In the recently rejuvenated Populetum near the Dutch town of Zeewolde grows what may well be the poplar of the future. The only things is, Wageningen research still has to pinpoint which one it is.
Researcher Paul Copini among the young poplars in the Populetum near Zeewolde. © Roelof Kleis
It is a lovely February day when researcher Paul Copini shows off ‘his wood’. The Populetum is not really his of course, but a joint project by Wageningen Environmental Research and the Dutch state forest service Staatsbosbeheer. Nor is it a wood yet. More a number of trial plots with spindly, bare tree trunks a couple of metres in height.
Here and there between the newly planted poplars, the huge stumps of the felled previous generation stick out of the ground. The old trees had had their day; their trunks have been harvested and used. Job done, and the future is for the new generation. Part of the total of 20 hectares has already been planted with new poplars. The rest will come next year.
The first Populetum was planted in the 1970s. ‘One of the aims was to select the best poplar clones of varieties for the newly drained polders,’ explains Copini. ‘The poplar is a pioneer species that grows fast and makes a lot of biomass. A real turbo tree with which you could create a new forest microclimate in a relatively short time, where other trees could flourish too.’
And Wageningen was the source of these poplars, the clones for which came from the extensive plant-breeding programme run by Rob Koster, one of Copini’s predecessors. His name lives on in the Koster poplar, a fast-growing variety that is popular both in the Netherlands and abroad. The clones from that programme are still in use.
In the new Populetum, which houses a total of 25 known poplar clones, there is also a trial plot with new clones. These are eight experimental clones from the breeding programme, which have not yet been made available. They are called Canadian poplars and are crosses between the European black poplar (Populus nigra) and the American black poplar (Populus deltoides). The Koster poplar is a member of this group too.
Copini might have the next ‘Koster’ in his wood. Factors in the selection, besides growth rate (wood volume), include things like trunk shape (for use for timber) and disease resistance. Research is also being done, in collaboration with the Forest Ecology and Forest Management group and SHR Houtresearch, on the scope for wood modification, to see whether poplar wood has potential for use as building material.