By Allison Kubo Hutchison

Research recently published in Science, which focuses on plants rather than the show’s usual star, dinosaurs, reveals new information about how rainforests are evolving. But don’t worry, we’ll talk about dinosaurs later. In the field of paleobotany, the study of fossilized plants, research into rainforests was once considered impossible. It was believed that the high levels of decomposition, supported by the high biodiversity, prevent fossilization. However, that is not entirely true. The fossils exist, they’re just super hard to find. The results of over fifteen years of work in today’s Colombia show the development of the modern rainforest through the study of pollen and leaves 72 to 58 million years ago.

Although millions of years have passed, Colombia’s climate was largely the same now and before the Cretaceous eruption ended. Before extinction, researchers found pollen and spores from ferns and flowering plants with conifers that towered over the rainforests. The canopies were sparse than they are today and let more light into the undergrowth. After extinction, due to extinction, climate change caused many of the conifers to die off and flowering plants and legumes to dominate the forests. Today, rainforests have thick leaves that do not let any light into the undergrowth, which means that leaves receive different amounts of light and many new niches. In addition, the thick canopy of leaves leads to increased evapotranspiration or the transport of water from the soil into the air through the leaves. This created a high level of humidity, which favors the many epiphytic species such as orchids (read more about orchids here).

Today, Colombian rainforests account for around 10% of the world’s biodiversity. The extent of biodiversity was decimated by extinction, which killed 75% of all life on the plant, and it took approximately 6 million years to reach forests similar to what we see today. Which factors lead to the extermination of the conifers and the densification of the rainforests? Maybe the lack of dinosaurs. The lack of large herbivores to devour the canopy may have led it to grow into the beautifully diverse habitat it is today. Another explanation is that the ash spread from the impact may have enriched the soil with valuable nutrients. Or the extinction of conifers reduced competition for flowering plants.



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