Geography of plants in the New World: Humboldt's relevance in the age of big data

Plant geography seeks to describe the patterns of species distributions and understand the underlying mechanisms. The foundation of the field is attributed to Alexander von Humboldt following the broad-scale insights he gained on his explorations of the New World two centuries ago. Today, in the age of "Big Data," advances in methods and data availability allow us to better assess the complex drivers of species distributions. In this essay, we give an overview of the relevant legacy of Humboldt in the field of plant geography. Comparing the foremost insights and approaches of Humboldt's time and of today, we highlight areas in which major changes have taken place and areas in which Humboldt's approach is still relevant. We present advances in the description and understanding of plant geography, which have changed our entire worldview to a much more dynamic one. Further, we present some of the outstanding challenges of the field, and how solving them requires going back to the "Humboldtian" approach to science, i.e., combining precise, quantitative empirical studies with a holistic approach. Finally, we discuss how our recognition of the planetary impact of humans in the Anthropocene means that much of our research is no longer exclusively driven by curiosity, but also by the societal need to make predictions of ecosystem responses to environmental change. There is thus a strong need for combining quantitative empiricism with a holistic perspective to address the complex challenges of the current epoch.