Global biogeography of plant chemistry: filling in the blanks.

It would perhaps come as a surprise to many nonbiological scientists (or even some biologists) to learn that despite our ability to characterize a number of environmental variables, such as climate, along regional or continental gradients, until recently we have had almost no basis for doing so for plant and soil chemistry. New work, including a paper by Han et al . in this issue (pp. 377–385), is beginning to fill in the blanks on this otherwise empty slate. It is well known that long-term climate records exist in a relatively well-distributed network across much, but not all, of the globe. Hence, we are able to quantify the difference in climate between, for example, central Saskatchewan, Canada and central Nebraska, USA but not the differences in plant or soil nutrient concentrations or contents between these two regions. Given the importance of nitrogen (N) and phosphorus (P) to plant function, to production of agricultural and unmanaged ecosystems and to global biogeochemical cycles, including the carbon (C) cycle, one could argue that knowledge of biogeography of their biochemistry is as useful as knowledge of many other kinds, yet it has been little emphasized. Why?