ISSN:
1573-5036
Keywords:
elevated CO2
;
forest ecosystem
;
N deposition
;
nitrate leaching
;
soil solution
;
soil type
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract The objectives of this study were to estimate how soil type, elevated N deposition (0.7 vs. 7 g N m−2y−1) and tree species influence the potential effects of elevated CO2 (370 vs. 570 μmol CO2 mol−1) on N pools and fluxes in forest soils. Model spruce-beech forest ecosystems were established on a nutrient-rich calcareous sand and on a nutrient-poor acidic loam in large open-top chambers. In the fourth year of treatment, we measured N concentrations in the soil solution at different depths, estimated N accumulation by ion exchange resin (IER) bags, and quantified N export in drainage water, denitrification, and net N uptake by trees. Under elevated CO2, concentrations of N in the soil solution were significantly reduced. In the nutrient-rich calcareous sand, CO2 enrichment decreased N concentrations in the soil solution at all depths (−45 to −100%). In the nutrient-poor acidic loam, the negative CO2 effect was restricted to the uppermost 5 cm of the soil. Increasing the N deposition stimulated the negative impact of CO2 enrichment on soil solution N in the acidic loam at 5 cm depth from −20% at low N inputs to −70% at high N inputs. In the nutrient-rich calcareous sand, N additions did not influence the CO2 effect on soil solution N. Accumulation of N by IER bags, which were installed under individual trees, was decreased at high CO2 levels under spruce in both soil types. Under beech, this decrease occurred only in the calcareous sand. N accumulation by IER bags was negatively correlated with current-years foliage biomass, suggesting that the reduction of soil N availability indices was related to a CO2-induced growth enhancement. However, the net N uptake by trees was not significantly increased by elevated CO2. Thus, we suppose that the reduced N concentrations in the soil solution at elevated CO2 concentrations were rather caused by an increased N immobilisation in the soil. Denitrification was not influenced by atmospheric CO2 concentrations. CO2 enrichment decreased nitrate leaching in drainage by 65%, which suggests that rising atmospheric CO2 potentially increases the N retention capacity of forest ecosystems.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1004831401190
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