Is Norway spruce (Picea abies (L.) Karst.) isohydric or anisohydric species?
This review paper states that spruce is isohydric, citing Physiologie und Ökologie der Gehölze by Lyr, Fiedler, &amp; Tranquillini:


  Spruce appears to reﬂect 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.