Is Norway spruce (Picea abies (L.) Karst.) isohydric or anisohydric species? Question from a thesis defense list ask me this. But I can't find the exact answer on the internet or in books. In my thesis, I described isohydric plants, for example maize, lupin, pea, poplar. This plants response to a decrease in soil water in same way. How Norway spruce response to decrease in soil water? As a isohydric plant or anisohydric? Thank you for your time and help.

This review paper states that spruce is isohydric, citing _Physiologie und Ökologie der Gehölze_ by Lyr, Fiedler, & Tranquillini:

> Spruce appears to reect an isohydric strategy (Lyr et al. 1992), reducing stomatal conductance at early stages of soil drought.

It's important to note that this is not a binary distinction, isohydric and anisohydric are two extremes in a spectrum of how plants respond to drought.