A tale of many cities: how people move and take their culture (and their plants) with them

Mountain Research and Development, 44(1):R1-R9 (2024). https://doi.org/10.1659/mrd.2023.00017

Maríá Virginia González, Lia Montti, Yohana G. Jimenez, Ezequiel Aráoz


  • Human mobility and connectivity between cities play a crucial role in urban expansion and landscape transformations, impacting species distributions.
  • Andean ecosystems, acting as biodiversity hotspots, are particularly vulnerable to environmental changes and the introduction of exotic species.
  • This study investigates how migratory flows and socio-environmental factors influence the prevalence of exotic woody plants in the Andean region.
  • Cultural drivers, such as the introduction of exotic species and their use in urban areas, heavily influence the prevalence of exotic species in woody plant proportion.
  • While global databases provide vast amounts of data, using them responsibly is essential to avoid biases and draw accurate conclusions.

In South America, cities are expanding: 90% of people are projected to be urbanite, and human migration is expected to reach 200 million by 2050. Such a flow of people connects distant places, blurring boundaries. In turn, in this context the introduction and establishment of species from other regions of the world is likely to grow in importance, with implications for species composition and the functioning of natural and semi-natural systems. Cities exist in an environmental and social context: their inhabitants design an environment according to their preferences and those plants from which they perceive some benefit. The plant pool in cities is a relict of these (historical and contemporary) choices that have been made, and past and present movements that determine their composition.

Our research delves into how migratory movements and socio-environmental factors influence the prevalence of exotic woody plants in the Andean region (encompassing sectors of Argentina, Bolivia, Peru, Ecuador, Colombia and Venezuela). To obtain indicators of alien species prevalence, we collected records of woody species occurrences from global biodiversity databases, such as the Global Biodiversity Information Facility (GBIF), the Botanical Information and Ecology Network (BIEN), the Integrated Digitized Biocollections (iDigBio) and Species Link. After systematizing the scientific names and classifying each species as native or non-native, we calculated the prevalence of non-native species for each first-order administrative unit (e.g. provinces) of the Andes. In addition, for the same units we collected data on migration flows obtained from the WorldPop Hub, and metrics of urban development, such as population, time since city founding and urbanization trend. Through statistical modeling  we observed  that migration flows are an important and constant element in explaining patterns of alien species prevalence. 

Furthermore, we found that regions with higher levels of immigration exhibit a significantly higher proportion of alien species records, highlighting the important role of human migration in shaping plant communities in the Andes. Understanding the complex interactions between human activity and ecological processes is crucial to ensure the preservation of valuable Andean ecosystems in the future. Finally, it is worth highlighting that global databases have broken down boundaries in terms of generating data on a constant basis. However, it is crucial to use this data responsibly, taking into account its advantages and disadvantages. Adequate curation is crucial to avoid biases that can lead to incorrect conclusions. By overcoming this barrier, we can ask ourselves more complex and insightful questions.


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