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Agroforestry Support Species for Cold Climates

Posted on by User Admin

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Silk tree in my garden serving as living trellis to arctic kiwifruit; also shade provider for shade crops including currant, mayapple, fuki, and edible hosta. Also fixes nitrogen.

Rafter Ferguson’s recent excellent article “Permaculture for Agroecology” challenges the permaculture movement to read up on whats happening in related fields like agroecology and agroforestry. I’m particularly interested in learning from the well-established agroforestry practices of the tropics to see what might be applied in cold climates. I’ve been learning a lot about what species are used in cold-climate agroforestry as I research the book I’m writing. Here are some species being used on farms for practices like alley cropping, contour hedgerows, living fences, windbreaks, living trellises, and shade for crops. They serve as our alternative to multipurpose tropical trees like Leucaena and Gliricidia.

Many more species could be used for these purposes and undoubtedly are. I’m focusing here on species are are reported in the literature and those that I have personally used or witness to be used for these purposes. My primary sources are Mansfeld’s Encyclopedia of Agricultural and Horticultural Crops, Participatory Agroforestry Development in DPR Korea, and Agro-Ecological Farming Systems in China. Please share your successes, failures, and observations – and set up some formal trials!

Here I’m defining cold climate as boreal (USDA zones 1-3) and cold temperate (USDA zones 4-6), and warm temperate (USDA zones 7-8). These are place with real winters, outside of the subtropics. Arid means 0-250mm of rainfall (1-10″), semi-arid is 250-1000mm (10-40″), and humid 1000+mm (40″ or more). Species market with an asterisk (*) fix nitrogen.

Cold-Climate Superstars

Two species clearly emerge as the most multifunctional (or at least most widely used and written about; many other species are potentially as versatile).

SILK TREE Albizia julibrissin

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The attractive flowers of the multifunctional Albizia julibrissin.

Silk tree, or mimosa, is a beautiful small tree from E. Asia. It is hardy through USDA Zone 6 through the tropics, and likes semi-arid to humid conditions. Throughout the lowlands and highland tropics, Albizia species are important agroforestry crops. This one is for us! Silk tree fixes nitrogen and resprouts vigorously. It is used in alley cropping and contour hedgerow systems, crop shade, and serves as a windbreak.

FALSE INDIGO Amorpha fruticosa

False indigo is native across North America, though it is mostly ignored here. In China and Korea it is an important agroforestry species. It is hardy to USDA Zone 3 though warm temperate, and handles semi-arid to humid conditions. In fact I have seen it grown in very dry high desert, and deeply flooded floodplains. False indigo is a multistemmed shrub, coppicing readily. It fixes nitrogen, and is used in alley crop, contour hedgerow, and windbreak applications.

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False indigo is a very cold-tolerant multipurpose agroforestry legume.

Alley Crop Species

Alley crop systems integrate rows of coppiced woody plants, usually nitrogen-fixers, with wider bands of annual crops. Some crop trees are also intercropped with annuals in alternating rows (like black walnut, pecan, and jujube), but here we are focused on alley crop plants that fix nitrogen to support the neighboring crops.

Albizia julibrussin* silk tree E. Asia cold temperate to subtropical humid
Amorpha fruticosa* false indigo N. America boreal to warm temperate semi-arid to humid
Hippophae rhamnoides* seaberry Eurasia Boreal to cold temperate Semi-arid to humid
Morus alba White mulberry E. Asia cold temperate through tropical semi-arid to humid

Contour Hedgerow Species

Contour hedgerows are essentially alley crops on slopes, planted on contour. They are an excellent erosion control strategy and over time can form living terraces. I suspect Cornus sericea would do a good job at this as well.

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Contour hedgerow of elderberry in Mexico.

Albizia julibrussin* silk tree E. Asia cold temperate to subtropical humid
Amorpha fruticosa* false indigo N. America boreal to warm temperate semi-arid to humid
Aronia melanocarpa chokeberry N. America boreal to warm temperate humid
Caragana microphylla* Littleleaf peashrub E. Asia boreal to warm temperate arid to semi-arid
Morus alba White mulberry E. Asia cold temperate through tropical semi-arid to humid
Sambucus canadensis Elderberry N. America to Mesoamerica Cold temperate to subtropical humid

Living Fence Species

Some of these are come from cuttings like proper tropical living fences, while others are grown from seed.

Caragana arborescens* Siberian peashrub E. Asia boreal to cold temperate semi-arid to humid
Cylindropuntia spp. Cholla Americas Cold temperate to tropical Arid to semi-arid
Gleditsia triacanthos honey locust N. America boreal to subtropical Semi-arid to humid
Maclura pomifera Osage orange N. America cold to warm temperate semi-arid to humid
Morus alba White mulberry E. Asia cold temperate through tropical semi-arid to humid
Prinsepia utilis Cherry prinsepia E. Asia cold temperate through tropical semi-arid to humid
Prunus spinosa sloe Europe warm and cold temperate humid

Windbreak

Cultivated to reduce the impact of wind on crops, livestock, or farm buildings.

Amorpha fruticosa* false indigo N. America boreal to warm temperate semi-arid to humid
Caragana arborescens* Siberian peashrub E. Asia boreal to cold temperate semi-arid to humid
Caragana microphylla* littleleaf peashrub E. Asia boreal to warm temperate arid to semi-arid
Elaeagnus angustifolia* Russian olive Eurasia boreal to warm temperate semi-arid
Elaeagnus umbellata* autumn olive Eurasia cold to warm temperate humid
Hippophae rhamnoides* seaberry Eurasia Boreal to cold temperate Semi-arid to humid
Populus spp. hybrid poplar hybrid boreal to warm temperate humid to semi-arid
Populus nigra black poplar Eurasia, N. Africa boreal to warm temperate semi-arid to humid
Robinia pseudoacacia* black locust N. America cold to warm temperate semi-arid to humid
Salix purpurea purple willow Europe, An. Africa boreal to warm temperate, humid humid

Living Trellis

Cultivated to serve as the trellis on which to grow vine crops. In my own garden I use Albizia julibrussin and Amorpha fruticosa for this purpose.

Populus spp. hybrid poplar hybrid boreal to warm temperate humid to semi-arid
Populus nigra black poplar Eurasia, N. Africa boreal to warm temperate semi-arid to humid

Crop Shade

These crops re intentionally cultivated to provide shade to crops that need it (like ginseng, coffee, etc.)

Albizia julibrussin* silk tree E. Asia cold temperate to subtropical humid
Alnus cordata* Italian alder Europe cold to warm temperate humid
Styphnolobium japonicum* Japanese pagoda tree E. Asia cold temperate to subtropical semi-arid to humid
Toona sinensis fragrant spring tree E. Asia cold temperate to subtropical humid

 

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