October 14, 2020
Definition: An enhanced living fence composed of three rows of shrubs and trees planted around the perimeter of the Forest Garden. A green wall is designed to protect the land and crops from strong winds, unwanted intruders, and livestock all while providing numerous secondary benefits.
A Closer Look: While a living fence around the perimeter of the field can provide adequate protection from animals, farmers who struggle with strong winds and larger intruders often choose to fortify their living fence by turning it into a green wall.
Instead of a single or double row of trees and shrubs, a green wall requires 3 rows that, when combined, create a fortified barrier capable of keeping out the biggest of unwanted intruders. In fact, a Forest Garden farmer in Kedougou, Senegal designed a green wall that was able to withstand multiple charges from a hippopotamus!
In addition to fortified protection, a green wall can also serve many additional purposes. Farmers often choose to plant tall, fast-growing trees like Leucaena leucocephala to form a multi-purpose windbreak that will protect the field from strong winds. Farmers also choose to include nitrogen-fixing species to revitalize the soils and other multipurpose species that can provide the likes of timber, fodder, food, and fuelwood.
Green Wall Composition:
The outer row - composed of thorny trees planted very closely together to form a thick hedge that animals cannot penetrate.
The middle row - formed using fast-growing but sturdy trees that provide the green wall with some structural integrity. This row is imperative as the structure is required to support the many thorny branches that are eventually woven among each other.
The interior row - composed of tall, fast-growing trees to form a multipurpose windbreak. If the wind is not an issue, rows of protein-rich, nitrogen fixing species such as pigeon peas can be planted and eventually harvested twice a year.