Increasing Water Use Efficiency Comes at a Cost for Norway Spruce

Tanja Sanders, Ingo Heinrich, Björn Günther, Wolfgang Beck
2016 Forests  
Intrinsic water use efficiency (WUE i ) in trees is an indication of the ratio of carbon assimilation to the rate of transpiration. It is generally assumed that it is a response to water availability. In agricultural research, the question of drought tolerance by increased WUE i has been well studied. In general, the increase is a trade-off for productivity and is therefore not desired. For forest trees, this question is less clearly understood. Using stable carbon isotopes derived from tree
more » ... erived from tree rings combined with productivity as the product of the annual growth increment and annual density measurements, we compared the change in WUE i over a 15 year period. While WUE i increased over this period, the productivity decreased, causing an opposing trend. The gradient of the correlation between WUE i and productivity varies between provenances and sites. Counterintuitively, the populations at the drier site showed low WUE i values at the beginning of the investigation. Slopes vary with the provenance from Poland showing the least decline in productivity. In general, we found that a decline in productivity aligned with an increase in WUE i .
doi:10.3390/f7120296 fatcat:do5uvjvwqveohghe2qkvmdwttm