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Provenance effects and allometry in beech and spruce under elevated CO₂ and nitrogen on two different forest soils
Journal
Basic and applied ecology
Volume
4
Number
5
Pages / Article-Number
467-478
Keywords
allocation, biomass, CO2 x soil interaction, environmental change, genotype, tree growth, model ecosystem, Fagus sylvatica, Picea abies
Abstract
Growth responses to atmospheric CO2 enrichment, enhanced nitrogen (N) supply and different forest soils were studied in four provenances (populations) of Fagus sylvatica and eight provenances (two populations and six clones) of Picea abies. Trees were grown together in realistic model communities in large open-top chambers. Systems with replicated genetic diversity were established on a nutrient-poor acidic and on a fertile calcareous soil. After 4 years growth under experimental conditions, biomass was determined at final harvest. Whereas Picea enhanced biomass in elevated CO2 on both soils, Fagus responded negatively to CO2 on acidic but positively on calcareous soil. Enhanced N supply increased growth of both species on acidic soil only, independent of CO2 treatment. Most interactions of CO2 or N with soil type were statistically significant. Growth responses varied considerably among provenances, especially in Picea and strongest with respect to CO2 and N treatments on calcarous soil and with respect to soil type. Allometric analysis revealed that Fagus enhanced allocation of dry matter to leaves on acidic as compared to calcareous soil, with significant variability among provenances and among their CO2 and N responses. Apart from this, however, allocation patterns were rather unaffected by treatments or soil type and could not explain observed growth differences. Our study demonstrates that the soil is a major determinant of plant responses to environmental changes, and that intraspecific differences in growth-sensitivity to CO2 or N are considerable, especially on fertile soils. In the longer term, such differences could alter genotypic composition of temperate forest communities.
