Green Cover Deceives: Eucalyptus Forests Lack Birdlife

In northwest Spain, native forests and eucalyptus plantations can look similarly green from afar, but a 2025 study published in Forest Ecology and Management revealed stark differences in their bird populations. Research conducted in Galicia's Fragas do Eume Natural Park, a rare example of Atlantic coastal forest, found that native deciduous forests are significantly more biodiverse.

During the 2022 breeding season, surveys at 130 natural forest locations and 110 eucalyptus plantation sites showed a marked imbalance. Typically, natural forest spots hosted around nine bird species and 14 individual birds, whereas plantation sites averaged only five species and seven birds. While the total number of bird species recorded across all sites was similar (35 in native, 36 in plantations), each individual plantation patch supported roughly half the birdlife found in native forest areas.

Eucalyptus, which is not native to Spain and now covers 30% of wooded areas in the northwest, presents a challenging habitat. The study identified that the proportion of eucalyptus trees was the most significant factor linked to lower bird counts. Scientists suggest this is due to plantations offering fewer tree cavities for nesting and a reduced supply of insect food necessary for young birds.

Mature native trees were found to be especially critical, providing essential habitat for species like the Eurasian nuthatch and crested tit. Mature eucalyptus trees, conversely, offered little benefit to these forest-dependent species. Previous research in 2019 also indicated that plantations have fewer bird and herb species and significantly less cavity-nesting forest birds compared to native forests.

To mitigate these impacts, study authors suggest leaving untouched strips within plantations to encourage shrub and native tree growth. They also advocate for stricter plantation policies and the restoration of native habitats within protected zones. While the study focused on one region and birdlife, it underscores that not all green cover is ecologically equivalent, prompting questions about the types of trees planted and the biodiversity they support.