When Trees Replace Grasslands, Specialist Birds Lose Their Habitat, New Study Warns
Researchers find that afforestation in natural grasslands can unintentionally displace specialist bird species, highlighting the need for habitat-specific conservation instead of blanket tree-planting campaigns.
Planting trees is widely regarded as a positive environmental measure, but new research suggests that converting natural grasslands into forests can have unintended consequences for biodiversity. Scientists have found that afforestation in open grassland ecosystems often drives away specialist bird species that depend on treeless landscapes for survival.
The study shows that grassland specialists—including birds adapted to open habitats—decline as trees spread across native grasslands. While woodland and edge-dwelling bird species increase in these newly wooded areas, they effectively replace birds that have evolved to thrive in expansive grasslands, leading to a significant shift in ecosystem composition.
Researchers found that rainfall plays a crucial role in determining the extent of biodiversity loss. In regions with higher rainfall, planted trees grow more densely and rapidly, resulting in greater habitat loss for grassland birds. In drier landscapes, the impacts are less pronounced but still evident over time.
The findings challenge the assumption that increasing tree cover always enhances biodiversity. Scientists argue that natural grasslands are ecosystems in their own right and should not be viewed as degraded land awaiting forest restoration. Many threatened birds, mammals and insects rely exclusively on open habitats that disappear once trees become established.
Similar conclusions have emerged from research in Japan, where rows of trees planted as agricultural windbreaks, known as shelterbelts, were found to reduce grassland bird abundance by more than 70% in nearby areas. Although these tree belts benefited shrub- and forest-associated birds, they significantly reduced habitat availability for grassland and wetland specialists.
The issue has particular significance for countries such as India, where open natural ecosystems—including grasslands, savannas and scrublands—support unique wildlife. Species such as the critically endangered Great Indian Bustard, larks, coursers and floricans depend on these habitats, which are increasingly threatened by both land-use change and inappropriate tree-planting initiatives.
Conservation experts say future restoration programmes should focus on protecting the right ecosystem rather than maximizing tree cover everywhere. They advocate a landscape-specific approach that preserves forests where forests naturally occur while safeguarding grasslands as equally valuable ecosystems essential for biodiversity, climate resilience and ecological balance.
The research reinforces a growing consensus among ecologists that successful conservation is not simply about planting more trees. Instead, it is about restoring and protecting native habitats in ways that support the full diversity of wildlife, ensuring that specialist species are not inadvertently displaced in the pursuit of broader environmental goals.
