Abstract

This thesis discusses the environmental and biological factors which control stem respiration
processes in beech and Norway spruce trees. The results are based on field
experiments in France in 1997-98 and in Sweden in 1999-2000. Effects of fertilisation
and elevated atmospheric CO2 concentration on stem growth and respiration were studied,
as well as the causes of seasonal and spatial variation in stem respiration. Woody
respiration varied with seasonal changes in temperature and secondary growth. Spatial
variation in stem respiration was explained by temperature gradients and the uneven
distribution of living cells within the stem, by differences in diameter increment along the
axis and variations in tissue vitality. Sapflow had little effect on stem respiration at breast
height. Higher respiration rates usually were found in the upper stem or in the crown.
Neglect of spatial variation in stem respiration led to errors in estimating annual
aboveground woody respiration (7?AG) of 30-110% and 30%, in beech and Norway spruce
stands, respectively. 7?AG, corrected for spatial variation in stem respiration, represented
30% of total annual respiration in the beech forest. ÄAG was 245-289 g C m'2 a'1 in beech,
64 and 134 g C m'2 a'1 in unfertilised and fertilised stands of Norway spruce, respectively.
Carbon use efficiency (CUE) was 0.58, 0.71, and 0.72 for beech trees, unfertilised and
fertilised Norway spruce trees, respectively.
Stem respiration was separated into its components, maintenance and growth respiration.
Growth respiration represented ca. 35% and 40% of total stem respiration. The wood
construction cost (rG) was on average 0.2 and 0.16 g C respired g’1 C fixed in the new
wood of beech and spruce trees, respectively. For both beech and spruce, rG was higher in
the crown than at breast height, but the causes of this were not identified. Fertilisation
tended to increase rG in Norway spruce, but maintenance respiration was not affected.
Elevated [CO2] treatment had little effect on rG in Norway spruce (+10% and 3.5% on
unfertilised and fertilised plots, respectively) and none in beech. [CO2] treatment had no
effect on the phenology of wood growth or maintenance respiration when fertilisation was
applied. On the unfertilised Norway spruce plot, however, maintenance respiration increased
by a factor of 2.5, and [C] also increased in the newly formed ring. A change in
the wood composition of trees grown in elevated [CO2] without fertilisation, apparently
caused the increase in rG and in maintenance respiration rates. In the perspective of global
warming, f?AG would increase by 25% and 14% in young beech and Norway spruce
forests, respectively, and the combined effect of elevated atmospheric CO2 and global
warming would increase 7?AG by a factor of 2.3 in Norway spruce stands.

Keywords

Fagus sylvatica; Picea abies; growth and maintenance respiration; wood construction cost; wood growth; Q10; living cells; nitrogen concentration; fertilisation; global change; up-scaling

Published in

Acta Universitatis Agriculturae Sueciae. Silvestria
2001, number: 219
ISBN: 91-576-6303-3
Publisher: Department for Production Ecology, Swedish University of Agricultural Sciences

SLU Authors

• Ceschia, Eric

  • Department of Production Ecology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Climate Research
Forest Science


Permanent link to this page (URI)

https://res.slu.se/id/publ/108013