Large-scale biogeographical patterns of species richness of trees

Biologists have long recognized the striking geographical variability of species richness1. A primary goal of contemporary ecology is to identify the factors responsible for this variability2. We have examined the spatial distributions of trees in North America to determine which characteristics of the environment are most closely related to the species richness of different regions. Realized annual evapotranspiration, which is correlated with primary production and is therefore a measure of available energy, statistically explains 76% of the variation in species richness. Topography and proximity to the sea are significantly related to the residual variation, whereas seasonal climatic variability and glacial history are not. Tree richness in Great Britain and Ireland can be accurately predicted from these North American patterns. Our data are best explained by the hypothesis that contemporary available energy limits species richness3,4.

[1]  R. Hosie,et al.  Native Trees of Canada , 1979 .

[2]  A. R. Clapham,et al.  Flora of the British Isles , 1962 .

[3]  Robert M. May,et al.  The Search for Patterns in the Balance of Nature: Advances and Retreats , 1986 .

[4]  H. Odum,et al.  Primary Productivity of the Biosphere , 1978, Ecological Studies.

[5]  Alfred Russel Wallace,et al.  Tropical nature, and other essays. By Alfred R. Wallace ... , 1878 .

[6]  V. K. Prest,et al.  Retreat of Wisconsin and recent ice in North America : speculative ice-marginal positions during recession of last ice-sheet complex , 1969 .

[7]  E. L. Little.  Atlas of United States trees. , 1971 .

[8]  E. Pianka.  Latitudinal Gradients in Species Diversity: A Review of Concepts , 1966, The American Naturalist.

[9]  James H. Brown,et al.  Competition Between Seed-Eating Rodents and Ants in Desert Ecosystems , 1977, Science.

[10]  M. Rosenzweig,et al.  Tilman's predicted productivity–diversity relationship shown by desert rodents , 1984, Nature.

[11]  M. Rosenzweig.  Net Primary Productivity of Terrestrial Communities: Prediction from Climatological Data , 1968, The American Naturalist.

[12]  Eric R. Pianka,et al.  Geographical Trends in Numbers of Species , 1978, Science.

[13]  J. Turner,et al.  Does Solar Energy Control Organic Diversity? Butterflies, Moths and the British Climate , 1987 .

[14]  H. Birks.  British Trees and Insects: A Test of the Time Hypothesis Over the Last 13,000 Years , 1980, The American Naturalist.

[15]  R. E. Cook,et al.  Variation in Species Density of North American Birds , 1969 .

[16]  A. Wallace.  Tropical Nature and Other Essays , 1972 .

[17]  James H. Brown.  Two Decades of Homage to Santa Rosalia: Toward a General Theory of Diversity , 1981 .

[18]  J. Silvertown.  History of a Latitudinal Diversity Gradient: Woody Plants in Europe 13,000-1000 Years B.P. , 1985 .

[19]  H. Lieth.  Modeling the Primary Productivity of the World , 1975 .