The black poplar is a tree of wet woodland and stream sides, particularly in the floodplains of lowland rivers. This native tree was widely cultivated for timber up until the mid 19 th century, when new, more productive hybrid strains of poplar were introduced from abroad. Virtually all the native black poplar trees remaining today date from before that time; very few have been planted since. Today the majority of planted poplars are of European P. nigra stock or are hybrid poplars with only some P. nigra ancestry, such as the popular Black Italian Poplar (Populus x euramericana �Serotina�).

The majority of surviving trees occur in lowlands to the south of the Humber and Mersey estuaries, particularly in the west Midlands, Welsh marches and East Anglia, with scattered individuals occurring as far north as the River Tees.

The native black poplar is Britain 's most endangered and rarest native timber tree and has declined close to extinction. Only approximately 2000-3000 trees remain nationwide. Most of these are nearing the end of their natural lifespan and will be lost in the next few years. Modern changes to the landscape, including drainage over the last forty years and the management of rivers and riverbanks has led to the disappearance of this tree's natural habitat. Today only a few trees still occur alongside rivers or stream; most occur as planted trees by ditches and ponds or in hedgerows, and occasionally planted in urban areas.

Durham has some of the northernmost records for the native black poplar, but only a small number of individuals are known to occur. The only suitable locality for this tree in the Durham area is in the lowland floodplain of the river Tees, in the Darlington area. In this area carrs, marshes, and other wetland habitat used to abound, before agricultural improvement led to drainage.

The current state of the black poplar in the Durham area is not well known, and is based on a handful of records in the Durham Flora and reports made to Darlington Borough Council. The widespread black Italian poplar, a poplar that has been frequently planted in woodland, copses, shelter-belts and along roads and hedgerows in central and eastern Durham has often been recorded in error for the true black poplar.

Records of black poplar dating over the last 20 years are almost entirely from the Darlington area. These include a tree in a hedgerow at Whessoe, a couple of single trees along the side of Baydale Beck and near Whessoe Holme and an avenue of trees at Middleton-St. George (these most certainly appear to have been planted as cuttings). There is also a record of a single tree at Craghead (Derwentside) in a garden.

Old age of trees. The majority of surviving native black poplars are approaching the end of their natural life spans. This is because planting of these trees ceased in the 19 th century with the introduction of continental varieties which continue to be planted today.

Very vulnerable to extinction. Genetic analysis of surviving trees suggests that the majority are extremely closely related. This suggests that many of the surviving trees were propagated from cuttings (the black poplar, like willows, is very easy to propagate vegetatively, compared to growing it from seed). Poor natural regeneration. Although they readily propagate vegetatively, natural regeneration of native black poplars takes place only very rarely. For the seed to germinate they need to land on bare wet soil (such as islands in rivers or eroded riverbanks) at the end of June, and the seedlings need to be kept moist until October, when the leaves fall. Both flooding and drought are fatal to the seedlings and they are unable to develop in competition with other vegetation. Few remaining black poplars are in their ideal habitat and this makes it difficult for them to reproduce successfully.

Shortage of female trees. There is an extreme shortage of female black poplar trees, which adds to the problems of natural regeneration and genetic impoverishment. Black poplars are dioecious (i.e. they have separate male and female trees and both are needed to successfully reproduce and maintain the necessary genetic variation in stock). Male trees were preferentially planted over female trees, since the latter produce copious amounts of fluffy seed.

Loss of suitable habitat for the native black poplar through agricultural improvement, riverbank development, canalisation of rivers has resulted in fewer suitable places for successful natural regeneration of surviving poplars to occur.

Difficulties in distinguishing native from introduced black poplars. Native black poplars are extremely difficult to identify and distinguish from the many hybrids that look very similar. This makes it difficult to establish the exact status of this tree and also very time-consuming, since expert advice is required to verify black poplar records. If reintroducing the tree to the landscape, there is also the problem that �contaminated� seed may be sold as the true native black poplar.

Propagation of native black poplar plants for planting. Planting should be carried out in lowland, floodplain areas, particularly in the Tees lowlands around Darlington , the area locally where most native black poplars remain.

Wherever possible, cuttings or seed used for propagation of new plants should be taken from trees of local provenance, to preserve local genetic integrity, and should always be of native stock.

Planting should be well away from buildings, archaeological sites, land drains and vulnerable wetland sites, as the tree has a very large root system and removes large amounts of water from the soil.

The black poplar is a very tall tree that casts a lot of shade and is light demanding and should be planted about 20 metres apart, otherwise trees will be prevented from developing their characteristic silhouette.

The most successful way to propagate black poplars is to take cuttings. There are several methods of taking cuttings (including taking long cuttings about 2-2.5 metres long, pointing the ends and sticking them in damp soil, taking straight shoots about 1 metre long and putting them half depth in damp soil, or placing cuttings a quarter of a metre long into cultivated soil with the top end parallel with the soil surface). All methods recommend cuttings be planted in October or November and kept moist through the winter. These will have rooted by the spring, but should ideally be kept in a nursery bed for a year before being planted out. Trees can be produced by seed although the fertility rate is not high.

The unauthorised intentional uprooting of any wild plant species in prohibited under The Wildlife and Countryside Act (1981). There are, however, allowances made for incidental actions that are an unavoidable result of an otherwise lawful activity.

Cooper F. (1998) Native black poplar in the upper Severn area of England and Wales The Dendrologist Vol. 12 No. 7

Graham G. G. (1988) The Flora and Vegetation of County Durham The Durham Flora Committee and The Durham County Conservation Trust

Mabey R. (1996) The native Black Poplar: A species in the ghetto? British Wildlife Vol. 8 No. 1 p.1-6

Milne-Redhead E. (1991) The BSBI Black Poplar Survey 1973-1988 Watsonia Vol. 18 p.1-5

Spencer J. (1994) The native Black Poplar � an action plan for its conservation English Nature: Newbury

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