Effects of human disturbances and plant invasion on liana community structure and relationship with trees in the Tinte Bepo forest reserve,Ghana

There are conflicting reports on the role of disturbances in maintaining liana community structure, and in determining their relationship with trees. The effects of plant invasion on these attributes of lianas are not known. The study investigated the effects of human disturbances and plant invasion on liana community structure and relationship with trees in the Tinte Bepo forest reserve, Ghana, in three distinct forest types to reflect both human disturbances and invasion: Undisturbed, Disturbed-Invaded and Disturbed Forests (UF, DIF and DF respectively). Trees ≥10 cm dbh were identified and their dbh measured in two 0.25 ha plots in each forest type. The trees were examined for the presence of lianas (≥2 cm dbh) and their dbh measured. A total of 380 lianas ≥2 cm dbh belonging to 20 genera and 12 families were identified in the 1.5 ha forest. Twelve liana species were unique to the DIF suggesting the probable positive influence of plant invasion on their colonisation. Liana density differed significantly across the forest types (df = 2, p = 0.043) with the UF recording the greatest number. The mean liana stem diameter and basal area were greater in the DF. Large diameter lianas were absent in the UF. Tree density and number of trees hosting lianas were greater in the UF followed by the DIF and DF. Liana infestation was generally high with 90% in the DF, 88.2% in the UF, and 85.7% in the DIF. Both liana load per tree species and mean liana load per infested tree were highest in the UF followed by the DIF and then the DF. Liana density was highly dependent on tree density in all the forest types (df = 1, r² = 0.50, p = 0.007; df = 1, r² = 0.99, p = 0.000 and df = 1, r² = 0.72, p = 0.000 in the UF, DIF and DF respectively). There was a significant positive relationship between liana dbh and host dbh in the UF (df = 1, r² = 0.096, p = 0.000), DIF (df = 1, r² = 0.11, p = 0.000) and DF (df = 1, r² = 0.16, p = 0.008). There was no significant relationship between host dbh and liana loads in all the forest types.     

Effects of intercropping of peanut with the medicinal plant Atractylodes lancea on soil microecology and peanut yield in subtropical China

Diverse intercropping is an effective way to control crop disease and improve productivity. The aim of this study was to investigate the effects of intercropping peanut (Arachis hypogaea L.) with the medicinal plant Atractylodes lancea on peanut yield and on the microbial community in the soil. A. lancea was intercropped with peanut in an upland that had been monocropped with peanut for 10 years in subtropical China. The results showed that all the intercropping treatments increased the peanut pod yield. Intercropping of peanut with A. lancea effectively reduced the accumulation of soil phenolic allelochemicals and increased soil urease and invertase activities. Compared with addition of fertilizer, the row spacing between peanut and A. lancea was a more important factor influencing the soil microbial community. Analysis of phospholipid fatty acid (PLFA) profiles showed that Gram-negative (G^?) bacteria were significantly affected by changes in the intercropping pattern. Especially in the rhizosphere region, which is nutrient-rich and has diverse substrate composition, the G^? bacterial population increase by 31.2–79.9 % in intercropping treatments. Soil G^? bacteria (as indicated by PLFA, including cy17:0, 18:1ω7, and 16:1ω9) were significantly promoted in the intercropping treatments. The increase in the G^? bacterial population and the decrease of phenolic allelochemicals resulted in the promotion of peanut growth and increased peanut yield in the intercropping treatments. Our results provide details on the mechanisms by which intercropping of peanut with A. lancea can improve the soil environment.     

3种植物外源激素对观赏桃花花期及品质的影响

为了研究植物外源激素对观赏桃花的花期及花径的影响情况,以‘照手桃’为材料,分别在其花前期、花中期、花后期喷施不同质量浓度的赤霉素(GA)、6-苄基腺嘌呤(6-BA,常见的人工合成的细胞分裂素)、水杨酸(SA)3种植物外源激素进行试验。结果表明:在花前期、花中期及花后期喷施GA,均可使‘照手桃’的花径增大,从而提高桃花的观赏品质。花前期,喷施浓度为120 mg/L的GA可使其花径达到最大值(49.80 mm);花中期,喷施浓度为150 mg/L的GA可使其花径达到最大值(52.94 mm);花后期,喷施浓度为90 mg/L的GA可使其花径达到最大值(50.61 mm)。而喷施不同浓度的6-BA和SA对其花径均表现出抑制作用。在花期调控方面,花前期及花中期喷施GA、6-BA及SA均不能使其进入始花期的时间提前;而在花后期,SA处理可使其开花持续的天数较对照组延长1~2 d。在应用实践中,可于观赏桃的花芽萌动期与始花期之间喷施90~150 mg/L的GA,且在始花期时喷施30~45 mg/L的SA,这样可以提高桃花的观赏性并且延长其观赏时间。     

高支化聚脲对脲醛树脂胶黏剂耐水性能和甲醛释放量的影响

引入高分子量、高支化度以及端基为尿素的高支化聚脲(HBPU)用于低摩尔比脲醛树脂(UF)改性,利用HBPU与游离甲醛的反应以及与UF组分的共缩聚反应实现树脂耐水性能的提升和人造板甲醛释放量的降低,有效平衡胶合性能和甲醛释放量之间的矛盾。在无溶剂、无催化剂条件下,通过尿素(U)与三(2-氨基乙基)胺(TAEA)的脱氨缩合反应,一步合成了具有尿素端基的HBPU,并对HBPU的分子量分布和结构进行了表征。使用HBPU水溶液,采用UF合成反应后期加入和共混2种方法对UF进行改性,通过胶合板性能测试以及甲醛释放量测定,考察了HBPU添加量和添加方式的影响。凝胶渗透色谱和碳-13核磁共振分析表明,通过本研究的合成方法可以获得具有高分子量、高支化度、尿素为端基且水溶性良好的HBPU,并且随着U与TAEA摩尔比的提高,更多尿素封端产物形成。电喷雾电离质谱对改性树脂的分析结果表明,HBPU不仅与UF中的一部分游离甲醛发生羟甲基化反应,同时与UF组分反应生成了部分共缩聚产物。胶合板性能测试结果表明,共混以及反应后期加入HBPU两种方式得到的改性树脂耐水性能均显著提升。同时,使用添加5%HBPU改性树脂制备...     

Effects of resveratrol on the ultrastructure of Botrytis cinerea conidia and biological significance in plant/pathogen interactions

Many roles have been ascribed to stilbenes, namely as antimicrobial, deterrent or repellent compounds in plants, protecting them from attacks by fungi, bacteria, nematodes or herbivores, acting both as constitutive and active defense (phytoalexin) compounds. More recently, stilbenes (especially resveratrol and its derivatives) were acclaimed for their wondrous effects and wide range of purported healing and preventive powers as cardioprotective, antitumor, neuroprotective and antioxidant agents. Although there is a huge number of works concerning the role of resveratrol in human health, reports on the antifungal activity of this compound are still scarce. This study was thus conducted in order to investigate the toxicity of resveratrol at an ultra- structural level to dormant conidia of Botrytis cinerea, the causal microorganism for gray mold. In grapevine particularly, this disease can affect all the green organs but is particularly damaging for ripening berries. Observations using transmission electron microscopy showed the occurrence of damages on conidia treated with sub-lethal doses, that is, 60 μg/mL (2.6 × 10^− 4 M) of resveratrol, a concentration usually reached in grapevine leaves and grape berries challenged by this pathogen. These results provide further data about the overall mode of action of this phytoalexin and its role in the B. cinerea/grapevine interaction.     

Agronomic and economic appraisal of alley cropping with Leucaena diversifolia on an acid soil in the highlands of Burundi

Although alley cropping has been shown elsewhere to permit continuous cropping, it has not been widely tested in the highlands of east and central Africa where it has the additional potential of controlling soil erosion. The effect of four rates (0, 30, 60 and 90 kg N ha^–1) of inorganic N on the performance of alley cropping using Leucaena diversifolia as the hedgerow species was studied in the central highlands of Burundi. Significant increase in maize yield (average of 26%) due to alley cropping was only first realised in 1992, three years after the commencement of the trial. In 1993, the average yield advantage of the alley cropping plots was 21%. The prunings augmented the response of maize yield to inorganic N in 1992 and 1993. Compared with the control, economic benefits over the five-year period for all the treatments were negative.     

人为干扰对绵阳三江迁徙水鸟停歇的影响

采用野外直接观察法和最小接近距离试验法对绵阳三江(涪江、安昌江和芙蓉溪)的迁徙水鸟的迁徙及人为干扰对水鸟停歇的影响进行了研究。结果表明,98%的水鸟在55 m或更小的距离上通过游走或惊飞对人类的活动做出反应。干扰类型为1人行走,2人行走,3人行走;1人奔跑,2人奔跑,3人奔跑对水鸟移动的距离、移动的次数以及水鸟对人类靠近的反应均具有一定的影响。人为干扰最小接近距离试验结果表明,水鸟的反应距离是30～60 m。干扰人数为1人时的最小接近距离小于2人和3人,2人小于3人,干扰类型为行走时最小接近距离小于奔跑。记录不同停歇地水鸟的觅食、规避时间,结果为在人为干扰下,水鸟的觅食时间显著减少。     

Effects of plant growth regulators,carbon sources and pH values on callus induction in Aquilaria malaccensis leaf explants and characteristics of the resultant calli

The endangered tropical tree, Aquilaria malaccensis, produces agarwood for use in fragrance and medicines. Efforts are currently underway to produce valuable agarwood compoundsn tissue culture. The purpose of this study was to develop an optimal growth medium, specifically, the best hormone combination for callus suspension culture. Using nursery-grown A. malaccensis, sterilized leaf explants were first incubated on basic Murashige and Skoog(MS) gel medium containing 15g/L sucrose and at pH 5.7. Different auxin types including 1-naphthaleneacetic acid(NAA), 2,4-dichlorophenoxyacetic acid(2,4-D), and indole-3-butyric acid(IBA), were tested at various concentrations(0.55, 1.1 and 1.65 μM) using the basic medium. Leaf explants were incubated for 30 days in the dark. Callus induced by 1.1 μM NAA had the highest biomass dry weight(DW) of 17.3 mg; however the callus was of a compact type. This auxin concentration was then combined with either 6-benzylaminopurine(BAP) or kinetin at 0.55, 1.1, 2.2 or 3.3 μM to induce growth of friable callus. The 1.1μM NAA + 2.2μM BAP combination produced friable callus with the highest biomass(93.3mg DW). When testing the different carbon sources and pHs, sucrose at 15g/L and pH at 5.7 yielded highest biomasses at 87.7mg and 83 mg DW, respectively. Microscopic observations revealed the arrangement of the friable cells as loosely packed with relatively large cells, while for the compact callus, the cells were small and densely packed. We concluded that MS medium containing 15 g/L sucrose, 1.1 μM NAA + 2.2 μM BAP hormone combination, and a pH of 5.7 was highly effective for inducing friable callus from leaf explants of A. malaccensis for the purpose of establishing cell suspension culture.     

Effect of acetylation on the chemical composition of hornbeam (Carpinus betulus L.) in relation with the physical and mechanical properties

Common hornbeam (Carpinus betulus L.) is a highly underused wood species despite its great hardness, strength, wear-resistance and toughness. It is mainly used as firewood in Hungary because of its wood defects, irregular shape and low-dimensional stability. These wood defects and small breast height diameter result in a low yield. It is non-durable outdoors as it tends to turn grey, crack and be attacked by wood-decaying organisms. Indoors it lasts for hundreds of years. One technology that could improve the stability and durability properties is acetylation. Hornbeam was acetylated with the Accoya® method under industrial conditions. The aim of this research was the assessment of acetylation affecting the chemical properties of hornbeam wood and how these are related to the change in physical and mechanical properties. Main wood constituents (cellulose, hemicellulose, Klason lignin, extractives and ash content) were determined and compared. Chemical parameters related to the degradation of structural polymers were also evaluated (total phenolic and soluble carbohydrate contents, pH and buffering capacity, furfural, levulinic acid, formic acid, acetic acid). Structural changes in acetylated wood and in the Klason lignin fraction were also assessed using FTIR spectroscopy.     

Effects of methanolic extract and fractions from Litsea cubeba bark on the production of inflammatory mediators in RAW264.7 cells

Both the methanolic extract and its fractions (0.01 mg/ml) from Litsea cubeba bark were found to inhibit NO and PGE2 production in LPS-activated RAW264.7 macrophages without significant cytotoxicity at less than 0.01 mg/ml concentration. Moreover, L. cubeba bark extract and its fractions significantly decreased the activity of myeloperoxidase catalyzing oxidation of chloride to HOCl and O2- production was reduced by methanol extract (0.05 mg/ml), chloroform fraction (0.025-0.05 mg/ml) and butanol fraction (0.005 mg/ml). These findings suggest that L. cubeba is beneficial for inflammatory conditions and may contain compound(s) with anti-inflammatory properties.     

Effects of Leucaena biomass application in conjunction with fertilizers on cassava and taro yields in the Philippines

With the soaring cost and scarcity at times of inorganic fertilizers in the country, there is a need to find alternatives to inorganic fertilizers by making use of indigenous materials such as leaves of leguminous plants, mudpress, and so enhance growth and development of crops. Application of ‘ipil-ipil’ (Leucaena leucocephala) green manure supplemented with inorganic P and K caused vigorous growth of cassava (Manihot esculenta). Application of ipil-ipil biomass at the rate of 7.23 t ha−1 resulted in high yield and better values of yield components of cassava. However, due to high expenses incurred in hauling, transport and cost of the green manure materials, their use is likely to be more economical and feasible only if ipil-ipil is readily available in the farm. With taro (Colocasia esculenta), combined application of ipil-ipil green manure and inorganic P and K promoted vigorous stand and higher yield of the crop. Significantly larger corms were formed resulting in higher total corm yields and marketability than the control (untreated) and those treated only with 60–39.6–74.7 kg ha−1 N, P, and K from inorganic fertilizer. Increasing the rate of inorganic N applied to plants (90–36.9–74.7 kg ha−1 N, P, K) during a third cropping, gave comparable yield to treatment involving 7.23 t ha−1 ipil-ipil supplemented with inorganic P and K. Despite the relatively higher gross income obtained from organic and inorganic treatment combinations, slightly lower net income was obtained compared with inorganic fertilizer-applied plants due to higher production expenses incurred with the former treatments. This revised version was published online in June 2006 with corrections to the Cover Date.     

缺苞箭竹叶片内细胞CO2浓度,气孔传导,气孔阻力和光合作用率的研究

本文采用美国LI—COR公司生产的LI—6200便携式光合作用分析系统,配合通风干湿球温湿度计,照度计等气象仪器,测定和研究了王朗缺苞箭竹叶片内细胞CO_2浓度、气孔传导、气孔阻力、光合作用率的日变化节律及其与环境因子的相互关系,筛选出了影响光合特性日变化的主要因子,建立经验公式,为合理采取人工措施改善光合性能,提高箭竹光合作用率提供依据。文中还系统地研究了叶肉CO_2浓度、气孔传导、气孔阻力以及环境因素对光合作用率的综合影响,以评价缺苞箭竹的光合作用。     

植物不同配置模式对绿地小气候温湿度的影响

经过选择密林、灌草、乔草、草坪、乔灌草、水生植物、灌木绿篱、硬化地面绿化共8种植物配置模式,并以硬化地面作为对照进行温、湿度的测量。运用SAS软件进行分析发现,在和硬化地面的温度差异性比较中,草坪、灌草、乔草、灌木绿篱、硬化地面绿化、乔灌草、密林皆差异性显著。在和硬化地面的湿度差异性比较中,灌木绿篱、乔灌草、密林、草坪、灌草差异显著。密林的不同水平位置之间,温度的差异显著,但湿度的差异并不显著。经过相关性分析发现,气温和植物的高度呈线性负相关,但是湿度与植物高度的相关性不明显。     

南靖丘陵竹杉混交造林与裸地种竹效果分析

针对闽南丘陵生态气候特点，南靖林场在杉木迹地更新二代杉木2年后套种毛竹与裸地种竹进行比较，结果表明，竹杉混交可提高毛竹造林成活率和新竹生长率，新竹数量多、质量好、竹鞭生长快，容易蔓延成林．以杉木初植密度1425株／hm~2的低密度套种300株／hm~2母竹，造林效果较好．裸地种竹可在山洼、中下坡水湿条件较好的立地采用．     

Effects of oleoresins and monoterpenes on in vitro growth of fungi associated with pine decline in the Southern United States

As a means of exploring pine resistance to root disease and declines, the effects of host plant secondary metabolites on the growth of root colonizing fungi associated with three diseases/declines of southern pines – loblolly pine decline, littleleaf disease and annosum root rot were tested. The associated fungi –Leptographium huntii, L. serpens, L. terebrantis, L. procerum, Heterobasidion annosum and Phytophthora cinnamomi– were grown in saturated atmospheres or in direct contact with, pure monoterpenes and crude oleoresin collected from the four southern pines (Pinus taeda, P. eschinata, P. palustris and P. elliotti) for 7 day. Fungal growth was measured at 3, 5 and 7 day. Root‐infecting fungi differed significantly in sensitivity to crude oleoresin and pure monoterpenes. All fungi tested were inhibited, to some extent, by the resins tested. H. annosum and P. cinnamomi were strongly inhibited by all the monoterpenes tested. The ophiostomatoid fungi were significantly less affected by the compounds tested. L. huntii and L. serpens were less inhibited by monoterpenes than either L. terebrantis or L. procerum. These fungal growth studies show that the kind and amount of secondary metabolite produced by the host plant have a profound effect on tree pathogens. Alterations of tree physiology may have implications for defenses against tree pathogens as well as to the ecology and management of forest ecosystems. Difference in incidence of root disease observed in the field may be explained by the ability of the fungus to tolerate these host defense mechanisms.     

Impacts of changing climate on the productivity of Norway spruce dominant stands with a mixture of Scots pine and birch in relation to water availability in southern and northern Finland

A process-based ecosystem model was used to assess the impacts of changing climate on net photosynthesis and total stem wood growth in relation to water availability in two unmanaged Norway spruce (Picea abies) dominant stands with a mixture of Scots pine (Pinus sylvestris) and birch (Betula sp.). The mixed stands were grown over a 100-year rotation (2000-99) in southern and northern Finland with initial species shares of 50, 25 and 25% for Norway spruce, Scots pine and birch, respectively. In addition, pure Norway spruce, Scots pine and birch stands were used as a comparison to identify whether species' response is different in mixed and pure stands. Soil type and moisture conditions (moderate drought) were expected to be the same at the beginning of the simulations irrespective of site location. Regardless of tree species, both annual net canopy photosynthesis (P(nc)) and total stem wood growth (V(s)) were, on average, lower on the southern site under the changing climate compared with the current climate (difference increasing toward the end of the rotation); the opposite was the case for the northern site. Regarding the stand water budget, evapotranspiration (E(T)) was higher under the changing climate regardless of site location. Transpiration and evaporation from the canopy affected water depletion the most. Norway spruce and birch accounted for most of the water depletion in mixed stands on both sites regardless of climatic condition. The annual soil water deficit (W(d)) was higher on the southern site under the changing climate. On the northern site, the situation was the opposite. According to our results, the growth of pure Norway spruce stands in southern Finland could be even lower than the growth of Norway spruce in mixed stands under the changing climate. The opposite was found for pure Scots pine and birch stands due to lower water depletion. This indicates that in the future the management should be properly adapted to climate change in order to sustain the productivity of mixed stands dominated by Norway spruce.     

在低温下ABA对九里香生理生化的影响

为了探明ABA(脱落酸)对九里香的抗寒效应,对九里香离体枝条采用了不同浓度的ABA溶液处理,并分别置于2℃和0℃的低温下处理,以研究其生理生化变化情况．结果表明:采用0．002 5％-0．005 0％的ABA溶液处理,对九里香离体枝条中的Vc含量、POD (过氧化物酶)活性的降低、可溶性糖的消耗、电导率和MDA(丙二醛)的升高等均具有抑制作用;用较高浓度的ABA(0．010 0％)溶液处理九里香,有的则有相反的变化,说明采用0．002 5％-0．005 0％的ABA溶液处理九里香离体枝条．能提高其抗寒能力．     

施加磷肥和钾肥对苗圃内印度黄檀木生长和结瘤的影响(英文)

本文探测了无机肥(磷和钾)对苗圃内培养的印度黄檀生长和结瘤的影响。播种前,磷和钾肥以不同比例混合后与营养匮乏的自然林土壤混合,然后混合土再补以粪肥(混合土:粪肥=3:1)。出苗后60天时记录植株结瘤状况(结瘤数、形状、鲜重、干重和颜色)和植株生长参数(枝条和根长及鲜重和干重、直径)。与对照相比,补充肥料的土壤显著地改变了植株生长和结瘤状况(P<0.05)。植株结瘤的数目、鲜重和干重均在磷钾施肥量为 160kg/hm2时达到最大值,分别为62, 0.05g和0.07g。不同比例的补肥处理改变了结瘤形状和颜色,同时显著地影响了枝条和根长、直径、鲜重和干重等生长参数。研究揭示:苗圃内生长的黄檀,在贫瘠的自然林土壤中施以160kg/hm2磷钾肥并混以粪肥(混合土:粪肥=3:1)可使植株生长和结瘤的形成达最佳。     

植物激素对杉木组培苗增殖和生根的影响

对NAA、IBA和6-BA对杉木组培苗增殖及生根的影响进行研究,结果表明,培养基中6-BA与NAA、IBA的比例适宜时能明显促进杉木组培苗生长和芽分化,适宜浓度的IBA比NAA更利于根的形成和生长,但激素浓度过高会抑制苗木生长。苗木质量主成分分析表明,增殖培养时,应选择利于芽分化和生长的培养基;生根培养时,应选择利于提高生根率、根数量、根长等的培养基。综合比较后以MS+NAA 0.05mg/L+6-BA 0.3 mg/L+琼脂7 g/L+蔗糖30 g/L为较适宜的增殖培养基,1/2MS+IBA 0.7 mg/L+琼脂7g/L+蔗糖25 g/L为较好的生根培养基。     

川南地区丛生竹硬头黄竹带状皆伐对其生长及产量的影响

以长宁县硬头黄竹为研究对象,分别在龙头镇、竹海镇样地设置长度均为60 m,宽度为3 m、6 m、9 m皆伐带;3 m^6 m、6 m^9 m皆伐带间设置保留带,保留带宽度均为6 m;另外在样地附近设置一个6 m×60 m对照带。采用机械式带状皆伐1年后,通过调查和数据处理,分析其生长状况,显著性特征、生物量(地上部分)。结果表明:(1)两个样地中均发萌枝,且萌枝面积均为9 m皆伐带>6 m皆伐带>3 m皆伐带。从龙头镇来看,各皆伐带和保留带的发笋量均明显高于对照带,最大为6 m^9 m保留带,达到4 976±97株·hm-2;从竹海镇来看,3 m皆伐带、3 m^6 m保留带、6 m^9 m保留带发笋数高于对照带,6 m^9 m保留带发笋数最高,达到11583株·hm-2。(2)单因素方差分析(ANOVA)和多重比较表明,龙头镇和竹海镇竹笋平均胸径除6 m皆伐带和9 m皆伐带间差异不显著外(p>0.05),其他每个带之间差异均显著(p<0.05);龙头镇竹笋平均高除3m皆伐带和6m皆伐带之间、6 m皆伐带和9m皆伐带之间差异不显著外(p>0.05),其余各带之间差异均显著(p>0.05),竹海镇竹笋平均高除6 m皆伐带和9 m皆伐带之间差异不显著外(p>0.05),其余各带之间差异均显著(p<0.05)。(3)根据张鹏等在长宁县对硬头黄竹胸径与生物量拟合的指数回归模型,可以计算出经过带状皆伐改造试验后,龙头镇3 m^6 m保留带、 6 m^9 m保留带1 a生竹每公顷产量分别比对照提高了92.76%、175.21%。竹海镇3 m^6 m保留带、 6 m^9 m保留带1a生竹每公顷产量分别比对照提高了111.89%、161.58%。(4)通过本试验对该地硬头黄竹进行带状皆伐改造,发现6 m^9 m保留带竹林长势最好,生物量最高,改造效果最好。