江苏太湖平原北翼的第四纪孢粉与环境

本文根据湖北侧4个钻孔的孢粉分析,^14C和古地磁测试,并结合钙质超微化石,介形类和有孔虫所确定的海侵地层,将太湖地区的划为10个孢粉带,再参照长江下游相关资料,着重对12．7－1．5万年以来的4个孢粉带作了较深入的环境探讨,揭示出VI带（12．7－7．0万年）为常绿落叶阔叶混交林,反映温暖湿润的亚热带气候,其主要温暖阶段冬温较今高4－5度,当时湿度相对偏大,当然其中也有凉湿与干凉时段,Ⅶ带（7．0－3．0万年）为疏林草原,反映冷（半）干气候,其主要寒冷阶段年均温为8度左右,但仍存在剧烈的气候波动,Ⅷ带（3．0－2．1万年）为温性常绿落叶阔叶混交林,反映温凉湿润的季风海洋性气候,其主要温凉阶段生长季月均温比现在低约3度,其中亦有更为干冷或暖湿时期,IX带（2．1－1．5万年）为森林草原－草原或干草原植被,其极干冷阶段年均温约8度,年降雨量400mm左右。     

黄土孢粉分析方法的研究

根据黄土的化学成分等特点,采取相应的化学及物理相结合的处理方法,把孢粉离析出来。在黄土最为发育的陕西、甘肃７ 个黄土剖面计９０ 多个样品中均获得丰富的孢粉,观察１—３ 张玻片,孢粉总数可达２０４—５９４ 粒以上,２５０ ｇ 的土样可获得３．９—５５．１ 万粒孢粉     

根据孢粉分析论青藏高原西部和北部全新世环境变化

通过对青藏高原西部班公湖钻孔和北部中昆仑山３个湖相剖面的孢粉研究,揭示青藏高原西部和北部地区全新世１万年期间植被的演替和气候变化,西部在全新世早期９９００－７８００ｙｒ．Ｂ．Ｐ．植被由荒漠转为草原,气候好转;中期７８００－３５００ｙｒ．Ｂ．Ｐ．,草原发展,气候较适宜,以７２００－６３００ｙｒ．Ｂ．Ｐ．为高温湿期,５５００ｙｒ．Ｂ．Ｐ．和３５００ｙｒ．Ｂ．Ｐ．出现干旱,晚期从３５００ｙｒ．Ｂ．Ｐ．至今植被为荒漠,气候干旱,其中７００ｙｒ．Ｂ．Ｐ．气候恶化。北部地区全新世时期为荒漠植被,当气候温湿时,蒿和禾本科,莎草科成份增加,藜科减少,气候干旱时则相反,北部全新世的气候分期和干湿波动与西部相近,两地在晚期气候朝干旱化发展。     

苏北盆地晚更新世以来的孢粉记录与气候地层学的初步研究

苏北盆地是我国西部高原至东部海洋之间的过渡地区,该地区的气候演变史对揭示东亚季风的时空变化有着重要的意义。根据气候地层学的原理,用孢粉分析的方法,结合^14C测年数据,再造了兴化地区自倒数第二次冰期以来的古植被与古环境,其演变史能与深海氧同位素记录进行良好的对比,孢粉带Ⅲ、Ⅳ、Ⅴ、Ⅵ、Ⅶ分别对应深海氧同位素阶段5、4、3、2、1,且孢粉带Ⅲ细分的5个亚带与MIS 5a-5e也有良好的对应。此外,从该地区末次冰期孢粉记录中检索出6次冷事件,通过与格陵兰冰芯及会宁黄土记录对比,推测这些冷事件可能对应于末次冰期气候变化中的Heinrich事件。     

日本本州北部白神山地圆齿水青冈林(Fagus crenata)表土花粉分析及水青冈属花粉的代表性

为揭示和探讨水青冈表土花粉与现生植被的关系及其花粉代表性,我们对日本本州北部白神岳圆齿水青冈林中苔藓表土花粉进行了分析,结合前人研究资料,结果表明Fagus花粉可有效指示青冈林森林植被:在水青冈优势林中Fagus花粉百分含量达35%—40%以上;偏离水青冈林或无水青冈林分布时,含量低于5%—10%;介于两者之间为含有水青冈的混交林。这一结果与我国众多学者报道的表土花粉研究显示Fagus花粉的低代表性不相一致,其主要原因可能与国内取样点松属(Pinus)花粉的突出含量及林地较高的植物多样性紧密相关,从而干扰"遮掩"了水青冈花粉具有合适代表性这一特点。     

高等植物花粉母细胞内肌动蛋白的聚丙烯酰胺凝胶电泳分析

采用聚丙烯酰胺凝胶电泳技术分析了黑麦、蚕豆和百合花粉母细胞内肌动蛋白的存在与动态,结果表明高等植物的花粉母细胞在细胞融合期内的确存在一定量的肌动蛋白,并且,这种蛋白在早偶线期时出现,到四分体时期后消失。文章讨论了肌动蛋白的存在及其与细胞融合现象的联系。     

SIZE-AND AGE-CLASS SEGREGATION OF BOWHEAD WHALES SUMMERING IN NORTHERN FOXE BASIN: A PHOTOGRAMMETRIC ANALYSIS

To determine whether Hudson Bay-Foxe Basin bowhead whales segregate on the basis of age, whales summering in northern Foxe Basin, were aerially photographed in August of 1996, 1997, and 1998. Image lengths on either the negatives or contact prints were measured and total body lengths were estimated. In all three years the majority of whales photographed were ≤13.5 m long. Calves and juveniles made up 89.3%, 96.6%, and 79.3% of the total number of measured whales in 1996 (n = 28), 1997 (n = 30) and 1998 (n = 29) respectively. The number of bowheads >13.5 m, the approximate size at which females reach sexual maturity, that were photographed was directly proportional to the number of calves photographed. Our results indicate that northern Foxe Basin bowheads are part of a more widely distributed stock. Adult males and resting adult females apparently summer in another part of the range, probably northwestern Hudson Bay. Northern Foxe Basin appears to be used as a summer feeding area by cows with young-of-the-year calves and by juveniles.     

贵州大干坝孢粉分析与古环境探讨

大干坝洼地发育了一套晚更新世河湖相地层，富含孢粉，明显可分两段：两万三千多年前为茂密的亚热带山地森林，水青冈属一度占优势；两万三千多年后森林稀化，蕨类植物生长，尔后阳性树种恢复，这反映该地从大理间冰段（阶）向盛冰期过渡时，环境条件发生了跳跃式的变化。     

DIFFERENTIAL SUCCESS OF POLLEN DONORS IN A SELF-COMPATIBLE LILY

If pollen donors are equally effective at siring seeds, the presence of equal proportions of pollen from two pollen donors on a stigma will lead to equal proportions of seeds sired by each pollen donor. Variation in germination rates, pollen-tube growth, and embryo viability may cause one donor to sire more seed than another. We looked for differential donor success in the field by simultaneously applying equal amounts of pollen from two pollen donors. We simultaneously applied equal amounts of self and outcross pollen to receptive stigmas and simultaneously applied pollen from two donors at different physical distances from the recipient. Following simultaneous application of self and outcross pollen, significantly more of the seeds were sired by outcross pollen donors. Seed set following simultaneous application of two outcross donors was also nonrandom. Pollen donors from 100 m were more likely to sire seeds when competing with pollen from plants nearby (1 m). To determine whether pollen-tube growth rates were responsible for these patterns of paternity, we varied the timing of deposition of outcross pollen allowing self pollen tubes a head start on the stigma. Outcross pollen was applied 3 or 24 h after self pollen. In spite of this time delay, the majority of the seeds were again sired by outcross pollen. There was no significant difference in the amount of seeds sired by self pollen between the two delay treatments. This result suggests that mechanisms operating after ovule fertilization may contribute to the discordance between the proportions of the pollen present and the proportions of seeds sired.