenile,mature and senescent) were examined to evaluate possible nutrient conservation strategies under nutrient limitation in Huian County,Fujian Province.The results showed that total phenolics(TP) contents,which were in the order juvenile stand > senescent stand > mature stand for senescent branchlets and decreased from 218.52 to 180.49 mg / g during stand development for mature branchlets,decreased during branchlet senescence in all stands.The extractable condensed tannin contents(ECT) in mature and senescent branchlets of C.equisetifolia were juvenile stand > senescent stand > mature stand.The ECT contents of C.equisetifolia increased during branchlet senescence both in the mature and senescent stands but decreased in the juvenile stand.The protein-bound condensed tannin(PBCT) contents of branchlets increased during senescence in juvenile and mature stands and remained the same in senescent stand.The fibre-bound condensed tannins(FBCT) of branchlets increased during senescence in mature stand and did not change in juvenile and senescent stands.Total condensed tannin(TCT) followed similar pattern as ECT during stand development.Protein precipitation capacity(PPC) in mature and senescent branchlets were significantly higher in juvenile stand than in mature and senescent stands.PPC decreased during branchlet senescence in the three stands.Significant positive linear correlations were found between PPC and TP or TCT.Nitrogen(N) concentrations both in mature and senescent branchlets obviously increased during stand development.Phosphorus(P) concentrations in mature branchlets were similar in juvenile and mature stands but lower in senescent stand.Phosphorus concentrations in senescent branchlets of juvenile stand were significantly higher than those of mature and senescent stands.Nitrogen: phosphorus ratios(N ∶P ratios) of mature branchlets,were all above 20,also increased during stand development.Nitrogen resorption efficiencies(NRE) in three stands were basically below 50%,the lowest in senescent stand.Phosphorus resorption efficiencies(PRE) were above 70% with the highest in mature stand(78.08%).There were significant negative correlations between N and P concentrations in mature and senescent branchlets.Nitrogen resorption efficiency had a particular strong relationship with the N ∶P ratios of branchlets.On the other hand,PRE was not significantly related to N ∶P ratios of branchlets.There were significant correlations between TP or TCT and N or P concentrations in branchlets except for the relationship between TCT and P concentrations in senescent branchlets.The above results indicated that the tannin level,nutrient concentration and resorption were affected by stand age.C.equisetifolia could adjust their nutrient conservation with stand development at intraspecific level.国家自然科学基金项目(41201293;41176092); 国家“十一五”科技支撑计划项目(2009BADB2B0302); 国家林业局南方山地用材林培育重点实验室和福建省森林培育与林产品加工利用重点实验室资助项

Contents of Some Mineral Elements and Their Resorption Efficiencies in Casuarina equisetifolia Branchlets Across a Coastal Gradient

对福建东山赤山林场不同海岸梯度上短枝木麻黄小枝中的钾(k)、钙(CA)、镁(Mg)、钠(nA)、铁(fE)、锰(Mn)和锌(zn)元素含量及其再吸收率动态进行了研究.结果表明,海岸梯度对短枝木麻黄小枝中各元素含量及其再吸收率均具有显著影响.在各海岸梯度上,k再吸收率为正值,且基干林带的再吸收率显著低于其它样地,fE和zn为负值,CA、Mg和nA再吸收率在防护林带前沿为负值,而在后沿林为正值,Mn则相反.这表明,基干林带严重的环境胁迫显著降低了短枝木麻黄小枝的养分再吸收率.短枝木麻黄成熟小枝中的k、Mg含量与其再吸收率存在显著正相关,而nA和fE与其再吸收率存在显著负相关,其它元素与其再吸收率之间没有显著相关性.除k外,各元素在衰老小枝中的含量与相应元素再吸收率之间均存在显著负相关,表明元素再吸收程度越高,其再吸收率就越高.CA、Mg、nA和fE再吸收率之间具有显著的正相关关系(P<0.01),zn除与Mn再吸收率呈显著正相关外,与其它元素均表现为负相关,Mn则与其它元素再吸收率之间没有显著相关性.因而短枝木麻黄小枝中不同类型的养分状况对其再吸收率具有不同的影响.表5参42Contents of some mineral elements and their resorption efficiencies in Casuarina equisetifolia branchlets across a coastal gradient were studied at the Chishan Forestry Center of Dongshan County,Fujian Province,China.The results showed that the distance to coast had a significant effect on the contents of mineral elements and their resorption efficiencies.Resorption efficiencies of K element(REK) were all positive across the coastal gradient,with the lowest value found at the coastline sampling site,while Fe and Zn resorption efficiencies(REFe and REZn) were all negative across the coastal gradient.Ca,Mg and Na resorption efficiencies(RECa,REMg and RENa),which were contrary to Mn(REMn),were negative in seaward plantations and positive in inland plantations.It was suggested that the resorption efficiencies of the mineral nutrients significantly decreased with severer environmental stresses.There were also significant positive correlations between the K and Mg content and their resorption efficiencies in mature branchlets while the correlations between the Na and Fe content and their resorption efficiencies were significantly negative.In senescent branchlets,the content of all the elements and their resorption efficiencies except for K were negatively correlated.In addition,the correlation was positive between REZn and REMn,while negative between REZn and resorption efficiencies of other elements.No correlation was found between REMn and resorption efficiencies of other elements.These results showed that nutrient conditions in branchlets had different effects on their resoption efficiencies for different mineral nutrients.Tab 5,Ref 42国家“十一五”重大科技支撑计划项目(No.2009BADB2B0302)资助---

木麻黄低效林不同发育阶段小枝养分和热值动态

对福建东南沿海防护林木麻黄低效林不同发育阶段小枝中养分(氮、磷)状况、内吸收率和热值的比较研究表明,木麻黄低效林小枝中氮含量分别高于正常林中相应发育阶段的小枝,而磷的含量在幼嫩小枝中低效林高于正常林,在成熟和衰老小枝中正常林高于低效林;低效林氮的内吸收效率稍低于正常林,而磷的内吸收效率则高于正常林;正常林和低效林小枝中的N:P比都高于16;低效林幼嫩和衰老小枝中的热值与正常林差别不显著,而低效林成熟小枝中的热值高于正常林。国家“十一五”科技支撑计划项目(2006BAD03A14-01);; 福建省重大科技专项(2006NZ0001-2);; 福建省森林培育与林产品加工利用重点实验室资助项

Nitrogen and phosphorus concentrations,N∶P ratio and resorption efficiency of leaves in different forest types

以福建东山沿海防护林中木麻黄、厚荚相思、刚果桉和湿地松4种主要树种为研究对象,探讨了纯林和混交林成熟叶与衰老叶中的养分状况、氮磷比、养分内吸收率以及它们之间的关系。结果表明:叶片中的养分浓度和内吸收率一般表现为纯林高于混交林、固氮树种高于非固氮树种。这是由于混交林和固氮树种改善了立地条件,林木能够从土壤中吸收较多的养分,从而降低了二者叶片中的养分内吸收率。各林分类型成熟叶片中的氮磷比都大于14,表明这些立地条件都存在不同程度的磷限制,导致大部分林分叶片磷内吸收率(rEP)大于氮内吸收率(rEn),因而衰老叶中的氮磷比大于成熟叶,但成熟叶和衰老叶氮磷比之间依然存在显著的正相关关系。不同林分类型成熟叶和衰老叶养分浓度、内吸收率和氮磷比在固氮树种和非固氮树种中存在互补性,表明固氮树种和非固氮树种在养分利用方面存在差异。不同树种的营养利用策略不同,在选择造林树种时,应优先考虑叶片养分含量低而内吸收率高的“营养保存型“树种。Nitrogen and phosphorus concentrations,N∶P ratio,nutrient resorption efficiency and their relationship in mature and senescent leaves in pure and mixed protection forest of Casuarina equisetifolia,Acacia crassicarpa,Eucalyptus ABL 12 W5 and Pinus elliottii were discussed in this paper.The results showed that nutrient concentration and resorption efficiency of leaves were higher in pure forest and N fixing species than in mixed forest and non-N-fixing species,respectively.This indicated that soil nutrient availability increased in mixed forest and N-fixing species,so the trees could absorb more nutrients from soil and depended less on nutrient resorption from senescent leaves.The N∶P ratios of mature leaves were all above 14,nitrogen was less limiting than phosphorus,and accordingly phosphorus resorption efficiency(RE_P)was higher than nitrogen resorption efficiency(RE_N).N∶P ratio was increased with leaf senescence.There was significant positive relationship between N∶P ratio in mature and in senescent leaves.Inter-and intraspecific correlations among nutrient concentrations,nutrient resorption and N∶P ratio of mature and senescent leaves in various forest types were different in N-fixing and non-N-fixing species.Due to the difference of nutrient use strategy for various life-forms,there was a significant correlation in N-fixing species,but no correlation in non-N-fixing species,and vice versa."Nutrient conservation" species,such as P.elliottii,with low leaf nutrient and high nutrient resorption efficiency should be prior selected for afforestation.“十一五”国家科技支撑计划项目(2006BAD03A14-01);福建省科技重大项目(2006NZ0001-2);国家林业局南方山地用材林培育重点实验室项

闽南沿海木麻黄基干林带的防风效应

为深入认识沿海木麻黄基干林带内外风速变化规律和空间分布,从2006年11月到2007年3月在东山岛木麻黄基干林带内外多个测点进行了风速测定。结果表明:基干林带风速变化规律为:林内下降和林外上升的开口向上的抛物线状;风速空间分布为林带内下凹、林带后上升的平滑曲面,中间出现一些小的凸出或下凹的斑快。基干林带内等值线比较平直均匀,林带后比较弯曲且分布不均匀。国家“十一五”科技支撑计划项目(2006BAD03A14-01);; 福建省重大科技专项(2006NZ0001-2

福建东山木麻黄基干林内的风速变化规律

从2006年11月到2007年3月在东山岛对不同发育阶段木麻黄基干林带内多个测点进行了风速测定,以探讨基干林带内部风速变化规律和空间分布。结果表明:木麻黄基干林带内风速呈逐渐下降趋势,各发育阶段林带内5h处风速小于2m/s,10h处低于1m/s。空间分布为平滑的下降曲面,局部有凸起和下凹。等值线比较平直和均匀,没有形成闭合区域。国家“十一五”科技支撑计划项目(2006BAD03A14-01);; 福建省重大科技专项(2006NZ0001-2

Soil heterotrophic respiration in Casuarina equisetifolia plantation at different stand ages

以中国亚热带木麻黄沿海防护林为研究对象,在2006年5月-2007年4月,利用lI-8100土壤呼吸自动观测系统对不同林龄(幼林、中林、成林)木麻黄人工林生态系统的土壤异养呼吸特征进行了监测。结果表明,不同林龄木麻黄林地土壤异养呼吸季节动态均呈单峰曲线,最大值出现在6~7月份,最小值则出现在12~1月份。土壤温度和水分对土壤异养呼吸的季节变化存在显著影响,并有明显的交互作用,进行单因素方差分析发现,土壤异养呼吸季节变化与5CM深的土温存在着较好的指数相关关系(P成林>幼林。随着林龄的增大,土壤异养呼吸对土壤温度的敏感性增强。土壤异养呼吸对土壤总呼吸的贡献在幼林、中林、成林中分别达到71.89%、71.02%和73.53%。幼林、中林、成林样地土壤异养呼吸CO2年释放量分别为29.072、38.964和30.530T·HM-2·A-1。The soil respiration rates (Rh) in 6-year-old (young), 17-year-old (middle-age), 31-year-old (mature) Casuarina equisetifolia coastal plantations were measured using an LICOR-8100 automated soil CO2 flux system from May 2006 to April 2007.Results show that Rh displayed an obvious seasonal pattern across the observed years.The maximum values of Rh occurred at June and July and the minimum at December and January.Soil temperature and soil moisture as well as their interaction had significant effects on the monthly dynamics of Rh.The analysis by one-way ANOVA showed that Rh had a significantly exponential relation (pmature plantation>young-age plantation.With the increase of growth age of plantation, the Q10 of Rh increased.The contribution of Rh to total soil surface CO2 flux was 71.89%, 71.02% and 73.53% for the young, middle-age and mature plantation, respectively.It was estimated that the annual CO2 fluxes from Rh were 29.07, 38.964 and 30.530 t·ha-1·a-1 for the young, middle-age and mature plantation, respectively.supportedbyKeyProjectsintheNationalScience&TechnologyPillarProgramduringtheEleventhFive-yearPlanPeriod(Nos.2006BAD03A14-01);ImportantScience&TechnologySpecificProjectsofFujianprovince(2006NZ0001-2);supportedbytheKeyLaboratoryofsouthmountaintimberculti-va