Andean uplift played a fundamental role in shaping South American climate and species distribution, but the relationship between the rise of the Andes, plant composition, and local climatic evolution is poorly known. We investigated the fossil record (pollen, leaves, and wood) from the Neogene of the Central Andean Plateau and documented the earliest evidence of a puna-like ecosystem in the Pliocene and a montane ecosystem without modern analogs in the Miocene. In contrast to regional climate model simulations, our climate inferences based on fossil data suggest wetter than modern precipitation conditions during the Pliocene, when the area was near modern elevations, and even wetter conditions during the Miocene, when the cordillera was around ~1700 meters above sea level. Our empirical data highlight the importance of the plant fossil record in studying past, present, and future climates and underscore the dynamic nature of high elevation ecosystems.

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Aim: Multiple abiotic and biotic factors, mainly the amount and seasonality of precipitation, fire regime, soil properties and species adaptation strategies, have been invoked to explain the existence of the tropical savanna-humid forest transition. We explored the rainfall variables that influence the probability of forest or savanna occurring in northwest South America, specifically monthly precipitation and the mean and maximum duration of wet and dry spells, defined as the number of consecutive wet (dry) days.

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