EGU25-10211, updated on 15 Mar 2025
https://doi.org/10.5194/egusphere-egu25-10211
EGU General Assembly 2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
Tectonic Control of Global Plant Biodiversity
Sean D. Willett1, Ao Luo2, Yanyan Wang1, Zhiheng Wang2, and Loïc Pellissier3
Sean D. Willett et al.
  • 1Dept of Earth and Planetary Sciences, ETH, Zurich, Switzerland
  • 2Peking University, Beijing, China
  • 3Dept of Environmental Systems Science, ETH Zurich

The distribution of plant species richness on earth suggests that tectonic mountain-building and its interaction with climate exert a defining control on species distributions and diversification rates. The two main pathways identified to increase species richness are, first, the broadening of environmental heterogeneity through the creation of new habitats formed by tectonic topography and, second, the disruption of existing landscapes by tectono-geomorphic processes, leading to time-dependent habitat fragmentation and increased allopatric speciation. Here, we resolve the contribution of these two pathways to explain global plant species richness. We build a model for environmental heterogeneity at the 100 km scale based on local richness at the 100 meter scale, which we take to be a function of local climate, and community turnover between 100 m cells based on environmental distance, which we take to be a global function. Each of these functions is calibrated to local field data. These two models can be combined to provide a prediction of species richness due to environmental heterogeneity at the 100 kilometer scale using global topography and climate data. Differencing this prediction from observed richness provides an estimate of the excess richness, which we argue is dominated by tectonic and geomorphic enhancement of allopatric speciation rates. We find that this excess component of richness is nearly always positive and is locally a factor of up to ten above that expected by environmental gradients alone. We conduct a categorical analysis, comparing the excess richness to active tectonic and geomorphic domains and find a close correspondence between the patterns of excess richness and recent tectonic and geomorphic activity. We conclude that high richness areas (biodiversity hotspots) overwhelmingly fall in areas of tectono-geomorphic activity, even after accounting for environmental heterogeneity, supporting the hypothesis that transient, tectono-geomorphic disruption is an important control on speciation rates and the distribution of biodiversity.

How to cite: Willett, S. D., Luo, A., Wang, Y., Wang, Z., and Pellissier, L.: Tectonic Control of Global Plant Biodiversity, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10211, https://doi.org/10.5194/egusphere-egu25-10211, 2025.