The edible forest of Alcalá de Henares

Edible forest
Area characterisation: 

The forest is located in the area called “Isla del Colegio” (College Island), an artificial island named after having belonged to the San Idelfonso univesity dorm, located in the south of the city. It has its origin in the artificial construction of a caz in the 18th century, which diverted part of the natural course of the river for hydraulic use.

The area includes the space delimited to the south by the river Henares and to the north, by the caz.

After the successful cultivation of all the space provided by the City Council in the College Island for the implementation of urban vegetable gardens, and once they are settled and functioning, the City Council planned to expand the project for the recovery of the Island of the School, very degraded by the action of humans, mainly by the intensive agriculture, that had reduced until the practical disappearance, the gallery forest associated to the river Henares. Therefore, the next phase was to focus on the recovery of this agricultural island with nature based solutions.

Currently part of the island is still agricultural, dedicated to the cultivation of cereals. The rest of the island has been, partly conditioned as a multifunctional park with asphalted walks and garden areas and partly left fallow. Part of this fallow was dedicated to the urban orchards, leaving an area between the orchards, the park and the river Henares currently unused and this was the area occupied by the edible forest.


Little explanation before starting first plantation Volunteers listening the explanations Plantation phase 1 Plantation phase 2 Plantation area at the beginning of the project Plantation area after two years 1 Plantation area after two years 2

The main objective of the project is to increase the biodiversity of a peri-urban area, re-naturalizing it through the creation of an urban edible forest.


Considering that the river Henares has a protected strip of 100m on each side that is included in the Nature 2000 Network, a natural separation of the area of action of that space was made. This area was specifically destined to be a forest associated to the river and because of that, thorny shrubs were planted to hinder the access to the strip and to allow the natural regeneration of the vegetative potential of the forest.

Outside of the protected area, plants, fruit trees, shrubs, vines, perennial and annual plants are being incorporated. This plantation was based on the creation of a community of vegetation species with high sustainability and low maintenance with which it was intended to imitate the successional dynamics of a forest, planning it in different strata, which in turn would recreate different types of habitats.

The edible forest is a forest orchard carefully designed to obtain food while retaining the benefits of a natural system. The food obtained is not for humans, it is for those animals that find shelter in the forest, that can feed equally and participate in the dispersal of the seeds or the pollination of the forest. In addition, the symbiosis between the roots and the microbial life have been taken into account in its design, considering also the mycological interest in the municipality.

upon the above mentioned, the creation of the forest is requiring an important amount of resources, both personal and economic. But the success of the initiative implies a low maintenance later, since the plant community created continues growing year after year, without the need for new plantings. This is because the vegetation community that has been established, will produce the Looking seeds that will be implanted naturally in the environment.

One of the problems associated with the massive use of pesticides and chemical fertilizers in agriculture together with intensification and monoculture is the progressive disappearance of pollinating animals, which can result in the decline of entire natural communities. In this sense, nectar species have been planted to attract pollinator insect species.

The strata that allows the creation of this edible forest, as a self-sufficient plant community are, the followings:

  1. Straight tall trees: Fruits and nut trees (apple, pear, plum, chestnut, etc.) and nitrogen fixing trees.

  2. Stratum low trees: Fruit trees and nuts, dwarf and / or naturally small (nectarine, almond, peach) and / or flowering trees and nitrogen fixing trees (dogwood, ash, etc.)

  3. Shrub stratum: Fruit trees and shrubs (blueberries, rose, currant, etc.)

  4. Herbaceous stratum: Perennial woody plants (flowers, herbs and ground plants)

  5. Soil cover layer: Cultivation of low plants that offer food or habitat, and push their way at the edges and empty spaces between plants (strawberries, cappuccino, clover, thyme, etc.)

  6. Stratum of vineyard: Plants that climb the trunks and branches of the trees (grapes, hops, passionflower, honeysuckle, squash, cucumbers, melons, etc.)

  7. Root stratum: Shallow roots of food (garlic, onion, radish, carrot, etc.)

The first plantation took place the 25 March 2017 and was carried out by volunteer citizens, so that from the beginning the citizens' involvement in the implementation phase of this nature based solution project it has been important in the way to recover the College Island. After the first plantation, new plantations have been carried out thanks to the Municipal voluntary Programme developed by the municipality where companies can fund plantations projects developed by themselves as a corporate social responsibility actions with which to compensate the impacts derived from their activity.

The idea is to continue increasing the surface of this edible forest in both directions; towards the river and to the urban orchards that are in the island.

Potential impacts/benefits: 


  • BIODIVERSITY: providing the required resources and habitats for species of interest
  • URBAN SPACE DEVELOPMENT AND REGENERATION: improving distribution and connection of green spaces at the urban level


  • QUALITY OF LIFE: psychological outcomes: psychological relaxation, stress relief, enhanced opportunities for physical activities


  • ENVIRONMENTAL JUSTICE: recognition of diversity, procedural justice, distributional justice, capabilities, responsibility

  • SOCIAL COHESION: increase social cohesion

NbS benefits 
  • Developing climate change adaptation; improving risk management and resilience
  • Reduce flood risk
  • Reducing temperature at meso or micro scale
  • Developing climate change mitigation
  • Carbon sequestration and storage
  • Restoring ecosystems and their functions
  • Greater ecological connectivity across urban regenerated sites
  • Improve connectivity and functionality of green and blue infrastructures
  • Increase Biodiversity
  • Increase quality and quantity of green and blue infrastructures
  • Enhancing sustainable urbanisation
  • Improve air quality
  • Increase accessibility to green open spaces
  • Increase amount of green open spaces for residents
  • Increase communities’ sense of ownership
  • Increase social interaction
  • Increase well-being
  • Provision of health benefits
  • Social inclusion
Transferability of the result: 

This project could be replicable in cities that have vacant areas or degraded green areas that they would like to recover or regenerate through re-naturalization strategies, with the aim of creating new green open spaces for citizens and increasing the biodiversity of the city.

The cities that want to bet on NbS, that have problems to finance these actions, would also be ideal candidates to implement this type of projects. The collaboration of local companies and citizens, their commitment to the city and their awareness with the environment, will be vital to advance in the development of the projects.

Lessons learned: 

The availability of spaces in which citizens can develop an activity or actions directly linked to their city and in favor of the environment, has revealed itself as a very interesting vehicle for the development of a sense of ownership and responsibility for its conservation. This can help to expand more easily sustainable and respectful behaviors to other areas of municipal management.


Non-estimated by the moment.

There isn’t a specific budget line for the project, although the City Council tries to find different ways to fund the actions developed in the Edible forest through the Municipal voluntary Programme.

Until now, the donations have come from mainly from different companies that have developed plantation projects. These projects have been planned within the corporate social responsibility actions that the companies carry out to minimize their carbon footprint. They fund the projects, buying all the plants and the material needed for the plantations and the volunteers that participate in the plantation are their workers. Eventually, the municipality has also contributed with punctual funding that cannot be planned and that have helped to increase the plantation surface of the forest punctually (minor actions).

Further information

Main results:

A disused space has been put in value after decades of use as unirrigated agricultural land. The activity itself reduced to a minimum the strip of gallery forest of the Henares River, now practically disappeared.

The area of action is of 7,080 m2 in which there have already been planted 1080 trees and shrubs adapted to the environment. However, in the first two years, plant thefts and acts of vandalism have been reduced the success of these plantations.

The species that are currently represented in the edible forest are hawthorns, strawberry trees, rose bushes, pistaceas, blueberries, ash trees, almond trees, apple trees, walnuts, fig trees, cotoneaster lacteus, lavender, peach, loquat, myrtle and rosemary. The fruits of these trees, act as source of seeds that replenish the space and as attractants of wildlife to the area. Insect hotels have been also installed for this purpose.

Main practical recommendations:

For the success of this type of actions, the selection of the site, the selection of the plantations, the management strategy and participation are very important factors.

The location will help to define the selection of the most appropriate species and the requirements of these plants and trees, in order they can grow up in a successful way, without being compromised by the access to water or other parameters. The best way to achieve this is re-introducing species naturally present in these ecosystems, as a guarantee of their development without additional requirements.

In addition, at the first stages of the implementation, a little maintenance will be necessary until its consolidation, but once the ecosystem is consolidated it will develop by itself, naturally.

Finally, it is interesting to create this type of spaces counting on citizens, because its implication helps its subsequent conservation thanks to the feeling of responsibility, rootedness and self-creation.