A mature forest canopy in a CO2-rich future: An experiment at the swiss canopy crane research site

Abstract

With a 50m tall construction crane (Fig. 14.1), tree crowns of over 100-year-old temperate deciduous forest trees were exposed to a futuristic scenario of 540ppm CO2 atmosphere for 8 years. Porous tubing was woven into the canopies of 30–35m tall dominant trees and CO2 released via computer control. This first and still only mature forest canopy CO2 enrichment experiment addressed whether trees in a natural setting are (1) taking up more CO2 when more is offered, (2) investing the extra photosynthates into more biomass, (3) undergoing qualitative changes, and/or (4) saving water.