 As concern grows about global warming, there is great interest to better understand the role of polyphenols as regulators of carbon cycling, in particular in northern boreal forests.Leaf litter and other decaying parts of kauri ("Agathis australis"), a tree species found in New Zealand, decompose much more slowly than those of most other species.Besides its acidity, the plant also bears substances such as waxes and phenols, most notably tannins, that are harmful to microorganisms.