Densities, plant sizes, and spatial distributions of six wild populations of Lophophora williamsii (Cactaceae) in Texas, U.S.A.

  • Anna Ermakova Imperial College London, Silwood Park
  • Carolyn V. Whiting University of Texas at Austin, Department of Integrative Biology
  • Keeper Trout Cactus Conservation Institute
  • Colin Clubbe Royal Botanic Gardens Kew
  • Martin K. Terry Cactus Conservation Institute
  • Norma Fowler University of Texas at Austin, Department of Integrative Biology
Keywords: cactus, Chihuahuan Desert, clustered distribution, conservation, density, endangered, population, size distribution, Tamaulipan thornscrub, threatened


Lophophora williamsii (Cactaceae) is thought to be threatened by habitat loss and overharvesting. However, basic demographic and habitat information to evaluate its conservation status have been lacking. We surveyed six wild populations of this species, three in South Texas and three in West Texas, to begin to address this gap. We found high levels of heterogeneity in plant presence and density at multiple spatial scales. While plant densities were not consistently different between South and West Texas, plants were significantly larger in West Texas. The two regions differ strongly in precipitation, temperature, elevation, and topography, all of which are correlated at the regional scale. Therefore, it was not possible to identify which of these variables, or other factors such as competition and human harvesting, may be responsible for the regional differences in plant size. However, our results provide initial information for determining the conservation status of this species.


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How to Cite
Ermakova , A., Whiting, C. V., Trout, K., Clubbe, C., Terry, M. K., & Fowler, N. (2021). Densities, plant sizes, and spatial distributions of six wild populations of Lophophora williamsii (Cactaceae) in Texas, U.S.A. Journal of the Botanical Research Institute of Texas, 15(1), 149-160.