Department of the Geophysical Sciences, University of Chicago, Chicago, IL 60637, USA.
Proc Biol Sci. 2010 Nov 22;277(1699):3437-43. doi: 10.1098/rspb.2010.0485. Epub 2010 Jun 16.
Movement of water from soil to atmosphere by plant transpiration can feed precipitation, but is limited by the hydraulic capacities of plants, which have not been uniform through time. The flowering plants that dominate modern vegetation possess transpiration capacities that are dramatically higher than any other plants, living or extinct. Transpiration operates at the level of the leaf, however, and how the impact of this physiological revolution scales up to the landscape and larger environment remains unclear. Here, climate modelling demonstrates that angiosperms help ensure aseasonally high levels of precipitation in the modern tropics. Most strikingly, replacement of angiosperm with non-angiosperm vegetation would result in a hotter, drier and more seasonal Amazon basin, decreasing the overall area of ever-wet rainforest by 80 per cent. Thus, flowering plant ecological dominance has strongly altered climate and the global hydrological cycle. Because tropical biodiversity is closely tied to precipitation and rainforest area, angiosperm climate modification may have promoted diversification of the angiosperms themselves, as well as radiations of diverse vertebrate and invertebrate animal lineages and of epiphytic plants. Their exceptional potential for environmental modification may have contributed to divergent responses to similar climates and global perturbations, like mass extinctions, before and after angiosperm evolution.
植物蒸腾作用将水分从土壤输送到大气中可以促进降水,但受到植物水力容量的限制,而植物的水力容量并不是一直保持不变的。在现代植被中占主导地位的有花植物,其蒸腾能力远远高于任何现存或已灭绝的其他植物。然而,蒸腾作用是在叶片水平上进行的,这种生理革命的影响如何扩展到景观和更大的环境仍不清楚。在这里,气候模型表明被子植物有助于确保现代热带地区季节性的高降水水平。最引人注目的是,被子植物被非被子植物植被所取代,将导致亚马逊盆地变得更热、更干燥和更具季节性,使热带雨林的总覆盖面积减少 80%。因此,开花植物的生态优势强烈改变了气候和全球水文循环。由于热带生物多样性与降水和雨林面积密切相关,被子植物对气候的改变可能促进了被子植物本身的多样化,以及各种脊椎动物和无脊椎动物谱系和附生植物的辐射。它们在环境改造方面的特殊潜力可能导致它们对类似气候和全球干扰(如大灭绝)产生不同的反应,而这些干扰发生在被子植物进化之前和之后。