Trees that shape the landscape

For me, it is the trees that give the landscape of lowland England its character, not just providing a backdrop to her vistas but also delivering a real sense of place. The character of some of these trees, such as that of the oak, have been enshrined in our literary tradition and used to say something about our own English character. Others, however, have been overlooked and undervalued, a reflection of their timber having little commercial value. Perhaps the most overlooked of these has been the native black-poplar, a tree of lowland flood plains that has lost out to years of agricultural drainage.

That the black-poplar should have slipped from our collective awareness is perhaps surprising. It is a large and highly distinctive tree, with its gracefully arching boughs, massive size when mature and an often-leaning trunk. During the 1970s, however, a burst of interest in the tree was revived thanks to the efforts of Edgar Milne-Redhead. Having recently retired from his job at the Kew herbarium, Milne-Redhead began to track down and document the locations of mature black-poplars across southern Britain, with much of his efforts concentrated here in East Anglia. The results of this work, coupled with that of more recent studies, suggest a national population somewhere in the region of 6,000 individuals.

References to native black-poplars in Norfolk can be found in the older literature, the earliest seemingly that included in a letter from Sir Thomas Browne to John Evelyn. James Grigor, writing in 1841, included a number in his records of notable trees from the region, some of which can be traced to individual trees still standing at sites within the county. The natural distribution is confused, however, by the presence of hybrid black-poplars planted because of their more upright form and faster growth. ‘Natural’ establishment requires the presence of male and female trees in close proximity, at sites where suitable conditions for seedling establishment are to be found. Many mature trees stand isolated, or are present in single-sex groups, leaving them, as Richard Mabey writes ‘marooned’, the ‘ghosts of a wilder and wetter landscape’.

In places, particularly where associated with a village, individual trees have been ‘adopted’ by the community and their importance is recognised and respected. As our knowledge of these trees increases, so we our discovering and documenting more relict populations. This knowledge should help to safeguard the future of this great tree, whose associations with the East Anglian landscape are captured in the works of Constable and other English landscape painters. The late Ted Ellis once wrote in his EDP column of a visit that he made to a particular black-poplar and later this year I hope to pay my respects to this ancient tree.

The invisible tree

Writing in 1996, the author Richard Mabey referred to the native black poplar as the invisible tree. Here was a tree of immense presence and with a strong cultural history, that had ‘passed so thoroughly out of common knowledge’. How could we have let this happen?

The black poplar (Populus nigra subsp. betulifolia) is a tree of deep alluvial soils, largely restricted to lowland river floodplains across southern Britain, northern France and western Germany. As our landscape has changed over recent centuries, so the drainage of land has seen the loss of black poplars from large parts of their former range. The most recent estimates suggest that there may be only 7,000 individuals left in Britain, most of which are males (black poplars are dioecious, the male and female catkins appearing on separate trees). The loss of these majestic trees had largely gone unnoticed until, in 1973, Edgar Milne Redhead, recently retired as deputy curator of the herbarium at Kew, took an interest in the species. Milne Redhead’s work revealed the extent of the loss and demonstrated that the remaining individuals had almost certainly originated as cuttings from a population of just 600 trees. Most of the trees were isolated and there was little hope that they would be able to secure natural pollination and seed set without intervention. There was also the threat of hybridisation with the various Italian black poplars favoured by local councils for tree planting schemes. The almost complete absence of seedlings within Britain is something that has been noted by many authors.

Here in Norfolk, the most recent survey revealed just 54 male trees, together with an impressive female tree on the village green at Old Buckenham. A map included in the most recent county flora shows that most of these trees are in the central southern part of the county, while just over the border into Suffolk there are many hundreds of trees. However, to really appreciate this tree at the landscape scale you have to visit the Vale of Aylesbury, where the presence of these trees can really be felt. The short trunk section, with its rough bark and bosses, almost always leans at an angle, supporting above it a rich green and luxuriant canopy.

The conservation of the black poplar will require a careful balancing act, securing the future of the species by establishing more individuals, while at the same time ensuring that these individuals are planted correctly within a cultural landscape. Many of the cultural traditions associated with the tree stem from its scarcity and position within the landscape (as boundary markers or centrepieces for village festivities) and so newly established trees must fit into this pattern.