Impacts of a mineral lick‐centred land use system on woody vegetation cover in an East African Savannah

Evaluation of woody vegetation changes with distance from a salt crater was conducted in the semi‐arid rangelands of southern Ethiopia. Data on live woody plants were collected over three seasons at 0, 1, 4, 6, 9 and 12 km from the salt crater. The density and diversity of woody plants differed significantly (p < .01) along the distance gradient. Six woody plant families were identified of which Fabaceae and Burseraceae were the dominant families. Acacia drepanolobium, Acacia nilotica, Commiphora africana and Acacia mellifera were among the severely encroaching woody species. There were high proportions of seedlings and saplings recorded closer to the salt crater showing a vigorous recruitment by woody plants. Woody plant encroachment along the 12‐km transect ranged from a low to severe encroachment, which could be translated into poor rangeland condition. Changes in soil characteristics increased grazing pressure and sedentary settlement around the salt crater, and the breakdown of traditional institutions seems to be major contributing factors to these vegetation changes. We suggest that severely encroached areas could be improved through a combination of methods such as bush clearing, prescribed fire, browsing animals and proper grazing management.     

西藏苔藓新植物

本种与多蒴异齿藓R．orthostegius相似,但区别为蒴柄平滑,叶边有单细胞锐齿,中肋达于叶尖稍下处终止。     

木本植物抗旱机理研究进展

干旱是主要的环境胁迫因子之一,严重影响植物的分布与生长发育。研究和探索旱生植物的抗旱机理已成为众多研究者关注的焦点。本文综述了部分抗旱木本植物根、茎、叶等与干旱环境相适应的结构特征,分析了干旱胁迫下,植物自身的渗透调节、抗氧化酶系统、内源激素变化、抗旱蛋白对干旱胁迫的响应机理,并概述了抗旱相关基因的研究进展。     

江苏省主要木本药用植物资源

概述了江苏省有分布或栽培的木本药用植物资源,其中对主要种类20种的分布及药用功效进行了详细介绍,对其他木本药用植物的分布进行了简单的概述。近年来,越来越多的药用木本植物成为国内外研究者研究的重点对象。建议本省中医药工作者重视木本药用植物的药用价值的研究与开发。     

Micropropagation of Mexican redbud,Cercis canadensis var. mexicana

Mexican redbud (Cercis canadensis var. mexicana) shoot cultures were initiated from explants taken from both mature and juvenile stock plants. Culture conditions affecting shoot growth and proliferation and rooting of three clones were investigated. Shoot growth was best on media supplemented with 0.25% activated charcoal and solidified with 0.2% Gelrite. Four commercially available salt formulations (Anderson's rhododendron medium, WPM, MS, DKW) were tested for growth of shoot cultures, and Anderson's rhododendron basal salt mixture was superior. Axillary shoots grew from explants cultured media supplemented with a wide range of concentrations of benzyladenine and thidiazuron. Benzyladenine at 5.6–22.2 M supported the best combination of shoot quality and number. Rooting of microshoots in vitro was best on half-strength WPM containing 6.71 M naphthaleneacetic acid and 0.1% activated charcoal.Abbreviations BA 6-benzyladenine - IBA indole-3-butyric acid - 2iP 6-(, -dimethylallylamino)purine - DKW Driver & Kuniyuki Walnut - kinetin 6-furfurlaminopurine - MS Murashige & Skoog - NAA -naphthaleneacetic acid - WPM Woody Plant Medium - TDZ thidiazuron - 1-phenyl-3 (1,2,3-thidiazol-5-yl)urea     

Induction of microspore embryogenesis in Camellia japonica cv. Elegans

Three methods of microspore culture were tested for the induction of microspore embryogenesis in Camellia japonica L. cv. Elegans. Culture was performed on 17 different media consisting of Murashige and Skoog (MS) and N6 basal media with different combinations of carbon, growth regulators, serine and glutamine. Microspore suspensions plated over solid MS medium containing 4.5 M 2,4-dichlorophenoxyacetic acid and 0.5 M kinetin, with sucrose (MS6) or glucose (MS9) were seen as the best culture conditions for induction of embryogenesis. The development of microspore derived proembryos was obtained in MS medium supplemented with 2.2 M N⁶-benzyladenine (MS10) and reached the highest level when the microspores were cultured in MS6 inducing medium. The development of microspore-derived embryos ceased at the maturation stage.Abbreviations BA N⁶-benzyladenine - 2,4-d 2,4-dichlorophenoxyacetic acid     

木本植物邻体干扰研究进展

植物种间关系一直是植物生态学研究的核心问题之一。密度和平均生物量之间的相关性研究在一定程度上揭示了植物之间的相互作用。对于单纯种群,已有３／２稀疏定律,但这种关系可能掩盖了植物生长和发育方面的重大变化,因为植物所具有的固着性及其表型的可塑性,使得局地...     

浙江省主要木本药用植物资源

本文介绍了浙江省有分布或载培的木本药用植物的种类（约118种）,以及主要种类（42种）的分布及药用功效,木本药用植物既具有药用价值,又可以绿化,美化环境,调节气候,建议重视木本药用植物的保护,载培及研究与开发。     

How to tell a shrub from a tree: A life‐history perspective from a South African savanna

The ecological differences between ‘shrubs’ and ‘trees’ are surprisingly poorly understood and clear ecological definitions of these two constructs do not exist. It is not clear whether a shrub is simply a small tree or whether shrubs represent a distinct life‐history strategy. This question is of special interest in African savannas, where shrubs and trees often co‐dominate, but are often treated uniformly as ‘woody plants’ even though the tree to shrub ratio is an important determinant of ecosystem functioning. In this study we use data from a long‐term fire experiment, together with a trait‐based approach to test (i) if woody species usually classified as shrubs or trees in African savanna differ in key traits related to disturbance and resource use; and (ii) if these differences justify the interpretation of the two growth forms as distinct life‐history strategies. We measured for 22 of the most common woody plant species of a South African savanna 27 plant traits related to plant architecture, life‐history, leaf characteristics, photosynthesis and resprouting capacity. Furthermore we evaluated their performance during a long‐term fire experiment. We found that woody plants authors call (i) shrubs; (ii) shrubs sometimes small trees; and (3) trees responded differently to long‐term fire treatments. We additionally found significant differences in architecture, diameter‐height‐allometry, foliage density, resprouting vigour after fire, minimum fruiting height and foliar δ¹³C between these three woody plant types. We interpret these findings as evidence for at least two different life‐history‐strategies: an avoidance/adaptation strategy for shrubs (early reproduction + adaptation to minor disturbance) and an escape strategy for trees (promoted investment in height growth + delayed reproduction).     

Isolation of plant DNA: A fast,inexpensive, and reliable method

We describe here a simple method to isolate DNA of high molecular weight from a wide variety of plant materials, such as trees, herbaceous plants, cell suspension cultures, calli, seeds, dried embryos, ferns and lichens. The crucial step of the extraction is the use of an acidic extraction medium. When necessary, the sample was separated on a fast RPC-5 column providing us with highly purified DNA suitable not only for restriction endonuclease analyses but also for PCR experiments, RLFP analyses, or detection of adducts.     

丽水大山峰木本植物区系研究

丽水市大山峰位于浙南山区,是浙江省木本植物区系最丰富地区之一,共有木本植物84科237属543种,而且古老孑遗植物和珍稀濒危植物较多,地理成分复杂多样,可划分为14个分布区类型,区系具有明显的热带-温带过渡性;木本植物区系中,中国特有种占绝对优势,共有338种,占总种数的62.2%,是构成大山峰森林植被的建群种和优势种的主要成分.与邻近山地植物区系比较发现,大山峰木本植物区系与浙江白云山关系最密切.     

In vitro propagation ofHancornia speciosa,a tropical fruit tree

Summary Hancornia speciosa fruit is highly desired for the juice and ice cream industry in tropical regions. A rapid reduction in germination ability ofH. speciosa seeds has been a problem for its large-scale cultivation. This paper describes anin vitro technique that may lead to an alternative propagation method forH. speciosa. Shoot apices and nodal segments from aseptically germinated young embryos were cultivatedin vitro on. Murashige and Skoog (1962) medium supplemented with growth regulators. Shoot multiplication was maintained by sequential subculture of shoot tips and nodal segments. N⁶-benzyladenine was the most effective cytokinin for the induction of shoot growth. N⁶-furfurylamino-purine, at various concentrations, yielded multiplication rates sevenfold lower than the highest multiplication rate found with N⁶-benzyladenine. Increased root initiation rate and root elongation was observed with the presence of γ-(indole-3) butyric acid in the half-strength Murashige and Skoog culture medium, especially at 10μM. N⁶-benzyladenine strongly inhibited rooting, even in the presence of γ-(indole-3) butyric acid. Thein-vitro-raised rooted plantlets were acclimatized to greenhouse environment through progressive reduction in relative humidity and later transplanted to the field.     

Inhibition of ethylene action prevents root penetration through compressed media in tomato (Lycopersicon esculentum) seedlings

In the genus Prunus , so far, somatic embryogenesis has not been reported either from cell suspensions or from their protoplast-derived cells. Rhizogenic cell suspensions of Prunus avium L., initiated from adventitious roots developed from cotyledon-derived callus of mature zygotic embryos, have been subcultured for more than one year without losing their morphogenic potential. A yield of 8 × 10⁵ protoplasts ml⁻¹ of packed cells with a viability of 98% has been routinely obtained. Optimum cell division frequency (around 2.5% at day 10 and 4–6% at day 15) occurs in agarose lenses, with Murashige and Skoog (1962. Physiol. Plant 15: 476–497)-based medium supplemented with 5 μ M naphthalene acetic acid, 1 μ M benzyladenine and 0.25 μ M zeatin. Colony formation has been achieved after 35 days with a plating efficiency of 3–4%. Cell suspensions have been initiated from protoplast-derived callus. While the older cell cultures express a rhizogenic response, the younger ones contain early stages of somatic embryo development. Ultrastructural examination confirms the polarization of these structures.     

祁连山北坡主要木本植物功能性状及其海拔分异

植物功能性状是植物对生境长期适应所形成的可测量特征,受植物遗传特性和环境因子的共同影响。祁连山是我国干旱区的一条重要山脉,北坡海拔介于2000—5000 m,分布着青海云杉、祁连圆柏等10余种木本植物。深入了解祁连山区木本植物功能性状随海拔梯度分异特征对认识山地植物的适应性和植被垂直地带分布具有重要意义。选取祁连山北坡天然分布的11种木本植物,其中灌木9种,分别是金露梅(Potentilla fruticosa)、银露梅(Potentilla glabra)、水栒子(Cotoneaster multiflorus)、猫儿刺(Ilex pernyi)、吉拉柳(Salix gilashanica)、鬼箭锦鸡儿(Caragana jubata)、刚毛忍冬(Lonicera hispida)、高山绣线菊(Spiraea alpina)和鲜黄小檗(Berberis diaphana),乔木2种,分别是青海云杉(Picea crassifolia)和祁连圆柏(Juniperus przewalskii),调查了木质密度、胡伯尔值、叶面积、叶干物质含量、叶含水率和比叶面积6个枝、叶功能性状。结果表明...     

Effect of Photoperiod and Nitrogen Supply on Basal Shoots Development in Rhododendron Catawbiense

In order to control young plant form by modifying culture conditions, plants of Rhododendron catawbiense from in vitro culture were grown in a greenhouse under different photoperiodic treatments (long or short days) combined or not with a several-week nitrogen starvation. After 12 weeks of culture under long days (16 h) with nitrogen supply, plants showed a rhythmic acrotonous development. When long days were combined with a six-week nitrogen starvation, the apical growth pause was extended leading to an increase of the number of acrotonous lateral ramifications. Short-day (8 h) treatment affected distal burst potential and moreover when a concomitant nitrogen starvation was applied. This lack of distal development allowed basal buds swelling, leading to basitonous plants. When plants were returned back to long days after 2, 4 or 6 weeks under short days, distal buds resumption competed with basal shoots development. Durable basitonous plants were obtained by a 12-week short days treatment combined with a 6-week nitrogen starvation.     

Plant regeneration from embryogenic suspension cultures ofCamellia Japonica

Summary Two methods (I and II) for somatic embryo production from embryogenic suspension cultures ofCamellia japonica are presented. Method I, embryogenic suspension cultures, was established from suspension cultures initiated from leaf-derived callus. These cultures were maintained by reducing agitation and increasing subculture interval. Induction of somatic embryogenesis was achieved in MS28 medium, 6, 12, 24, and 36 mo. after culture establishment. Embryo production decreased after 1 yr of culture. Method II, suspensions of single embryogenic cells and proembryos, was obtained from leaves cultured in liquid MS13 medium 6 wk after culture initiation. Embryo production was 23 embryos/ml. Germination of cell suspension-derived embryos on MS56 medium was 16.7 % (&#x00B1;4.2%) for method I, and 35.4% (&#x00B1;5.1%) for method II. The embryos germinated into plantlets with 0 to 7 axillary shoots.     

甘肃4种亚热带常绿阔叶木本植物分布新记录

报道了甘肃省4种亚热带常绿阔叶木本植物分布新记录：黄丹木姜子〔Litsea elongata （Wall. ex Nees） Benth. et Hook. f.〕、总梗女贞（Ligustrum pricei Hayata）、攀缘胡颓子（Elaeagnus sarmentosa Rehder）、栓叶安息香（Styrax suberifolius Hook. & Arn.）。其中,栓叶安息香和攀缘胡颓子也是秦岭植物分布新记录。这些植物的发现进一步丰富了甘肃省亚热带常绿阔叶木本植物资源,对于研究西秦岭地区亚热带木本植物的物种多样性和植物区系具有重要意义。新记录凭证标本存放于陇南师范高等专科学校植物标本室。     

Coarse woody debris can reduce mammalian browsing damage of woody plant saplings in box‐gum grassy woodlands

The critically endangered box‐gum grassy woodlands of south‐east Australia face numerous threats including the failure of woody plant regeneration caused by over‐browsing. In the Australian Capital Territory, over‐browsing of tree and shrub saplings is likely caused by dense populations of Eastern Grey Kangaroo (Macropus giganteus) found in many nature reserves free of livestock. One possible way to protect these saplings is using coarse woody debris (CWD) as a browsing deterrent. We tested this idea by planting palatable Red Stemmed Wattle (Acacia rubida) saplings among manually applied CWD, among naturally fallen CWD, and in the open, in five woodland reserves. We recorded the proportion of saplings browsed, the number of weeks to first browsing and the browsing severity (sapling height lost). Applied CWD protected saplings from being browsed only at relatively low‐to‐moderate kangaroo browsing pressure (as measured by faecal pellet counts). At relatively high browsing pressure, the probability of a sapling being browsed among applied CWD was 100%, similar to the probability in the open treatment (no CWD). Natural CWD, in contrast, provided some protection even at high browsing pressures. Time to browsing was most affected by browsing pressure, although CWD cover also had an influence. Browsing severity was similar between the three treatments and was only affected by browsing pressure. These results indicate that without protection, palatable woody plant saplings have a high chance of being browsed by kangaroos in woodland reserves, and therefore, some protection is needed for successful regeneration. The CWD being applied to reserves has a limited capacity to protect regenerating saplings. If more protection is wanted a CWD structure more resembling natural fallen timber should be used. This could be done by artificially placing branches around plantings. However, the most important action to facilitate regeneration is to manage kangaroo populations to reduce overall browsing pressure.     

Invasive alien plant control: The priority to save one of the most rapidly declining island-endemic plant species worldwide

Up to 6,800 plant species endemic to oceanic islands are highly threatened with extinction. Although habitat destruction and fragmentation have greatly contributed to this, it is generally recognised that invasive alien species currently pose the single most important threat to island plants. Most studies exploring the role of novel interspecific interactions in driving declines of island plants, focus on threats mediated by animals, be it direct (e.g. browsing, seed predation, mutualism disruption) or indirect (e.g. extinction of seed dispersal or pollination mutualists). Relatively few studies have investigated the specific role of plant-plant interactions, particularly in-situ. We studied a threatened island endemic plant in rapid decline to evaluate the short (1–2 years) and medium-term (about 1–2 decades) influence of invasive alien plants (IAPs) on individuals and a variety of proxies of plant fitness. We compared mortality of traceable individuals that were recorded 12–20 years previously between habitats that are invaded with IAPs and habitats where IAPs are absent, or have been removed decades ago. We also carried out an in-situ manipulative experiment using 14 randomly chosen plants from around which IAPs were removed, paired with controls, at two sites. Canopy cover change before and after IAPs’ removal was quantified along with above ground biomass of IAPs removed for use as potential explanatory variables of change in proxies of plant fitness. Ten branches were randomly selected per plant and branch dynamics, leaves’ sizes and reproductive structure production were monitored quarterly for two years. Over the medium term, plant mortality was recorded only in presence of IAPs (X² = 4.80, df = 1, p < 0.05). Over the short term, at the plant level, IAPs’ removal triggered overall weak to moderate improvements in the number of surviving and new branches as well as change in number of branches at one of the sites. At the leaf and branch levels, we found weak evidence for positive effects of IAPs removal on surviving leaves, flower buds produced and difference in leaf surface area per branch in one site. We therefore provide some experimental evidence of negative effects of alien plants on overall fitness of the threatened species in-situ presumably through competitive interactions. We posit that these effects were found to be weak to moderate due to the short experimental period over which they could develop (1–2 years). Overall, IAPs stand out as the most severe threat from among all documented threats to the species, for being the only one capable of causing mortality of adult plants. Results hence highlight island plants’ vulnerability to IAPs, and how their timely control would improve the survival and fitness of threatened plants, even at the scale of single individuals. Such a strategy could be more often employed. Our study stresses on prioritising IAPs’ control for rescuing long-lived threatened plants that grow in habitats invaded by alien plants (itself a very common situation on oceanic islands) before addressing other subtler, slower-acting threats, like disrupted pollination or seed dispersal mutualisms, florivory or seed predation.     

DNA Isolation and AFLP™ Genetic Fingerprinting of shape Theobroma cacao (L.)

Accurate identification of parental plants and their hybrids is essential for an effective breeding programme. Traditional classification of cocoa varieties relies on the characterisation of agricultural traits at plant maturity. A rapid and reliable method is described, based on genotypic analysis. An efficient DNA isolation procedure was developed, yielding unsheared DNA of high purity. Two genetic fingerprinting techniques, RAPD and AFLP, were evaluated for their suitability in distinguishing cocoa varieties. RAPD analysis was unsatisfactory due to the low frequency of polymorphisms and poor reproducibility. AFLP was reliable in distinguishing phenotypically identical, known varieties of cocoa. Importantly, AFLP also revealed intra- and inter-varietal variation.Abbreviations: AFLP, amplified fragment length polymorphism; APS, ammonium persulphate; CTAB, hexadecyltrimethylammonium bromide; DEB, DNA extraction buffer; f.wt., fresh weight; NEB, nuclei extraction buffer; PMSF, phenylmethanesulphonyl fluoride; RAPD, random amplified polymorphic DNA; T4 PNK, Bacteriophage T4 polynucleotide kinase; Taq, Thermus aquaticus; TBE, tris-borate-EDTA; TEMED, NNNN tetramethylethylenediamine.