被子植物演化和水循环  

Evolution of the angiosperms and hydrologic cycle

作　　者：史恭乐[1,2] Gongle Shi(State Key Laboratory of Palaeobiology and Stratigraphy,Nanjing Institute of Geology and Palaeontology,Chinese Academy of Sciences,Nanjing 210008,China;Center for Excellence in Life and Paleoenvironment,Chinese Academy of Sciences,Nanjing 210008,China)

机构地区：[1]中国科学院南京地质古生物研究所,现代古生物学和地层学国家重点实验室,南京210008 [2]中国科学院生物演化与环境卓越创新中心,南京210008

出　　处：《科学通报》2023年第12期1487-1500,共14页Chinese Science Bulletin

基　　金：中国科学院战略性先导科技专项(B类)(XDB26000000);中国科学院青年创新促进会(Y2021082)资助。

摘　　要：陆地植物的蒸腾作用将部分降水再循环到大气中,是陆地水循环非常重要的一个环节.地质历史中陆地植物的形态和解剖结构不断演化,其蒸腾作用能力也在不断演化.现代陆地生态系统中占优势的被子植物具有导水性较强的导管和较高的叶片叶脉密度,使得它们在水分运输效率和蒸腾作用能力方面远高于其他现生和已灭绝的植物.早白垩世早-中期被子植物演化的最初阶段其叶脉密度较小,与其他现生和已灭绝植物的叶脉密度相近.但在白垩纪中期和白垩纪-古近纪之交被子植物经历了两次叶脉密度的显著增加,代表了两次被子植物蒸腾作用能力的显著提高.单穿孔板导管的出现和叶片叶脉密度的增加显著提高了被子植物的导水率、蒸腾能力和光合能力,进而增加了被子植物在生态系统中的竞争优势,并很有可能同时增加了水循环的活跃程度和降水量.利用被子植物化石可以重建古降水和古湿度等多个与水循环相关的气候指标.前人基于植物化石的研究发现,全球温暖的晚白垩世、古新世和始新世时期,现今为严寒荒漠的北极地区具有常年温凉湿润的海洋性气候和茂盛的温带森林.温暖的北冰洋和广布的森林导致了北极地区旺盛的水循环和较高的空气湿度,进而又有助于维持这一地区常年的温凉湿润气候.Terrestrial vegetation especially forest plays a critical role in the terrestrial hydrologic cycle.Plant transpiration transfers water from soil to atmosphere and the recycling of water through transpiration is one of the most important sources of terrestrial precipitation.However,the transpiration capacity of different groups of plants in the geological past would have been distinct,mainly because of differences in the vein density of their leaves,and in the structure of their water-conducting tissues.Angiosperms,which are dominant in most modern terrestrial ecosystems,have transpiration rate much higher than other extant and extinct plants.Fossil evidence shows that the earliest forests appeared in the Middle Devonian.During the Late Carboniferous and Permian,wetlands forests,known as Paleozoic tropical rain forests and dominated mainly by arborescent lycopsids,tree ferns,seed ferns,Cordaitales and Gigantopteridales,were well developed in large areas of the palaeotropics.During the Triassic,Jurassic and Early Cretaceous,the Earth’s forests were dominated mainly by ferns,conifers,ginkgophytes,cycads and Bennettitales.The earliest angiosperm fossils are from the early Early Cretaceous,but angiosperms had not become ecologically dominant until the Late Cretaceous.The origin and evolution of angiosperms involved many innovations in both reproductive and vegetative structures,and their rise to ecological dominance in the Late Cretaceous ecosystems has been considered to be the result of the competitive advantages of these evolutionary innovations.The key innovations of angiosperms that relate to transpiration capacity and water transport are the xylem vessels which transport water from roots to leaves,and the broad leaves with reticulate,open venation,freely ending veinlets and high vein density.The long,multicellular xylem vessels of angiosperms are thought to be evolved from the short,unicellular tracheids of non-angiosperms.However,comparative physiological studies show that the early diverging angiosperms bear

关 键 词：被子植物 蒸腾作用 水循环 导管 叶脉密度 叶相 

分 类 号：Q941[生物学—植物学]