Is sensitivity to drought associated with stem volume to surface area ratio in giant cacti?

Volume‐to‐surface area ratio (V:S) across stem succulent taxa varies by almost two orders of magnitude. The broad range in V:S of cacti and other succulent species likely has considerable importance for adaptation since stem volume determines the storage capacity of water, carbon and nutrients and stem surface area is directly related to whole-stem photosynthetic capacity. We therefore predict that giant cacti display functional tradeoffs in physiological capacity and stress tolerance related to stem geometry, and that these tradeoffs determine species-specific sensitivity to climate and climate change.