Fire and fire-adapted vegetation promoted C4 expansion in the late Miocene.
Fire and fire-adapted vegetation promoted C4 expansion in the late Miocene.
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DOI：
10.1111/j.1469-8137.2012.04202.x
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发表时间：
2012-08
期刊：
影响因子：
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通讯作者：
S. Scheiter;S. Higgins;C. Osborne;C. Bradshaw;D. Lunt;B. Ripley;Lyla L. Taylor;D. Beerling
中科院分区：
文献类型：
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作者：
S. Scheiter;S. Higgins;C. Osborne;C. Bradshaw;D. Lunt;B. Ripley;Lyla L. Taylor;D. Beerling
地球陆地表面的大部分被以C（4）草为主的生物群落所覆盖。这些以C（4）为主的生物群系起源于中新世晚期，距今300 - 800万年（Ma），但有证据表明，C（4）草在中新世/渐新世早期进化了大约20 Ma。对这种演化和扩张之间的滞后的解释援引了大气CO（2）的变化，气候和火灾的季节性。然而，对于这些因素中的哪一个触发了C（4）草地扩张，仍然没有达成共识。我们使用一个植被模型，自适应动态全球植被模型（aDGVM），以测试如何CO（2），温度，降水，火和植被的火耐受性影响C（4）草原扩张。模拟被迫与哈德利中心耦合的海洋-大气-植被大气环流模式产生的中新世晚期气候。我们表明，C（3）和C（4）光合途径之间的生理差异不能解释C（4）草入侵森林，但火是一个关键的驱动程序。促进燃烧的植物特性有助于扩大以C（4）为主的生物群落可以持续存在的气候空间。我们认为，三种机制参与了C（4）的扩张：低大气CO2下的C（4）禾本科植物的生理优势，使他们能够入侵C（3）草原;火允许草入侵森林;和耐火稀树草原树木的进化扩大了稀树草原可以入侵的气候空间。
Large proportions of the Earth's land surface are covered by biomes dominated by C(4) grasses. These C(4)-dominated biomes originated during the late Miocene, 3-8 million years ago (Ma), but there is evidence that C(4) grasses evolved some 20 Ma earlier during the early Miocene/Oligocene. Explanations for this lag between evolution and expansion invoke changes in atmospheric CO(2), seasonality of climate and fire. However, there is still no consensus about which of these factors triggered C(4) grassland expansion. We use a vegetation model, the adaptive dynamic global vegetation model (aDGVM), to test how CO(2), temperature, precipitation, fire and the tolerance of vegetation to fire influence C(4) grassland expansion. Simulations are forced with late Miocene climates generated with the Hadley Centre coupled ocean-atmosphere-vegetation general circulation model. We show that physiological differences between the C(3) and C(4) photosynthetic pathways cannot explain C(4) grass invasion into forests, but that fire is a crucial driver. Fire-promoting plant traits serve to expand the climate space in which C(4)-dominated biomes can persist. We propose that three mechanisms were involved in C(4) expansion: the physiological advantage of C(4) grasses under low atmospheric CO(2) allowed them to invade C(3) grasslands; fire allowed grasses to invade forests; and the evolution of fire-resistant savanna trees expanded the climate space that savannas can invade.