孢子花粉与植物大化石:地质记录的差异及其古植物学意义

分散孢粉与植物大化石地质记录的不一致是常见现象,基本上是受孢粉的高产量及其外壁的较强抗腐蚀性,以及沉积环境的影响所致。主要根据我国古、中生代孢粉及植物化石资料,举例说明其地质记录的差异和其导致的不同解析和结论,及其古植物学意义。涉及的问题包括：1．新疆北部石炭二叠纪和塔里木盆地二叠纪的植物区系性质,2．我国古、中生代的主要成煤植物,3．古植代／中植代界线和植物在二叠纪末有无群体灭绝,4．某些植物类群的最早化石记录或起源,5．某些地层的地质时代问题。本文对此等问题提出的与古植物学家不甚一致的结论,如塔里木自早二叠世已属亚安加拉区,我国古、中生代主要成煤植物是真蕨类尤其是树蕨,而非鳞木类、科达类,或中生代裸子植物;如果将盾籽类作为中植代植物,则古植代／中植代界线在亚安加拉区要下降到Bashkirian之内或Bashkirian—Moscovian之交,等等,是否正确,有待检验。     

Reappraisal of two of Witham's species of fossil wood with taxonomical and nomenclatural notes on Planoxylon Stopes, Protocedroxylon Gothan and Xenoxylon Gothan

Fossil wood collections at the Natural History Museum, London, were searched for the type material of two important species, described as early as 1831 by Witham, on the basis of material at least partly furnished by Nicol and collected in the Liassic of Whitby (Yorkshire, UK). The names given to these two species by Witham are the basionyms for more than ten other species names, while these species names also provide syntypes for several generic names. Despite this, the original material has been only rarely and partly revised, leading to much confusion.We managed to locate some of the original material. Several topotypes were also studied. On the basis of this review we propose here a neotypification for Peuce huttoniana Witham, a lectotypification for Cupressinoxylon barberi Seward and a lectotypification for Tiloxylon Hartig. We evidence several taxonomical and nomenclatural synonymies, assign Peuce lindleyana Witham to Protocedroxylon and P. huttoniana to Xenoxylon Gothan, and introduce the new combination Xenoxylon huttonianum (Witham) nov. comb. as the correct name for Xenoxylon ellipticum Gottwald & Holleis ex Schultze-Motel.A topotype of Araucariopitys americana Hollick & Jeffrey was also reviewed, which, together with previous results, leads us to suggest that Araucariopitys Hollick & Jeffrey, Protocedroxylon Gothan and Planoxylon Stopes should not be considered as taxonomical synonyms. This point is crucial to the interpretation of the fossil record of Early Abietinae.     

X-射线CT扫描技术在中新世松属球果化石研究中的应用

利用X-射线CT扫描技术观察云南晚中新世松属球果化石的内部结构,并与现代种的内部结构进行比较。这是该技术在中国古植物学研究中的首次报道。通过内部结构的比较发现,松属化石最接近于现生种喀西亚松(Pinus kesiya)。CT扫描技术可以在不破坏标本的前提下观察植物化石的内部结构,对于较珍贵的化石研究作用尤为明显,但是分辨率的高低是该技术广泛应用于古植物学的重要因素,随着扫描仪器分辨率的不断提高,CT扫描技术将提供植物化石内部结构的更多细节信息,从而为古植物学研究开辟一条新的技术途径。     

Two new genera of Glossopteridae

Two glossoptcrid fructifications from the Permian are described. Mudgea , from Australia, consists of a tuft of scales bearing winged orbicular seeds and Breytenia is an urceolate receptacle with biconvex ovules.     

Fusinite of fossil coals as an information source about the anatomy of ancient plants

“Clarification” and ion and high-frequency etching of fusinite are described. These methods allow microscopic examination of fusinitized plant tissues in fine anatomical detail, revealing the outlines of cells, the structure of cell walls, the outlines of bordered pits, and, occasionally, even cellular microstructures. It is supposed that the effects of “clarification” and etching are caused by those optical differences between the composition of organic biopolymers that constituted the anatomical structures of plants that have been preserved in the fossil state.     

基于树木年轮学的古树树龄估算——以敦煌市香水梨为例

树龄是古树鉴定的唯一标准。本研究采用树轮年代学方法调查敦煌市莫高镇窦家墩村四组(原杨家园子)梨园中最老的香水梨树的树龄。因老梨树均腐朽中空,调查同时采集不同树龄的香水梨树样芯,建立树木径向生长生理年龄曲线,据此估算缺失段的树轮数。结合准确树轮计数,复原香水梨树树龄。结果表明: 梨园13棵老香水梨树的平均树龄为(280±35)年。由此证明,《敦煌志》中记载的古梨树是真实存在的。按树龄来说,该批梨树至少为三级古树,应妥善保护。本研究为解决敦煌市古梨园存留争议提供了详实的科学依据。     

甘肃省古树名木资源现状、问题与建议

丰富多彩的自然景观和璀璨的历史文化孕育了甘肃省丰富的古树名木资源。如今,发展古树名木绿色经济已成为甘肃省生态文明建设的重要途径。本文在归纳整理已有文献资料的基础上,对甘肃省古树名木资源现状进行梳理。甘肃省古树名木资源主要分布在农村和偏远山区,人类活动/病虫害和气候变化(干旱为主)分别是居住区及其周边和偏远山区古树名木生存面临的主要威胁因素。不同区域古树名木研究和管理的内容有较大区别: 居住区及其周边主要以养护及复壮技术为主,偏远山区多注重古树科学价值开发而忽视了古树自身保护研究。针对目前甘肃省古树名木树龄鉴定精度和效率低、管护方案可行性差、法律制度不健全、公众参与度低等诸多问题,建议从以下4个方面推动甘肃省古树名木保护工作: 1) 优先发展年轮鉴定法和年轮-直径回归估测法,设立专业机构或团队,提高树龄鉴定精度和效率;2) 加强衰老古树名木的种群特征及其生物学机制研究;3) 深化对古树不同年龄段生长规律的认识,制定可行的古树保护措施;4) 完善相关法律法规及提高公众参与度。     

An Early Miocene Plant Assemblage Severely Influenced By A Volcanic Eruption, Styria, Austria

Sediment and organic facies as well as leaves, pollen, and diaspores co-occurring in a tuffite exposed in Oberdorf (Ko¨flach/Voitsberg lignite area, Styria, Austria) were investigated. The tuffite is distinguishable from the under- and overlying clastic sediments and shows locally normally-graded lapilli, which is assumed to be a sign of direct airfall. The plant assemblage partly resulted from a volcanic eruption that coincided with the season in which many woody plants were flowering; deciduous ones were leafless or in the state of opening their buds; diaspores were not yet developed. Leaves of evergreen woody species, buds/bud scales, and clusters of immature pollen partly with adhering anther material were stripped off their parent plants and quickly embedded in the tuffite. The leaves of deciduous taxa and herbaceous monocotyledons, diaspores, partly also pollen, and organic facies components indicate progressive degradation. Such degraded plant debris probably accumulated in the backswamp sediments prior to the volcanic eruption. The tephra can only be correlated to the 'Lower Rhyolite Tuffs' in the Pannonian Basin (Hungary), indicating a (Late) Eggenburgian/Early Ottnangian age. The new species Ternstroemites waltheri is described. Distylium fergusonii Knobloch and Kvaček and Laurophyllum rugatum Kvaček and Bůžek are first reports from Austria.     

Plant carbon balance, evolutionary innovation and extinction in land plants

The plant fossil record was reviewed to highlight how consideration of plant carbon balance strengthens our understanding of various evolutionary innovation and extinction events. Following a brief physiological primer to carbon acquisition and allocation in C3‐plants, specific evolutionary events are discussed in connection with postulated carbon‐based mechanisms. Primary topics include: (i) the evolution of plants with the C4‐photosynthetic pathway; (ii) the surprising lack of plant extinctions during the Pleistocene (1.6 million years ago, Ma); (iii) the trend toward declining plant diversity and increasing rates of herbivory across the Palaeocene/Eocene transition (57–52 Ma); and (iv) megaherbivore extinctions at the end of the Pleistocene (10 thousand years ago, Ka). A framework is presented for testing hypotheses on the cause–effect relationships between global carbon cycling, plant carbon dynamics and the evolution of terrestrial ecosystems.     

The Early Holocene treeline in the southern French Alps: new evidence from travertine formations

Aims The present paper concerns the analysis of macro‐remains (plant imprints) from high altitude travertine deposits dating back to the early Holocene (9800 BP ). Our results allow us to discuss treeline location and ecology, and to supplement previous data based on pollen from natural sediments and charcoal from natural soil. Location The travertine under study is located in the Queyras massif, in the southern French Alps, along the Italian border. The site is situated on a south‐facing slope. Methods The travertine deposit has been dated by ²³⁰Th/²³⁴U. Taxonomic identification of plant imprints was achieved by comparison of the morphology of fossil specimens with extant material. Results Imprints of Pinus uncinata (cones and needles), broad‐leaved trees (Betula cf. pubescens, Populus tremula and Salix spp.), and unidentified trunks have been found. The plant assemblage records the existence at a high altitude (2200 m) of shade‐intolerant vegetation at around 9800 BP. Our data indicate that the treeline limit was at least 100 m higher than previously thought. The morphological features of the travertine, the plant assemblage and trunk diameters indicate that during the travertinization process, vegetation around the site was probably dense with tall upright trees. Main conclusions Our data show that Pinus uncinata and broad‐leaved trees developed at 2200 m, while regional pollen analyses locate the treeline at lower altitudes. Different research methods appear to provide different results. Around 9800 BP tree regeneration and growth were made possible up to at least 2200 m a.s.l., probably as a result of warmer and wetter summers. Warmer conditions are inferred from the predicted increase in incoming solar radiation based on calculated orbital variations, and wetter conditions are inferred from the build‐up of the travertine.     

弗特吉族在中国的发现及其意义

在连续数年的稀有濒危植物调研中,发现特产于江苏宜兴的小叶金缕梅实属一误订。该植物花两性,绝无花瓣,故可以肯定是金缕梅亚科中我国唯一缺少的弗特吉族植物。弗特吉族在中国的发现,使中国成为世界上唯一拥有该亚科五个族的国家,证明中国是世界金缕梅亚科的多样性中心,填补了该族在东亚分布的空白,为中国新生代植物研究和对金缕梅科以及被子植物的系统学研究提供了不可缺少的活材料。