城市行道树对交通环境的响应

以远离交通环境的公园作为相对清洁区,研究了位于广东佛山种植最普遍的8种城市行道树树黄葛榕(FicusvirensAit.var.sublanceolata(Miq.)Corner),大叶紫薇(Lagerstroemiaspeciosa(L.)Pers.),芒果(MangiferaindicaL.),细叶榕(FicusmicrocarpaL.),阴香(Cinnamomumburmanii(Nees)Bl.),垂叶榕(FicusbenjaminaL.),白兰(MicheliaalbaDC.),红花羊蹄甲(BauhiniablakeanaDunn)在交通密集区生长在不同方位的植物器官对交通环境的响应。结果表明,交通密集区的城市行道树的叶片和树皮器官吸收重金属铅和镉、硫含量、电导率和pH值等指标在不同的方位呈现显著的差别,即城市行道树位于快车道一侧生长的植物的器官(以下简称P1)、位于面向人行道一侧生长的植物的器官(以下简称P2)及相对清洁区采集的植物样品(以下简称P0)各指标测定值的分析结果为:其叶片和树皮硫、重金属铅和镉、电导率等特征值基本呈现P1>P2>P0的大小规律,在显著度为0.05时差异显著;而pH值基本呈现P1相似文献   

嗜酸乳杆菌在不同pH条件下生长和存活情况的研究

以豆汁为基质,研究了嗜酸乳杆菌（Ｌａｃｔｏｂａｃｉｌｌｕｓ ａｃｉｄｏｐｈｉｌｕｓ）在不同ＰＨ值的发酵基质和保存基质下的生长和存活情况。结果表明：嗜酸乳杆菌适宜生长的ＰＨ值在５．７左右,然而经过１０周保存实验,在较低ＰＨ值（４．５）培养的嗜酸乳杆菌存活率最高,在最适生长ＰＨ值（５．７）的菌活率却最低。将培养好的嗜酸乳杆菌置于不同ＰＨ值的豆汁中进行保存实验,偶然ＰＨ值对活菌的存活有一定的影响,但影响     

类胡萝卜素产生菌深红酵母的培养条件的优化研究

本文研究深红酵母及其产生的类胡萝卜素的培养优化条件,并对其进行了小型发酵试验,结果表明ＰＨ值对深红酵母和类胡萝卜有影响,初始ＰＨ值越低,我素的积累量越高, 酵过程中控制ＰＨ值能有铲地增加色素积累的速度和初始色素积累量,但随着发酵时间的延长,色素积累量逐渐下降。     

模拟酸雨对绿豆、玉米生理生态特性的影响

探讨了模拟酸雨对绿豆、玉米的影响．结果表明,叶绿素含量、叶绿素ａ／ｂ值、叶片活力、叶汁ＰＨ、土壤ｐＨ与模拟酸雨ｐＨ值呈正相关;相对电导率、ＰＯＤ活性和脯氨酸含量与模拟酸雨ｐＨ呈负相关;ＳＯＤ活性随模拟酸雨ｐＨ减小而下降．     

盐碱地柽柳“盐岛”和“肥岛”效应及其碳氮磷生态化学计量学特征

为了探讨“盐岛”和“肥岛”效应影响下盐碱土的养分特征,对黄河三角洲盐碱地柽柳植株周围不同土层的pH值、电导率和碳氮磷含量及其生态化学计量学特征进行了研究.结果表明: 土壤pH和电导率均随土层的加深而升高,0～20 cm土层土壤电导率随离植株距离的增加而降低,全磷含量则升高.20～40 cm土层土壤有机碳、全氮、N/P和C/P随离柽柳植株距离的增加而降低,C/N则升高.随着土层的加深,有机碳和全氮均呈降低趋势,而全磷则先降低后升高.土壤pH与电导率呈显著正相关,且二者与土壤碳氮磷及其生态化学计量比之间均呈显著负相关.     

氮源流加对Alcaligenes eutrophus 积累聚β-羟基丁酸的影响

以真养产碱杆菌（Ａｌｃａｌｉｇｅｎｅｓ ｅｕｔｒｏｐｈｕｓ）为聚β－羟基丁酸９ＰＨＢ）的生产菌株,在分析了ＰＨＢ发酵过程参数变化的基础上,进一步探讨了ＰＨＢ合成期不同的硫酸铵流加速度对ＰＨＢ合成的影响。研究结果表明,在ＰＨＢ合成阶段,培养基中氮源的完全缺乏。导致细胞合成ＰＨＢ能力的下隆;在ＰＨＢ合成期,不同的氮源流加速率对ＰＨＢ合成过程存在着显著的影响,当流加速率较小时,尽管最终胞内ＰＨＢ含量很高     

盐碱地土壤改良对银中杨叶片、树枝和树皮绿色组织色素和C_4光合酶的影响

在松嫩平原重度盐碱地上,选择通过土壤改良使得盐碱成分降低、结构显著改善的土壤作为处理样地(pH值9.17;电导率388μscm-1;土壤紧实度1170kPa),邻近未改良重度盐碱地为对照样地(pH值10.15;电导率1220μscm-1;土壤紧实度2199kPa),对生长在对照和处理样地上的银中杨不同器官叶绿素和C4光合相关酶研究发现:1)生长在处理样地的银中杨叶片叶绿素a+b、叶绿素a/b、类胡萝卜素含量显著高于对照未处理,但树枝和树皮绿色组织内这些指标的差异远小于叶片;2)所测定3种C4光合酶结果显示,当以单位鲜重表示时,3种器官以及盐碱化程度对结果影响较小;3)当以单位叶绿素酶活性表示时,不同器官以及盐碱化程度对酶活性影响显著:树皮和树枝磷酸烯醇式丙酮酸酶(PEPC)活性是叶片的4.4和3.1倍,盐碱地改良使这一差异变成8.6和2.6倍;对照样地内树皮、树枝的苹果酸酶(NADP-ME)活性是叶片的1.7和2.1倍,盐碱地土壤改良使得这一差异达到17.2和6.4倍;与此类似,在对照盐碱地上,树皮和树枝内苹果酸脱氢酶(NADP-MDH)活性是叶片的1.7和1.4倍,盐碱地土壤改良使得这一差异变为6.4和13.7倍。上述结果说明,银中杨树干和树枝绿色组织内C4相关酶含量较叶片高出很多,而且受盐碱胁迫程度影响显著,盐碱化程度轻的情况下,这种差异会增大,这些酶的变化可以作为植物响应土壤盐碱程度变化的一种生理生化指示指标。     

森林降水酸度及电导率的时空变化

在离大气污染源距离不同的两片杉木(Cunninghamia lanceolata)人工林中建立监测场,对降水化学进行了为期3年(1994～1996)的定位监测。降水通过林冠截留后,其酸度和电导率均明显增加,尤以树干径流为显著。在 FFC监测场,降雨、穿透雨和树干径流雨量加权平均pH值分别为6.13、6.06和4.18,在XQF监测场,其相应的数值分别为5.86、5.67和3.37;降雨和穿透雨的酸度表现出一定的季节变化动态,其最低月均pH值出现在夏委,最高值在冬季。在FFC监测场,降雨、穿透雨和树干径流雨量加权平均EC值分别为28.51μs·cm-1、63.71μs·cm-1、240.85μs·cm-1,在XQF监测场,其相应的数值分别为36.99μs·cm-1、66.41μs·cm-1、501.85μs·cm-1：降水电导率表现出显著一致的季节变化格局,其月均值均以夏季最低,冬季最高,春秋季居中,这种格局强烈受降雨量的影响。离污染源较近的XQF监测场,降水酸度和电导率明显高于相对未受污染的FFC监测场。     

聚皂凝胶对蛋白分子的吸附与释放

以牛血清白蛋白为对象,研究了丙烯酸－丙烯酰胺型９ＰＢｕＡＭＡ）和疏水改性的四乙烯五胺－环（ＨＰＴＥ）聚合物凝胶对蛋白质的及附与释放过程。在吸附过程中,当溶液ＰＨ值在牛血清白蛋白电点（４．７）附近时,凝胶蛋白抽的吸附值最大;而在释放过程中,ＰＨ＝７的释放率远大于其它ＰＨ值时的释放率。实验表明凝胶结构对蛋白质吸附与释放有较大影响。未疏水改性的凝胶与疏水改性的凝胶相比,前 的释放速率约为后者的２倍。结果     

光肩星天牛产卵刻槽含水量与pH值的分析

测定了光肩星天牛Anoplophora glabripennis(Motsch.)在柳树皮上产卵刻槽、模拟刻槽及健康树皮的含水量和pH值。结果表明:柳树在不同受伤条件下的含水量及pH值都有所不同,其中含水量的顺序为产卵刻槽>健康树皮>模拟刻槽;pH值的顺序为产卵刻槽>模拟刻槽>健康树皮。这些结果为进一步研究刻槽内微生物的种类和丰度及树木在不同受伤条件下的生理反应提供依据。     

Variations in bark acidity and conductivity over the trunk length of silver fir and Norway spruce

 Before using bark to determine the degree of acidity in the environment due to atmospheric pollution, a better understanding of the internal factors which are involved in the evolution of the physico-chemical characteristics of bark is necessary. In this paper, variation of acidity and bark conductivity over the trunk length of silver fir and Norway spruce are examined. First, we show that it is more accurate to measure average bark pH and conductivity in each 2 m section of a tree by starting at the top than by starting at the base of the tree. A positive pH and conductivity gradient is observed over the trunk length; bark thickness decreases towards the top of the trunk. In the upper part of both silver fir and Norway spruce there are good correlations between acidity, conductivity, bark thickness and height, but in the lower part of the trees, silver fir and Norway spruce show contradictory behaviour. In silver fir, pH is linked with bark thickness and distance from the ground, while conductivity is not correlated with these two criteria. In Norway spruce we observe opposite results. It appears that conductivity measured on the external part of bark is directly influenced by the proximity of internal tissues, which are rich in ions, while acidity depends on the length of exposure to leaching due to water flowing down the trunk. Received: 15 June 1993/Accepted: 30 January 1995     

Vertical distribution and assemblages of corticolous myxomycetes on five tree species in the Great Smoky Mountains National Park

Corticolous myxomycetes of the Great Smoky Mountains National Park were studied in relation to their association with certain tree species and height of occurrence in the forest canopy. Using the double-rope climbing method, bark was collected at 3 m increments to the tops of trees of five different species. Bark samples from 25 trees were used to prepare 418 moist chamber cultures maintained and observed 4 wk. Eighty-four myxomycete species were identified, including 30 species not known to occur in the park. Tree species, pH, height in tree and water-holding capacity of the bark samples were analyzed to determine the relationships of myxomycete assemblages cultured on the bark. Results suggested that myxomycete community composition among selected tree species were similar, but occurrence and abundance of certain species were related to differences in bark pH. Community similarity values among trees of different species show that trees with the most similar myxomycete communities also have the most similar bark pH. Most myxomycete species in this study have a pH optimum. No variation in species richness was detected at different heights in the trees, and most species were obtained at all heights up to at least 24 m. The water-holding capacity of the bark could not be correlated with species richness or abundance of myxomycetes that inhabit the bark of living trees. This is the first study to characterize myxomycete communities of tree canopies.     

行道树毛白杨树干中重金属元素分布

采用电感耦合等离子体发射光谱法(ICP),测定分析首都机场高速公路旁毛白杨(Populus tomentosa Carr.)树干中Pb、Cd、Cr、Cu、Zn、Ni和Mn 7种重金属元素的含量及积累量,比较分析树干不同组织、不同方位、不同龄级年轮重金属含量差异及与交通量、关键气候因子的相关性。结果表明:树干木质部中各重金属平均含量由大到小依次为Zn、Cu、Cr、Mn、Ni、Pb、Cd,树皮中依次为Zn、Mn、Cr、Pb、Cu、Cd、Ni,树皮中各重金属元素的含量明显高于木质部;同一树干木质部中,各重金属元素在不同方位的分布有所差异,其中,靠近车道一侧的各重金属元素含量均高于背离车道一侧,南北向比较中,Ni、Zn为南侧含量高于北侧,其他5种重金属元素均为北侧高于南侧;以5a为一个龄级将年轮划分为5个龄组,各龄级年轮中重金属含量随时间的变化趋势各异,其中Pb、Cd、Cu、Zn总体呈递减趋势,且与年降水量、最低气温、日照时数、雨天日数和大风日数呈正相关趋势,与年平均气温和最高气温呈负相关趋势;各元素在毛白杨树干木质部中的积累量表现为ZnCrCuMnPbNiCd。     

Effect of water availability and fertilization on water status,growth, vigour and the resistance of Scots pine to fungal mass inoculation with Ophiostoma ips

Abstract

The effect of water and nutrient availability on the performance of Scots pine (Pinus sylvestris L.) against Ophiostoma ips (Rumb.), a bark beetle-associated phytopathogenic blue-stain fungus, was investigated. Field-grown trees were subjected for 18 months to water-stress and/or fertilization, and the effects of such treatments on the needle nutrient status, tree vegetative growth and vigour were examined. At the end of the experimental period, the trees were mass-inoculated (800 inocula m^?2) with the fungus, and the relationship between resource availability and tree performance against pathogen attack was also tested. Predawn shoot water potential (Ψ_PD) of irrigated trees was significantly higher than that of water-stressed trees, and fertilized trees had a significantly lower C/N ratio. The Ψ_PD values and needle nitrogen content suggest that resource-limited trees were under moderate stress. Improved nutrient availability significantly increased tree growth and tree vigour. However, no evidence for an effect of improved nutrient availability on tree fungal resistance was found in our study.     

Environmental filtering structures fungal endophyte communities in tree bark

The factors that control the assembly and composition of endophyte communities across plant hosts remains poorly understood. This is especially true for endophyte communities inhabiting inner tree bark, one of the least studied components of the plant microbiome. Here, we test the hypothesis that bark of different tree species acts as an environmental filter structuring endophyte communities, as well as the alternative hypothesis, that bark acts as a passive reservoir that accumulates a diverse assemblage of spores and latent fungal life stages. We develop a means of extracting high‐quality DNA from surface sterilized tree bark to compile the first culture‐independent study of inner bark fungal communities. We sampled a total of 120 trees, spanning five dominant overstorey species across multiple sites in a mixed temperate hardwood forest. We find that each of the five tree species harbour unique assemblages of inner bark fungi and that angiosperm and gymnosperm hosts harbour significantly different fungal communities. Chemical components of tree bark (pH, total phenolic content) structure some of the differences detected among fungal communities residing in particular tree species. Inner bark fungal communities were highly diverse (mean of 117–171 operational taxonomic units per tree) and dominated by a range of Ascomycete fungi living asymptomatically as putative endophytes. Together, our evidence supports the hypothesis that tree bark acts as an environmental filter structuring inner bark fungal communities. The role of these potentially ubiquitous and plant‐specific fungal communities remains uncertain and merits further study.     

Cork oak vulnerability to fire: the role of bark harvesting, tree characteristics and abiotic factors

Forest ecosystems where periodical tree bark harvesting is a major economic activity may be particularly vulnerable to disturbances such as fire, since debarking usually reduces tree vigour and protection against external agents. In this paper we asked how cork oak Quercus suber trees respond after wildfires and, in particular, how bark harvesting affects post-fire tree survival and resprouting. We gathered data from 22 wildfires (4585 trees) that occurred in three southern European countries (Portugal, Spain and France), covering a wide range of conditions characteristic of Q. suber ecosystems. Post-fire tree responses (tree mortality, stem mortality and crown resprouting) were examined in relation to management and ecological factors using generalized linear mixed-effects models. Results showed that bark thickness and bark harvesting are major factors affecting resistance of Q. suber to fire. Fire vulnerability was higher for trees with thin bark (young or recently debarked individuals) and decreased with increasing bark thickness until cork was 3-4 cm thick. This bark thickness corresponds to the moment when exploited trees are debarked again, meaning that exploited trees are vulnerable to fire during a longer period. Exploited trees were also more likely to be top-killed than unexploited trees, even for the same bark thickness. Additionally, vulnerability to fire increased with burn severity and with tree diameter, and was higher in trees burned in early summer or located in drier south-facing aspects. We provided tree response models useful to help estimating the impact of fire and to support management decisions. The results suggested that an appropriate management of surface fuels and changes in the bark harvesting regime (e.g. debarking coexisting trees in different years or increasing the harvesting cycle) would decrease vulnerability to fire and contribute to the conservation of cork oak ecosystems.     

Tree age and bark thickness as traits linked to frost ring probability on Araucaria araucana trees in northern Patagonia

Frost events may damage the cambium and consequently the newly produced tracheids whose cell walls have not yet completed their lignifications, leading to the formation of frost rings. This study deals with the presence of frost rings in Araucaria araucana trees according to cambial age and bark thickness, under the assumption that these factors may be involved in physical or physiological mechanisms that increase resistance to freezing temperatures that impact the cambial tissue. The study was conducted in northern Patagonia at two sites of contrasting geomorphology, and therefore potentially associated with a differential degree of exposure to extreme cold. Wood plus bark cores were extracted from main stems at two heights from the ground and from each of the four cardinal point directions for 30 individuals per site. A Linear Mixed Model and a Generalized Linear Mixed Model were applied in order to relate the bark thickness and the frequency of frost rings in accordance with the different sampling points on the stem. It was observed that as bark becomes thicker with cambial age, the frequency of frost rings decreases, indicating a possible thermal-induced mechanism of bark protection. Consequently, there is an increase in the presence of frost rings at the younger stages of tree life. Although the mechanisms of cold hardiness in trees can be complex, including aspects of the tree physiology, our data indicated that as tree age increases, the thickness of the bark is higher, resulting in a potential effect of isolation and passive protection against the harmful effects of frosts. This mechanism may be relevant in the ecology, conservation and management of forests faced with extreme variability in future climate and changing scenarios.     

Past attacks influence host selection by the solitary bark beetle Dendroctonus micans

1. A spatio‐temporal study of host selection and local spread of a solitary bark beetle attacking live spruce Dendroctonus micans (Kugelann) was carried out using a combination of standard statistical methods, geostatistical analyses, and modelling. The study was based on data from three plots (150–300 trees, 0.3–1 ha) from 1978 to 1993. All trees were mapped and successful and abortive bark‐beetle attacks on each tree were counted annually. Because the attacked trees usually survived, temporal attack patterns as well as spatial patterns could be analysed. 2. The distribution of successful insect attacks on the trees was slightly aggregative, indicating some degree of choice rather than totally random establishment. 3. The level of yearly individual attacks per tree was very stable, suggesting that D. micans usually leave the host in which they develop. 4. The attacked trees were distributed randomly in the plots; at the study's spatial scale, the insects dispersed freely throughout the plot (no spatial dependence). 5. On the other hand, time dependence was strong; some trees were attacked repeatedly while others were left untouched. 6. Among a choice of scenarios (random attack, fixed variability in individual host susceptibility, induced host susceptibility following random attack), the best fit was obtained with the model involving induced individual host susceptibility. This type of relation to the host tree contrasts strongly with patterns generally described in host–plant relationships (including gregarious, tree‐killing bark beetles), where local herbivore damage results in induced resistance. 7. These results suggest that the first attacks in a new stand are made at random, that all or most of the beetles emerging from a tree disperse and resample the stand, and that they settle preferentially on trees that were colonised successfully by previous generations.     

Influence of bark pH on the occurrence and distribution of tree canopy myxomycete species

This study compares the occurrence and distribution of myxomycete species in the canopy of living trees and neighboring grapevines. Corticolous myxomycetes of three temperate forests in southeastern USA were studied on six tree species (30 trees) and grapevines (30 vines) to determine distribution and occurrence of myxomycete species relating to geographic location, host species, and bark pH. The double-rope climbing technique was used to access the canopy and sample bark up to 16.5 m. Bark samples were examined in 580 moist chamber cultures and 44 myxomycete species were identified representing 21 genera, averaging 3.0 +/- 2.1 species per sample site. Jaccard's coefficient determined community similarity between five individuals of six tree species, Acer saccharum, Fraxinus americana, Liquidambar styraciflua, Liriodendron tulipifera, Platanus occidentalis and Tsuga canadensis, and neighboring grapevines, Vitis aestivalis and V. vulpina. Vertical variation in species richness was significantly different only for Platanus occidentalis and might be attributable to flaking of bark with increasing height in the canopy. Tsuga canadensis and neighboring grapevines had greatest community similarity. Cribraria violacea was observed on all tree and grapevine species except T. canadensis and neighboring grapevines. Occurrence and species assemblages of myxomycetes were associated with bark pH, not geographic location. Bark of V. aestivalis (pH 4.5) was more acidic than neighboring T. canadensis (pH 4.1), compared to grapevines of the same species neighboring other tree species. Results indicated that most species are not regionally restricted, and although some myxomycetes are associated with a certain pH range, others develop on any substratum. Future research protocols for corticolous myxomycetes should emphasize sampling adequate amounts of substrata in a local region from different host species that have a wide range of bark pH, ensuring a representative sample of species for an entire region.