South American palaeobotany and the origins of neotropical rainforests
South American palaeobotany and the origins of neotropical rainforests
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DOI：
10.1098/rstb.2004.1531
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发表时间：
2004-10-29
影响因子：
6.3
通讯作者：
Johnson, KR
中科院分区：
文献类型：
--
作者：
Burnham, RJ;Johnson, KR
现存的新热带雨林生物群落的特点是被子植物和藤本植物的多样性和丰度高，全缘叶的比例高，大叶（大于4500毫米）的比例高，滴水尖的丰度高，以及一套具有特色的优势科：仙人掌科、樟科、豆科（蚕豆科）、漆树科和棕榈科（云杉科）。我们的目标是确定现存雨林的参数，以便在南美洲的化石记录中识别它们，并评估所有已知的南美洲植物化石组合，以获得第一个证据和这些参数的持续存在。我们问这些关键的雨林特征是什么时候出现的？什么时候植物参数达到了我们在新热带森林中看到的丰富程度？此外，什么时候特定的谱系在新热带森林中变得普遍？我们的回顾表明，在古新世之前，新热带雨林的证据非常罕见和模糊。即使在古新世，南美洲热带雨林存在的唯一证据是花粉多样性较高。相比之下，北美的遗址提供的证据表明，热带雨林的树叶地貌是在古新世早期建立起来的。在始新世的南美洲，一些证据表明，新热带雨林是多种多样的，在外貌上可以识别为热带雨林，在分类上与现代新热带雨林相近。关于高多样性古植物学遗址与预测的热带气候遗址之间起源年龄的证据不匹配，应与在南美洲加强收集工作相协调。我们确定了几条有前途的研究路线，这些研究将有助于将以前不同的方法结合起来，研究南美高度多样性植物群的起源、寿命和维持。
Extant neotropical rainforest biomes are characterized by a high diversity and abundance of angiosperm trees and vines, high proportions of entire-margined leaves, high proportions of large leaves (larger than 4500 mm(2)), high abundance of drip tips and a suite of characteristic dominant families: Sapotaceae, Lauraceae, Leguminosae (Fabaceae), Melastomataceae and Palmae (Arecaceae). Our aim is to define parameters of extant rainforests that will allow their recognition in the fossil record of South America and to evaluate all known South American plant fossil assemblages for first evidence and continued presence of those parameters. We ask when did these critical rainforest characters arise? When did vegetative parameters reach the level of abundance that we see in neotropical forests? Also, when do specific lineages become common in neotropical forests?Our review indicates that evidence of neotropical rainforest is exceedingly rare and equivocal before the Palaeocene. Even in the Palaeocene, the only evidence for tropical rainforest in South America is the appearance of moderately high pollen diversity. By contrast, North American sites provide evidence that rainforest leaf physiognomy was established early in the Palaeocene. By the Eocene in South America, several lines of evidence suggest that neotropical rainforests were diverse, physiognomically recognizable as rainforest and taxonomically allied to modern neotropical rainforests. A mismatch of evidence regarding the age of origin between sites of palaeobotanical high diversity and sites of predicted tropical climates should be reconciled with intensified collecting efforts in South America. We identify several lines of promising research that will help to coalesce previously disparate approaches to the origin, longevity and maintenance of high diversity floras of South America.