| The Overstory #11
Authors:
Kim Wilkinson and Craig Elevitch
Contents:
== The Understory: A Unique Niche for Valuable Crops ==
== Examples of Understory Species ==
== References ==
== How to Contact Us ==
== The Understory: A Unique Niche for Valuable Crops ==
(Note: Last issue, we highlighted the practice of Sequential Planting, or
planting short-term crops in tree plantings to realize a return while
waiting for long-term yields. This time, we focus on permanent interplanting
of trees and crops in a layered agricultural system.)
Traditionally, tropical farmers have always managed and exploited the shady environment under trees, called the understory. There are many valuable cash and subsistence crops that thrive in the shady climate under trees. When cultivated in combination with tree or forest crops, understory crops enable farmers and foresters to diversify and increase their yields while reducing labor and making more efficient use of land. The understory is a niche worth cultivating.
Plantings that take advantage of the understory range from simple systems
consisting of one species in the overstory and one in the understory, to
complex systems with many layers of trees, shrubs, and herbaceous plants
stacked together as appropriate for their needs.
A few successful examples involving a simple overstory/understory mix:
* Macadamia nut trees with coffee understory (Hawaii)
* Native forest areas cultivated underneath for traditional medicinal or
culturally valuable plants (in Hawaii, these can include maile for leis,
kava, and a variety of herbaceous medicinals)
* Timber trees (such as Cordia alliodora, or Laurel) with coffee or cacao
underneath (Central and South America)
* Teak plantations with patchouli (an essential oil) underneath (Indonesia)
* Sesbania, a nitrogen fixing tree (for firewood, mulch, or animal fodder)
supporting and shading passion fruit vines (Africa)
* Coconut plantations with taro, kava, or cattle underneath (Polynesia and
Melanesia)
* Heavy-shade mixed reforestation projects with cut flowers and foliage
(such as anthuriums, heleconias, etc.) underneath (Central America)
The understory is a unique environment, involving more than just shade. The shade trees provide brings about a whole complex of environmental changes, affecting not just available light but also air temperature, humidity, soil temperature, soil moisture content, wind movement, and more. These factors impact plants, and the effect can be very beneficial to a wide array of
crops.
The moister, shadier, cooler microclimate in the understory can have the
following effects:
* Reduces evapotranspiration (evaporation of water through the leaves and
branches of the plant), conserving moisture in the plants and reducing water
use and susceptibility to drought (provided the overstory trees are not
overly competitive for water)
* Buffers crops from temperature extremes and fluctuations
* Naturally suppresses most invasive problem "weeds", which tend to prefer
open conditions and full sun
* Supports a range of beneficial soil microlife that do not thrive in the
open
The conditions in the understory will be determined by the kinds of trees
that form the canopy above. Some trees create dappled sunlight or light
shade; others create a thick canopy with dense shade beneath. Understory
crops must be carefully selected so they are compatible with and make best
use of the understory environment.
== Examples of Understory Species ==
Here are a few examples of shade tolerant understory crops (some are highly shade-loving, some tolerate light shade only):
Essential oils: lemon grass, vetiver, patchouli
Spices: pepper vine, cinnamon, ginger, vanilla, cardamom, wild turmeric
Fruits: pineapple, annona species, and guava
Root crops and vegetables: taro, arrowroot, yams, long beans, and velvet
bean
Herbs: oregano, basil, and chili pepper
Building/fiber materials: rattan, fan palms
Mushrooms: many culinary and medicinal fungi thrive in the understory
Other: coffee, tea, cacao, betel vine, kava
Some farmers discover that one of their current crops actually thrives in
understory conditions, and rather than focus on exploiting their understory,
they may look for trees to use as a canopy for their existing crop. Here in
Kona, for example, several sustainable Kona coffee farmers are experimenting with interplanting timber or nitrogen fixing trees to provide a light canopy for their coffee trees.
The understory is a unique microclimate that enables farmers and foresters
to diversify, increase their yields, reduce labor, and make more efficient
use of land. As with any new venture, we recommend you research thoroughly, experiment carefully, and start small as you begin to explore the possibilities for your understory environment.
Do you know of a successful shade tolerant understory crop system not
mentioned here? We invite you to write with your experiences!
== References ==
International Institute of Rural Reconstruction. Agroforestry Technology
Information Kit, 1990. IIRR, Room 1270, 475 Riverside Dr., New York, NY
10115. One of the most practical references in tropical agroforestry. To
order this book through our association with Amazon.com link to:
<http://www.amazon.com/exec/obidos/ISBN=0942717317/agroforestercom/>
P. Ramachandran Nair, An Introduction to Agroforestry. 1993. Kluwer Academic Publisher. This comprehensive textbook bridges the gap between theoretical and practical knowledge in agroforestry. To order this book through our association with Amazon.com link to:
<http://www.amazon.com/exec/obidos/ISBN=0792321359/agroforestercom/>
W.C. Clark, R.R. Thaman (Editor), Agro-Forestry in the Pacific Islands:
Systems for Sustainability. 1994. Unipub. Very thorough treatment of
agroforestry practices in the Pacific. Includes list and descriptions of
many agroforestry species. To order this book through our association with
Amazon.com link to:
<http://www.amazon.com/exec/obidos/ISBN=9280808249/agroforestercom/>
Integrating Understory Crops with Tree Crops introduces planning considerations for planting crops with forestry, orchard, or other tree-based systems. Examples of understory intercropping systems in the tropics are included, as well as a species list of over 75 trees, shrubs, and vines used as understory crops. <http://agroforestry.net/afg/book.html>
Related Editions of The Overstory
The Overstory #72--Microenvironments (Part 1)
<http://www.agroforestry.net/overstory/overstory72.html>
The Overstory #71--Nontimber Forest Products (Temperate)
<http://www.agroforestry.net/overstory/overstory71.html>
The Overstory #56 Integrating Understory and Tree Crops <http://www.agroforestry.net/overstory/overstory56.html>
The Overstory #55 Nontimber Forest Products Part II: NTFP Enterprises <http://www.agroforestry.net/overstory/overstory55.html>
The Overstory #53 Nontimber Forest Products--An Introduction <http://www.agroforestry.net/overstory/overstory53.html>
The Overstory #33--Mushrooms in Agroforestry <http://www.agroforestry.net/overstory/overstory33.html>
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