Climate change negatively impacting how trees produce new seeds, research finds

The warming climate is having a negative impact on tree reproduction by throwing their seed production systems out of synchronisation, according to a new study co-authored by a Keele researcher.

A number of plants, including European beech trees, benefit from a synchronised system of year-on-year variation in the amount of seeds they produce. This process, known as masting, increases the efficiency of plant pollination and reduces seed loss by starving seed-eating animals in years of low seed numbers, and overwhelming these animals in years of plenty, so some seeds get left to grow.

But a new study, conducted with colleagues in the UK, New Zealand and Poland and published in Nature: Plants, has found that while climate change has increased the amount of seeds produced by European beech trees, it has had a negative impact on this masting process by decreasing the year-on-year variation of seed production among individual trees, as well as individual trees falling out of synchrony with their neighbours.

This means that the benefits that the warming climate brings to the trees - an increased amount of seeds being produced - are offset by the negative impacts, as pollination becomes less effective and more seeds are lost to predators each year.

This could be crucial for maintaining the health of forests as the climate continues to change due to human activity, as the strength of masting is vital for plant fitness and forest regeneration. This means that changes to the masting process could have a significant knock-on effect for the health and stability of forest ecosystems.

The researchers studied data obtained over 39 years, and found that where plants that use masting systems are concerned, the main beneficiaries of climate-driven increases in seed production are seed predators, not the plants themselves.

Emeritus Reader Dr Peter Thomas, from Keele’s School of Life Sciences, was one of the co-authors of the research. Dr Thomas said: “As the synchronisation in seed production declines, predators build up since there are always some seeds to eat each year, and so more seeds get eaten overall. As a consequence, the cost to the tree of producing a viable seed has more than doubled over the last 40 years.”