SEEING THE WOOD FOR THE TREES

Widespread responses of birds to woody encroachment

- JOSEPH WHITE

Two of the species most impacted by changes in woody cover. The Long-crested Eagle is a winner, while the Greater Blueeared Starling is a loser.

Across southern Africa, native woody plants are encroaching into open systems. Multiple factors have changed the fine balance between grasses and trees, including increases in atmospheric carbon dioxide and changes in rainfall, temperature, fire frequency and herbivore densities. In many areas shrubs and trees are winning their competition with grasses.

Satellite imagery allows us to map and document this change. In the past decade, several science teams have harnessed this imagery to record changes in grasslands and savannas. Importantly, archived images enable us to measure the historical rates of change. Such studies have shown a general shift from open grasslands to woodier, more closed ecosystems both in southern Africa and more broadly across the world's grasslands.