人工辅助授粉探寻濒危红树植物红榄李种质资源挽救途径

为了探索濒危红树植物红榄李(Lumnitzera littorea (Jack.) Voigt)种质资源挽救途径, 以三亚铁炉港红榄李为授粉材料, 采集三亚铁炉港和陵水新村港红榄李花粉进行人工辅助异花授粉试验, 结合野外观察和种子萌发实验进行验证。结果表明: 三亚铁炉港红榄李的花期较长, 从花芽开始膨大到落花期末, 最短60 天, 最长可持续140 天, 且开花不整齐; 用培养基法对三亚铁炉港和陵水新村港红榄李的花粉生活力进行检测, 均不超过10%; 人工辅助异花授粉后种子的萌发率有显著提高(自然授粉种子萌发率为0.2‰), 但最高也只能达到5.6‰。实验室萌发种子能够长成幼苗, 且野外林下发现一株红榄李幼苗, 这说明通过人工辅助异花授粉对提高红榄李种子繁育能力有一定的积极作用。     

红树植物改造桐花树次生灌木林效果的研究

通过对16a生的木榄、红海榄、海莲红树植物在桐花树次生灌木群落中进行人工改造的形成的新群落调查与分析,结果表明:海莲、红海榄和木榄都能成功在桐花树灌木林群落定居,其中以木榄的地径、树高生长量较大;红海榄、海莲的造林的株行距为1m×1m或0.8m×1m,木榄的株行距为1.5m×2m为宜;引入红树林乔木树种海莲、红海榄、木榄小苗16年后,桐花树密度呈不同程度的减少,其中木榄的引入较不利于桐花树次生灌木群落的发展;海莲、红海榄各自生物量或群落总生物量均比桐花树群落总生物量增加,以红海榄的生物量增加量最大,为桐花树群落总生物量的1.9倍;海莲、木榄具有良好的更新状况,特别在海莲群落中,平均每方米超过2株幼苗,说明该群落开始步入发育盛期,可以预见未来的15年内,可使红树林群落茂密复生。     

盐胁迫对红树植物红榄李幼苗叶绿体超微结构及光合荧光特性的影响

探讨红榄李幼苗对盐胁迫的响应机制,为濒危红榄李保护提供理论依据。以红榄李幼苗为材料,研究了不同浓度NaCl(50、150、450、750 mmol·L^-1)对红榄李植株叶片光合、荧光参数、光合色素变化、抗氧化酶活性、叶绿体超微结构及气孔特征的影响。150 mmol·L^-1 NaCl处理下红榄李幼苗叶片净光合速率(P_n)、气孔导度(G_s)、潜在最大光能转换效率(F_v/F_m)、实际光能转换效率(Φ_PSII)、总叶绿素(Chl)含量、类胡萝卜素(Car)含量、超氧化物歧化酶(SOD)活性及过氧化物酶(POD)活性等均显著高于其他处理。当NaCl浓度超过450 mmol·L^-1时,上述指标值均显著下降,而胞间CO₂浓度(C_i)、过氧化氢(H₂O₂)含量、丙二醛(MDA)含量、超氧阴离子(■)产生速率等显著上升,其中,750 mmol·...     

非胎生红树植物繁殖体特征及潮间带分带现象

研究了香港4种非胎生红树植物榄李(Lumnitzeraracemosa(Jack.)Voigt.)、银叶树(Heritieralittoralis(Drgand.)Ait.)、海漆(Excoecaria agallocha L.)和老鼠簕(Acanthusilicifolius L.)的繁殖体特征和萌发技术,并分析了其在潮间带分带的决定因素.所有直接种植的新鲜榄李繁殖体均不能萌发,但经湿润贮藏35 d和50d的繁殖体能萌发,说明该物种具有种子休眠的特性.榄李萌发率随盐度升高而下降,盐度高于25则不能萌发.银叶树繁殖体果壳的去除可加速其萌发.海漆和老鼠簕的繁殖体分别在2 d和3 d开始萌根.在繁殖体萌发方面,老鼠簕的耐盐性比榄李强.4种非胎生红树植物对潮间带不稳定环境的适应方式有:(1)繁殖体的寿命较长,如榄李和银叶树;(2)萌根速度快,如海漆和老鼠簕;(3)具有沉性繁殖体,如榄李.繁殖体的悬浮性是决定这4种非胎生红树植物潮间带分带的最重要因素:榄李因具有沉性繁殖体而自然分布于最靠海的区域,而银叶树、海漆和老鼠簕因具有浮性繁殖体而更靠陆岸分布.对于繁殖体悬浮性相同的物种,萌根速度是影响潮间带分带的重要因素:完整的银叶树繁殖体需要108 d才能萌根,因而分布于最靠陆岸的区域,而海漆和老鼠簕因萌根速度快而在相对更靠海的区域分布.环境盐度、繁殖体大小、动物啃食和幼苗大小等因素则不能解释香港非胎生红树植物在潮间带的分带现象.     

广西北部湾红树林资源现状及可持续发展对策

红树林作为热带和亚热带沿海滩涂上特有的植被类型和生物资源,在自然生态平衡中起着特殊的作用。作者通过线路走访和选取固定地点采样法对广西北部湾红树林资源现状进行调查,调查表明：广西北部湾红树林现存面积8374．9hm^2,有真红树8科11种,半红树6科8种,伴生植物12科14种。红树林主要树种有：秋茄、桐花树、白骨壤、红海榄、木榄、海漆、榄李、老鼠筋、卤蕨、无瓣海桑等。最后对北部湾红树林资源的保护利用以及可持续发展提出相应的对策。     

非胎生红树植物繁殖体特征及潮间带分带现象

研究了香港4种非胎生红树植物榄李(Lumnitzera racemosa(Jack．)Voigt．)、银叶树(Heritiera littoralis(Drgand．)Ait．)、海漆(Excoecaria agallocha L．)和老鼠筋(Acanthus ilicifotius L．)的繁殖体特征和萌发技术,并分析了其在潮间带分带的决定因素。所有直接种植的新鲜榄李繁殖体均不能萌发,但经湿润贮藏35d和50d的繁殖体能萌发,说明该物种具有种子休眠的特性。榄李萌发率随盐度升高而下降,盐度高于25则不能萌发。银叶树繁殖体果壳的去除可加速其萌发。海漆和老鼠筋的繁殖体分别在2d和3d开始萌根。在繁殖体萌发方面,老鼠筋的耐盐性比榄李强。4种非胎生红树植物对潮间带不稳定环境的适应方式有：(1)繁殖体的寿命较长,如榄李和银叶树;(2)萌根速度快,如海漆和老鼠筋;(3)具有沉性繁殖体,如榄李。繁殖体的悬浮性是决定这4种非胎生红树植物潮间带分带的最重要因素：榄李因具有沉性繁殖体而自然分布于最靠海的区域,而银叶树、海漆和老鼠筋因具有浮性繁殖体而更靠陆岸分布。对于繁殖体悬浮性相同的物种,萌根速度是影响潮间带分带的重要因素：完整的银叶树繁殖体需要108d才能萌根,因而分布于最靠陆岸的区域,而海漆和老鼠筋因萌根速度快而在相对更靠海的区域分布。环境盐度、繁殖体大小、动物啃食和幼苗大小等因素则不能解释香港非胎生红树植物在潮间带的分带现象。     

广东湛江保护区红树林种群的生物量及其分布格局

本文研究了广东湛江红树林自然保护区高桥镇红寨村及德耀村海滩红树植物的种群分布格局与生物量。结果表明：５年生桐花树群落、白骨壤群落、秋茄群落、１０年生木榄群落、３０年生红海榄群落的总生物量分别为５５４７５ｇ／ｍ２、１６３７０１ｇ／ｍ２、６２６４４８ｇ／ｍ２、４１３８４３ｇ／ｍ２、９６１０２０ｇ／ｍ２;其中地下部分生物量占总生物量的比例依次为３２２８％、４５４５％、４１３１％、２９８５％和２８２９％。计算得Ｓｈａｎｎｏｎ－Ｗｉｅｎｅｒ物种多样性指数为２２３２。种群的分布格局中桐花树、白骨壤、红海榄和秋茄种群为集群分布,而木榄种群为随机分布。     

广西英罗湾红树植物群落的研究

 对广西英罗湾红树植物群落的种类组成、类型、外貌、结构、物种多样性和演替等进行了较系统的探讨。组成群落的优势红树植物有木榄、红海榄、秋茄、桐花树、白骨壤和海漆6种,隶属6属4科。主要的群落类型有木揽群落、木榄+红海榄群落、红海榄群落、红海榄+秋茄群落、秋茄群落、秋茄+桐花树群落、秋茄+白骨壤群落、桐花树群落、白骨壤群落、白骨壤+桐花树群落和海漆群落等11个群系。群落外貌由单叶、革质、全缘、中型叶的高位芽植物决定。群落层次结构简单．单层或两层。和陆地植物群落相比较,组成群落的红树植物的物种多样性较低。受潮滩土壤质地、养分状况、环境盐度和潮淹程度以及红树植物自身对盐渍生境的适应性等因子制约,群落的分布形成了明显的生态系列。随着海平面的相对降低和土壤理化性质的改善,群落具有向陆生植物群落演化的趋势。     

莲叶桐对热带珊瑚岛环境的生理生态适应性

为探究莲叶桐(Hernandia nymphaeifolia)对热带珊瑚岛季节性干旱、强光、盐碱等环境的生理生态适应性,该文对海南省文昌市试验苗圃(以下简称文昌苗圃)和移栽到热带珊瑚岛的莲叶桐的叶片形态解剖结构、抗氧化能力、抗逆渗透物质含量和光合色素等进行了研究.结果表明:(1)与文昌苗圃相比,莲叶桐在移栽到热带珊瑚岛...     

广西的红树林

本文主要讨论广西沿海的红树林的植物种类成分、外貌、适应形态学特点、群落类型和演替规律,以及生产管理问题。 该地区的红树植物种类计有8科、12属、12种,以红树科植物占优势。群落类型有:白骨壤群落、桐花树群落、秋茄-桐花树群落、红海榄群落、木榄群落、木榄-桐花树群落、桐花树-海漆稀树群落和红海榄+秋茄-桐花树群落等。     

Radial growth response of Pinus sylvestris L. and Fagus sylvatica L. to technological solutions applied in rope climbing parks

Vitality is a genetic preservation factor that keeps a tree in the right condition. Changes in tree vitality are a measure of the impact exerted on trees by environmental factors, such as injuries to trunks and branches, and are among the basic parameters of the state of their preservation. The dynamics of changes in the width of annual increments of trees is one of several parameters characterizing the level of their vitality. The aim of the study is to determine changes in radial increment and linking them to the level of the vitality of Scots pines (Pinus sylvestris L.) and European beeches (Fagus sylvatica L.), on which the standard (old system) and specially designed (new system) systems of fastening of wooden platforms were installed as part of adventure park infrastructure. In the old system, the platforms were installed on square wooden beams placed in milled tree trunks, while in the new system on semi-circular metal brackets matching the curvature of the trunks. The present research is aimed to determine the dynamics of incremental trends in trees with different platform systems in relation to the reference group, and to determine the impact of the tested support systems on trees with different levels of vitality. Most of the studied trees were in the optimum stage of increment. The initial tree vitality level recorded at the beginning of the experiment was clearly better for the beech stands. In the case of Scots pine, the average vitality was close to stable. Pines that were initially in better condition responded much worse to the installation of old system platforms compared to those with the specially new platform system. A similar trend was also visible in the case of beeches, but the differences were not that clear and the annual increments of the trees with platforms installed were slightly higher compared to the reference trees. The trees that were initially in worse condition, both pines and beeches on which the old system of platforms had been installed, responded by increasing the width of annual increments during the measurement period. The described response of trees most probably does not result from the lower harmfulness of the old support system, but from the defensive responses of trees subjected to stronger stress.     

板栗扦插生根过程的解剖结构和生理变化研究

以5年生和30年生板栗插穗以及30年生板栗母树不同月份(5、6、7月)插穗为材料,进行不同浓度(0、200和500mg/L)吲哚丁酸(IBA)处理,观测各类处理材料的生根情况,并对扦插前插穗(初始茎)和扦插后插穗愈伤组织的碳氮代谢物质、褐化相关物质和解剖学结构进行分析观察,探讨不同年龄母树及不同月份插穗扦插生根能力,为板栗扦插生根技术体系奠定理论基础。结果表明:(1)5年生板栗的初始茎和愈伤组织中碳氮代谢相关物质淀粉和可溶性糖含量明显高于30年生板栗,而其可溶性蛋白含量30年生高于5年生板栗,但其γ-氨基丁酸(GABA)含量在不同年龄母树间无明显变化;30年生板栗插穗初始茎中可溶性蛋白、GABA和可溶性糖含量均随着月份的增加而逐渐降低,但是在愈伤组织中GABA、可溶性糖和淀粉含量随着月份增加而逐渐升高。(2)板栗插穗初始茎和愈伤组织的褐化相关物质单宁、酚类和类黄酮含量均表现为30年生不同程度低于5年生;除类黄酮含量在7月份的愈伤组织中有显著升高外,不同月份板栗的单宁、酚类、类黄酮含量均没有明显变化。(3)生根状况及解剖学观察结果显示,5年生板栗插穗的愈伤率和生根率高于30年生的插穗,且30年生插穗6月份扦插的愈伤率最高;板栗插穗属于诱导生根类型,皮层中存在环状厚壁组织;5年生板栗插穗的木质素含量低于30年生板栗,但形成层细胞层数高于30年生。研究认为,板栗扦插生根过程中插穗褐化现象严重,生根率较低;不同年龄母树和不同月份的板栗插穗在扦插过程中的碳氮代谢相关化合物含量都有明显的差异,而褐化相关物质含量仅在不同年龄母树间有较大的差异,不同月份间大部分无明显差异。     

Leaves of Field-Grown Mastic Trees Suffer Oxidative Stress at the Two Extremes of their Lifespan

Leaf senescence is a complex phenomenon occurring in all plant species, but it is still poorly understood in plants grown in Mediterranean field conditions and well-adapted to harsh climatic conditions. To better understand the physiological processes underlying leaf senescence in mastic trees (Pistacia lentiscus L.), we evaluated leaf growth, water and N content, photosystem II (PSII) photochemistry, lipid peroxidation and levels of photosynthetic pigments, antioxidants, abscisic acid, and salicylic acid and jasmonic acid during the complete leaf lifespan, from early expansion to late senescence in relation to natural climatic conditions in the field. While mature leaves suffered from water and N deficit during late spring and summer, both young (emerging) and old (senescing) leaves were most sensitive to photo-oxidative stress, as indicated by reductions in the F v/F m ratio and enhanced lipid peroxidation during late autumn and winter. Reductions in the F v/F m ratio were associated with low α-tocopherol (vitamin E) levels, while very old, senescing leaves additionally showed severe anthocyanin losses. We have concluded that both young (emerging) and old (senescing) leaves suffer oxidative stress in mastic trees, which may be linked in part to suboptimal temperatures during late autumn and winter as well as to low vitamin E levels.     

Biomass distribution of different-aged needles in young and old Pinus cembra trees at highland and lowland sites

Conifer needles of different ages perform differently in ecophysiology. However, no study has investigated the biomass distribution of different-aged needles in a tree crown or/and a stand canopy. We carried out a study on young (∼50 years old) and old (∼200 years) Pinus cembra L. trees at highland (2100–2300 m a.s.l.) and lowland (570 m) sites in Switzerland. We found that both the young and the old trees living in the highlands had more needle biomass per tree than the same-aged trees of the same species living in the lowlands. This is mainly due to the greater longevity of needles in highland trees. It reflects the strategic responses of trees to low resource availability or high abiotic stress level. Having older needles increases the time that nutrients are resident in trees in less favorable environments, and compensates for shorter growing period in cold temperatures.     

Production of embryogenic callus from nonembryonic explants of Norway Spruce Picea abies (L.) Karst

Callus has been induced on needle and bud explants from 2, 6 and 26 year old Picea abies (L.) Karst, trees. Seventy seven percent of the needle explants from the youngest material was productive compared to 0.2% for the old tree. New embryogenic sections appeared in the non-embryogenic callus derived from 2, 6 and 26 year old trees after prolonged culture and was promoted by the use of an established embryogenic callus line in a nurse culture system.Abbreviations EDTA Ethylenediaminetetraacetic acid - RAPD Random amplified polymorphic DNA     

Influence of flood-preconditioning and drought on leaf gas exchange and plant water relations in seedlings of pecan

Four-month old seedlings of pecan [Carya illinoensis (Wangenh) C. Koch] were either not flooded or flooded for 14 days, then transferred to well-drained conditions for 23 days. Water was withheld from one-half of the trees for 6 days, then trees were rewatered, and water was withheld from all trees. Leaf expansion, leaf dry weight, and the number of new leaves that developed were reduced by flooding, but not trunk or root dry weights. Evapotranspiration rates of flooded trees after transfer to well-drained conditions were initially higher than those of unflooded trees, but decreased to rates of control trees after 12 days. Flooding had no effect on photosynthesis after trees had been transferred to well-drained conditions for 23 days. Drought-stressed trees with leaf water potentials as low as − 1.93 MPa had lower leaf photosynthetic CO₂ assimilation rate (A), transpiration (E), and leaf conductance to CO₂ (g_L) as compared to wellwatered trees. Leaf internal CO₂ concentration (c_i) was reduced only by the most severe water-stress treatment. Water use rates and relative water content were lower at the permanent wilting point during a second drought stress when trees had been exposed previously to drought stress.     

Root deformation in plantations of container-grown Scots pine trees: effects on root growth,tree stability and stem straightness

Root system deformation was studied in 23 Scots pine (Pinus sylvestris L.) stands in central Sweden. The study comprised both plantations created with container-grown plants (Paperpot) and natural stands including young (7–9 year old) and older (19–24 year old) trees. Trees were measured with regards to distribution of roots, root deformation, stability, stem straightness and wood properties in stumps. Root distribution was most uniform for naturally regenerated trees. Older trees generally showed a better root distribution than young trees. The young planted trees displayed a high frequency of severely spiralled root systems, while only a few of the older trees had spiralled root systems. No severe root deformations were observed on naturally regenerated trees. Naturally regenerated trees were more stable than those which had been planted. Differences in bending moment, when trees were pulled to an angle of 10°, were considerable between young planted and naturally regenerated trees, but less pronounced for the older trees. Young planted trees had the highest frequency of severely crooked stem bases, while naturally regenerated trees had the straightest mode of growth. Tensile strength in peripheral wood samples of the stumps was substantially lower for planted than for naturally regenerated trees. Strain values to breakage of wood samples, taken from the root collar and the central- and peripheral part of the stump were lower for planted trees. The conclusions from this study are that root distribution, tree stability and stem straightness of planted Paperpot-grown trees will improve after a certain time and approach the state of naturally regenerated trees. As trees grow older, early established crooked stem bases will be compensated by radial growth and the tree will appear straighter. Inside the stem, however, problems may still remain with abnormal fibre direction and compression wood together with inferior root strength due to fibre disturbances as a result of spiralled roots. This revised version was published online in June 2006 with corrections to the Cover Date.     

我国古树资源的生存现状评估及威胁因素分析

古树是生态系统的组成部分,具有重要的生态功能和丰富的遗传多样性。为加强古树的科学保护和管理,本文分析了我国古树资源的分布、生存和保护现状以及受威胁因素。结果表明: 我国古树共记录1066万株,其中内蒙古自治区和云南省均超过100万株。分析全国102个县级地区的44万株古树的生长现状,发现有94.3%的古树生长良好,5.5%生长衰弱或濒危,0.2%已经死亡。古树受威胁因素主要有高温、干旱、火灾等自然灾害,以及城市化和土地利用、病虫害和乱砍偷盗等。病虫害的威胁最严重,有83个地区(81.4%)受病虫害威胁严重;其次是自然灾害的威胁,有68个地区(66.7%)发生过自然灾害。大部分古树(89%)分布在农村等偏远地区,缺乏有效的保护措施。可以利用无人机等新技术监测古树生长状态,加强病虫害防治和规避自然灾害,并建立古树资源数据库实现信息及时更新共享,避免偷盗砍伐。     

Spatial and age-dependent tree-ring growth responses of Larix gmelinii to climate in northeastern China

Tree-ring width chronologies from 276 Larix gmelinii cores taken in northeastern China were used to analyze spatial and age-dependent growth–climate response relationships. Tree radial growth from five localities showed similar patterns, while exhibiting different tree-ring growth responses to local climate. The rotated principal component analysis (RPCA) indicated that tree age, growing season moisture conditions, and ambient air temperature variations resulted from location differences (e.g., longitude, latitude, and altitude), which could explain the non-stationary spatial climate–growth relations observed. The study tested the fundamental assumption that the climate–growth of L. gmelinii was age independent after the removal of size trends and disturbance signals. The age-related climate–growth relationship might potentially improve the veracity of past climate reconstructions. Bootstrapped correlation function analyses suggested that the response of L. gmelinii radial growth to climate differed between trees ≥150 years old and <150 years old. Mean sensitivity and standard deviation for trees increased with age in the <150 years old tree class; whereas trees ≥150 years old had no significant relationship with age. These results showed that the assumption of age-independent climate–growth relationship is invalid at these sites. Physiological processes and/or hydraulic constraints dependent on tree age, together with detrending techniques could be the possible causal factors of clear age-dependent responses. These results suggested the importance of incorporating trees of all ages into the chronology to recover a detailed climatic signal in a reconstruction of L. gmelinii for this region.     

Diameter increment in mature eastern white pine<Emphasis Type="Italic"> Pinus strobus</Emphasis> L. following partial harvest of old-growth stands in Ontario,Canada

Little is known about the responses of large, old trees to release from competition, though such trees are of great interest in forest ecology, conservation and silviculture. Increment cores were taken from mature eastern white pines (Pinus strobus L.) in 144 sample points in 12 partially harvested and 6 unharvested control stands in Ontario, Canada, to determine how these trees responded to a 'structural retention harvest' that had occurred 9 years previously. Prior to harvest, increment growth was slightly lower in control stands, but not significantly so. Strong correlation in diameter increments among stands indicates external climatic forcing or internal synchronicity, e.g. reproductive allocation. Three years after harvest, growth in harvested stands overtook that in control stands, and increased to 63±8% SE above expected levels by 8 years after harvest. The study demonstrates the ability of old trees to respond markedly to reduced competition, questioning the concept of an age-related decline in forest productivity. In addition to increased timber production, growth responses of old trees have important implications for stand regeneration, wind firmness, and maintenance of wildlife habitat elements following partial stand harvests. Comparison of disturbed stands with undisturbed stands allows better estimation of tree responses than methods in which disturbance is inferred from diameter increment variation within individual trees.