How to make a meal of our sea buckthorn problem
If you find you’re not beating alien invasive plants, you could always try eating them, as a project to help rescue the flora of North Bull biosphere reserve is doing
Berry merry: chef Liam Moloughney and Pat Corrigan of North Bull biosphere reserve, harvest sea-buckthorn fruit. Photograph: Dublin City Council staff
People often wonder, sometimes despairingly, what they can do when alien invasive plants crowd out native flowers and wildlife in places they love. Dublin City Council has an innovative solution: you may be able eat them. They may also give new flavours to local restaurants, so providing a profitable link between business and biodiversity.
The seeds of this solution began to grow when two council staff observed birds feeding voraciously on sea buckthorn’s orange berries on North Bull Island, in Dublin Bay, and apparently getting happily tipsy in the process. If birds liked them so much, perhaps we humans might enjoy them also.
And then they observed something else: humans were indeed sometimes picking them there. The pickers were mainly “new Irish” immigrants, whose traditions often tie them more closely to foraging for wild food than ours do.
So Pat Corrigan, supervisor of the North Bull biosphere reserve – a Unesco designation – and Mick Harford, district parks officer, began to wonder if longer-established Irish people might also be encouraged to appreciate sea-buckthorn berries. They needed help, and this plant was causing them an awful lot of grief.
The orchids and other wild flowers that light up the dune slacks along the centre of the island are one of Dublin’s great botanical treasures. But these rare plant communities are threatened by the advance of sea buckthorn, an exotic shrub originally planted as shelter belts on the island’s two golf courses.
The golfers have done a pretty good job, especially at St Anne’s, in clearing buckthorn from their premises, now that they have been made aware of the problems it causes. But those birds that so favour the berries have long since spread the seeds they contain to several especially rich areas of the nature reserve.
Left to itself, the buckthorn forms impenetrable thickets, shading out native species almost completely. It also enriches the soil, by fixing nitrogen through its roots and by adding a layer of leaf litter every year.
That might sound like a good thing, but in fact the native species that flourish in the dunes are dependent on nutrient-poor soil, so they may take time to re-establish even when the buckthorn is cleared.
The reserve staff have battled to contain the advance of the buckthorn, with limited success. They are also constrained by clashing conservation priorities. On the one hand they are obliged to clear alien invasive plants. On the other they are not permitted to clear shrub vegetation during the spring and summer nesting seasons, as many birds find the buckthorn thickets an attractive protection from predators.
So autumn and winter are critical times for clearance. But there’s another catch: in autumn the buckthorn plants are festooned with berries. And clearing the shrubs in this condition scatters its seeds in the ground disturbed by clearance, where they will germinate most easily.
So clearance can simply facilitate further infestation.While brainstorming solutions to this particular problem with Niamh Ní Cholmain, the council’s community biodiversity facilitator, Corrigan and Harford had a eureka moment.