It was an ambitious signal of green intent when Ukraine's President Volodymyr Zelensky declared this month that a billion extra trees would be planted within three years, and a million hectares would be reforested in a decade. The EU's 27 member states have set a much more modest goal of at least three billion new trees by 2030. But green experts fear that, far from improving Ukraine's environment, the pledge could have a detrimental impact on biodiversity and natural ecosystems. Up to 70% of Ukraine's lands are used for farming, which is among the highest rates in Europe and a legacy collective agriculture of its communist past. Many of these lands were natural steppes that were turned into fields. Steppes are belts of grassland, usually treeless plains, that stretch from Ukraine through Russia and Central Asia and into Mongolia and China. "Around 40% of Ukraine's territory is made up of steppe climate zone, but only 3% of the country has preserved the natural steppe ecosystems with their abundant flora," says Olexiy Vasyliuk, from the Ukrainian Nature Conservation Centre. He has spent years mapping the steppes and classifying their flora. Close to the capital Kyiv lies a forest blooming with flowers. Olexiy shows me a white orchid growing by the path. It is one of 69 types of wild orchid in Ukraine, and some can survive only in their natural habitat of Ukraine's steppes. "I fear for the fate of such beautiful flowers as this one," he tells me. "I don't feel relieved when the government says it will plant trees in degraded farmlands but won't touch the steppes. Many of Ukraine's steppes are, in fact, degraded farmlands by law." So if the government really is planning to leave other farmland untouched, the question is where the billion trees will go.