5 resultados para Cephalotaxaceae
Resumo:
球果类植物是现存裸子植物中最为繁盛的一群,也是目前组成北温带森林植被的重要成分,我国是球果类植物科属的重要分布、分化或保存中心。对这些科属的分类和系统发育的研究,无疑对北温带的森林植被的研究,以及林业生产均具有重要的理论和实用价值.本研究即是围绕着球果类中的Pinaceae,Taxaceae及Cephalotaxaceae等科展开的研究,内容主要包括以下几方面: 一、在《中国植物志》第七卷的基础上,完成了《FLORA OF CHINA》中裸子植物Ginkgoaceae,Arancariaceae Pinaceae,Taxaceae,和Cephalotaxaceae各科的修订和编写. 建立2个新种、2个新变种、12个新组合、64个新异名、2个新分布,2个新启用名,分类群及其名称的变动和增补,以及增补异名57个。 二、根据植物的地理分布与系统发育统一的原理,在资料分析和实验的基础上,运用表征分析和分支分析研究方法,同时结合化石和地史资料,针对松科的分类、地理分布、以及起源分化和扩散等问题进行了一系列系统的研究,主要结论如下: 1.提出松科分类的新系统,将松科划分为三个亚科:松亚科Subfam.Pinoideae:仅一属Pinus Linn.: 落叶松亚科Subfam.Laricoideae Melchior&Werderm, emend.N.Li et L.K.Fu:包括四属Larix Mill.,Cathaya Chun&Ku:tng, Picea A Dretr. andPseudotsuga Carr.;冷杉亚科Subfam.Abietoideae Pilger, emend.Frankis:包括五属Abies Mill.,Cedrus Trew, Pseudolarix Gord.,Keteleeria Carr.,and Tsuga Carr. 2.构思和绘出了以地质年代为纵座标的松科系统发育树。 3.进行松科植物分区,将松科划分为6区、4亚区。并分别附有分区图、各区所分布种数的统计表、以及各属目前的地理分布和化石分布图。 4.松科在地质时期曾是一个很庞大的类群,现代松科只是其祖先中少部分喜温性分支的后裔,其兴旺与温带成份的出现关系密切,可能是一类衍生类群. 5.松科的起源时间虽然可追溯到侏罗纪甚至三迭纪,但现代松科各属的出现时间大约是在早白垩纪至第三纪之间。 6.松科各属可能并非起源于同一时间和地点。松属可能是现存的、最早分化出来的类群,于侏罗纪至早白垩纪间起源于欧美古陆;其它属则到晚白垩纪至第三纪早期(有1-2属至中期)才陆续从其祖先复合体中分化出来。 7.现代松科的早期扩散可能存在着以下三条主要的迁陡路线,即:欧美路线、欧亚路线和古白令路线.
Resumo:
首次报道了云南元谋盆地(虎跳滩土林、湾堡土林和新华土林)晚上新世的硅化木材植物群和山西太谷盆地晚上新世的炭屑木材植物群,分析了这两个盆地当时的植被、环境和气候,为认识我国西南地区和北方中部地区晚上新世气候变化提供了生物学证据。 1。云南元谋盆地晚上新世沙沟组(相当于钱方等1991元谋组下部一、二段)化石木植物群包括:裸子植物1种,归属于三尖杉科(Cephalotaxaceae)三尖杉属(Cephalotaxus)或红豆杉科(Taxaceae)穗花杉属(Amentotaxus);被子植物11种,分别归属于楝科(Meliaceae)香椿属(Toona)、大戟科(Euphorbiaceae)秋枫属(Bischofia)、榆科(Ulmaceae)榉属(Zelkova)、豆科(Fabaceae)黄檀属(Dalbergia)、壳斗科(Fagaceae)锥属(Castanopsis)、青冈属(Cyclobalanopsis)、 千屈菜科(Lythraceae)紫薇属(Lagerstroemia)、桑科(Moraceae)桑属(Morus)、胡桃科(Juglandaceae)、豆科和壳斗科。其中三尖杉属或穗花杉属、楝科香椿属、豆科黄檀属、壳斗科锥属、青冈属、千屈菜科紫薇属、桑科桑属、胡桃科和壳斗科的化石木在我国为首次报道。依据植物群的组成,当时该盆地周围山地上的森林是以锥属、青冈属和三尖杉属或穗花杉属为主要分子的常绿针阔混交林,盆地内的树木包括楝科香椿属、大戟科秋枫属、豆科和千屈菜科紫薇属等植物;当时的气候为亚热带气候,温暖湿润。与印度同时代植物群相比,元谋植物群不具有典型的热带雨林分子如龙脑香科植物,而在印度晚第三纪则常见热带雨林分子。这种差异可能是因为中印植物区系起源不同,以及地质历史时期青藏高原的隆升造成区域气候分异,从而导致中印古植物区系不同。 2.山西太谷盆地晚上新世小白组化石木植物群包括榆科(Ulmaceae)榆属(Ulmus)、蔷薇科(Rosaceae)李属(Prunus)和桑科柘属(Cudrania),它们的标本保存为炭屑木材。该化石木群的发现,以及综合通过孢粉学研究得出的古气候研究结果,表明当时当地属于典型的温带气候。化石木清晰的生长轮表明当时气候具明显的季节性。现代生态木材解剖学研究发现温带干旱地区植物群中导管分子壁的螺纹加厚比例较高、且明显。化石木标本导管分子壁具明显的螺纹加厚也表明盆地内为温带的气候类型。孢粉学研究和地层中丰富的石膏层也表明当时气候具有明显的干湿波动,地层中多层炭屑的存在证明了当时气候条件下森林火频繁发生。这些炭屑木材的发现丰富了太谷盆地晚上新世植物群,为古植被重建和古环境恢复提供了新的证据
Resumo:
Sannai-Maruyama is one of the most famous and best-researched mid-Holocene (mid-Jomon) archaeological sites in Japan, because of a large community of people for a long period. Archaeological studies have shown that the Jomon people inhabited the Sannai-Maruyama site from 5.9-4.2 +/- 0.1 cal. kyr B.P. However, a continuous record of the terrestrial and marine environments around the site has not been available. Core KT05-7 PC-02, was recovered from Mutsu Bay, only 20 km from the site, for the reconstruction of high-resolution time series of environmental records, including sea surface temperature (SST). C37 alkenone SSTs showed clear fluctuations, with four periods of high (8.4-7.9, 7.0-5.9, 5.1-4.1, and 2.3-1.4 cal. kyr B.P.) and four of low (-8.4, 7.9-7.0, 5.9-5.1, and 4.1-2.3 cal. kyr B.P.) SST. Thus, each SST cycle lasted 1.0-2.0 kyr, and the amplitude of fluctuation was about 1.5-2.0 °C. Total organic carbon (TOC) and C37 alkenone contents, and the TOC/total nitrogen ratio indicate that marine biogenic production was low before 7.0 cal. kyr B.P., but was clearly increased between 5.9 and 4.0 cal. kyr B.P., because of stronger vertical mixing. During the period when the community at the site prospered (between 5.9 and 4.2 +/- 0.1 cal. kyr B.P.), the terrestrial climate was relatively warm. The high relative abundance of pollen of both Castanea and Quercus subgen. Cyclobalanopsis supports the interpretation that the local climate was optimal for human habitation. Between 5.9 and 5.1 cal. kyr B.P., in spite of warm terrestrial climates, the C37 alkenone SST was low; this apparent discrepancy may be attributed to the water column structure in the Tsugaru Strait, which differed from the modern condition. The evidence suggests that at about 5.9 cal. kyr B.P, high productivity of marine resources such as fish and shellfish and a warm terrestrial climate led to the establishment of a human community at the Sannai-Maruyama site. Then, at about 4.1 +/- 0.1 cal. kyr B.P., abrupt marine and terrestrial cooling, indicated by a decrease of about 2 °C in the C37 alkenone SST and an increase in pollen of taxa of cooler climates, led to a reduced terrestrial food supply, causing the people to abandon the site. The timing of the abandonment is consistent with the timing (around 4.0-4.3 cal. kyr B.P.) of the decline of civilizations in north Mesopotamia and along the Yangtze River. These findings suggest that a temperature rise of ~2 °C in this century as a result of global warming could have a great impact on the human community and especially on agriculture, despite the advances of contemporary society.