The Botanist Effect Revisited: Plant Species Richness, County Area, and Human Population Size in the United States
The “botanist effect” is thought to be the reason for higher plant species richness in areas where botanists are disproportionately present as an artefactual consequence of a more thorough sampling. We examined whether this was the case for U.S. counties. We collated the number of species of vascular plants, human population size, and the area of U.S. counties. Controlling for spatial autocorrelation and county area, plant species richness increased with human population size and density in counties with and without universities and/or botanical gardens, with no significant differences in the relation between the two subsets. This is consistent with previous findings and further evidence of a broad-scale positive correlation between species richness and human population presence, which has important consequences for the experience of nature by inhabitants of densely populated regions. Combined with the many reports of a negative correlation between the two variables at a local scale, the positive relation between plant species richness in U.S. counties and human population presence stresses the need for the conservation of seminatural areas in urbanized ecosystems and for the containment of urban and suburban sprawl.
Keywords: North American flora; biogeography; density–area relationship; ecología urbana; esfuerzo de muestreo; flora norteamericana; habitat heterogeneity; heterogeneidad de hábitat; macroecology; macroecología; native and exotic plants; plantas nativas y exóticas; relación densidad-área; relación especies-energía; relación especies-área; sampling effort; species–area relationship; species–energy relationship; urban ecology
Document Type: Research Article
Affiliations: 1: Division of Biology, Imperial College London, Wye Campus, High Street, Wye, Kent, TN25 5AH, United Kingdom, Email: [email protected] 2: Department of Earth and Planetary Sciences, 1412 Circle Drive, 306 Earth and Planetary Sciences Building, The University of Tennessee, Knoxville, TN 37996-1410, U.S.A.
Publication date: 01 October 2007