It is almost exactly 49 years since we first botanised these gravel banks beside the River Wear, during the long summer drought of 1976. New to the area, we’d heard that the mounds of river‑smoothed pebbles, where the water table was always within reach of roots, were well known among local botanists as lucky-dip hunting grounds, even in the driest summers. A place colonised by a pioneering flora of native ruderal species, alongside a cosmopolitan community of exotic garden throw-outs washed up by receding floods in spring.
My diary for that day records monkey flower (Mimulus guttatus), a native to riverbanks in America’s Pacific north-west, but often cultivated upstream in Weardale’s cottage gardens. Memory can be treacherous, but my recollection is of drifts of its yellow flowers. Today, after half an hour’s searching, we found just one – monkey flower is an alien with a tenuous foothold here and has never become invasive, unlike some international arrivals. In the riverbank woodland, pink and white thickets of Himalayan balsam mingle with tall, yellow‑flowered drifts of Canadian golden rod and central European dotted loosestrife that all established a strong bridgehead then moved inland.
It’s a community of species that evolved in isolation, on separate continents, now thrown together to become part of an accidental, unpredictable ecological experiment, in an era of rapid climate change. A conservationists’ unfolding horror story maybe, but also an abundant new food resource exploited by native nectar- and pollen-feeding hoverflies and bees.
The course of the river has changed too since we first walked its banks. Every summer, alder and willow seedlings become deeply rooted in fertile silt between the pebbles. This summer’s new recruits have grown fast and next year they’ll be saplings, slowing the flow when the river rises in winter, trapping stones and debris, creating islands, nudging the river to seek new wriggle room downstream. A relentless cycle of building and erosion.
Half a century of change, for better or worse? Nature is indifferent to such sentiments; its ability to adapt and evolve delivered the native flora we strive to conserve today but, like the islands in the stream, when we deflect its path it will always find another route.