WMI propagates rare black poplar subspecies for tree planting across the site

26 July 2023

Ecological studies identified a single tree of a rare subspecies of the already endangered native black poplar Populus nigra on the West Midlands Interchange site. Native to northwest Europe and a declining species in the UK, the black poplar has been identified by the Forestry Commission as the most endangered native timber tree in Britain; with a population of just 7000 trees, of which only 600 are seed-producing females, pollination in the wild population is unlikely.

While centuries ago, the Black Poplar would have been found growing naturally in winter-flooded riverine woodlands, widespread land drainage means our subspecies betulifolia is now confined to small pockets in the UK, including the northern West Midlands, western Germany and northern France only.

As part of WMI’s commitment to biodiversity net gain and sustainability, we have commissioned Whitings Nursery at Bromsgrove to propagate some 250-300 hardwood cuttings from our tree, which sadly is in a progressively declining state and unlikely to survive long term, for recolonization across three areas of the site. Black poplar is a valuable food plant for the caterpillars of many moths, including the hornet, wood leopard, poplar hawk and figure of eight. The catkins provide an early source of pollen and nectar for bees and other insects, and the seeds are eaten by birds.

Our young trees are now showing the first signs of growth, as shown in the pictures below. However, the cuttings have proved to be vulnerable to Sciarid fly larvae present in the compost affecting their root development. In response, we are using a natural biological nematode treatment to control the flies and prevent egg laying in the soil.

These trees will be planed in our community parks, so please look out for them and look after them when the community parks open for visitors!