Why a native species can fail in an urban environment

A native species can fail in the city because the urban environment is very different from the habitat where it evolved. Restricted rooting volume, compacted soil, reflected heat, sealed surfaces, salt, wind, pollution and irregular watering alter water availability and temperature. Native status does not correct a poorly prepared site.

A tree from a cool valley can be native and still suffer in a narrow tree pit between paved surfaces. Urban soil can have low porosity, rubble, interrupted drainage and temperatures higher than those of the surrounding landscape.

These differences explain why selection should start from the profile of the site, not just from natural distribution.

Without enough soil volume, the roots reach little water and the tree becomes vulnerable to heatwaves. Frequent watering solves neither compaction nor lack of oxygen. Continuous soil systems, protection against compaction and drainage are part of the solution.

The establishment period still requires watering, even for species that tolerate drought once established.

Characteristics such as wood density, leaf area, stomatal control strategy, root architecture and capacity for recovery help to predict performance, but no matrix removes uncertainty. Recent studies suggest that functional traits may explain the initial response better than climatic niche alone.

In larger-scale projects, pilot batches and monitoring make it possible to reduce risk before the species is repeated.

The most frequent mistakes are planting in a small tree pit and blaming the species; doing without watering because it is native; ignoring reflected heat and wind; and using natural distribution as the only criterion.

At Diaplant, selection for the city begins with the real conditions of the street, courtyard or square. The fact that a species occurs naturally in a region does not guarantee that it will cope with reflected heat, compaction or a small volume of soil.

The right native in the wrong place is still the wrong choice. Urban performance depends on the species and on how the habitat where it will be planted is built.

• Forest Research. Urban Tree Manual. (2018).
• Relating the climate envelopes of urban tree species to their drought and thermal tolerance. (2021).
• Functional traits are better than climate niche approach at predicting the vital growth and mortality rates of urban tree species. (2026).
• Forest Research. Urban forests — climate change advice. (2026).