Ratio of 18O to 16O Stable Isotopes in Tree Stem Cores at HJA, HFR, NWT, CWT, LUQ, and Barro Colorado Island

Patterns of biodiversity, such as the increase toward the tropics and the peaked curve during ecological succession, are fundamental phenomena for ecology. Such patterns have multiple, interacting causes, but temperature emerges as a dominant factor across organisms from microbes to trees and mammals, and across terrestrial, marine, and freshwater environments. However, there is little consensus on the underlying mechanisms, even as global temperatures increase and the need to predict their effects becomes more pressing. The purpose of this project is to generate and test theory for how temperature impacts biodiversity through its effect on biochemical processes and metabolic rate. A combination of standardized surveys in the field and controlled experiments in the field and laboratory measure diversity of three taxa -- trees, invertebrates, and microbes -- and key biogeochemical processes of decomposition in seven forests distributed along a geographic gradient of increasing temperature from cold temperate to warm tropical. The most abundant tree species (by basal area) were sampled at each experimental site (HJA, HFR, NWT, CWT, LUQ, and Barro Colorado Island) for ratio of stable isotopes of 18 Oxygen to 16 Oxygen in parts per million from ground and homogenized tree stem cores as part of a macrosystems biodiversity and latitude project supported by the National Science Foundation under Cooperative Agreement DEB#1065836. .