Rapid Changes in Flowering Time in British Plants

TLDR

Flowering timing is highly sensitive to prior‑month temperature, with spring species showing the greatest responsiveness. Across 385 British plant species, first flowering dates have advanced on average 4.5 days per decade, 16 % of species flowering earlier by an average of 15 days, while 3 % flowered later, underscoring a strong biological signal of climate change and revealing interspecific differences that may alter community structure and gene flow.

Abstract

The average first flowering date of 385 British plant species has advanced by 4.5 days during the past decade compared with the previous four decades: 16% of species flowered significantly earlier in the 1990s than previously, with an average advancement of 15 days in a decade. Ten species (3%) flowered significantly later in the 1990s than previously. These data reveal the strongest biological signal yet of climatic change. Flowering is especially sensitive to the temperature in the previous month, and spring-flowering species are most responsive. However, large interspecific differences in this response will affect both the structure of plant communities and gene flow between species as climate warms. Annuals are more likely to flower early than congeneric perennials, and insect-pollinated species more than wind-pollinated ones.