Combined effects of elevated winter temperatures and CO2 on Norway spruce seedlings
Silva Fennica 30(23): 135143
A total of 1800 3-year old seedlings of Norway spruce (Picea abies (L.) Karst.) from two Norwegian and one German provenance were treated with two different nitrogen levels during the 1992 growth season. The plants were kept during the following winter at two different temperature levels. In the spring of 1993 the nutrient application was resumed, and the plants were divided between three different treatments, 350 and 650 p.p.m. in open top chambers and a control plot outside the chambers. This treatment was repeated also during the following 1994 growth season.
The growth and primary production was studied by photosynthesis experiments and by non-destructive growth measurements.
The results indicate that raised winter temperatures may lead to increased needle loss and reduced growth the following season, particularly in northern provenances.
Carbon dioxide significantly influenced growth in addition to nutrient level and winter temperature. High CO2 also seemed to cause increased photosynthesis at early season, and earlier budbreak and growth cessation than in control plants.
Received 22 September 1995 Accepted 10 July 1996