不同浓度氮源引起的红松苗木根际pH变化及其对Fe、Mn、Cu、Zn有效性和吸收的影响(英文)

在中科院长白山生态系统定位站,从地表20cm处采集土壤样品,用两种不同形式的氮肥(NO3--N,NH4 -N和NH4NO3)处理土壤样品,用盆栽试验研究了两年生红松苗木受不同浓度N源影响而产生的根际pH变化及其对根际Fe、Mn、Cu和Zn等微量元素的有效性和吸收的影响。结果表明,与对照处理相比,施加铵态氮使根际pH降低,而施加硝态氮则使根际pH增加。根际pH变化的方向与程度取决于N源及施加的浓度。根际pH的变化对根际微量元素的有效性具有显著影响,进而影响到苗木对养分的吸收利用。根际有效Fe、Mn、Cu和Zn的含量与根际pH呈负相关,而苗木叶中Fe、Mn、Cu和Zn含量与根际有效养分含量呈正相关。图5参11。     

第二代杉木林速生阶段微量元素含量与分布

分析了第2代杉木林速生阶段生态系统内各组分微量元素的含量和分布,及杉木各组分微量元素含量与土壤中微量元素含量的相关性.结果表明土壤中微量元素含量高低依次为Fe＞Mn＞Zn＞Cu,死地被物层中(除Mn外)Fe、Cu、Zn含量均低于土壤中的含量,且含量大小顺序为Mn＞Fe＞Zn＞Cu;草本层中Fe、Mn、Cu、Zn含量普遍高于灌木层;杉木叶片中微量元素含量与杉木的生长级无关,而与叶龄有关.在杉木各器官中,微量元素含量的排列顺序为叶＞枝＞皮＞根＞干.杉木对不同微量元素的吸收系数有明显的差异,对Mn的生物吸收系数最高,平均为1.744,杉木是富集Mn的植物.     

桤木人工林根系—土壤复合系统养分含量的变化规律

对桤木人工林根系-土壤复合系统中大量元素、微量元素、土壤有机质含量和pH值等的季节动态变化进行了研究,结果表明:在桤木根系中大量元素N、Ca、K、Mg、P含量冬季最高,春季最低,微量元素Fe、Mn、Zn、Cu、Pb、Ni、Cd含量冬季最低,春夏季较高;土壤中大量元素N、Ca、K、Mg、P含量冬季最低、夏季最高,微量元素Mn、Zn含量在冬季最低、秋季最高,Fe、Ni、Pb、Cu、Cd含量在冬季最高、春秋较低;土壤有机质含量、pH值的季节动态变化与根系大量元素变化趋势保持一致;土壤各层有机质含量大小顺序为0～15 cm层、＞15～30 cm层、＞30 cm层,pH值大小顺序为＞15～30 cm层、0～15 cm层、＞30 cm层.     

不同林龄灰木莲人工林土壤微量养分特征

以广西高峰林场的10、12、18和51 a灰木莲人工林为研究对象,对比分析土壤中微量元素Fe、Mn、Cu、Zn、B、Al在不同林龄林分中的含量差异及其与土壤有机质、pH值及物理性质之间的相关性,为评价灰木莲人工林的土壤改良效果及养分管理提供依据。结果显示：(1)林龄变化对土壤微量元素含量特征存在显著影响(P<0.05),其中土壤微量元素Fe、Mn、Cu、Zn含量均随着林分年龄的增加而显著增加,有效B含量无显著变化,交换性Al含量显著降低。(2)各微量元素有效性指数从大到小依次为Fe、Cu、Mn、Zn、B、Al,除Al(0.57)外,其余元素的有效性指数均大于1,且随林龄增加而增大。不同林龄间微量元素有效性综合指数从大到小依次为51、18、10、12 a,整体呈现出随林龄增加而增大的趋势。(3)土壤有效态微量元素与土壤有机质、容重、持水量及总孔隙度之间相关性显著,其中有机质对土壤有效态微量元素含量变异的解释度最高(55.7%)。研究结果表明：灰木莲人工林土壤微量元素含量受林龄变化的影响,并且土壤有机质是引起不同林龄人工林土壤微量元素含量变化的关键因子;灰木莲的长期经营提高了土壤微量...     

连栽马尾松林根际与非根际土壤养分及酶活性研究

通过配对样地法,对连栽马尾松林根际与非根际土壤养分及酶活性的差异性进行分析。结果表明:根际与非根际土壤全N、全K、全Ca和全Mg含量2代低于1代,而有机质、碱解N、速效P、全P和速效K含量2代却高于1代,且有机质、碱解N和速效P含量在1、2代之间的差异均达显著或极显著水平;连栽后根际土壤全Al、全Cu和全Zn含量2代高于1代,而全Fe和全Mn含量2代却低于1代,且全Mn含量在1、2代之间的差异达显著水平;非根际土壤除全Cu含量2代高于1代外,其余全Fe、全Al、全Zn、全Mn含量2代均低于1代,且差异均达显著或极显著水平;根际与非根际土壤脲酶、蛋白酶、磷酸酶、过氧化氢酶和多酚氧化酶活性2代均高于1代,且脲酶、磷酸酶、过氧化氢酶活性在1、2代之间的差异均达显著或极显著水平。     

桤木人工林细根与土壤养分含量季节动态变化

对桤木人工林细根、土壤养分含量的季节变化及其两者之间的关系进行了研究.结果表明:(1)桤木细根中大量元素N、Ca、K、Mg、P含量冬季高,春季最低;微量元素Fe、Mn、Zn、Cu、Pb、Ni、Cd含量冬季最低,春夏季较高.(2)土壤各层中大量元素N、Ca、K、Mg、P含量冬季最低,夏季最高;微量元素Mn、Zn含量在冬季最低,秋季最高;Fe、Ni、Pb、Cu、Cd含量在冬季最高,春秋较低.(3)细根和土壤中大量元素含量在冬季存在负相关关系,微量元素Fe、Ni、Cd含量在一年四季均存在显著负相关关系,Mn、Cu含量在春季、夏季和秋季存在负相关关系,Zn、Pb含量在春季、夏季和秋季存在正相关关系.     

洞庭湖西岸区防护林土壤与植物微量元素含量特征

对洞庭湖西岸区4种防护林地土壤与植物中微量元素含量进行研究。结果表明:(1)环湖低丘平原封山育林和补植封山育林的水土保持林、平原湖区防护林土壤pH值为4.54~5.27,呈酸性反应;防浪护堤林土壤pH值为8.18,呈碱性反应。(2)全Cu、全Fe、全Zn以环湖低丘平原补植封山育林水土保持林土壤含量最高;全Mn、全Cd、全Ni、全Pb却以防浪护堤林土壤含量最高;全Co则以环湖低丘平原封山育林水土保持林土壤含量最高。(3)4种防护林土壤微量元素含量均表现为FeMnZnNiCuPbCoCd,Pb、Zn、Cu和Cd含量均未超过国家规定的三级标准;各防护林群落中植物体内不同微量元素含量差异很大,同一元素在不同植物体内含量的变化范围亦很大。(4)植物对土壤中Cd的吸收能力最强,对Mn、Zn、Cu、Ni、Pb其次,对Fe最弱;木本植物青冈、冬青和山矾具有较强的Cd积累能力。研究结果可为土壤环境质量评价及防护林体系建设提供理论依据。     

森林草原交错区沟塘草甸土壤微量元素分析

为研究森林草原交错区不同坡向沟塘草甸土壤化学计量特征,以内蒙古阿尔山市的沟塘草甸为研究区域,通过野外调查与室内实验相结合的方法,对阴坡阳坡不同深度土层有效微量元素(Fe,Mn,Cu,Zn)含量及有机C,全N,全P含量进行比较分析,探究沟塘草甸土壤化学计量特征。结果表明:1)阴坡阳坡土壤有效Fe和有效Mn含量均随着土层深度增加呈现先增后减趋势,而有效Cu含量随着土层深度变化差异不显著;2)阴坡阳坡土壤有效微量元素含量均呈现Fe>Mn>Zn>Cu趋势;3)土壤有效微量元素含量与pH值无相关性,有效Fe含量与有效Mn、有效Cu、有效Zn含量相关性(P<0.01)极为显著;4)同一坡向不同深度土层C∶N,N∶P差异均不显著,而C∶P差异显著;5)土壤pH在不同坡向不同深度土层均无显著差异。研究结果为沟塘草甸土壤微量元素分析提供数据支持。     

马尾松、巨尾桉及其混交林土壤微量元素调查

纯林造林模式是制约人工林可持续发展的重要因素。微量元素是植物生长过程中必需的养分,对土壤肥力有重要的影响。通过对马尾松(Pinus massoniana)和巨尾桉(Eucalyptus grandis×E.urophylla)不同造林模式进行土壤理化性质分析,评价不同模式土壤微量元素有效含量,结果表明:各林分皆为酸性土壤,有效Fe含量很丰富,有效Cu含量均为适中水平,有效Zn仅巨尾桉纯林整体水平达到适中水平,其他林分皆为缺乏水平,有效Mn和有效B的含量均缺乏。同时有效Zn、有效B和有效Fe的含量与土壤有机质含量间存在显著正相关。     

宁县黄甘桃土壤养分与果实品质的典型相关性分析及优化方案

【目的】探索宁县黄甘桃园土壤养分与果实品质的关系，提出土壤养分含量优化方案，对照方案分析土壤营养的丰缺状况，为该桃的科学配方施肥提供理论依据。【方法】通过测定调查桃园的果实品质和土壤养分含量，运用典型相关分析和多元线性回归分析等方法，筛选出影响宁县黄甘桃果实品质的主要土壤养分因子，建立并求解基于果实品质与土壤养分关系的线性方程组，获得生产优质果品所对应的土壤养分含量优化方案。【结果】调查桃园的土壤均呈碱性，除有机质处于缺乏水平外，其余指标均处于中等或丰富的水平。宁县黄甘桃果实品质是土壤养分因子共同作用的结果。多元统计分析结果表明，单果质量主要受土壤硝态氮、有效Mn和有效B的影响，果实可溶性固形物含量主要受土壤pH值、有机质和有效Fe的影响，硬度主要受土壤硝态氮、速效钾、有效Zn和有效B的影响，“L”值主要受土壤有机质和硝态氮的影响，“a”值主要受土壤pH值、有机质、交换性Ca和有效B的影响，“b”值主要受土壤pH值、有机质、速效磷和交换性Ca的影响，可滴定酸含量主要受土壤pH值、硝态氮和有效Mn的影响，固酸比主要受土壤pH值、有效Fe、有效Mn、有效Cu、有效Zn和有效B的影响。【结论...     

Antimicrobial activity of some endemic plants growing in the Eastern Black Sea Region, Turkey

The Eastern Black Sea Region has an extensive flora because of ample rainfall lasting all year. In this study, antimicrobial effects of 74 crude extracts of 22 endemic plants were investigated. Among the 30 active crude extracts, water-insoluble crude extracts from Betula medwediewii, Heracleum platytaenium, Primula longipes, Anthemis cretica ssp. argaea and Centaurea helenioides were the prominent ones with their MIC values.     

利用三种梢栖真菌生物防治落叶松枯梢病的研究

从落叶松梢栖真菌筛选出对落叶松枯梢病病原菌有抑制作用的菌株,对落叶松枯梢病进行生物防治。将自落叶松梢部分离到的11种梢栖真菌与落叶松枯梢病病原菌进行对峙培养,根据被覆盖程度、抑菌率、拮抗系数和防治预试验的结果,综合评价后发现:粪生粪壳、深绿木霉和球毛壳3种梢栖真菌对落叶松枯梢病有良好的拮抗作用。利用这3个菌株在黑龙江省勃利县通天一林场国富沟进行林间防治试验,结果表明:防治效果为粪生粪壳>代森锰锌400倍液>深绿木霉>球毛壳;深绿木霉和粪生粪壳喷洒浓度50%和球毛壳喷洒浓度75%时,真菌多样性最多,梢栖真菌系统较其他浓度更为稳定,与化学防治相比,既达到了防治目的又具有不污染环境的优势。     

Screening of antioxidant activity of three Euphorbia species from Turkey

Euphorbia acanthothamnos, E. macroclada and E. rigida were investigated for their antioxidant activity. The antioxidant potential of extracts of E. acanthothamnos, E. macroclada and E. rigida was evaluated using different complementary antioxidant tests.     

Antibacterial activity of plant extracts from Brazilian southeast region

A screening was conducted with 26 plants collected in the Brazilian southeast region, to identify plant extracts with antibacterial properties against Aeromonas hydrophila, Bacillus subtilis, Pseudomonas aeruginosa and Staphylococcus aureus. Initially, the agar diffusion method was employed. Then, those extracts presenting activity were submitted to a broth microdilution assay to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). It was observed that 13 of the tested extracts showed antibacterial activity. The best results were obtained with those from Lantana lilacina and Phyllanthus tenellus.     

Growth and physiological response of six Australian rainforest tree species to a light gradient

An understanding of growth and photosynthetic potential of subtropical rainforest species to variations in light environment can be useful for determining the sequence of species introductions in rainforest restoration projects and mixed species plantations. We examined the growth and physiology of six Australian subtropical rainforest tree species in a greenhouse consisting of three artificial light environments (10%, 30%, and 60% full sunlight). Morphological responses followed the typical sun-shade dichotomy, with early and late secondary species (Elaeocarpus grandis, Flindersia brayleyana, Flindersia schottiana, and Gmelina leichhardtii) displaying higher relative growth rate (RGR) compared to mature stage species (Cryptocarya erythroxylon and Heritiera trifoliolatum). Growth and photosynthetic performance of most species reached a maximum in 30–60% full sunlight. Physiological responses provided limited evidence of a distinct dichotomy between early and late successional species. E. grandis and F. brayleyana, provided a clear representation of early successional species, with marked increase in A_max in high light and an ability to down regulate photosynthetic machinery in low light conditions. The remaining species (F. schottiana, G. leichhardtii, and H. trifoliolatum) were better represented as falling along a shade-tolerant continuum, with limited ability to adjust physiologically to an increase or decrease in light, maintaining similar A_max across all light environments. Results show that most species belong to a shade-tolerant constituency, with an ability to grow and persist across a wide range of light environments. The species offer a wide range of potential planting scenarios and silvicultural options, with ample potential to achieve rapid canopy closure and rainforest restoration goals.     

Insecticidal activity of Vitex mollis

Organic extracts from the leaves of Vitex mollis were assessed for their toxic effect on fall armyworm neonate larvae (Spodoptera frugiperda), an important insect pest of corn. The extracts showed insecticidal and insect growth regulatory activity, being CHCl(3)-MeOH (1:1) extract the most active, also found to be toxic in the Artemia salina test.     

Ungulate herbivory of regenerating conifers in relation to foliar nutrition and terpenoid production

Ungulate browsing greatly influences regeneration dynamics of some forest ecosystems, yet the relationship between browse susceptibility and foliar chemistry of forest tree seedlings is not well understood. We applied field fertilization (15N-9P-10K controlled-release fertilizer at 0, 20, 40, and 60 g per seedling) and investigated how subsequent changes in terpenoid production and foliar nutrition influence ungulate browse preference for Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), western hemlock (Tsuga heterophylla Raf. Sarg.), and western redcedar (Thujaplicata Donn ex D. Don) seedlings across four sites in northwestern Oregon, USA. Fertilization increased foliar N concentration of all three species, but above-ground growth of only Douglas-fir and western hemlock. Foliar monoterpene concentrations for western hemlock and western redcedar also increased at higher fertilization rates, while Douglas-fir monoterpene production was not affected by fertilization. Regardless of monoterpene levels, ungulate browse preference was greater for fertilized western hemlock seedlings. The opposite response, however, was observed for western redcedar at two of the four study sites where the likelihood of browse was greater for non-fertilized than fertilized seedlings. Differences in browse preference among species may depend on the type and amount of individual monoterpenes manufactured in response to fertilization. Western redcedar produce α- and β-thujone, oxygenated monoterpenes known to promote gastroenteritis and possibly inhibit microbial rumen activity, which were absent from Douglas-fir or western hemlock. Higher concentrations of α- and β-thujone associated with increasing fertilizer rate provide a plausible explanation as to why ungulates preferred non-fertilized western redcedar. Our results illustrate species-specific adaptation in browse avoidance and selective ungulate browsing behavior of individual trees as linked to foliar chemistry.     

Effects of prescribed fire and season of burn on direct and indirect levels of tree mortality in Ponderosa and Jeffrey Pine Forests in California,USA

Many forests that historically experienced frequent low-intensity wildfires have undergone extensive alterations during the past century. Prescribed fire is now commonly used to restore these fire-adapted forest ecosystems. In this study, we examined the influence of prescribed burn season on levels of tree mortality attributed to prescribed fire effects (direct mortality) and bark beetles (Coleoptera: Curculionidae, Scolytinae) (indirect mortality) in ponderosa pine, Pinusponderosa Dougl. ex Laws., and Jeffrey pine, Pinusjeffreyi Grev. and Balf., forests in California, USA. A total of 816 trees (9.9% of all trees) died during this 3-yr study. Significantly higher levels of tree mortality (all sources) occurred following early and late season burns compared to the untreated control, but no significant difference was observed between burn treatments. The majority (461 trees) of tree deaths were attributed to direct mortality from prescribed burns and was strongly concentrated (391 trees) in the smallest diameter class (<20.2 cm diameter at breast height, dbh). For the largest trees (>50.7 cm dbh), significantly higher levels of tree mortality occurred on early season burns than the untreated control, most of which resulted from indirect mortality attributed to bark beetle attacks, specifically western pine beetle, Dendroctonus brevicomis LeConte, and mountain pine beetle, D. ponderosae Hopkins. Red turpentine beetle, D. valens LeConte, was the most common bark beetle species found colonizing trees, but tree mortality was not attributed to this species. A total of 355 trees (4.3% of all trees) were killed by bark beetles. Dendroctonus brevicomis (67 trees, 18.9%) and D. ponderosae (56 trees, 15.8%), were found colonizing P. ponderosa; and Jeffrey pine beetle, D. jeffreyi Hopkins, was found colonizing P. jeffreyi (seven trees, 2.0%). We also found pine engraver, Ips pini (Say) (137 trees, 38.6%), and, to a much lesser extent, Orthotomicus (=Ips) latidens (LeConte) (85 trees, 23.9%) and emarginate ips, I. emarginatus (LeConte) (3 trees, 0.8%) colonizing P. ponderosa and P. jeffreyi. Few meaningful differences in levels of indirect tree mortality attributed to bark beetle attack were observed between early and late season burns. The incidence of root and root collar pathogens (Leptographium and Sporothrix spp.), including species known to be vectored by bark beetles, was low (18% of trees sampled). The implications of these and other results to management of P. ponderosa and P. jeffreyi forests are discussed in detail.     

Anti-HBV activities of Streblus asper and constituents of its roots

The extracts from leaves, heartwood, barks and roots of the Streblus asper were investigated for anti-HBV activities, separately. The results suggested that the MeOH extracts of the heartwood, barks, and roots exhibited good anti-HBV activities. Further investigations displayed that ethyl acetate and n-butanol soluble parts of their MeOH extracts showed more significant anti-HBV activities. Moreover, a new lignan, together with 11 known compounds, was isolated from n-butanol-soluble part of MeOH extract of the roots of S. asper. The structures were elucidated by spectroscopic methods, including 1D NMR ((1)H NMR, (13)C NMR), 2D NMR (HMQC, HMBC) and HR-EI-MS experiments. Compounds 1-3 were evaluated for their anti-HBV activities. Honokiol showed significant anti-HBV activity with IC(50) values of 3.14μM and 4.74μM for HBsAg and HBeAg with no cytotoxicity respectively, while lamivudine (3TC, positive control) exhibited weak anti-HBV activity with IC(50) values of 11.81μM and 25.80μM for HBsAg and HBeAg respectively.