Plant science: Warmer springs may not lead to greener grass

Seasonal water deficits may limit the benefits for plant growth of earlier, warmer springs in the Northern Hemisphere, reports a paper published this week in Nature. These findings highlight the impact of lagged effects of spring warmth on plant productivity during the subsequent summer and autumn.

Earlier, warmer springs - a consequence of climate change - have lengthened the northern growing season and have increased plant productivity earlier in the year. However, there is some evidence that there may be both beneficial and adverse lagged effects on plant growth later in the year, although our current understanding of these trends is limited.

Wolfgang Buermann and colleagues analysed a range of data, including satellite measurements of vegetation greenness, and report regional differences in beneficial and adverse lagged effects on plant growth across the Northern Hemisphere. Areas in Eurasia above a latitude of 50° north (such as the UK, Scandinavia and parts of Russia) displayed positive correlations between warm springs and plant growth, whereas areas in western North America, Siberia and temperate eastern Asia showed negative correlations. Altitude and particularly seasonal precipitation seem to strongly influence these regional lagged growth patterns, a finding that contrasts with the idea that temperature and sunlight are key limiters of northern plant growth.

The authors suggest that the accumulation of seasonal water deficits may result in regional adverse lagged effects in plant growth in response to warmer springs - a key factor to consider when modelling the effects of climate change on plant productivity.