The engineer Ildefonso Cerdá, while planning the grid of the urban expansion of Barcelona, summarised his work programme as “urbanising the countryside and ruralising the city”. A century and a half on from Cerdá, today pressurised by the urgent demands of climate change, renaturalisation of cities is a global objective. Making the boundaries of the city permeable to the entry of nature has great significance for the entire planet and for each and every one of us. And in this enormous task the tree stands out for its functional versatility, because every tree is an integrating element in the urban landscape and provides environmental, aesthetic, recreational, social and economic benefits. Therefore, selection of the most suitable species to be integrated in the city entails careful consideration of the characteristics of the space, as well as the services and functionalities that we would like to ask of the trees.

The Belloch Canon is the result of an ambitious scientific study conceived to determine the optimum tree planting for our cities in the Iberian Peninsula, based on a holistic perspective. It is not only a question of previously unstated scientific curiosity, but it also exemplifies the social commitment of Belloch Forestal to promoting the best offer for all. When we started our business venture, we reached the point of cultivating 300 different species and varieties. Now, in view of the results obtained, we prioritise the production of 40 demonstrably optimum canonical varieties, whilst always trying to offer the best examples of each one of them.

Formulated as a singular roadside tree planting catalogue, it has been designed to provide a selection of high performance species in terms of urban suitability and functionality. To achieve this, a series of criteria and parameters have been established which, once weighted, have enabled around forty species of special interest to be prioritised. And this is not only because of their adaptability to the city, but also because of their added value in areas such as small-scale climate regulation, capture of atmospheric pollutants or adaptation to climate change scenarios.

The species included in the catalogue combine a series of contrasting attributes that make them particularly interesting on account of their overall capabilities, performance and tolerance to the urban environment. Does this mean to say that a species that is not in the Canon is not recommended for linear tree planting? Not necessarily. In this respect, the Canon has no dogmatic pretensions. In the future, it may be subject to revisions and/or extensions given that there are still numerous knowledge gaps to be filled and potential new species to consider for evaluation.


The Canon’s catalogue has been selected from an initial list of 115 species commonly used for linear tree planting in cities in our geographical and climatic context. The desire to limit the number of species reflects a commitment to establishing a true priority list, whilst maintaining a reasonable diversity of botanical statures, morphologies and taxa. In turn, this makes it easier for Belloch Forestal to specialise in the production of high quality specimens of these species, thus ensuring the ability to offer the performance for which they have been selected.


Our nursery cultivates its trees using the Air-Pot, a unique pot which, due to its design, uses oxygen to prune the roots, preventing root spiralling. This constant pruning stimulates extensive development of new fibrous roots in the tree that ensure its future adaptation to its final location, increasing transplant success to more than 98% thanks to the increased capacity to absorb nutrients and water. Furthermore, the radial arrangement of the roots, which are neither spiralling nor constricted, ensures rapid and reliable anchoring.