The role of water in the design of a forest garden

If you are familiar with forest gardens – sustainable food gardens based on a forest system – you will know that the initial design phase is important. If you neglect a crucial element of the design, the forest garden might not develop as you expected. In forest gardening, change is expected – but if we know it’s coming, we can plan for it as best we can. By thinking carefully about the design before starting, we can avoid making common mistakes and falling into known pitfalls.

I have worked on many forest garden designs for sites around the world and have spoken with many clients about the design process. Many gardeners clearly understand the problems associated with fertility and nutrient cycles in a forest garden; but one common element is often overlooked: water.

A lack of respect for the water, water flow, and water management at a site is a common reason things go wrong.

In this article, I will discuss some of the common water management issues that arise in the design of forest gardens. Hope reviewing these questions can help you start thinking about how water can be managed on your own site and what role water will play in the successful design of your forest garden.

Soil, water and trees

Much of the design of forest gardens comes down to considering the intersection of soil, water and trees. One of the key goals of a forest garden is figuring out how to create a stable and largely self-sustaining system. And understanding the soil, water flow and vegetation cover at a site, and how they interact, is crucial.

Water is stored at one site both in the soil and in trees and other plants. How the soil is treated and the plants chosen are two key things that will determine the amount of water stored.

In many situations, you will want more water to be stored in the soil and plants on your property. In some situations, however, you may want to reduce waterlogging in the soil in order to grow a wider range of plants in a particular location. You may want to use trees and vegetation to absorb more moisture from the soil – or to filter the water as it is directed elsewhere where it is most urgently needed.

Riparian planting areas

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Riparian planting areas (areas next to a river, stream, or other stream) require special consideration and attention. Forest gardening can help develop sustainable riverfront plantings, which, by reducing harmful runoff, stabilize riverbanks and keep water flowing freely and cleanly.

Understanding how water flows through a landscape will facilitate the design of forest garden systems that manage water before it reaches riparian areas and as it passes through them. Understanding the water requirements and the growth and water-related habits of certain trees and other plants can help create systems that work naturally and efficiently.

Flood and flow management: slopes in a forest garden

Special attention is also required when it comes to water management in forest gardens on slopes. Excess water, flooding and runoff can damage the soil and make it difficult to establish a successful forest garden. On sloping sites, the planting itself can help ameliorate potential problems. But other interventions may be necessary in some cases before planting. Earthworks may be necessary.

For example, on gentler slopes, rills and berms on the contour can be created to slow down and maintain the flow of water downhill. But these need to be considered carefully and may not always be the best option for areas with high rainfall or particularly sloping sites.

Earthworks may be a better option for maximizing the potential of a forest garden site – especially where there are steeper slopes.

In some circumstances, drainage ditches leading to ponds or reservoirs for water collection may be required or desired.

Water management in forest gardens in arid climates

In arid areas, too little water rather than too much water is the problem. Managing water in low flow areas will naturally also involve the use of gullies, basins and other water features on the contour designed to conserve any water that is in the vicinity.

Water management in these systems may also involve pre-planting earthworks. But of course, choosing pioneer drought tolerant species, increasing vegetation cover, and intensive mulching to improve the soil are key strategies that are also used to effectively manage water over time.

In both the design and maintenance of a forest garden, water is key. Make sure to think about water and how it interacts with the other elements of your site whenever you make a decision. This can be a complex consideration, but it is certainly not an issue to be overlooked.

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