Drylands Tree Crop selection is determined not only by the dryness of the climate but of course also by temperatures. Having worked in both Mediterranean areas, temperate drylands, and tropical brittle climates, there is some crossover in some of the climates but not in others. Bill Mollison defined drylands as below 500 mm of precipitation but we must also realize that there are climates that we think of drylands because they are brittle climates. So although they may fall just above that, like where I worked in Southern Spain in 2016-17 (600 mm of rain), they are really just brittle climates that go around seven months with little rainfall and an exacerbated sporadicness in these changing days of climate. Additionally, where I worked in Neuquen, Argentina was a drylands area but also very temperate so this list focuses on those warmer parts of the drylands. Also this list is very general and the reality is that often local environments have edible plants that locals incorporate in their diets traditionally and modernly and need to be considered. When composing this list in a PDC with students, you will always find that this happens as students throw out a name of a plant they interacted with in their travels or home lands. Thats what makes this listing hard because does one search for such list in the tropical section or temperate even though they live in a drylands?
All drylands planting are aided by some sort of infiltration earthwork in general so do remember that. Microclimate accentuation is also very important. For example I saw citrus thriving in Ibiza, Spain next to Carob and Olives whilst there for a PDC assignment. However within these amazing terraces that all three were planted on, the Citrus were in the valleys, which the terraces also crossed. You could see
the soil was better there than on the ridges and I also think that had to do with how they treated the soil in the valleys as well. Because it wasn’t as straight and uniform as the long ridges, the soil seemed to be less often plowed giving more integral resilience to the valley soil. Also it always comes up, in reflection of Geoff Lawton’s Greening the Desert Film, irrigation will always help plantings get off the ground. As stated in that video very plainly, drip irrigation was used to get those plantings up off the ground. Of course in some parts of the world this is not possible but hand watering periodically does occur to ensure establishment. Also not stated in that video was the fact that Dr. Elaine Ingham was there spraying compost tea so seeding those microbes back in the ecosystem is very critical to success. Furthermore, you may see certain crops grown in the drylands of certain areas like California or Central Asia but are often sucking out groundwater through massive irrigation infrastructure. Furthemore, remember that in drylands there are specific establishment strategies, which some are seen at my other article called Corridor Planting. And part of that also involves establishing pioneer plants before hand, hardy in their nature, and often nitrogen fixers to accelerate succession and evolution. Also windbreaks are sometimes needed before any tree crop planting is done and often some form of mechanical or biological soil treatment. Basically a forwarding of succession needs to occur before planting; building soil, providing a better microclimate through slowing winds and sun, and infiltrating more water.
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