A new long term study has found that climate change is sharply reducing the reproductive capacity of Europe’s forests, even as many woodlands still appear healthy on the surface.
Researchers reported that viable seed production in five major European tree species declined by more than 30 per cent over the past 34 years, raising concerns that forests may be losing their ability to naturally regenerate under rising temperatures.
The study, published in the journal Nature Climate Change analysed more than 40,000 seed harvest observations collected in Poland between 1988 and 2021. Scientists examined reproductive trends in English oak, sessile oak, Scots pine, silver fir and European beech.
Among the hardest-hit species were oaks and Scots pine, which recorded declines of roughly 65 per cent and 64 per cent respectively in viable seed production. Silver fir showed a 44 per cent drop, while European beech declined by around 32 per cent.
Researchers said warmer summer temperatures emerged as the strongest and most consistent factor behind the decline. Moisture levels and spring temperatures appeared to play a smaller role.
The findings suggest climate change may be affecting forests in ways that are not immediately visible. Trees can continue standing for decades while gradually losing the ability to reproduce effectively, scientists warned.
Lead author Jessie Foest from the Adam Mickiewicz University Forest Biology Centre in Poland said forests may appear stable even while their long term capacity to replace themselves is weakening. According to the researchers, this hidden reproductive stress could eventually affect biodiversity, carbon storage, ecosystem recovery and overall climate resilience.
The study also highlighted disruptions in “masting” patterns, particularly in European beech forests. Masting refers to cycles in which trees produce large seed crops during certain years. Scientists found that climate stress may be interfering with these cycles, reducing successful pollination and increasing seed losses to predators.
Researchers noted that similar declines in forest fecundity have already been observed elsewhere around the world, including reduced seed production in UK beech forests, lower cone production in pinyon pine forests in New Mexico and declining fruit production in Central African forests.
The authors warned that falling seed production combined with worsening conditions for seedling survival could accelerate forest decline in the coming decades. In species such as Scots pine, climate driven mortality and reduced reproduction together may eventually prevent forests from naturally recovering population losses.
Scientists say the findings add to growing evidence that climate change is not only increasing tree deaths and heat stress, but is also quietly weakening the biological systems forests rely on for long-term survival.