Link between continuous stem radius changes and net ecosystem productivity of a subalpine Norway spruce forest in the Swiss Alps
Article first published online: 21 MAY 2010
© The Authors (2010). Journal compilation © New Phytologist Trust (2010)
Special Issue: Featured papers on ‘Amazonian rain forests and drought’
Volume 187, Issue 3, pages 819–830, August 2010
How to Cite
Zweifel, R., Eugster, W., Etzold, S., Dobbertin, M., Buchmann, N. and Häsler, R. (2010), Link between continuous stem radius changes and net ecosystem productivity of a subalpine Norway spruce forest in the Swiss Alps. New Phytologist, 187: 819–830. doi: 10.1111/j.1469-8137.2010.03301.x
- Issue published online: 19 JUL 2010
- Article first published online: 21 MAY 2010
- Received: 12 March 2010, Accepted: 19 April 2010
- carbon balance;
- climate change;
- eddy covariance;
- Picea abies (Norway spruce);
- Seehornwald Davos;
- stem radius changes;
- tree water relations;
- wood growth
- •Continuous stem radius changes (DR) include growth and water-related processes on the individual tree level. DR is assumed to provide carbon turnover information complementary to net ecosystem productivity (NEP) which integrates fluxes over the entire forest ecosystem. Here, we investigated the unexpectedly close relationship between NEP and DR and asked for causalities.
- •NEP (positive values indicate carbon sink) measured by eddy covariance over 11 yr was analysed at three time scales alongside automated point dendrometer DR data from a Swiss subalpine Norway spruce forest.
- •On annual and monthly scales, the remarkably close relationship between NEP and DR was positive, whereas on a half-hourly scale the relationship was negative. Gross primary production (GPP) had a similar explanatory power at shorter time scales, but was significantly less correlated with DR on an annual scale.
- •The causal explanation for the NEP–DR relationship is still fragmentary; however, it is partially attributable to the following: radial stem growth with a strong effect on monthly and annual increases in NEP and DR; frost-induced bark tissue dehydration with a parallel decrease in both measures on a monthly scale; and transpiration-induced DR shrinkage which is negatively correlated with assimilation and thus with NEP on a half-hourly scale.