中国不同气候带植被挥发性有机化合物通量与生态系统演替的相关性

从群落水平和生态系统演替的角度对中国热带,亚热带和温带生态系统植物挥发性有机化合物（VOC）通量的研究表明,异戊二烯通量呈现出在生态系统演替的早期到中期阶段随着演替的的进行而升高,在先锋性灌木和乔木阶段达到高峰,然后又随着演替的发展而逐渐下降的演替格局,而其他VOC通量则有随着演替的进行而上升的趋势。生态系统不同演替阶段异戊二烯通量的变化可能与植物获取养分氮有关,根据植物VOC释放通量的生态演替格局,可以建立全球陆地生态系统的VOC模型,对大气化学过程中的VOC时空动态进行很好的模拟。     

UPPER BARREMIAN (CRETACEOUS) HETEROCERATID AMMONITES FROM SOUTH AFRICA AND THE CAUCASUS AND THEIR -PALAEOBIOGEOGRAPHIC SIGNIFICANCE

Heleroceratid ammonites are abundant in the Upper Barremiansediments of Zululand, South Africa, and representatives ofthe genera Heteroceras, Colchidites and Paraimerites are describedbelow. This assemblage shows strong similarities to faunas knownfrom the Caucasus region of the USSR, a similarity that persistedinto the succeeding Aptian. This similarity presents somethingof a paradox, because the genera concerned are among the leasthydrodynamically streamlined of ammonites. Their distributionsuggests an open marine connection between the Mediterraneanparts of Tethys and the eastern coast of Africa, linked, inthe Barremian — early Aptian at least, to Patagonia. Theirwide distribution also supports the view that climatic gradientswerelow during the Barremian and that the climate was generallywarmer than at present. (Received 12 January 1983;     

TURRILITIDAE (CRETACEOUS AMMONOIDEA) FROM SOUTH AFRICA, WITH A DISCUSSION OF THE EVOLUTION AND LIMITS OF THE FAMILY

The helically coiled mid-Cretaceous family Turrilitidae Meek,1876 are abundant in late Albian and Cenomanian sediments ofEastern South Africa, including representatives of the generaPseudhelicoceras, Turrilites, Hypoturrilites, Ostlingocerasand Mariella, together with a new genus, Neostlingoceras (typespecies Turrilites carcitanensis Matheron, 1842).a Hypoturriliteshomoeomorph derived from Ostlingoceras. Twenty-two species andsubspecies are described, four of them new: Hypoturrilites crickisp. nov., Mariella (Mariella) acanthotuberculata sp. nov., Mariella(Mariella) oehlerti (Pervinquière) sulcata subsp. nov.and Mariella (Mariella) gallienii evoluta subsp. nov. The systematicpart.of the paper providesa basis for the discussion of thephylogeny, and some of the evolutionary trends shown by thefamily. An annotated synopsis of all genera and species referred tothe family is also included (Received 10 March 1977;