黄土丘陵沟壑区土壤侵蚀环境下芽库的季节动态及垂直分布

研究了陕北黄土丘陵沟壑区5种土壤侵蚀环境（阳沟坡、阳峁坡、峁顶、阴峁坡、阴沟坡）下的植被组成、芽库组成、芽库季节动态及垂直分布特征.结果表明： 该区拥有永久性芽库的多年生物种占总物种数的80.3%,具季节性芽库的一年生植物占19.7%.在侵蚀严重的阳沟坡和阳峁坡,植物返青期的永久性芽库存量较大,而在侵蚀强度较小的峁顶、阴沟坡和阴峁坡,植物开花结实期的季节性芽库密度较大.不同侵蚀环境下地下部分芽库库存量占总永久性芽库的比例较稳定,地面永久性芽库存量在阳坡较大,而地上部分季节性芽库存量在阴坡和峁顶较大.由于不同侵蚀环境下植物群落的物种组成不同,加上土壤侵蚀干扰和植物季节更新,影响了芽库在季节及垂直分布上的变化.在黄土丘陵沟壑区植被更新过程中, 芽库具有重要作用.     

粘液繁殖体及其生态功能

对粘液繁殖体的概念、粘液性质、粘液繁殖体的研究现状及粘液繁殖体研究中存在的问题进行了论述。分布在干旱区的十字花科、爵床科、菊科等植物具有粘液繁殖体。有关粘液繁殖体的研究集中在具有粘液繁殖体植物的识别、粘液形态结构及成分、粘液溶出机制及过程、粘液繁殖体的生态功能等几个方面。尽管已有研究表明,粘液繁殖体具有促进种子远距离传播、促进繁殖体的萌发及苗的发育、使种子免受摩擦损害和动物捕食等生态功能,但目前人们对粘液繁殖体的生态意义尚不十分清楚,从多物种比较研究中阐明粘液繁殖体生态意义的研究尚很少见。继续识别具有粘液繁殖体的植物,改善现有的研究手段,加强粘液繁殖体对植被恢复价值的研究是目前粘液繁殖体研究面临的挑战。     

塔里木河下游主要荒漠植物繁殖体的形状、大小与质量比较

研究了塔里木河下游主要荒漠植物(21种)繁殖体的形状、大小、质量(17种为种子,4种为果实)。用三维方差衡量繁殖体形状,用三维之和衡量繁殖体大小,繁殖体百粒质量衡量繁殖体质量。结果表明：1)21种植物繁殖体的形状差异很大,且豆科(Fabaceae)植物的繁殖体形状接近圆球形,菊科(Compositae)植物的繁殖体形状较大地偏离圆球形(方差>0.05)。21种植物繁殖体大小、质量差异也很大;2)繁殖体大小的表现趋势与其相应的质量的表现趋势具有一定的一致性;3)研究区主要荒漠植物中,多年生草本植物的种类虽然不及灌木(半灌木)的种类丰富,但其繁殖体平均质量却比灌木(半灌木)多18%;4)在21种植物的繁殖体中,9种具有持久土壤种子库。100%的柽柳科(Tamaricaceae)植物、100%的菊科植物都具冠毛,这些附属物对植物繁殖体的传播和定居具有重要的意义。     

科尔沁沙地78种植物繁殖体重量和形状比较

研究了科尔沁沙地 78种植物的繁殖体 (2 3种为种子 ,5 5种为果实 )重量和形状 ,其重量差别很大 ,最小的单粒重不足 0 .1mg,最大的超过 130 mg;形状差异也很大 ,最小的方差不足 0 .0 3,最大的超过 0 .18。综合本研究和以前研究的全部 14 0种植物的研究结果 ,进行了分析。结果表明 :1计有 2 4种植物繁殖体单粒重小于 1mg并接近圆球形 (方差小于 0 .0 9) ,它们可能具有持久种子库 ;2 1年生植物 (平均方差为 0 .0 70 )与 2年生植物 (平均方差为 0 .12 9)间的形状差异显著 (P<0 .0 5 ) ,2年生植物的繁殖体更加扁、长 ;1年生植物也与多年生草本植物 (平均方差为 0 .10 9)之间形状差异显著 (P<0 .0 5 ) ,多年生草本植物的繁殖体更加扁、长 ;3有 5 5 %的豆科植物、70 %的藜科植物繁殖体接近圆球形 (方差 <0 .0 6 ) ,所有的菊科、萝摩科植物繁殖体都很扁、长 (方差 >0 .0 6 )。豆科植物显著比菊科、禾本科、藜科植物繁殖体的重量大 (P<0 .0 5 ) ;4繁殖体附属物在植物的传播和定居方面具有重要的作用 :6种萝摩科植物和 3种杨柳科植物具有绢毛 ,6 0 %的菊科植物具有冠毛 ,6种植物有翅 ,8种植物有宿存花柱或宿存花萼 ,这些植物可能易于被风传播 ;5 4 %的禾本科植物具芒 ,减小了传播可能 ;苍耳、雾冰藜、鹤虱、蒺藜、     

塔里木河下游21种荒漠植物繁殖体形态特征及对环境的适应

以塔里木河下游分属于9科16属的21种荒漠植物为对象,调查了它们的植冠种子库情况以及繁殖体的附属物、形状(三维方差)、大小(三维之和)及质量(百粒重)等形态特征,并探讨了各种繁殖体的生态适应对策.结果表明:(1)13种荒漠植物可利用植冠种子库来躲避环境干扰:7种繁殖体具绢毛,2种繁殖体具翅,1种繁殖体具芒,3种繁殖体具冠毛,可利用风力实现传播与定居,而且它们可利用有水时期的速萌特性来适应当地生态输水这一辅助措施;5种繁殖体形状远离球形(三维方差≥0.126),6种繁殖体形状接近圆球形(三维方差＜0.06).(2)5种具速萌特性的繁殖体(形状圆筒形、圆锥形和蝌蚪形)与8种具有持久土壤种子库的繁殖体(三维方差较小≤0.1且三维之和≤2.75 mm)利用它们互补的生态适应对策使其在研究区成功定居与繁衍; 13种以r-型生活史对策为主且粒小质轻的繁殖体(三维之和≤2.75 mm,单粒重<1 mg)与4种粒大质重的繁殖体(三维之和≥4.8 mm,单粒重＞3.3 mg)利用其互补式繁殖对策将研究区生物多样性维持于一定水平.(3)7～9月份为一年生草本、多年生草本、(半)灌木植物及乔木同时落种的时期,可将人工输水集中于这一时期以实现研究区种子最大数量地萌发.     

黄土高原先锋种猪毛蒿叶片形态解剖与生理特征对立地的适应性

为了揭示黄土丘陵沟壑区撂荒地植被演替前期优势种猪毛蒿(Artemisia scoparia)对该区立地环境的适应性,探讨猪毛蒿演替生态位的变化,研究了陕北黄土丘陵沟壑区3种立地环境下(阳峁坡、峁顶、阴峁坡)猪毛蒿叶片形态解剖和生理特征的变化,以及这些变化与生态因子之间的相互关系。结果表明:(1)猪毛蒿叶片具有适应该区半干旱环境的形态及解剖结构:叶片针形化、具表皮毛、环栅型叶肉组织、海绵组织特化为贮水组织、维管束退化、具裂生分泌腔,C3植物呈现类似CAM植物的叶片特性;(2)在土壤、空气湿度相对干燥和强光生境的阳峁坡与峁顶,猪毛蒿具有较小的叶面积、发达的栅栏组织、致密的表皮毛和紧密的细胞间隙,而在生境条件较好的阴峁坡则呈相反趋势;(3)阳峁坡猪毛蒿叶片相对含水量和叶绿素含量较小,超氧阴离子自由基增加,但植物体内超氧化物歧化酶和抗坏血酸含量增加以清除植物体内产生的活性氧;(4)冗余及相关性分析表明,猪毛蒿叶片形态、解剖和生理指标的可塑性对立地光照强度、土壤水分和有机质含量较为敏感,同时其形态解剖与生理可塑性可共同调节来适应生境。综合分析,猪毛蒿对陕北黄土丘陵沟壑区撂荒初期光照强度大、土壤贫瘠但土层干化现象尚未出现的立地环境有较好的适应性,使其成为黄土高原植被自然演替过程中的先锋物种。     

黄土丘陵沟壑区土壤侵蚀环境下芽库的季节动态及垂直分布

研究了陕北黄土丘陵沟壑区5种土壤侵蚀环境(阳沟坡、阳峁坡、峁顶、阴峁坡、阴沟坡)下的植被组成、芽库组成、芽库季节动态及垂直分布特征.结果表明:该区拥有永久性芽库的多年生物种占总物种数的80.3%,具季节性芽库的一年生植物占19.7%.在侵蚀严重的阳沟坡和阳峁坡,植物返青期的永久性芽库存量较大,而在侵蚀强度较小的峁顶、阴沟坡和阴峁坡,植物开花结实期的季节性芽库密度较大.不同侵蚀环境下地下部分芽库库存量占总永久性芽库的比例较稳定,地面永久性芽库存量在阳坡较大,而地上部分季节性芽库存量在阴坡和峁顶较大.由于不同侵蚀环境下植物群落的物种组成不同,加上土壤侵蚀干扰和植物季节更新,影响了芽库在季节及垂直分布上的变化.在黄土丘陵沟壑区植被更新过程中,芽库具有重要作用.     

荒漠植物角果藜的地上地下结果性

对分布于准噶尔荒漠中角果藜(Ceratocarpus arenarius)果实的形态特征、空间位置、发育特性及散布特性进行了比较研究,结果表明:角果藜具有地上地下结果性,地上果实和地下果实在颜色、形状、大小、质量、数量、空间位置、成熟期和散布特性上均有显著差异。角果藜地上地下结果性是植物适应荒漠多变环境所具有的一种特殊的繁殖方式。这种独特的繁殖方式增加了物种在荒漠极端环境中成功生存的机率,保证了物种的顺利繁衍。这是首次在藜科植物中发现的地上地下结果性现象。     

荒漠植物种子粘液的生态学意义

种子粘液是在种皮外层细胞的高尔基体内产生并分泌到胞腔内或细胞壁层的吸湿膨胀的一类果胶类多糖物质。具粘液种子的植物大多生长在荒漠地区,广泛存在于十字花科、菊科和车前科等类群中。粘液的存在对荒漠植物种子的扩散、萌发、防御以及幼苗的生长等都具有重要的生态学意义,是荒漠植物适应干旱少雨的生态环境的有效对策之一。对粘液种子的研究不仅可全面揭示荒漠植物的生态适应机制及其进化生态意义,还可为研究基因控制的糖类生物合成和分泌、细胞次生壁的生物合成及形态分化建立理想的模式体系。为此,在广泛查阅相关文献的基础上,该文综合分析了国内外种子粘液的研究进展,并重点探讨了以下几方面问题：（1）种子粘液的化学成分：（2）粘液及粘液种皮的形态特征：（3）粘液细胞分化与粘液生物合成的细胞学及基因调控机制以及粘液的释放方式：（4）种子粘液的生态学意义。在此基础上展望了今后的研究方向,以期为推动我国荒漠植物种子生态学的理论与应用研究及西部荒漠区的植物物种多样性保护和生态保育提供重要理论依据。     

四棱草属比较形态及其分类系统位置的研究Ⅰ．四棱草属及近缘属叶片毛状体微形态

采用“外类群对比准则”（ＯｕｔｇｒｏｕｐＣｏｍｐａｒｉｓｏｎＣｒｉｔｅｒｉａ,Ｃａｒｃａｒｆｔ１９８３）的性状分析方法,对我国特有植物四棱草属Ｓｏｈｎａｂｅｌｉａ及其近缘属筋骨草属Ａｊｕｇａ,香科科属Ｔｅｕｃｒｉｕｍ（唇形科）和莸属Ｃａｒｙｏｐｔｅｒｉａ大青属Ｃｌｅｒｄｅｎｄｒｏｎ（马鞭草科）等５属６种主要植物比较研究,首次发现在这些植物叶片上,具有一种新的毛状体,其形状呈箭形,故定名为箭形毛（Ａｒｒｏｗ—ｓｈａｐｅｄ—ｈａｉｒ）,在扫描电子显微镜下观察是由头部、柄部和基部组成,在光学显微镜下,确认这类毛状体属于多细胞单列毛,由细胞变形而成形。此外,尚有长柔毛（Ｓｈａｇ－ｈａｉｒ）,盾状毛（Ｐｅｌｔａｔｅ—ｈａｉｒ）和鳞片毛（Ｓｃａｌｅｓ—ｈａｉｒ）等四种类型。从以上毛状体的微形态特征及其演化规律,作者认为四棱草属和近缘属在唇形科与马鞭草科系统演化框架里,可能是处于中间过渡类型。     

Species,Diaspore Volume and Body Mass Matter in Gastropod Seed Feeding Behavior

Background

Seed dispersal of ant-dispersed plants (myrmecochores) is a well studied ecosystem function. Recently, slugs have been found to act as seed dispersers of myrmecochores. The aim of our study was to (1) further generalize the finding that gastropods feed on seeds of myrmecochores and hence may act as seed dispersers, (2) to test whether gastropod body mass and the volume of diaspores have an influence on the seed dispersal potential.

Methodology and Principal Findings

We assessed the seed dispersal potential of four slug and snail species with a set of seven myrmecochorous plant species from seven different plant families common to Central European beech forests. Diaspores differed in shape and size. Gastropods differed in their readiness to feed on diaspores and in the proportion of seeds that were swallowed as a whole, and this readiness generally decreased with increasing diaspore size. Smaller Arionid slugs (58 mm body length; mean) mostly fed on the elaiosome but also swallowed small diaspores and therefore not only act as elaiosome consumers, a nutrient rich appendage on myrmecochorous diaspores, but may also disperse seeds. Large Arionid slugs (>100 mm body length) swallowed diaspores of all sizes. Diaspores swallowed by gastropods were defecated without damage. Within-species variability in body size also affect seed dispersal potential, as larger individuals of the red slug (Arion rufus) swallowed more diaspores of wood anemone (Anemone nemorosa) than smaller ones.

Conclusions and Significance

Our results help to generalize the finding that gastropods consume and potentially disperse seeds of myrmecochores. The dispersal potential of gastropods is strongly influenced by diaspore size in relation to gastropod size.     

植物锥形繁殖体结构及其适应

植物的锥形繁殖体是具有吸湿芒和锐利尖端的一种繁殖体类型。锥形繁殖体结构的功能几乎在植物生活史的各个阶段上都有体现,然而,其最基本的功能是通过繁殖体的打钻作用将自身埋入土壤。从植物繁殖体的形态结构出发,对锥形繁殖体的各项功能进行了综述,重点阐述植物繁殖体打钻作用及其机制方面的研究进展,面临的主要问题和未来的研究方向。     

Interaction Between “Safe Sites” and “Safe Sides” for Germination of Neurada procumbens (Neuradaceae) in the Middle East

The seed bank of Neurada procumbens, a prostrate annual common in sandy desert habitats, is vulnerable to surface disturbances. Moreover, its seeds are highly heteromorphic, having both spinose and non-spinose sides, which affects both the vertical distribution of seeds and diaspores, and the precise position in which they lie in the soil. Here we explore the ecological implications of two factors, “safe sites” within habitats and seed orientation or “safe sides”, on seedling establishment and the seed bank. In three natural populations, the vertical distribution of buried, germinable diaspores decreased with soil depth. Most diaspores occurred at the surface (0–1 cm below the surface), while none were observed below 10 cm. Seedling emergence decreased with depth and reached zero in diaspores below 5 cm. Seedling emergence also proved highly sensitive to the orientation of diaspores in soil. Diaspores lying on their smooth side with the spinose upper side directed upwards reached the highest seedling emergence of 61 %. Root length ranged from 10 to 16 cm, and the root to shoot ratio varied between 22.8 and 30.3 cm, depending on diaspore size. Diaspores near the surface may constitute a more transient component of the seed bank, as few of these remained viable for more than a year. Persistence of Neurada seed banks seems to depend not only on vertical movement of diaspores among habitat “safe sites” but also on different seed position alternatives.     

D3: The Dispersal and Diaspore Database – Baseline data and statistics on seed dispersal

Seed dispersal is hard to measure, and there is still a lack of knowledge about dispersal-related traits of plant species. Therefore, we developed D³, the Dispersal and Diaspore Database (available at www.seed-dispersal.info), which aims at simplifying ecological and evolutionary analyses by providing and integrating various items related to seed dispersal: empirical studies, functional traits, image analyses and ranking indices (quantifying the adaptation to dispersal modes).Currently, the database includes data for more than 5000 taxa and 33 items as well as digital images of diaspores (i.e. the dispersal units), seeds, fruits and infructescences. The included items cover common traits like diaspore mass, size, shape, terminal velocity and seed number per diaspore. Furthermore, we present newly or further developed items like ecomorphological categorizations of the diaspore and fruit as well as information from literature on prevailing dispersal modes. Finally, we introduce several items which are not covered in other databases yet: surface structure and form of the diaspore, the exposure of the diaspores in the infructescence and dispersal rankings. Dispersal rankings allow estimations of how well certain species are adapted to a specific dispersal mode in comparison to a larger species set. They are calculated as the percentile rank of an indicator of species’ dispersal potential in relation to a larger species set.Especially for the new and further developed items we outline the basic concepts in detail, describe the measurement and categorization methods and show how to interpret and integrate these data for single species as well as for larger species sets. Thereby, we calculate baseline statistics of seed dispersal of the Central European flora. We found that diaspores of 72% of the taxa show specializations related to long-distance dispersal, i.e. most often elongated appendages or nutrient-rich tissues. Diaspore masses, sizes and terminal velocities vary over several orders of magnitude and can be approximated by lognormal distributions.     

Mucilage secretion: an adaptive mechanism to reduce seed removal by soil erosion?

Diaspores of many plant species inhabiting open vegetation in semi‐arid environments secrete mucilage after wetting (myxospermy) that glues the diaspores to the ground and prevents movement when the mucilage dries. In the present study, we test whether mucilage secretion can be considered as a selective response to soil erosion in plant species inhabiting semi‐arid environments. We relate the amount and type of mucilage secretion by seeds of Helianthemum violaceum and Fumana ericifolia (Cistaceae) to the number of raindrop impacts needed to remove these seeds after gluing them with their own mucilage to the ground and also the time that these seeds resist water run‐off without detaching. We also compare the amount of seed mucilage production by plants growing in habitats without erosion and plants affected by severe erosion by fitting mixed effect models. Our results show an important phenotypic variation in the amount of mucilage secretion in both species, although it is suggested that the effect of mucilage secretion in the rate of seed removal by erosion is species‐ and mechanism‐dependent. For F. ericifolia, the amount of mucilage secreted by the seeds is directly proportional to their resistance to raindrop impacts and is positively related to the intensity of the erosive processes that the plants experience. Nevertheless, all the seeds resist the force of run‐off during 60 min, irrespective of the amount of mucilage they produce. In H. violaceum, mucilage secretion per se, and not the amount of mucilage produced by the seeds, has an effect on the rate of seed removal by erosive processes. Furthermore, cellulosic fibrils were found only in the mucilage of F. ericifolia but not in H. violaceum. Overall, our results only partially support the hypothesis that a selective response to soil erosion exists. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 241–251.     

Ants as diaspore removers of non-myrmecochorous plants: a meta-analysis

Diaspore (e.g. seeds, fruits) dispersal is pivotal for plant communities and often involves several steps and different dispersing agents. Most studies focusing on diaspore dispersal by animals have highlighted the role of vertebrates, neglecting the role of ants in the diaspore dispersal of non-myrmecochorous plants. Diaspore dispersal by ants is especially relevant in the current scenario of declining of vertebrate populations and, consequently, collapse of the dispersal system of large-seeded plants. Although ants can never compensate for the dispersal service provided by vertebrates, they can mitigate the impact of vertebrate decline via removal of diaspores deposited on the ground. We have used a meta-analytical approach to investigate the contribution of ants in the removal of non-myrmecochorous diaspores (through vertebrate exclusion experiments). We considered the number of diaspore removal as effect size and factors such as plant growth forms, diaspore and ant size, habitat type as moderators. In addition, we investigated the role of such factors on the diaspore removal distance by ants. Ants played complementary role to non-myrmecochorous diaspore removal services provided by vertebrates (mean Hedges’ g of −0.30). The ant diaspore removal was 69% higher for diaspores from shrubs than that of tree diaspores and removal of small-sized diaspores were 69% and 70% higher in comparison to medium- and large-sized diaspores, respectively. Regarding the diaspore removal distance by ants, those of tree species were removed 32% farther than those of shrub species, and diaspores were removed three- times farther in the savanna than in rainforest ecosystems. Our results highlight the shrubs and small-sized diaspores. Regarding the diaspore removal distance, the ants can be crucial for the dispersal of tree diaspores and in the savanna ecosystems. Finally, considering the biodiversity crisis, the ants may play an even more important role than appreciated in diaspores dispersal.     

Dispersal traits and dispersal patterns in an oro-Mediterranean thorn cushion plant formation of the eastern High Atlas, Morocco

This study describes the dispersal traits and dispersal patterns of 51 perennial plant species belonging to 19 families in an oro-Mediterranean thorn cushion plant formation on the High Atlas, Morocco. Diaspore type, mass, number, antitelechoric mechanisms and dispersal time were studied with respect to growth forms, dispersal modes and spatial dispersal. Species spanned 10⁵ range of diaspore mass, which coincided with those found in other high mountain regions. Diaspore mass was significantly higher in trees and shrubs than in semi-shrubs and perennial herbs. Barochorous and zoochorous species are more likely to have heavy diaspores, whereas anemochorous and ballistic species have a medium diaspore mass and semachorous and ombro-hydrochorous species have low diaspore mass. Diaspore number was significantly higher in trees and shrubs than in semi-shrubs and perennial herbs. The barochorous, ombro-hydrochorous and zoochorous species tended to produce higher diaspore numbers than species with other dispersal modes. Bradyspory was well-developed by trees and large shrubs dispersed by biotic vectors. Synaptospermy was represented by its long dispersal component. Myxospermy was significantly associated with semi-shrubs and perennial herbs with restricted spatial dispersal. It seems that ombro-hydrochory combined with myxospermy and a high number of light seeds is an efficient mechanism that ensures successful establishment of the most typical and endemic thorn cushion plant species, such as Alyssum, Vella and Ormenis. In our study area, the highest dispersal availability was synchronized with the dry summer season (July–August) and the beginning of the rainy months (September). The dispersal peak for the wind-dispersed species, which is the most effective primary dispersal mode, occurs during the dry season, while dispersal for the biotic-dispersed species takes place throughout the year.     

Seed size and survival in the soil in arid Australia

Abstract We investigated the relationship between seed size and seed survival in the soil in 67 species from arid Australia. There was a very weak, marginally significant positive relationship between the viability of fresh seeds and diaspore mass. However, by the time seeds had been buried in the soil for 1 year in nylon mesh bags, there was a highly significant positive relationship between diaspore mass and diaspore viability. Over the range of seed masses observed, a tenfold increase in diaspore mass was associated with a threefold increase in the odds of surviving 1 year of burial in the soil. Thus, large‐seeded species were favoured over small‐seeded species during this important selective process. However, the magnitude of this advantage was small compared with the advantage experienced by small‐seeded species during seed production. We also investigated aspects of diaspore morphology in relation to viability retention during burial. We found no relationship between seed survival and the amount of protective tissue per unit diaspore surface area. Diaspore mass was a better predictor of survival than was diaspore surface area.     

Simple Traits among Diaspore Weight/Number, Plant Height and Ability of Vegetative Propagation

Several expected correlations among followed internal plant traits were confirmed using the dataset of 492 herbaceous species from the temporal zone of Central Europe. Average diaspore weight (seed mass), reproductive capacity of population (number of produced diaspores), species height, and ability of lateral spread were the plant traits considered. The evident correlations were confirmed among all investigated traits: (i) The reproductive capacity of population negatively correlated with diaspore weight, plant height, and vegetative propagation. The diaspore weight and their number are closely correlated and co-adapted. (ii) Bigger plant species produce bigger diaspores. These trends are obvious at the inter- and intra-family levels. (iii) Larger plant species showed higher ability to vegetative propagation.