Seed dispersal by domestic goats in a semiarid thornscrub of Mexico     

E. Baraza  A. Valiente-Banuet 《Journal of Arid Environments》2008,72(10):1973-1976

Previous studies conducted in the semiarid thornscrub of the Biosphere Reserve of Tehuacán-Cuicatlán have reported a high consumption of cactus and legume fruits by domestic goats. To test the hypothesis that goats may effectively disperse seed, we collected domestic goat feces from different microhabitats (bare ground, under shrub or under tree). The area occupied by each microhabitat was measured in the field. We then quantified the presence of viable seeds in goat feces and their deposition in microhabitats suitable for seedling establishment. We collected 209 seeds and using a seed reference collection, we identified these as belonging to three endemic cactus species, two legumes and several unidentified species. A high proportion of the cactus seeds germinated. Although most of the feces were found in open areas, more than 30% were recorded beneath the canopies of perennial plants, a suitable microhabitat for seedling establishment and survival. Contrary to the general assumption that goats cause only degradation of vegetation, these findings show that goats can effectively disperse viable seeds of diverse species. Studies that evaluate the ecological role of goats as important elements of biotic interactions are needed in order to generate an adequate management program for livestock.  相似文献   

3种驼绒藜属植物种子萌发期耐盐性试验研究   总被引：13，自引：8，他引：5  

李得禄  王继和  李爱德  刘虎俊  安富博 《中国沙漠》2006,26(6):1009-1014

用0.3％,0.6％,0.9％,1.2％,1.5%、1.8%的NaCl溶液对3种驼绒藜属植物种子进行处理,观测它们的发芽率、发芽势、幼苗长度指标来研究驼绒藜属3种植物种子的耐盐性。试验研究表明:以1.2%或1.5%的NaCl溶液鉴定驼绒藜属植物耐盐性较为合理,3种驼绒藜属植物种子耐盐性存在明显差异。以NaCl溶液为培养液,随着浓度的增加,种子发芽率降低,种子发芽高峰的出现延迟,同时幼苗长度随盐分浓度的递增而呈减小趋势。综合分析发芽率、发芽势及幼苗长度,认为3种驼绒藜属植物种子的耐盐顺序为:华北驼绒藜最强、绵毛优若藜次之,驼绒藜最差。  相似文献   

大叶藻(Zostera marina L.)胚的结构和种子萌发过程的研究     

田萍萍  刘延岭  崔翠菊  梁广津  李霞  赛珊  钱冠兰  王宏梅 《海洋科学进展》2012,30(3):402-407

以采自山东荣成褚岛桑沟湾南岸成熟的大叶藻种子为材料,研究了种子的外部形态特征、胚乳成分及胚的解剖结构,并初步了解了大叶藻种子的萌发过程。结果表明,大叶藻种子是单子叶有胚乳的种子,呈暗褐色,椭圆形或长圆形,种皮革质且有17～20条纵肋,胚乳丰厚坚硬,胚乳细胞被淀粉粒充满;胚弯曲,由胚根、胚轴、胚芽和子叶组成,子叶U形棒状,其弯曲部有一裂缝,胚芽位于裂缝处,胚轴较短,其下是两个对生的胚根,有中央维管束贯穿胚根、胚轴、胚芽和子叶。在子叶出土萌发的植物类型中,大叶藻种子萌发过程是罕见的。萌发初期,子叶优先生长突破种皮而长出地面,此后胚根才开始生长并产生不定根。对大叶藻种子结构和萌发过程的研究,为探讨大叶藻种子萌发和幼苗更新的限制因素提供了一定的理论依据。  相似文献   

古尔班通古特沙漠南缘32种藜科植物种子萌发策略初探   总被引：1，自引：0，他引：1  

刘会良  宋明方  段士民  王喜勇  张道远  尹林克 《中国沙漠》2012,32(2):413-420

对古尔班通古特沙漠南缘32种藜科植物的萌发特性（萌发率、萌发开始时间、平均萌发时间和萌发持续时间）进行研究,以探讨藜科植物的不同萌发对策及其生态适应意义。结果表明,32种植物萌发率呈双峰型,其中萌发率大于80%,或小于20%的种占大多数;萌发开始时间呈单峰型,28种植物在1~3 d内开始萌发;平均萌发时间也呈单峰型,平均萌发时间小于5 d的植物21种,最大的为杂配藜（23.7 d）;萌发持续时间种间差异较大,其中15种植物萌发持续时间小于15 d,10种植物持续时间在15~30 d,5种植物大于30 d。主成分分析和聚类分析结果表明,32种植物可划分为4种萌发类型:爆发型、过渡型、缓萌型和低萌型。以上结果揭示出32种藜科植物种子萌发策略不尽相同,表现为机会主义萌发策略、下注萌发策略和谨慎萌发策略,这与植物所处土壤盐渍化程度存在差异有关。此外,Log尺度下32种藜科植物种子大小及其变异范围较小（10-2~101）,暗示多数藜科植物多为小种子,其容易沿缝隙进入土壤形成短暂或永久种子库,这也是沙漠植物生存策略的重要一环。  相似文献   

几种旱生灌木种子萌发特性及化学成分     

李茜  任运涛  牛得草  张宝林  赵慧  傅华 《中国沙漠》2015,35(2):345-351

研究了旱生灌木白沙蒿(Artemisia sphaerocephala)、红砂(Reaumuria soongorica)、梭梭(Haloxylon ammodendron)、羊柴(Hedysarum mongdicum)、霸王(Zygophyllum xanthoxylum)、白刺(Nitraria tangutorum)、沙冬青(Ammopiptanthus mongolicus)、柠条(Caragana korshinskii)种子的化学成分、适宜发芽条件下的吸水发芽特性及两者之间的关系,测定和计算了其发芽率、吸水率,淀粉、脂肪、蛋白质、碳(C)、氮(N)、磷(P)含量及C:N、C:P、N:P值,并分析了这些指标间的相关性,以期归纳出西北干旱荒漠区植物种子萌发适应干旱环境的基本特性。结果表明:脂肪含量、蛋白质含量、氮含量与种子的最低萌发需水量之间呈显著正相关,而种子的单一化学成分及C:N、C:P、N:P值并没有对发芽率形成显著影响。8种植物种子萌发对环境的适应机制大致可分为两类:需要外界较高水分供应,萌发迅速而集中;不需要外界较高水分的供应,萌发持续而分散。  相似文献   

干旱胁迫对唐古特白刺(Nitrariatangutorum)种子吸胀萌发和幼苗生长的影响   总被引：1，自引：0，他引：1  

罗光宏  王进  颜霞  陈能海  张勇 《中国沙漠》2014,34(6):1537-1543

以生长在荒漠地区的唐古特白刺(Nitraria tangutorum)种子为材料,采用PEG-6000模拟干旱条件,研究了6种渗透势(-0.05、-0.148、-0.295、-0.490、-0.734、-1.032 MPa)下种子吸水特性、萌发特性和幼苗生长特性.结果显示:唐古特白刺吸水速度快,效率高,3 h吸水量随水势的降低而增高;随着干旱胁迫程度的加剧,唐古特白刺种子的萌发率、发芽指数、活力指数降低,萌发起始天数推迟,初生芽高度和幼苗生长量表现出降低的趋势,而幼苗干重、根干重和根冠比均呈先升后降的趋势,表明唐古特白刺种子在适当的干旱胁迫下可以提高幼苗的抗旱性,有利于培育壮苗;唐古特白刺种子萌发对水势变化既敏感又抗旱,种子能够萌发的最低渗透势阈值为-0.490 MPa;因干旱胁迫未能萌发的种子复水后萌发率较高.唐古特白刺种子萌发和幼苗生长对干旱胁迫的响应特征对幼苗的成功定植和避旱具有重要生态学意义,但在人工栽培时保证土壤墒情应是保障建植成功的关键措施.  相似文献   

沙地恢复过程中两种一年生植物种子萌发和幼苗种群动态研究     

何玉惠  赵哈林  刘新平  张铜会 《中国沙漠》2010,30(6):1331-1335

狗尾草和虫实是科尔沁沙地两种常见一年生草本植物,在沙地恢复过程中起着非常重要的作用。采用固定样方法对自然条件下两种植物种子萌发和幼苗种群动态进行了研究。结果表明,沙地恢复不同阶段虫实和狗尾草萌发数量随季节和样地的变化而变化,种子萌发和幼苗存活显示出强烈的降雨依赖性,并且虫实和狗尾草种子当年可萌发数量都随沙地固定程度增加而逐渐增大。从4月到8月,各月虫实种子萌发比例依次降低,但大多数狗尾草种子在5月到6月才开始萌发。虫实和狗尾草种子呈现出分批萌发的策略。虫实和狗尾草主要分4批出苗,相对虫实而言,狗尾草出苗对降雨的响应存在一定的滞后性,且狗尾草萌发所需的温度较虫实高。虫实和狗尾草的存活曲线均属于C型曲线,是较为典型的r对策者。  相似文献   

九寨沟林下28种乡土观赏植物种子基本特征     

苏维维  包维楷  周志琼 《山地学报》2010,28(1)

为了筛选九寨沟旅游退化地段林下植被恢复的适宜物种,并揭示乡土植物种子基本性状特征,研究了九寨沟28种观赏性乡土植物种子基本特征 (长宽、种皮厚度、千粒重、活力、萌发率)以及低温层积提高种子发芽能力的作用.调查研究结果是:1) 28种植物种子中4种为小种子(<1 mg),53.6%是中等大小的种子(1～9.9 mg),32.1%为大种子(>9.9 mg).小种子均出现萌发,与小种子相比,种子休眠普遍存在于中等大小和大的种子中.2) 77%的物种种子活力较高(>72%),但仅有7种常规条件下能萌发;窄叶鲜卑花的萌发率最高,达到80%左右,6种植物的萌发率3%～50%.3)低温层积显著提高了蔷薇、毛果铁线莲、宽叶旌节花、假升麻的萌发率(P<0.05),也相对较早地提高了陇东海棠、鲜黄小檗、独活的萌发,但对大多数种子萌发没有促进作用.综合分析表明,九寨沟28种林下或林缘乡土植物中只有窄叶鲜卑花、毛果铁线莲、宽叶旌节花、假升麻、陇东海棠、鲜黄小檗、蔷薇等12种可直播或通过低温层积处理后直播用于旅游干扰退化地段的林下植被恢复中,而其他种类尚需进一步寻求打破休眠的措施和方法.  相似文献   

Evidence for reduced post-spill recovery by the halophyte Sporobolus iocladus (Nees ex Trin.) Nees in oil-contaminated sediments     

Youssef T 《Marine pollution bulletin》2002,44(4):334-339

The germination behavior of Sporobolus iocladus seeds including germination percentage, accumulated germination percentage, the average incubation period to germination and germination velocity was studied under laboratory conditions. Treatments included six salinity regimes (0, 70, 140, 210, 280 and 350 mM NaCI) and three sources of oil hydrocarbons; Light Arabian Crude, polynuclear aromatic hydrocarbons (PAHs) including diaromatic or triaromatic hydrocarbons (in crude oil equivalent concentrations, COEC). The average incubation period needed for seeds to germinate was significantly longer for seeds germinated in 350 mM NaCl (6 +/- 1.16 days) compared with the control (4 +/- 00 days). The accumulated germination percentage gradually decreased with increasing salinity (control: 90 +/- 10, while 350 mM NaCl: 63 +/- 8.8). Oil hydrocarbons significantly affected all germination parameters of S. iocladus seeds regardless of salinity levels. COEC of di- and triaromatic hydrocarbons suppressed seed germination more than crude oil. Seeds exposed to diaromatic hydrocarbons failed to germinate. Hydrocarbon's salinity interaction significantly reduced the number of germinated S. iocladus seeds. It is concluded that hydrocarbon pollutants adversely affect S. iocladus through reducing germination. It is also suggested that the toxic effect of hydrocarbons on seeds is not solely mediated through their interaction with salinity. The ecological implications of these findings are discussed in relation to other studies on the post-spill recovery of halophytes.  相似文献   

Pollen Viability for Air Pollution Bio-Monitoring     

Elena Gottardini  Fabiana Cristofolini  Elena Paoletti  Paolo Lazzeri  Giancarlo Pepponi 《Journal of Atmospheric Chemistry》2004,49(1-3):149-159

Biological characterization of Corylus avellana L. and Pinus nigra L. pollen samples was carried out to determine the actual value of pollen as a bio-indicator of the effects of atmospheric pollution, using samples from plants naturally developed in sites controlled for air pollution. In Trentino (North Italy), we selected six stations at three different levels of air pollution, which are constantly monitored with automatic gauges by the Environmental Protection Agency of Trento.First results showed that pollen viability of both species, germinability and pollen tube length of P. nigra, were higher in areas with no road traffic compared to heavy traffic ones. Pollen viability of P. nigra was positively correlated to ozone (O₃) concentrations and altitude but negatively to sulphur dioxide (SO₂), particulate matter with a diameter less than 10 m (PM₁₀), nitrogen oxides (NO_x) and nitrogen dioxide (NO₂) concentrations.  相似文献