The storage effect due to frequency-dependent predation in multispecies plant communities

Frequency-dependent seed predation (FDP) has been shown to be a powerful coexistence mechanism in models of annual plant communities. However, FDP undermines the competition-based coexistence mechanism called the storage effect (SEc), which relies on temporal environmental fluctuations that drive fluctuations in competition. Although environmental fluctuations also drive fluctuations in predation, a storage effect due to predation (SEp) may not arise due to a time lag between a change in the environment and the resulting change in the predation rate. Here we show how SEp can arise with multispecies FDP, and in a two-species setting with density-dependent frequency-dependence, partially compensating for the reduction in SEc, in the presence of predation. These outcomes occur when predatory behavior is flexible, and can accommodate to changes in prey abundances on a within-year time scale, leading to changes in predator preferences in response to prey abundances in a given year. When predator preferences are determined by average prey abundances over several years, FDP is still a strong coexistence mechanism but undermines SEc without creating SEp.     

南亚热带常绿阔叶林几个树种的种子萌发和幼苗发育

南亚热带常绿阔叶林树种光叶红豆（Ｏｒｍ ｏｓｉａ ｇｌａｂｅｒｒｉｍ ａ Ｗｕ）、扁斗青冈（Ｑｕｅｒｃｕｓ ｈｕｉＣｈｕｎ）、罗浮柿（Ｄｉｏｓｐｙｒｏｓ ｍｏｒｒｉｓｉａｎａ Ｈａｎｃｅ）和阳性速生树种木蝴蝶（Ｏｒｏｘｙｌｕｍ ｉｎｄｉｃｕｍ （Ｌ．）Ｖｅｎｔ．）、香椿（Ｔｏｏｎａ ｓｉｎｅｎｓｉｓ （Ａ． Ｔｕｓｓ．） Ｒｏｅｍ ．）和泡桐（Ｐａｕｌｏｗ ｎｉａ ｆｏｒｔｕｎｅｉ（Ｓｅｅｍ ．） Ｈｅｍ －ｓｌ．）的种子中,除光叶红豆外都为迅速萌发,处理２—３ ｄ 便开始萌发,２—４周萌发完全。光叶红豆因种皮特性而延迟萌发,切破种皮即能迅速萌发。速生树种的萌发较快。森林树种和阳性速生树种木蝴蝶、香椿在光、暗下均能萌发,种子微小的速生树种泡桐则几乎只在光下萌发。种子萌发过程中吸水显示出３个阶段,不同种有所不同。幼苗的形态可能和耐阴性和生长速度有关。在暗中,光叶红豆能形成正常的叶,植株不徒长,其它种不能形成正常的幼苗,植株徒长,不形成叶子（或仅有黄色的子叶）。森林树种的幼苗生长较慢。     

湖南张家界天门山种子植物区系新资料

基于对湖南省张家界市天门山国家森林公园种子植物标本的采集鉴定,报道了湖南省新记录13种2变种,隶属于11科15属。即小山飘风Sedum filipes Hemsl．、绿花石莲Sinocrassula indica（Decne．）Berger var．viridiflora K．T．Fu、扇叶虎耳草Scocifraga rufescens Balf．var．flabellifolia C．Y.Wu et J．T．Pan、滇池海棠Malus yunnanensis（Franch．）Schneid．、北枳棋Hovenia dulcis Thtmb．、橄榄槭Acer olivaceum W．P．Fang et P．L．Chiu、大叶柴胡Bupleurum longiradiaum Turcz．、重齿当归Angelica biserrata（R．H．Shan et C．Q．Yuan）C．Q．Yuan et R．H．Shan、羌活Notopterygium incisum T．T．Ting ex H．T．Chang、直瓣苣苔Ancylostemon sarasilia（Hemsl．）Craib、野丁香Leptodermis potanini Batalin、毛华菊Dendranthema vestitum（Hemsl．）Ling、长冠鼠尾草Salvia pleetranthoides Griff．、茖葱Allium victorialis Linn．、节根黄精Polygonatum nodosum Hua。其中羌活属和野丁香属为湖南分布新记录属。凭证标本均存放在中南林业科技大学树木标本室（CSFI）。     

KCl处理对百合柱头生理及结实的影响

以百合（Lilium）品种‘Pollyanna’为材料,研究了KCl处理对柱头中SOD、POD及CAT等3种保护酶活性、可溶性蛋白含量以及电阻率的影响。结果表明,处理后3种酶的活性均表现出不同程度的应激性升高,其中SOD活性在花开当天和花开1d显著升高,在蕾期与花开2d极显著升高;花开当天及花开1d的POD活性极显著升高;CAT活性在花开1d升高显著,花开2d及3d时升高极显著。柱头可溶性蛋白含量及电阻率无显著变化,表明KCl处理削弱了细胞膜的膜脂过氧化作用,延缓了柱头衰老,提高了授粉受精作用,且与结实率升高表现出一定相关性。     

拟南芥菜(Arabidopsis thaliana)子叶中蛋白体形成的超微结构和免疫电镜定位研究

本文对拟南芥菜(Arabidopsis thaliana)种子发育过程中贮藏蛋白的积累和蛋白体的形成进行了超微结构和免疫电镜定位的研究。常规超薄切片的电镜观察表明,在开花后第10天(10 DAF),高电子密度的蛋白质物质开始在子叶细胞的液泡中沉积。这一过程一直延续到种子接近成熟(14 DAF),这时液泡中充满了蛋白质物质,转变成为大的蛋白体。利用了该种植物主要种子贮藏蛋白之一的12 s球蛋白的单克隆抗体作为免疫探针,以蛋白质A-胶体金电镜技术对12 s种子蛋白进行了细胞内定位,证实了在液泡中积累的物质为种子贮藏蛋白。实验结果表明在拟南芥菜中,子叶细胞中的液泡是蛋白体的前体,肯定了蛋白体的发生起源于液泡的观点。本文还对应用胶体金电镜技术进行细胞内定位的某些问题作了初步探讨。     

Deposition of exotic bird-dispersed seeds into three habitats of a fragmented landscape in the northeastern United States

Dispersal by frugivorous birds facilitates invasion by many exotic plants. We measured the seed rain of ornithochorous native and exotic plants at three habitats of a fragmented landscape of the northeastern United States for 1 year. We studied maple-beech forests, old fields, and abandoned conifer plantations. Across all sites we collected 2,196 ornithochorous seeds, including seeds from six exotic species and 10 native species. The majority (90%) of collected seeds were from exotic species. Seed dispersal was broadly similar among habitats, though seed rain of exotic species was higher in old fields than forested habitats. Seed rain was not strongly influenced by artificial perches for most species. However, seeds of exotic species were more commonly found in traps under an artificial perch in old fields. Seed rains for the exotic Elaeagnus umbellata, Rhamnus cathartica, and Rosa multiflora were positively associated with local density of mature plants. Seed rain of R. cathartica was positively associated with abundance of seedlings but not saplings, suggesting that post-dispersal mortality was important. Seed dispersal of the exotic Lonicera spp. was high in all habitats, accounting for 66% of all seeds collected. With the exception of Lonicera spp., seed rain of common exotic invaders was affected by the abundance of seed sources, and these species might be effectively controlled by elimination of local fruiting plants. Fruits of Lonicera morrowii, which has extensively invaded our area, are apparently a common component in the diet of frugivores.     

重要藏药川西獐牙菜种子萌发的研究

比较了温度、生长素(赤霉素GA3)和储藏条件对川西獐牙菜(SwertiamussotiiFranch)高海拔野生自然种群和低海拔栽培后种子发芽率的影响。未经任何处理的高海拔野生自然种群种子的发芽率明显高于低海拔栽培种群。无论是赤霉素处理还是低温处理对种子的发芽率都有显著提高。经过处理后,两种来源的种子最终发芽率没有明显的变化。结果表明:(i)野生的或栽培的川西獐牙菜种子都存在休眠现象;(ii)通过引种栽培不能打破川西獐牙菜种子的休眠,该机制可能是受遗传因素的控制;(iii)赤霉素处理和4℃低温冷藏对打破种子的休眠具有重要作用。     

鹅掌楸的花部数量变异与结实率

濒危植物鹅掌楸（Ｌｉｒｉｏｄｅｎｄｒｏｎｃｈｉｎｅｎｓｅ（Ｈｅｍｓｌ．）Ｓａｒｇ．）的花被片一般为９枚,对贵州松桃（Ｇ）、湖南龙山（Ｈ）和浙江龙王山（Ｚ）三地自然居群３年的观察发现,少数单株出现花被片数目变异,有１０、１１、１２枚花被片情况。与居群Ｇ和Ｈ相比较,居群Ｚ在单花花粉量,花粉大小和雌蕊数目等方面的变异较小,且无花被片数目变异。结实率与花部数目变异明显相关,变异较大的居群其结实率也高。居群间花粉平均大小与结实率有较好的正相关（ｒ＝０７６）,并在居群间比较了结实率与花粉胚珠比（Ｐ／Ｏ）的关系（ｒ＝－０７４）,发现Ｐ／Ｏ低的居群趋向于有较高的结实率,暗示资源配量限制了鹅掌楸的结实率。花部数量变异与结实率的关系表明潜在的遗传多样性对种子产量有明显影响。     

胁迫时间与非毒性离子对重金属抑制拟南芥种子发芽及幼苗生长的影响

测定了Hg²⁺、Cd²⁺、Cu²⁺、Pb²⁺单一重金属胁迫对拟南芥种子发芽和幼苗生长的影响.结果表明,重金属对幼苗生长的毒性大于对种子发芽的毒性,以抑制种子发芽的IC₅₀为指标,4种重金属的毒性顺序为Hg²⁺＞Cd²⁺＞Pb²⁺/Cu²⁺,以幼苗生长为指标,则毒性顺序为:Cu²⁺＞Hg²⁺＞Cd²⁺/Pb²⁺,并随着胁迫时间延长,种子萌发率下降.此外,不同重金属在不同发芽时段对种子的毒性也不尽相同,Cd²⁺的毒性在种子吸水后的0～12 h大于12～24 h,而Hg²⁺毒性在12～24 h大于0～12 h,其中,种皮对减轻重金属毒性起着十分重要的作用.通过非毒性离子(Ca²⁺、Mg²⁺、K⁺、Na⁺)与重金属离子(Hg²⁺、Cd²⁺、Cu²⁺、Pb²⁺)交互作用对拟南芥种子发芽及幼苗生长效应的研究发现, mmol·L^-1的Ca²⁺、Mg²⁺、K⁺、Na⁺可以增强Hg²⁺对种子发芽的毒性,但对Cd²⁺的毒性却没有影响.对于幼苗来说,Ca²⁺、Mg²⁺、K⁺、Na⁺可以显著增强Hg²⁺的毒性,Ca²⁺可以缓解Cd²⁺的毒性,但却增加Cu²⁺的毒性,K⁺可以缓解Pb²⁺对幼苗的毒害作用.最后,本文对重金属的毒害机理进行了探讨.     

新疆焉耆盆地种子植物区系特征分析

焉耆盆地位于新疆天山中段南麓,在植被地理区划上属于新疆暖温带灌木、半灌木荒漠区,其独特的自然地理位置和生态环境孕育了较为丰富的植物资源,研究其种子植物区系多样性分布特点对该区植物资源保护及可持续开发利用具有极其重要的意义。本研究通过野外实地调查及查阅相关文献资料,对新疆焉耆盆地的种子植物区系分布特点进行了系统分析。结果显示,该区种子植物约有1035种,隶属于80科373属,其中新疆特有种有38种,占新疆特有种总种数的14.18%。区系地理成分中,在科级水平上,焉耆盆地种子植物80科可划分为6个分布区类型和7个变型,并以温带地理成分为主(共有22个科),占该区非世界分布科总科数的57.89%;在属级水平上,焉耆盆地种子植物373属可划分为12个分布区类型和17个变型,并以温带地理成分为主(共197属),占非世界分布属总属数的62.54%。焉耆盆地种子植物生活型中,草本植物占优势,共有901种,占该区种子植物总种数的87.05%;灌木有110种(占10.63%),乔木17种(占1.64%),藤本7种(占0.68%)。焉耆盆地种子植物生态类型中,中生类型676种,占该区种子植物总种数的65.31%;旱生类型有191种(占18.45%),湿生类型123种(占11.88%),水生类型45种(占4.35%)。