A lesser known way that trees benefit the understory crops that they grow with is through a process called hydraulic redistribution. Tree roots can transfer water between soil layers, redistributing soil water from deep in the soil to dryer surface layers, where shallower crop roots can access it. Tree roots can also move water in the reverse direction during wet times, essentially helping to stabilize soil water availability for the crop below. Since this process was first studied, it was found that plants are assisted in this process of water sharing by fungal networks which grow on the root system and promote water redistribution. Which brings us to the next way in which trees help…
Tree roots offer a more permanent home and food source for soil life in comparison to short term annual crops. The result is more diversity of life in our soils, which leads to better soil structure and stability. Factor in the leaf litter and mulch provided by trees to the soil life, and the effect is even greater.
Finally, we are not just interested in growing any old trees—we are producing food with trees! While often this is considered the whole point of a fruit trees, with all the known benefits it just feels more like an added bonus!