Elevated CO₂ influences nutrient availability in young beech-spruce communities on two soil types

Area of Science:

• Forestry and soil science
• Plant physiology
• Environmental science

Background:

• Forest ecosystems face increasing atmospheric carbon dioxide (CO2) levels.
• Nutrient cycling in forests is crucial for ecosystem health and carbon sequestration.
• Understanding plant and soil responses to elevated CO2 is vital for predicting future forest dynamics.

Purpose of the Study:

• To investigate the influence of soil type and nitrogen (N) deposition on elevated CO2 effects on nutrient accumulation in spruce and beech.
• To determine how elevated CO2 affects soil nutrients and the net accumulation of essential elements (N, P, K, S, Ca, Mg, Fe, Mn, Zn).
• To compare the responses of Picea abies (spruce) and Fagus sylvatica (beech) to these environmental changes.

Main Methods:

• Establishment of model ecosystems in open-top chambers on two distinct forest soils: acidic loam and calcareous sand.
• Application of elevated N deposition (0.7 vs 7 g N m-2 a-1) and elevated CO2 concentrations (370 vs 570 µmol CO2 mol-1).
• Measurement of net nutrient accumulation in tree biomass and analysis of soil and soil solution nutrient concentrations.

Main Results:

• The effect of elevated CO2 on nutrient accumulation was significantly dependent on soil type and varied between spruce and beech.
• On acidic loam, CO2 suppressed nutrient accumulation in beech but stimulated it in spruce.
• On calcareous sand, elevated CO2 enhanced nutrient accumulation in both species; N deposition did not alter CO2 effects.

Conclusions:

• Soil type is a critical factor mediating forest responses to elevated CO2, influencing nutrient dynamics and species-specific accumulation.
• Elevated CO2 alters nutrient ratios in tree biomass, with a relative decline in nitrogen accumulation.
• Forest management and conservation strategies must consider soil properties and species composition to predict and mitigate impacts of climate change.