Figure 1.

Map of BIFoR site with note water and soil sampling sites. Note that FACE Rings stand for Free-Air Carbon Dioxide Enrichment (FACE). They are a series of approximately cylindrical ring structures, as high as the tree canopy (around 25 m) and 30 m wide, supporting pipes that deliver CO₂ in such a way that the woodland inside the ring is immersed in elevated CO₂, but the rest of the woodland remains largely unaffected. For more details, the reader is kindly asked to visit BIFoR’s web site [31].