When Spring Comes Early

Spring in Britain is arriving earlier than it once did. Research led by the University of Cambridge, drawing on more than 400,000 records from the Woodland Trust's Nature's Calendar, found that plants now reach their first flowering on average a full month earlier than they did before 1986. The UK Spring Index, which tracks the timing of recurring natural events, places the onset of spring around eight days earlier than it was a century ago. For anyone who watches the seasons closely, the blackthorn blossom, the first bumblebees, and the early butterflies are all appearing sooner than they used to.

A warmer, earlier spring might sound benign, even welcome, but it carries a quieter risk. Plants, insects, birds, and the relationships between them have evolved over thousands of years to stay roughly in step, so that flowers open when their pollinators are active, and pollinators emerge when there is food to sustain them. A changing climate is now pulling these finely tuned schedules apart. Studies of British bees show that both flowering and insect emergence are advancing, but not at the same pace. The result is a growing risk of what ecologists call phenological mismatch, where an insect emerges into a landscape that is not yet, or no longer, in flower.

For an early-flying solitary bee, or a butterfly roused by an unseasonably warm February, the consequence is stark. An adult insect that emerges before adequate forage is available may not find the food it needs to survive and reproduce, and a flower that blooms before its pollinators are on the wing may set little seed. Repeated across a season, and across many species, these small failures of timing compound, weakening populations that are already fragile. Pollinators across the UK are in steep decline, having lost both the habitat and the floral resources they depend upon, and a desynchronised spring adds a further pressure at precisely the moment they can least absorb it.

Planting can help, but only when it is designed with this question of timing in mind. Too often, schemes are chosen for how they look rather than for the insects that rely on them, and a generic wildflower mix or an off-the-shelf palette can leave conspicuous gaps in the flowering calendar, particularly in the early spring and late autumn shoulder seasons when forage is scarcest. A scheme can appear abundant in June and yet offer almost nothing when a queen bumblebee emerges in March. Closing those gaps means knowing which pollinators are active in a given place, when they fly, and which plants genuinely sustain them.

Whilst the evidence is clear, what we can do about it is less so. The differing reactions of different species in different parts of the country represents a huge challenge, and one which will require further study to properly comprehend. What we can say with confidence is that planting guided by evidence, rather than by appearance or habit, gives us a better chance of softening the impacts of this shift.

This is the thinking behind a pollinator-informed planting tool under development at Kew Reach. The tool brings together multiple datasets to help define a palette of plants for a given place that should help support our native pollinators.  Combining pollinator observations and their activity periods (as far as we can define them in our rapidly shifting climate) with which plants sustain them and how many of these are known in the area. From this it builds a picture, month by month, of where the local food supply falls short of what pollinators need, and it points towards the species best suited to closing those gaps.

The value of this approach is that it replaces guesswork with evidence wherever the evidence allows. Rather than a palette chosen for appearance, it offers one grounded in the actual ecology of a place, capable of targeting a particular species of conservation concern, or of supporting native pollinators at large across the whole of the flowering season. For clients in the built environment, it helps provide the evidence base that planting and biodiversity proposals need in order to meet planning requirements, support biodiversity net gain, and demonstrate measurable nature outcomes to investors. For rural and infrastructure clients, it offers a locally grounded route to species selection that reflects the real character of a place rather than a generic mix.

A changing climate has made the timing of nature less predictable, and that unpredictability falls hardest on the small, early-emerging insects that so much else depends upon. We cannot slow the advance of spring on our own, and we cannot claim to have all the answers, but we can plant with more care and better evidence than we have tended to in the past, with the flowering calendar and the lives of pollinators held firmly in mind. Doing so will not undo the shift, yet it gives the pollinators already present a better chance, and that, in an uncertain world, is well worth the effort.

Read our deep dive on UK bees to learn more, or get in touch at info@kewreach.com to find out how the tool could support your site.