News about carbon in plant leaves…

Text and graphs by Ülo Niinemets

Carbon, C, is the most frequent chemical element in plant leaves, but leaf carbon content is a surprisingly understudied plant trait. Modern elemental analyzers typically give estimates of nitrogen, N, and C contents, but often only N (that is present in proteins) is used and C is neglected. We have just shown that C in combination with Ca provides key insight into leaf structure and function both at local and global scales. Looking back at this work, publication of these two papers was a saga. Lots of rejections, invitations to resubmit, revisions and rejections again. Many good comments, but also comments in a style “I just do not believe it”. This was the frustrating part of it. Perhaps it reflected the feeling in the research community that C and Ca are that common elements that there is nothing to find. Yet, people had not looked at these two key elements together. Taken alone, C and Ca are non-informative. Taken together, a marvelous set of patterns with major functional implications emerges. The work builds upon an earlier study of Niinemets and Tamm (2005) that demonstrated a negative scaling between leaf structural carbon and leaf Ca content across woody species.