We have been having an unexpectedly dry spring and I fear that summer maybe worse.
I have read that it is better not to prune drought stressed trees as they exert resources to heal.
I'm wondering if anyone has information or thoughts on heavy pruning of sacrificial trees to aid nearby trees?
I have an abundance of tagasaste and other nitrogen fixing support trees inter planted in my food forest as well as a few mature trees. My thinking was that cutting them back should free up moisture for other plants and maybe even shed some of the outer roots and contained water. Obviously I can also use prunings to mulch those trees that require assistance.
Soil is mostly clay, and becomes very hard and dry.
If they're sacrificial, then there's not a lot to lose if they don't survive being cut back; and I would gladly sacrifice my support trees if it meant saving the more valuable trees/plants.
Additionally, I'd probably start planning for water retention now instead of waiting until summer by getting organic matter on & in the soil. I've been successful with burying rotted logs & sticks under the surface of the forest garden. They held moisture like a sponge and the tree roots grew towards them to get the moisture.
I've also buried green plant matter that will release the moisture as it breaks down. Cacti & succulents seem to be the best since they hold so much water, but any green growth should contribute at least some moisture to the soil.
Scotch broom is my primary nitrogen producer. I have used loppers to prune it back in order to provide mulch material for desired trees. This helps to keep moisture down and to keep root temperatures lower. So pretty much the same thing you plan to do with the tagasaste.