Ceschia, Eric
- Institutionen för skoglig produktionsekologi, Sveriges lantbruksuniversitet
Sammanfattning
This thesis discusses the environmental and biological factors which control stem respirationprocesses in beech and Norway spruce trees. The results are based on fieldexperiments in France in 1997-98 and in Sweden in 1999-2000. Effects of fertilisationand elevated atmospheric CO2 concentration on stem growth and respiration were studied,as well as the causes of seasonal and spatial variation in stem respiration. Woodyrespiration varied with seasonal changes in temperature and secondary growth. Spatialvariation in stem respiration was explained by temperature gradients and the unevendistribution of living cells within the stem, by differences in diameter increment along theaxis and variations in tissue vitality. Sapflow had little effect on stem respiration at breastheight. 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 annualaboveground woody respiration (7?AG) of 30-110% and 30%, in beech and Norway sprucestands, respectively. 7?AG, corrected for spatial variation in stem respiration, represented30% 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 andfertilised 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 woodconstruction cost (rG) was on average 0.2 and 0.16 g C respired g’1 C fixed in the newwood of beech and spruce trees, respectively. For both beech and spruce, rG was higher inthe crown than at breast height, but the causes of this were not identified. Fertilisationtended 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% onunfertilised and fertilised plots, respectively) and none in beech. [CO2] treatment had noeffect on the phenology of wood growth or maintenance respiration when fertilisation wasapplied. On the unfertilised Norway spruce plot, however, maintenance respiration increasedby a factor of 2.5, and [C] also increased in the newly formed ring. A change inthe wood composition of trees grown in elevated [CO2] without fertilisation, apparentlycaused the increase in rG and in maintenance respiration rates. In the perspective of globalwarming, f?AG would increase by 25% and 14% in young beech and Norway spruceforests, respectively, and the combined effect of elevated atmospheric CO2 and globalwarming would increase 7?AG by a factor of 2.3 in Norway spruce stands.
Nyckelord
Fagus sylvatica; Picea abies; growth and maintenance respiration; wood construction cost; wood growth; Q10; living cells; nitrogen concentration; fertilisation; global change; up-scaling
Publicerad i
Acta Universitatis Agriculturae Sueciae. Silvestria
2001, nummer: 219
Utgivare: Department for Production Ecology, Swedish University of Agricultural Sciences
SLU författare
UKÄ forskningsämne
Klimatvetenskap
Skogsvetenskap
Publikationens identifierare
- ISBN: 91-576-6303-3
Permanent länk till denna sida (URI)
https://res.slu.se/id/publ/108013