Will forests need vitamins?

Commun. Biol. 3, 125 (2020)

Atmospheric CO₂ has increased from 350 to 410 ppm in the last three decades, which has been associated with greater plant growth and more efficient photosynthesis. The impacts of elevated CO₂ on vegetation are, however, not all positive. Enhanced growth and photosynthesis can dilute nutrient concentrations in leaves, and plant physiological responses to elevated CO₂ and associated climate changes can limit nutrient uptake. Together with other global change factors, rising CO₂ may thus negatively impact the nutritional quality of forests.

Credit: Justin Paget / DigitalVision / Getty

To determine this effect, Josep Penuelas from CREAF-CSIC-UAB, Spain, and colleagues measured changes in leaf elemental composition over the past 30 years for European trees and investigated underlying drivers of these changes. They find the nutrient quality of leaves has generally decreased throughout Europe, with the greatest decreases observed in Mediterranean and temperate forests due to rising CO₂. In contrast, concentrations of nitrogen, sulfur and calcium have increased in boreal forests because temperature and precipitation have become more favourable. These results indicate a potential negative feedback on forest carbon sequestration under climate change, particularly for southern European forests.