One of the models for the Al Baydha Project's agricultural system is a 2000 year old food forest in Morocco that is awash in date palms, olives, citrus, bananas, and other verdant fruiting trees.  Date palms are an enormous part of the heritage of Saudi Arabia, provide numerous benefits and functions, and make a fantastic canopy layer in desert food forests.  

Unlike the forest in Morocco, the ecology being planted at Al Baydha Project's demonstration site is primarily envisioned as a forest-grazing system rather than a forest-orchard system.  The people in Al Baydha are experts in caring for goats, camels, and sheep, so we are demonstrating a system of forestry that will provide for those animals year-round.  

With that in mind, it is important to remember our water goal:  to reforest the demonstration site using less water than we catch in the earthworks--thus over time refilling the shallow aquifer that supplies the site's well.   This imposes a strict water budget, which is key in understanding the question that is fundamental to permaculture design:  What is the land on the demonstration site willing to give us if we cooperate with it?  

Date palms require 40 liters of water per day to live, and in palm orchards are often given upwards of 150-200 liters per day (with flood irrigation).  Conversely, a Moringa tree, requires 5-10 liters per week, depending on its microclimate, age, and the season.   In evaluating our water budget, 1 date palm requires the equivalent of 35 moringa trees.  The moringa is as useful as the date palm is, though certainly less culturally significant.   On that basis, it seems almost ludicrous to think of planting date palms, unless we can create an oasis-type climate where we have significantly more water than what we need to establish forest in the area.  This is a possibility in the long term, and on a site with a greater ratio of catchment to productive area.  

In the short term, however, the priority is to establish shade, wind break, and ground cover, using the least amount of water possible, while maintaining progress towards a grazing-oriented forest.  Those are the criteria for establishing a forest that can survive--lowering the rate of evaporation, lowering the soil temperature (through reduced solar exposure), and establishing an entirely different microclimate.  35 Moringa trees will shade an area of 35 square meters, while a date palm will shade about 9.  Furthermore, while a date palm will give dates, Moringas produce oil, forage, and medicine.  So there will be few date palms on the demonstration site; probably not more than 10.  But there will be thousands of other trees, like the moringa, that offer significantly greater benefit per drop of water.