Tree Crop Selection

Written by Doug Crouch

Introduction Pattern

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

cold desert conditions of a project I worked at for six months in 2011-12 in Neuquen province Argentina

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

Terraces on the island of ibiza looking downhill. Moves from more intensely planted zone 1 and 2 to an other zone of Carob and Almonds.

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.

Below I present a list of plants I have come across in my times in drylands/ Mediterranean climates.  I will present a bit on each one, especially those I have grown.  Unfortunately, or fortunately, most of my work has been in reforestation or establishing food forests so the harvest part was left to the land and the clients.

Tree Listing

Fig– This drought hardy classic is easily propagated through cuttings and is a divine fruit.  It grows relatively fast and there is a myriad of cultivars allowing for quite a long harvesting season.  Normally, I just look for those growing in my locale and go with cuttings through that variety.  Of course nurseries will carry a selection as well to help bring in more diversity.  Winter deciduous, very soft wood that is hollow on the inside, and a fruit that can be eaten fresh or dried.

Pomegranate– This highly nutritious fruit takes some time to get established but then produces heavily upon maturity.  It’s a beautiful addition to the landscape no matter what with its glossy vegetation and red flowers and fruits.  It can be propagated by cuttings but I usually buy varieties from a nursery with its slow growth habits to speed things up.  Hotter climates help to ripen them well. It loses its leaves for a short period of time in Mediterranean climates.

 

Mulberry– This beautiful tree is grown widely for its fresh fruits that feed both wildlife, domestic livestock (fruit and leaves), and humans.  It is fast growing, propagated by cuttings, and is deciduous.  I look for local varieties and go with those as grafting is very tough on mulberries (cultivars propagated through cloning cuttings).  There are a lot of different cultivars and when in the drylands go with varieties from the drylands obviously.

Jujube- This small tree or shrubby form is extremely drought hardy and is also known as Chinese Date.  I have seen it grown in more humid temperate conditions as well and the taste is great.  It’s a really important part of Chinese Medicine thus offering another market beyond just fresh eating. There are many cultivars to choose from and are a great addition to your landscape.

Strawberry Tree- This shrub is an amazing creation as it takes such tough conditions and is able to thrive also in partial shade.  It is part of the natural European Mediterranean food forest structure growing under oaks and produces a fruit that is usually processed although sometimes eaten raw.  It is mostly made into a hard liquor but also jams.  Its flowering time also supports bees well as it flowers just before the rains come in late summer or early fall.

Olive- This tree typifies drylands tree crops and I am astounded at the amount of abuse these trees put up with.  They grow in degraded sites but are now suffering from many diseases because people think the more they abuse them the better the results in Europe. Usually grown on hillsides where soils are thinner naturally not in the more fertile valleys. With their need of pruning to make harvesting easier, this tree crop produces a tremendous amount of biomass.  It is mostly burnt in chemical farming but can be cycled back appropriately in permaculture systems to build fungal resources.  Olives are of course eaten fresh after a pickling process or pressed for oils.  Also now a leaf tea is being procured from them.

Apricot/ Plum/Peach/ Nectarine- These stone fruit trees are all drought hardy but of course are supported by irrigation in their beginnings.  I have found that in my many years of work in Mediterranean conditions around the planet that the plum is the hardiest of trees.  They all flower early so a south-facing microclimate might not be the best place for them as flowering is induced earlier.  This can lead to a late frost destroying the flowers and the subsequent crop.  They are all beautiful additions to the landscape, help to feed bees, and give a fruit with varying eating possibilities.

Peach in Portugal

Nectarine in Portugal

 

Date Palm- Although I have never interacted directly with the date palm, it is of course a part of legendary tales from the most dry places in the warm parts of the world.  Its fruits are super sugary and the palm tree in general amazes me in its toughness.

Carob- This tree grows in the warmer and drier parts of the Mediterranean as the more humid it gets the better chance the pods will rot.  This is exactly what we are after, the bean pods, as this is a Legume tree (Fabaeacae). The pods are enjoyed by animals fresh or dried and humans can eat the sap in the pods fresh or it is processed into a delicious and nutritious powder. Furthermore, it is called the giving tree because it also gives its flowers to the bees and its foliage to animals.  It’s a quite beautiful tree as well and I have seen ancient ones on the island Ibiza, stabilizing the terraces and forming microclimates.

Almond- This is the nut of the stone fruit family and has all the same qualities as the fruits described above.  Again is drought hardy, thriving in areas of heat, but is supplemented by irrigation often commercially.  I even saw in my days in New Zealand, 2006-07, the small fruits around the almond being carefully eaten by sheep leaving the shells intact with the nuts inside. Plans around processing and storage are vital for this tree crop selection.

Oak- While there are many oak trees around the world, the drylands oaks are astounding.  In the west coast of North America and in the Mediterranean in Europe I have seen these trees thrive.  In Portugal, my main stay from 2009-2017, the cork oak and holm oak create the foundation of the ecosystem.  They both produce acorns with of course the cork tree also producing, well cork.  The Holm Oak is much hardier it seems and produces huge acorns seen in the picture below feeding wildlife and livestock animals within an agroecology system.  The acorns of the Holm Oak are also a great human food, try them after the first few rains have hit! Of course they produce amazing wood and firewood and again create the ecosystem itself, a true keystone species.

Pistachio- I have seen this one but not cultivated it either.  I have of course delighted in this nut resource like most in the west.  Originating from Central Asia, this tree has made its way into other dry areas of the world for commercial growing.

Macadamia- This tree I have both harvested from mature 30 plus year old trees and planted anew in New Zealand.  Once they get established these trees pump out quite a delightful treat.  They were one of my staples at Edible Tree Crop Farm in Nelson, New Zealand (number 99 in the picture insert of the designers manual).  It did take some work harvesting and a specialized cracker because of their incredibly thick shell, but worth it nonetheless.  They thrived in the relatively dry Mediterranean climate where the farm was located. For new plantings they need wind and sun protection in their early years as they are sensitive.

 

Pine nut- This very large tree is quite a feature in the landscape with its rounded shape and large presence.  It does grow in degraded sites and was planted widely in Portugal because of an EU subsidy (its how it works in the EU). The large pine cones produce the nuts and each cone has quite an amount of seeds.  The problem is getting them at the right time and getting them out but specialized crackers help with this as well.

Prickly Pear Cactus- This cacti, quite attractive for the most part, forms a fruit that can be eaten fresh or preserved.  It’s a cactus so it is quite hardy and endures a bit of frost but not too cold of temperatures.  I saw huge populations of it be decimated over the last few years of Portugal because of a disease as it became more widespread along roadsides and cultivated unfortunately. Care is taken in its harvesting and processing because of the spines.

Nopale Cactus- I have grown this one in Portugal but never to the size of eating.  It grows much like the prickly pear but without the spikes and spines making it easier to process.  This one you eat parts of the pad leaf instead of a fruit.

Old Man Salt Bush- This drought hardy bushy shrub grows in salted soils and helps to process that degrading force in Nature.  Then you eat the leaves of it and have a salt resource that comes from the plant.  It’s an amazing symbiosis in Nature and saltines of soils is of course one of the main factors to watch for in drylands areas.

Grape- this plant, much like the olive, fascinates me in its resilience to the abuse it takes.  Like olives, it is pruned and manipulated heavily, and its fruits are used for a myriad of purposes from fresh eating to alcohol to jams and more.  It is trained on trellises or grown free-standing or even clambers over trees in the old way depending on the cultivar and cultivation style.  Its deep tap roots allows it to thrive in these harsh conditions but again with better care less disease would incur for a more sustainable crop.

Capers- I can’t find my pictures from Spain of this low-growing, scrambling, slightly thorny, incredible beast.  It produces orchid like flowers first and can grow in areas where no other herb layer is green during the summer and yet it takes over. It actually dies back in the winter when moisture is present and lower temperatures. Its waxy leaves help and its fruits are of course pickled into capers.  Amazing part of the Mediterranean food forest!

Globe Artichoke-  This plant thrives during the winter rains of the Mediterranean but does survive the summer drought in a dormancy state and pops back up when the rains hit again in the autumn.  Its deep taproots help to keep it going as the spring rains taper off and it produces these flower buds that we eat.  If we let it go without harvesting a big beautiful flower comes out which is great for the bees.  The seeds are then dispersed by birds as they are an important food resource for them.

Again it all depends on your hardiness zone so do cross reference this basic list with other resources.  Its a lot of work getting plants established in these zones but a very fun task indeed.  Happy planting!

Written by Doug Crouch

Header Art Bonita Edwards

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2 Responses to Tree Crop Selection

  1. Pingback: New Article Release: Drylands Tree Crop Selection | A Permaculture Design Course Handbook

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