The Botanist Effect Revisited: Plant Species Richness, County Area, and Human Population Size in the United States

Abstract

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.

Aphid biodiversity is positively correlated with human population in European countries

“…This is unlikely, given the quality of the Fauna Europaea project (Fontaine et al 2007), and given the generality of the species-people relationship for many other taxa and regions. Moreover, it has been shown for birds in Britain and vascular plants in USA that such a sampling argument may not explain observed positive species-people relationships (Evans et al 2007;Pautasso and McKinney 2007), although the available data do not allow similar analyses for aphids. Sampling eVort might actually be greater in smaller countries, but these are the countries with lower human population size, and this eVect might compensate any higher survey eVort in countries with higher human population size due to a larger presence of taxonomists.…”

Macrofungal taxa and human population in Italy’s regions

“…However, sampling bias does not appear to explain the observed species-people correlation for birds in Britain and for plants in the USA (Evans et al 2007;Pautasso and McKinney 2007). Similarly, the flora of German urban areas is believed to be naturally species-rich (Kühn et al 2004).…”

Relationship between remotely sensed variables and tree species diversity in savanna woodlands of Southern Africa

“…The most common ways to collect data on species diversity distributions are intensive ground surveys or inventories of species in the field. However, the expense and time required for such studies make it difficult, or even impractical, to expect that all potential sites for biodiversity conservation can be inventoried in a timely fashion (Moerman andEstabrook 2006, Pautasso andMcKinney 2007). In addition, consistency of results of ground-based biodiversity surveys is often difficult to achieve.…”