1O个树种耐水淹能力的比较

以黄连木(Pistacia chinensis)、石楠(Photinia serrulata)、蓝果树(Nyssa sinensis)、薄壳山核桃(Carya illinoensis)、榉树(Zelkova papyrifera)、一球悬铃木(Platanus occidentalis)、白蜡(Fraxinus chinensis)、乌桕(Sapium sebiferum)、墨西哥落羽杉(Taxodium macronatum)、花叶杞柳(Salix integra cv.Hakuro Nishiki)等10种树种为研究对象,在人工控制的淹水条件下,观察其叶形态受害程度,运用涝害指数方法分别研究各树种的耐水淹能力.结果表明:淹水胁迫下,黄连木、石楠、榉树、薄壳山核桃、蓝果树、一球悬铃木涝害指数达到0.90的时间分别在10,20,25,35,40,50 d左右;乌桕、白蜡水淹50 d涝害指数分别为0.54和0.80,耐涝性明显;墨西哥落羽杉和花叶杞柳受水淹60 d内无明显受害现象.乌桕、白蜡、墨西哥落羽杉、花叶杞柳等树种水淹后茎基部能产生不定根和皮孔,是对淹水胁迫的积极适应,可作为河岸带绿化的备选树种.     

10个树种耐水淹能力的比较

以黄连木(Pistacia chinensis)、石楠(Photinia serrulata)、蓝果树(Nyssa sinensis)、薄壳山核桃(Carya illinoen-sis)、榉树(Zelkova papyrifera)、一球悬铃木(Platanus occidentalis)、白蜡(Fraxinus chinensis)、乌桕(Sapium sebiferum)、墨西哥落羽杉(Taxodium macronatum)、花叶杞柳(Salix integracv.Hakuro Nishiki)等10种树种为研究对象,在人工控制的淹水条件下,观察其叶形态受害程度,运用涝害指数方法分别研究各树种的耐水淹能力。结果表明:淹水胁迫下,黄连木、石楠、榉树、薄壳山核桃、蓝果树、一球悬铃木涝害指数达到0.90的时间分别在10,20,25,35,40,50 d左右;乌桕、白蜡水淹50 d涝害指数分别为0.54和0.80,耐涝性明显;墨西哥落羽杉和花叶杞柳受水淹60 d内无明显受害现象。乌桕、白蜡、墨西哥落羽杉、花叶杞柳等树种水淹后茎基部能产生不定根和皮孔,是对淹水胁迫的积极适应,可作为河岸带绿化的备选树种。     

两个树种在涝渍胁迫下的生长及生理变化研究

文章通过为期60d田间模拟试验,以1年生落羽杉、乌桕实生苗为试才,采用完全随机试验设计,对两个树种在涝渍胁迫下的生长变化、光合特性及荧光动力学参数进行了初步研究。结果表明:在涝渍处理条件下,两个树种均产生了大量的不定根且生物量增量和相对生长率也表现出对涝渍胁迫的适应性。涝渍处理下,2个树种的净光合速率(Pn)、气孔导度(Gs)、最大光化学量子效率(Fv/Fm)均显著降低,涝渍程度越强,其下降幅度越大。两个树种相比,落羽杉具有更强的耐涝性。     

水盐胁迫对上海常见4种绿化树种根系生长的影响

试验选取了上海较为常见的4种绿化树种,落羽杉、乌桕、栾树、喜树,针对上海泥质海岸沿海防护林的建设需要,对其进行了模拟海水的耐盐、耐水淹交叉胁迫处理。结果表明,栾树和喜树的根系在水盐胁迫环境中受到的影响比乌桕和落羽杉大,从根系表面积、长度、体积、平均直径来看,栾树和喜树的敏感程度比较大,均出现早期上升,中后期下降的情况。落羽杉和乌桕根系对环境的表现则不是那么明显。     

淹水胁迫对乌桕幼苗叶片活性氧代谢的影响

以2个耐涝性不同的乌桕种源为材料,研究淹水胁迫对乌桕叶片保护酶活性和膜质过氧化作用的影响。结果表明,耐涝的浙江种源叶片相对电导率在渍涝胁迫下呈先上升后下降的趋势,不耐涝的福建种源则逐渐下降;浙江种源超氧物岐化酶(SOD)活性总体上保持在较高水平,福建种源则逐渐下降;2个种源过氧化物酶(POD)活性呈现下降趋势;丙二醛(MDA)含量、超氧阴离子自由基(O2.-)产生速率和过氧化氢(H2O2)含量均随淹水时间的持续逐渐上升。     

淹水胁迫对2种杨树1年生苗叶片超微结构和光合特性的影响

选取耐涝的Ⅰ-69杨和不耐涝的小叶杨为试材进行对比淹水试验,研究淹水胁迫对杨树叶片的超微结构和光合特性的影响.结果表明:淹水胁迫对杨树叶片的超微结构产生明显伤害,显著抑制叶片的光合性能,且随胁迫程度的加重和淹水时间的延长而严重:淹水8天时,Ⅰ-69杨与小叶杨叶片的净光合速率(Pn)、光系统Ⅱ(PSⅡ)最大光化学量子效率(Fv/Fm)、叶绿素含量均略有下降,叶片超微结构出现淀粉粒大量减少、嗜锇体数量略有增加、类囊体略有膨胀,少部分片层出现轻微扭曲等现象,但2者间差异不明显.淹水15天时,2者间出现明显差异.Ⅰ-69杨仍然能够维持较完整的叶片超微结构,从而保持较高的Pn,Fv/Fm,叶绿素含量.小叶杨叶片的Pn,Fv/Fm,叶绿素含量显著降低.叶片超微结构严重受损,出现质壁分离,叶绿体膨胀、被膜消失,类囊体膨胀,基粒片层扭曲、解体,线粒体内嵴减少、内含物外渗等症状.叶绿体对淹水胁迫敏感,线粒体结构相对稳定.叶片超微结构,尤其光合机构的损伤程度与Pn,Fv/Fm,叶绿素含量的变化趋势一致,是造成淹水胁迫下光合性能下降的重要原因.不同杨树叶片的超微结构对淹水胁迫的抗性明显不同.淹水胁迫下,耐涝杨树叶片的超微结构明显比不耐涝杨树稳定,损伤症状轻,出现时间晚.叶片超微结构的稳定性与杨树的抗涝性呈正相关关系,可作为杨树抗涝性鉴定的细胞学参考.     

6种园林树木对持续性淹水胁迫的生理响应及其比较

以榔榆、榉树、朴树、女贞、枇杷、珊瑚树2年生幼苗为材料,采用盆栽控水试验研究了持续淹水对不同树种外部形态及主要生理指标的影响,探讨了不同树种的抗涝性特性与差异.结果表明:1)淹水胁迫下,不同树种幼苗的生长均受到不同程度的影响,外形表现出明显的水渍斑点和黄化特征,但不同树种受害程度存在一定差异.2)淹水胁迫下,不同树种2种保护酶活性呈现出不同的变化态势.榔榆叶片抗氧化保护酶的活性反应最为敏感,表现为淹水初期SOD活性的显著上升和POD活性的剧烈增加,但后期两种保护酶活性趋于平缓变化;榉树、朴树在整个淹水期SOD活性呈现先期下降后期抬升的波动变化;而女贞、珊瑚树在整个淹水期SOD、POD活性的变化相对较小,不同处理期的测定值差异均不显著.3)榉树、朴树的游离脯氨酸含量变化呈现前期略有下降后期缓慢上升的变化;而女贞、枇杷两树种的游离脯氨酸含量变化呈现先期下降,后期平缓变化的态势.4)淹水初期榔榆MDA含量明显上升,并于淹水第13天时含量最高,榉树和朴树的MDA含量变化呈现先期下降后期缓慢上升的变化,枇杷、女贞的MDA含量变化几乎呈一直线变化.5)6树种叶片中叶绿素含量均随淹水时间的延长而下降.采用隶属函数法对6种树种的耐涝性进行评估,其耐涝性强弱大致排序为:女贞、枇杷、珊瑚树、朴树、榉树、榔榆.     

持续淹水胁迫对美洲黑杨幼苗生长及生理生化的影响

比较‘2025’杨及其2个芽变红叶品种(‘全红杨’‘中红杨’)的耐涝能力,以3个品种嫁接苗为试验材料,采用随机区组设计,盆栽模拟淹水环境,以正常浇水样本为对照。研究不同胁迫处理时间下,3个杨树品种植株表型、光合特性的响应变化及对叶片部分生理指标的影响,并采用隶属函数和灰色关联分析法对抗涝能力和指标进行评价,为新品种的选育及推广提供理论依据。结果表明:通过84 d的模拟试验,3个杨树品种的叶片始终保持有净光合速率,表现出稳定的耐涝遗传特质。淹水28 d,胁迫引起的叶片气孔限制因素使Pn快速下降,高生长均略高于对照(P 0.05);淹水42 d, MDA含量、SOD和CAT酶活性升高,茎基部产生不定根,叶绿素降解减缓,Pn回升;淹水56～70 d,3个杨树品种高生长量分别较CK下降了53.33%、42.79%和49.96%。SOD、CAT活性下降,膜透性增大,叶片叶绿素加速降解,Pn再次下降。通过各生理指标隶属函数进行综合评价,‘全红杨’的抗淹水能力较弱(P 0.05),‘中红杨’与‘2025’杨差别不大(P 0.05)。关联分析表明,质膜相对透性、抗氧化CAT和SOD酶活性是影响3个杨树品种抗涝性的主要指标。     

淹水胁迫对枫杨等3个树种生理生化特性的影响

通过模拟季节性淹水发生的情况,以枫杨、落羽杉和枫香为试验材料,研究这3个树种在淹水胁迫下的适应性和生理调节机制。结果表明:(1)枫杨等3个树种可耐长期水淹,对淹水胁迫具有很强的适应性。(2)不同淹水深度胁迫下,枫杨SOD、POD、CAT活性无显著差异,MDA含量随淹水深度增加呈现出递减趋势。枫香随淹水深度增加,SOD、POD活性逐渐减少,且渍水与深度淹水间存在显著差异(P 0.05);CAT活性随淹水深度增加而逐渐增加,但不同淹水深度间无显著差异。落羽杉在渍水时SOD活性显著高于轻度淹水,深度淹水时CAT活性极显著(P 0.01)高于渍水和轻度淹水时;MDA含量随淹水深度增加呈现出逐渐增加趋势,但无显著差异。(3)随淹水时间的延长,3个树种的SOD、POD、CAT保护酶活性多呈现出降低-升高-降低的波状起伏变化;枫杨、枫香的MDA含量呈现出先升高后降低的趋势,落羽杉的MDA含量变化不明显。(4)淹水胁迫解除后,枫杨等3个树种的SOD、POD、CAT酶活性及MDA含量普遍呈现先升高后降低的趋势。     

淹水胁迫对3个树种叶绿素含量的影响

通过模拟长江滩地季节性淹水过程,研究枫杨等3个树种在淹水胁迫下叶绿素含量的变化。结果表明:(1)不同淹水深度胁迫下枫杨叶绿素含量均比对照有所降低,但降低值与淹水深度并无明显相关性;落羽杉在不同淹水深度胁迫下其叶绿素含量变化不明显;只有枫香叶绿素含量明显随着淹水深度增加而逐渐减少。(2)不同淹水时间长度胁迫下,3个树种所有处理组叶绿素含量均呈波状变化趋势。(3)淹水胁迫解除后,枫杨、落羽杉叶绿素含量均低于对照组,也低于相同处理未解除淹水胁迫的处理组,而枫香叶绿素含量低于对照组,但稍微高于未解除淹水胁迫组;随胁迫解除时间延长,3个树种叶绿素含量变化呈现高-低-高的变化趋势。     

Diffusion of chemicals into archaeological waterlogged hardwoods obtained from the Thang Long Imperial Citadel site,Vietnam

This study shows a method to easily develop suitable impregnation procedure of chemicals for preserving the archaeological waterlogged wood (WW) using diffusion constant. The steady-state diffusion coefficients of polyethylene glycol 4000 (PEG4000), trehalose, and keratin through eight archaeological waterlogged wood species were obtained from the total amounts of the chemicals diffused through the wood samples. The diffusion coefficients were strongly affected by the anatomical structures of the wood species and degree of wood deterioration. Within the same species of wood, the highest diffusion rates were measured in the longitudinal direction, followed by those in the radial and tangential directions. The longitudinal diffusion coefficients were 1.5- to 8.1-times higher than the radial diffusion coefficients, which were in turn approximately 1.1- to 5.7-times higher than the tangential diffusion coefficients. The diffusion rates were found to be inversely proportional to the molecular weight of the diffusing chemical. The diffusivity of trehalose through the waterlogged woods was found to be higher than those of keratin and PEG4000. This study provides a potential method to easily estimate chemical diffusion coefficients for dip-diffusion treatments.     

Changes of plant species composition in the Šumava spruce forests,SW Bohemia,since the 1970s

Vegetation dynamics of three forest communities were studied by resampling of relevés recorded in the 1970s in the Bohemian Forest (Šumava Mountains). Results of multivariate analysis (RDA) confirmed significant time changes in species composition of the climax (Calamagrostio-Piceetum) and waterlogged (Bazzanio-Piceetum) spruce forests. The changes in the sphagnum-rich waterlogged spruce forests (Sphagno-Piceetum) are close to the level of significance. The main vegetation changes are represented by a decrease in cover and/or frequency of hygrophilous or sciophilous species (e.g. Athyrium distentifolium, Oxalis acetosella) in climax spruce forests, and an abundant increase of species, indicating a preference to drier stands or better light conditions (e.g. Calamagrostis villosa, Vaccinium vitis-idaea or Avenella flexuosa), in waterlogged spruce forests. We also found a higher proportion of meadow species (e.g. Anthoxanthum odoratum, Festuca rubra or Luzula multiflora) in the newly recorded relevés from waterlogged forests. Analysis of species number per plot showed a remarkable shift to species-rich communities, especially in waterlogged stands.We tried to find the possible factors responsible for the observed changes. Unfortunately, only indirect measurement of environmental factors using Ellenberg’s indicator values could be used and did not yield sufficient results. Thus, the changes observed in climax spruce forests were ascribed mainly to a decrease in canopy cover, which was directly estimated. In waterlogged forests, a complex of several general factors, which influence the climax spruce forest, had to be taken into account, such as: (i) a decrease in atmospheric acidification during the last 10–15 years and subsequent improvement in soil conditions, especially in waterlogged stands; (ii) fragmentation of forests as a result of bark-beetles attack; (iii) climate warming documented by long-term local meteorological measurements.     

Hydraulic and stomatal adjustment of Norway spruce trees to environmental stress

A study of how the water conducting systems of 30-50-year-old Norway spruce (Picea abies (L.) Karst.) trees growing at three sites adjust to shade and waterlogging indicated that water relations characteristics varied with the life histories of the trees. Xylem was more efficient at conducting water and stomata were more sensitive to atmospheric evaporative demand in trees subjected to favorable growth conditions (control trees) than in trees growing in shade or waterlogged conditions. At the same soil water availability, shade-grown trees suffered more severely from water deficit than control trees. Under conditions of high atmospheric vapor pressure deficit, foliage of shade-grown trees exhibited low water potentials, as a result of low hydraulic conductance of the vascular system and inefficient stomatal control. Because of the increased internal resistance to water flow, more negative leaf water potentials (Psi(x)) must be reached to provide an adequate water supply to the foliage. It is concluded that dynamic water stress is one of the main causes of the continuing growth retardation in suppressed Norway spruce trees after their release from the overstory. Trees growing in waterlogged soil (bog-grown trees) were characterized by weak stomatal control, resulting in large water losses from the foliage. Although bog-grown trees exhibited uneconomical water use, they possessed mechanisms (e.g., osmotic adjustment) that allowed leaves to tolerate low Psi(x) while stomata remained open. Under conditions of sufficient soil water availability and moderate atmospheric vapor pressure deficit, soil-to-leaf conductance was highest in bog-grown trees (1.45 +/- 0.06 mmol m(-2) s(-1) MPa(-1)), followed by control and shade-grown trees (1.04 +/- 0.04 and 0.77 +/- 0.05 mmol m(-2) s(-1) MPa(-1), respectively). The lowest soil-to-leaf conductance (0.45 +/- 0.04 mmol m(-2) s(-1) MPa(-1)) was recorded in control trees at high atmospheric evaporative demand, and was probably caused by tracheid cavitation.     

谈人工湿地的类型及其功能

阐述了人工湿地的类型及其功能,进而说明人工湿地对蓄水防洪除涝、补充地下水、处理污水、提供食物、美化环境等诸多方面具有不容忽视的作用。     

淹水程度对滩地枫杨木材化学性质的影响

通过研究淹水程度对滩地枫杨木材化学性质的影响 ,以期全面了解滩地主要造林树种的化学性质 ,提出合理的定向培育技术及进一步综合利用措施 .研究结果表明 :滩地枫杨木材的 p H值均小于 6.5 ,属于酸性木材 ,第一、二组木材的 p H值分别为 5 .41和 5 .0 0 ,在 0 .0 5水平上差异显著 .除碱性缓冲容量外 ,第二组木材的酸性缓冲容量、总缓冲容量以及每降低 1p H值消耗的 HC1量均比第一组高 .淹水程度对滩地枫杨木材纤素含量几乎无影响 ,其值均为 45 .2 %左右 ;但第一、二组的半纤维素分别为 14 .0 4%和19.5 0 % ,增加了 3 8.9% ;第一、二组的木质素含量分别为 19.9%和 2 0 .6% ,增加了 3 .5 % .     

Transpiration and forest structure in relation to soil waterlogging in a Hawaiian montane cloud forest

Transpiration, leaf characteristics and forest structure in Metrosideros polymorpha Gaud. stands growing in East Maui, Hawaii were investigated to assess physiological limitations associated with flooding as a mechanism of reduced canopy leaf area in waterlogged sites. Whole-tree sap flow, stomatal conductance, microclimate, soil oxidation-reduction potential, stand basal area and leaf area index (LAI) were measured on moderately sloped, drained sites with closed canopies (90%) and on level, waterlogged sites with open canopies (50-60%). The LAI was measured with a new technique based on enlarged photographs of individual tree crowns and allometric relationships. Sap flow was scaled to the stand level by multiplying basal area-normalized sap flow by stand basal area. Level sites had lower soil redox potentials, lower mean stand basal area, lower LAI, and a higher degree of soil avoidance by roots than sloped sites. Foliar nutrients and leaf mass per area (LMA) in M. polymorpha were similar between level and sloped sites. Stomatal conductance was similar for M. polymorpha saplings on both sites, but decreased with increasing tree height (r(2) = 0.72; P < 0.001). Stand transpiration estimates ranged from 79 to 89% of potential evapotranspiration (PET) for sloped sites and from 28 to 51% of PET for level sites. Stand transpiration estimates were strongly correlated with LAI (r(2) = 0.96; P < 0.001). Whole-tree transpiration was lower at level sites with waterlogged soils, but was similar or higher for trees on level sites when normalized by leaf area. Trees on level sites had a smaller leaf area per stem diameter than trees on sloped sites, suggesting that soil oxygen deficiency may reduce leaf area. However, transpiration per unit leaf area did not vary substantially, so leaf-level physiological behavior was conserved, regardless of differences in tree leaf area.     

乐昌含笑繁殖初探

乐昌含笑是中国特有的经济、园林树种之一,本文中,主要对乐昌含笑的生物学特性、播种繁殖育苗及组织培养进行了探讨。结果表明：乐昌含笑在播种繁殖时,完全成熟种子出苗率可达71％以上,种子切忌掠青,同时,圃地积水时间不宜太长,在进行组织培养时可优先考虑采用其茎作为外植体进行愈伤组织诱导,其诱导率可达50％。     

水分胁迫对栓皮栎幼苗生理特性及生长的影响

通过盆栽实验，研究了在不同的水分条件下栓皮栎幼苗生理特性的变化和苗木生长量的变化。研究表明，在水分胁迫初期，随土壤含水量的降低，栓皮栎叶片的净光合速率、蒸腾速率下降，而水分利用效率提高。在水分胁迫末期，由于长期的干旱胁迫，水分条件最差的一组苗木已干枯死亡，土壤含水量从38．123％下降到20．323％时，净光合速率和蒸腾速率均下降，水分利用效率也下降。随着土壤含水量的降低，苗高、地径和生物量均有下降的趋势，其中生物量下降的幅度最大。     

Research on the effect of yield strength of circular saw blade on roll tensioning process

In this paper, a 2-D and 3-D finite element model of roll tensioning process of circular saw blade were established by Static/General module of ABAQUS software based on finite element method. The rolling force and tensioning stress distribution of circular saw blade were calculated by these two models which were proved to be true and reliable. The effects of yield strength of circular saw blade on tensioning stress distribution and rolling force were studied. The research achievements showed that a circular saw blade made with high yield strength obtained a higher tangential compressive stress and radial compressive stress in the rolled region during roll tensioning process, which has both advantages and disadvantages for the stability of the saw blade. Besides, a circular saw blade made with high yield strength also put forward higher requirements for roll tensioning equipment because of the large rolling force during roll tensioning process.     

Evaluation of chemical treatments on dimensional stabilization of archeological waterlogged hardwoods obtained from the Thang Long Imperial Citadel site,Vietnam

In this article, the conservation of seven archeological waterlogged woods (WW) with polyethylene glycol (PEG) 4000, trehalose, and feather keratin was investigated. The results showed that the dimensional stability of WWs significantly improved after the different treatments. The anti-shrink efficiency values of the WWs treated with keratin ranged between 72.5 and 96.2% depending on the species and degree of wood degradation. These values varied from 82.4 to 96.9% for the WWs treated with PEG or trehalose. Microscopic observations showed that the chemically-treated woods maintained their original cell structures, forms, and shapes. It was also revealed that the reinforcement of cell walls by the feather keratin treatment was different from those observed for the PEG or trehalose treatments. It was observed that PEG and trehalose primarily filled the wood voids, while keratin predominantly absorbed on the cell walls and middle lamellae. Based on the improved dimensional stability of wood, shortened impregnation time, removability of chemical, and esthetic results obtained from the treatment, keratin showed a good performance in average as a preservation agent.