Syntropic Agroforestry: Rapid Yield Strategies for Mediterranean Fruit Orchards
Intercropping apple trees, berries, and paulownias in an agroforestry system in a Mediterranean garden
This article describes a certain agroforestry system that works well in a Mediterranean context and enables farmers and gardeners to have quick production (and income) while waiting for the fruit trees to start producing fruit.
One of the key challenges that complicate farmers' adoption of agroforestry systems on a larger scale is the time it takes from planting the trees to harvesting. In the case of most fruit trees in temperate and Mediterranean climates, it can take anywhere between 5 and 15 years, depending on the species, to obtain good yields. For example, in the case of chestnuts, it can take 15-20 years for the trees to reach a significant yield.
The key question for the farmer is, thus, how to implement agroforestry systems financially (with a profit).
Intercropping in orchards for rapid yields
Luckily, there are ways to plant trees and produce crops rapidly on the same land. A common practice to achieve this is alley cropping, which is planting trees in rows alternated with alleys of (often annual) crops like vegetables or grains. For the first 5-15 years, crops are grown in the alleys between the rows of trees, and those crops pay in a certain way for the trees. After a few years, as the trees get bigger, there is less space to grow crops between the tree lines (due to actual space limitation or shadow). At this moment, the trees start to produce a significant crop, and the farmer can switch from annual crops to harvesting the tree crop (fruits/nuts). This system enables the farmer to plant trees while at the same time continuing to get revenue from the land and is, hence, an interesting way to implement agroforestry systems.
The system I am describing in this article is an example of an alley-cropping system. I have tested it on a garden scale, but it is scalable to a larger (farm) scale. The long-term objective of this system is to create a fruit orchard. Depending on your context, you can choose a fruit tree suitable for your local conditions. In my context (Corsica, Mediterranean climate, 600 m altitude), apples grow well, and I chose them as my key fruit species.
Using berries as a high-value companion crop
I chose red fruits, strawberries, red and black currants, and raspberries as my ‘cash crops’ because they grow quickly and produce after just one or two years. They are high-value crops and can ‘finance’ the development of fruit trees. I also included different pioneer species in the rows of apple trees to produce shade and wind protection, which is crucially important for the system as a whole. I will describe these trees later in more detail. The system is relatively simple to understand (see image 1 & 2 below):
Image 1: a 2-year-old red fruit syntropic agroforestry system in Corsica (photo taken in early spring)
- A row of fruit trees every 4-5 meters (remember this is on a garden scale; distances can be larger, but this should be considered the minimum distance)
- Within the row of fruit trees, you should respect 4-6 meters between the different fruit trees depending on the species and rootstock. The next step is optional but highly recommended: add pioneer trees such as paulownia, poplar, or alder for quick shade production and (in certain cases) nitrogen fixation. You can plant one or two pioneer trees between the fruit trees, which should be sufficient for providing shade.
- Next to the tree rows, you can plant a row of raspberries or currants. Depending on the design, this row is relatively narrow (less than 1 meter in general). You can choose only to grow raspberries or currants between the tree rows. In this case, you should foresee one or more pathways to access the tree lines and fruit shrubs.
- If you choose to also grow strawberries in the middle of the alley between the tree rows, you can plant them next to the raspberries/currants.
Image 2: a 3-year-old red fruit syntropic agroforestry system in Corsica (photo taken in spring)
The number of rows of strawberries and/or raspberries that should be planted between the tree rows depends on different factors such as slope, climate, etc. As you can see in image 3, the row of raspberries casts a lot of shade on the two righter rows of strawberries. This is not optimal for production, and it would probably be better not to have added this row of raspberries or the row of strawberries. The grower should take into account the distance between the tree rows, the row orientation, and the tolerance (or preference) of the companion crop for shade. It requires some experimentation. As stated above, it is possible to plant strawberries, raspberries, or currants exclusively between tree rows.
Image 3: a 2-year-old red fruit syntropic agroforestry system in Corsica.
The tall trees in images 2 and 3 are paulownia trees that I planted for quick shade production. Under the right growing conditions, they can grow about 5 meters per year and are, therefore, perfect shade producers. You can coppice them regularly and they will re-grow next year. If, for example, they start producing too much shade, you can simply coppice them to allow more sunlight to reach the berries. The biomass is a great fertilizer and should be added to the berries to stimulate their growth.
How to care for such an agroforestry system - Water needs, weed management, and companion plant species
In my Mediterranean context, a drip irrigation system was installed. I irrigate about 5-10 min daily, and all the rows indicated in the images have their own irrigation tube. I used a plastic mulch for the strawberries to keep them weed-free. The raspberries have woodchips and no plastic mulch, as they are much more competitive with weeds than strawberries. You could, of course, use exclusively wood chips if you want to avoid plastic, but I must admit that I have tried this without much satisfaction due to the high number of weeds.
The layout of the agroforestry orchard
Within the tree lines, I have planted the following tree species:
- Sichuan pepper trees: produce edible pepper (visible in image 4: in the back behind the tall Paulownia tree in the left row there are two trees visible).
- Apple trees: my key fruit species. They have grown very well with a bit of shade produced by the paulownia trees and the constant drip irrigation. I planted multiple trees in 2021, such as 1 m tall trees that have now reached 5 meters in height and have flowered abundantly in 2024 for the first time.
- Paulownia trees: my key pioneer species in the system. They grow exceptionally fast and have a natural tendency to grow an umbrella-like canopy. This is great because in summer, it allows morning light to reach the understory, but from 11 AM onwards when the sun’s getting high in the sky, its large leaves produce some much-needed shade for the understory. Note not only how tall they are in image 4 (>6 m) but also how wide their trunk is (>10 cm after only three years!).
This case can serve as an example alley cropping system for people in similar climatic zones (Mediterranean, temperate) and can and should be adapted to your individual needs. Depending on the requirements, you can modify the system to become more or less complex by changing the number of species, the distance between the rows, etc. Its basic design can be used as a starting point for other contexts.
Image 4: a 3-year-old red fruit syntropic agroforestry system in Corsica. Note the tall paulownia trees that act as umbrellas for the heat-sensitive red fruit shrubs in the undergrowth.
Further reading
Agroforestry: Intercropping with trees on farms and pastures – with a focus on the subhumid tropics
Agroforestry – combining trees and agriculture to improve Soil – Water Conservation
Shade-Grown Coffee in an Agroforestry System
The Impact of Syntropic Agroforestry on Water Usage and Farm Resilience