Climatic gradients in woody plant (tree and shrub) diversity: water-energy dynamics, residual variation, and topography

摘要: Recent studies at the macro-scale have demonstrated that geographic gradients in richness of plants, particular woody plants such as trees and shrubs, can be viewed by-products water-energy dynamics. According to this view, they are climatic rather than latitudinal/longitudinal gradients, relating coincident predictable variations planetary surface-atmosphere thermal dynamics consequent patterns biological activity. Previous analyses shown a two-variable model capturing dynamic relationship between energy (heat/light) water (rainfall) accounts for most variation plant across southern Africa species, genus, family levels. Here we move towards more complete explanation, while demonstrating how analysis residuals used identify type sequence additional variables inclusion, either same or discrete scales analysis. Residual from displays pattern unrelated longitude latitude. Regional clusters under- over-prediction point topographic relief significant factor. When is added third variable, explanatory power (R2) increases by 7 12%, subsequent becomes even unpredictable. What clustering remains points other macro-, meso- micro-scale need considered. Such top-down, trans-scalar approach permits systematic objective development explanations, three-variable developed herein basis powerful research tool ecologists, biogeographers, conservationists bio-climatologists alike.