Globally consistent nitrogen release (backlog No. 2)
Article for 2 July 2007:
Parton W, Silver WL, Burke IC, Grassens L, Harmon ME, Currie WS, King JY, Adair EC, Brandt LA, Hart SC, Fasth B, 2007. Global-scale similarities in nitrogen release patterns during long-term decomposition. Science 315:361-364.
Finding a global pattern in nature would be a worthy achievement for any scientist, and this is what this large team seems to have done. The research itself was truly of a global scale - a ten-year study of leaf litter decomposition with sites in most of the earth's biomes.
The similarity that the authors found was that the amount of nitrogen release and immobilization (as a fraction of total litter N) was independent of climate zone. The rate of net nitrogen release was not, however, independent of climate. N release also depended on initial N content, with consistent remaining-N vs. remaining mass of litter plots for different categories of initial N content. In fact, the initial N content was found by the authors to be "the dominant driver of net N immobilization and release ... regardless of climate" (p.364).
An interesting result was obtained when comparing data for humid and arid grasslands, where a clear difference between biomes was observed. The authors suggested that this represented the importance of photodegradation as a mechanism in arid climates (seen previously, for example, by Austin & Vivanco, 2006, who we've cited before).
In a way, the existence of a global similarity or pattern owes its existence less to the comprehensive dataset, than to the way in which the authors looked at their data. That's probably a lesson for us all...
I have worked at UWA since 1995, coming from New Zealand to take an appointment as Lecturer in the Soil Science group in the former Faculty of Agriculture. I completed my PhD, from Lincoln University in New Zealand, in 1991. If you really want to find out about work stuff go
here. In real life I love my wife, daughter and guitar. Occasionally, I wish I had chosen a career as a carpenter, counsellor or poet.