Oligocene plant ecological strategies in low-latitude Asia unraveled by leaf economics

Abstract

The Oligocene represents an important epoch in the history of the stepwise global climate evolution from a warm climate to a cooler climate. The change probably introduced selective pressures influencing ecological strategies and caused the past ecosystems restructured. However, little is known about the paleoenvironment and adaptive plant ecological strategies in the terrestrial realm of the low latitudes. Here, based on the plant fossils from the Baigang Formation of the Baise Basin, low-latitude China, the paleoclimate, paleovegetational type, and paleoecological strategy are reconstructed using leaf physiognomic analyses, Integrated Plant Record and leaf economics spectrum, respectively. The results show that, under a warm and wet sub-tropical climate with low seasonality, the Oligocene Baise flora was dominated by ‘slow-return (maximized resource retention)’ species but mixed with a considerable proportion of ‘fast-return (rapid resource acquisition)’ species. These ecological strategies might promote the community to maximize the use of limited living resources, and at the same time to better tolerate potential extreme situations. These results allow us to examine which ecological strategies that fossil plants selected under a given paleoclimate condition and might potentially provide a clue to predict the direction of ecological strategy changes in a future climate change scenario.