Walking through any Spanish city reveals an interesting diversity of urban trees, true protagonists of the landscape and essential factors for the environmental quality of our cities. Although many believe there should be more vegetation and larger green spaces, the existing trees offer benefits that go far beyond mere ornamental benefits. These trees are not planted at random; their selection and location respond to rigorous technical and ecological criteria that seek to improve urban life, ensure sustainability, and properly manage resources.
Importance of trees in the Spanish urban landscape
Urban trees provide a multitude of ecosystem services These range from air purification and pollution reduction to improving citizen well-being. They act as barriers against wind, sun, and noise, demarcate areas, and even function as natural filters against dust and pollutants. They also regulate temperature, mitigate the heat island effect, and help prevent flooding by promoting water infiltration into the ground.
The presence of urban trees is key in the design of public spaces.They beautify streets, squares, and parks, provide shade on hot days, and offer shelter and food for birds and pollinating insects, thus increasing urban biodiversity. However, their development in urban environments poses special challenges due to pollution stress, limited space for root and canopy growth, and increased risks of pests and diseases.
Criteria for the selection of urban trees
Before selecting a tree species for the urban environmentIt is essential to evaluate multiple factors that will ensure the success of the planting and the healthy development of the plant in conditions so different from those of its natural habitat. The following criteria stand out:
- Climate adaptation and drought resistance: Prefer species that tolerate local climatic conditions, including aridity, winds and thermal variations.
- Soil characteristics: Consider the quality, composition and depth of the soil to ensure the proper development of the root system.
- Available space: Choose species whose size and root distribution are compatible with the width of sidewalks, streets and parks, avoiding future conflicts with urban infrastructure or buildings.
- Ornamental and ecological value: Prioritize species that combine beauty (flowering, foliage color, canopy shape) and contribute biodiversity, favoring the presence of local fauna.
- Low maintenance and pest resistance: Select trees that require little intervention in pruning and phytosanitary treatments, thus reducing costs and environmental risks.
It is important to remember that the species diversification prevents problems associated with urban monocultures, such as the proliferation of specific pests.
Advantages of using native species in urban environments
The use of native or autochthonous species It is considered the best option for garden design and urban alignments in Spain for the following reasons:
- High adaptability: They are resistant to local climatic factors and soil conditions, including periods of drought and high temperatures.
- Reduced maintenance: Its evolution in the natural environment allows for vigorous development without the need for abundant fertilizers, pruning or chemical treatments.
- Biodiversity Conservation: They promote the presence of local associated fauna (birds, bees, butterflies) and contribute to the ecological balance of cities.
- Reduction of water consumption and lower emissions of pollutants from transport, since they do not require long trips from distant nurseries.
- Scenic and educational value: They promote respect and connection with native nature, also serving as an educational tool to raise awareness among the population.
Key factors in the establishment and management of urban trees
To maximize the benefits of trees, it is essential to:
- Plan the location and separation between specimens, avoiding conflicts with infrastructure and allowing natural development of the canopy.
- Take care of the preparation and quality of the soil, ensuring adequate volume and structure for root growth.
- Implement efficient irrigation systems in the first years of life, prioritizing sustainable methods such as drip irrigation.
- Promote ecological maintenance, minimizing the use of chemicals and enhancing plant and animal biodiversity.
Main urban tree species in Spain
Now they present the most used and valued species for their characteristics and benefits in the Spanish urban landscape, along with its botanical, ornamental and ecological aspects:
Cercis siliquastrum (Tree of love)
This popular deciduous tree is known for its pink or white flowers that emerge in spring before the heart-shaped leaves emerge. It tolerates drought and warm climates well, although it is affected by severe frost. It is noted for its ornamental value and its ability to attract pollinators. They typically reach up to 5 meters in height after 15 years and provide pleasant shade.
acer negundo
A fast-growing tree, capable of reaching 25 meters, with compound leaves and petalless flowers that promote wind pollination. Resistant to urban pollution and well adapted to moist soils, it is used in wide-open alleys and garden areas.
catalpa bignonioides
Growing up to 12 meters tall, this deciduous tree stands out for its lush foliage, white flowers, and tolerance to varied soils and dry seasons. It provides excellent shade and intense spring colors, making it ideal for parks and recreational areas.
Gleditsia triacanthos (Three-thorn Acacia)
A large tree (up to 30 meters tall), drought-tolerant and preferring sunny, humid areas, it produces sweet, edible pods. It is noted for its hardiness and adaptability, and is commonly planted in wide rows.
Koelreuteria paniculata (Lantern Tree)
It is characterized by its yellow summer flowers and pink capsules. It grows to 15 meters and is remarkably resistant to pollution and drought, although its longevity is moderate. Its ornamental value is highly appreciated for adding color to streets and squares.
Morus alba (White Mulberry)
Common in urban environments, the mulberry tree is very hardy and grows up to 18 meters tall. Its dark, flavorful fruits, along with its adaptability to both wet and dry climates, make it ideal for providing shade and food for local wildlife.
Paulownia tomentosa (Empress tree)
Known for its large, heart-shaped leaves and vanilla-scented lilac flowers, this tree stands out for its rapid growth and resistance to both drought and cold climates. Its elegant appearance and spring blooms make it a standout choice for parks and avenues.
Populus alba (White Poplar)
A deciduous tree that can reach 25 meters, it prefers cool soils but tolerates urban environments. Its whitish foliage and wide canopy provide dense shade, and it is frequently found in urbanized riparian areas.
Prunus cerasifera (Ornamental plum)
A small tree, ideal for streets with narrow sidewalks. Its reddish leaves in autumn, pink or white flowers, and small fruits make it very attractive in urban design.
Quercus ilex (holm oak)
It graces the Mediterranean landscape with its medium-tall growth, dense canopy, and acorn production. It is one of the most abundant and drought-resistant native trees, providing permanent shade and refuge for wildlife.
Robinia pseudoacacia (False acacia)
This fast-growing species blooms profusely in spring, producing clusters of fragrant white flowers. Hardy and ornamental, although its seeds are toxic, its flowers have traditionally been eaten by children in urban areas.
Tilia platyphyllos (Large-leaved lime)
The linden tree, with heart-shaped leaves, a broad crown, and fragrant summer flowers, grows up to 30 meters tall and is widely used as an ornamental tree in parks and tree-lined streets.
Platanus hybrida (Steel plane)
One of the largest trees used in the city, it grows quickly and is resistant to urban stress. It provides abundant shade and is common in avenues and large parks thanks to its air filtration capacity and tolerance to air pollution.
Integrating other native and adapted species
In addition to the species mentioned, The current trend in urban landscaping is to focus on including a wide diversity of native and adapted flora., following criteria of sustainability, resilience, and improving urban biodiversity. Some recommended species include:
- Lavandula angustifolia (lavender or lavender): An aromatic, drought-resistant, and easy-to-maintain plant. Ideal for urban borders and rockeries.
- Geranium robertianum (gypsy): Long-flowering herbaceous plant that helps to fix the soil and attracts pollinators.
- Cistus ladanifer (sticky rockrose): Very resistant Mediterranean shrub that beautifies with its flowering and thrives in poor, sunny soils.
- Lonicera etrusca (Mediterranean honeysuckle): A climber of great ornamental value that provides fragrance and attracts local fauna.
- Santolina chamaecyparissus (santolina): Ideal for xerophytic and low-maintenance gardens, as well as acting as a natural insect repellent.
- Thymus vulgaris (thyme): A fundamental aromatic plant in the Mediterranean landscape, easy to grow and a valuable contribution to biodiversity.
- Rubus ulmifolius (blackberry): Climbing plant that offers edible fruits and shelter for wildlife, recommended for ecological projects.
- Pistacia lentiscus (mastic tree) y cistus clusii (male rosemary): Evergreen shrubs suitable for natural hedges and visual barriers in urban gardens.
- Digitalis purpurea (foxglove): A biennial of great ornamental value, ideal for providing verticality in urban green spaces.
Common problems and inconveniences associated with urban trees
While The benefits of urban trees are countlessThere are also certain drawbacks that must be managed through proper planning and maintenance. These include:
- Possible allergies due to pollen or volatile organic compound (VOC) emissions.
- Impact on infrastructure: roots that damage pavements, drainage systems, or walls.
- Loss of leaves, flowers or fruit on sidewalks, causing dirt or stains.
- Specific pests or diseases that can develop in monocultures or due to a lack of diversity.
- Risk of falling branches or trees due to extreme weather conditions or poor maintenance.
The key to avoiding these problems lies in species diversification, the technical knowledge of responsible personnel, and informed and well-funded public intervention.
Management, maintenance and citizen participation
La Urban tree management is primarily the responsibility of city councils, who must ensure the proper maintenance, health, and safety of the planted trees. Financial investment and the professionalization of the sector are decisive factors in ensuring the survival of the trees and the effectiveness of this public service.
La citizen participation It is essential to raise awareness about the benefits of urban greenery. Furthermore, collaboration with professionals, maintenance companies, and specialized technicians improves the sustainability and longevity of green spaces. Promoting environmental education and connection with nature fosters respect for and protection of trees.
Among the technical recommendations are:
- Evaluate the development and natural form of the tree to avoid drastic pruning and conflicts with buildings.
- Prioritize excavations and soil replacement in tree pits to ensure good anchoring and nutrition.
- Avoid the abuse of chemical treatments and promote preventive and biological practices against pests and diseases.
- Promote genetic diversity and adaptive through the introduction of new species, after experimentation and monitoring.
Main environmental and social services of urban trees
- Air purification and CO2 capture, contributing to the fight against climate change.
- Reduction of ambient temperature by the shade and transpiration of the leaves.
- Creation of meeting spaces and psychological well-being in citizenship.
- Promoting the urban hydrological cycle, reducing the risk of flooding.
- Support for urban wildlife and biodiversity recovery within the built space.
The presence of more and better trees In the urban environment, it strengthens green infrastructure, connects natural spaces, and provides a healthier and more resilient city. The key lies in plan and manage each tree as a living and valuable resource, addressing both their needs and those of the city and its inhabitants. Incorporating well-selected species and promoting environmental awareness will ensure greener, more balanced, and more livable Spanish cities for current and future generations.
