Dutch cities Haarlem and Hoorn expand urban tree programs

Dutch municipalities Haarlem and Hoorn are implementing strategies to expand and manage their urban tree populations to combat climate change and improve biodiversity.

In Haarlem, the municipal government has released a draft ‘Tree Program’ (Programma Bomen) for public consultation. The initiative focuses on protecting, managing, and expanding the city's tree stock by ensuring adequate underground and above-ground growth space. The goal is to increase canopy cover to prevent the city from becoming a ‘gray, paved city’ without biodiversity, though officials note that canopy expansion will vary by neighborhood due to differing urban layouts.

Meanwhile, Hoorn reports a significant increase in its tree population, adding 707 trees over the past year. The city now has 45,375 municipal trees, meeting its target of at least 1.3 trees per home. Hoorn’s policy is shifting focus from simple tree counts to ‘tree crown volume’ to better measure the quality and cooling benefits provided by healthy, mature trees. The municipality is also prioritizing diverse species to increase resilience against pests and climate-related changes.