In industrial estates of new towns that were built following the end of World War II, or even in industrial estates built within pre-WWII towns, planting schemes (typically completed during the 1980s by local authorities) seem to typically involve hybrid black poplars. Of course, this isn’t an all-encompassing statement, as there are plenty of industrial estates that have other planting scheme styles, though I can’t help but notice at least a bit of a trend.
So why do planting schemes heavily involve the hybrid black poplar? I can think of many reasons.
Firstly, poplars are very quick growers. Industrial estates aren’t usually attractive places from an aesthetic standpoint, and the high-sided factories dominate the landscape. To counteract this, poplars can be planted to quickly lessen the gap between man-made visual dominance and natural visual dominance. The fact many industrial estates have wide verges aids with the use of poplar. In as little as 15 years, poplars may begin to tower above factory blocks, and improve the amenity value of the area as a result. No longer are the factory units foreboding, and nor do they harshly contrast with the skyline. Particularly where articulated lorries may routinely visit, the poplars provide visitors to the industrial site with a sense of scale – yes, the lorries are large, but the trees are huge. Suddenly, the industrial estate isn’t as unwelcoming.
Poplars are also cheap to acquire, and thus there’s no real concern over there being robust aftercare regimes. The land owner, perhaps the local authority, can just plant a load of bare-rooted standards (they can be as cheap as £10-20 per) in winter, and if there’s no scope for aftercare, or aftercare is only limited, there is not a huge degree of concern – more can be planted. Poplars are economically disposable, whilst ornamental and exotic trees are not. For financially ‘astute’ land owners, the planting of poplars may even be a way of decreasing expenditure and thus increasing profit. After all, it is unlikely that visitors to the industrial estate will be too concerned over the species of tree being used, but rather be concerned only with there being trees.
Perhaps more importantly, poplars are good at tolerating pollution. Like sycamore and birch, they’ll persist even in environments that would likely see a beech struggle significantly. Therefore, where there is likely to be both air pollution and soil pollution, hybrid black poplars won’t necessarily suggest this to visitors. Particularly in summer, their dense foliage and massive size will signify to visitors that everything is fine, as the trees aren’t all dying.
On a more philosophical level, it could be suggested that the planting of such a ‘vanilla’ species signals a lack of desire, knowledge, or even care. An industrial estate will likely not receive the same level of maintenance as an amenity park, or even a residential street, so why bother having interesting tree species? Lorries may frequently churn up grass verges, damage curbs, or even pathways, and so if a poplar suffers for whatever reason, is it really the end of the world as far as everyone who uses the site is concerned? Another one can simply be planted in its place.
There are however risks associated with the use of hybrid black poplars. Not only are they short-lived, but they have a tendency to drop branches as they mature – Rodney Helliwell, in his article Management of Tree Populations, recognises this. Because of this, they may quickly become potential hazards, and maintenance down the line may negate the initial cost-savings of planting such an ‘instant’ species. This can be seen in the below images, where poplars have either died, or are becoming a hazard due to poor health or a structural issue.
Additionally, as many poplars are planted in very dense rows and the lack of aftercare meant the stands were not thinned some time afterwards, there becomes an ongoing maintenance issue. Are stands removed entirely and re-planted, or are poplars removed as they die or become a hazard – and will removal mean the now exposed neighbours are hazards? As Helliwell states: “Should they be left to grow until they start to shed branches (as hybrid black poplars have a tendency to do)? Should some be removed to make room for some new trees to be planted? Or should a mixture of species have been planted in the first instance, so that that the poplars could have been gradually removed to allow slower growing species to gradually take their place?” He notes that the last option would be best, but that’s working with hindsight.
In my own view, I can see the reasons for and against using hybrid black poplars. From an amenity aspect, their presence is necessary (as they are simply so large and so quick to grow), but using a mix of species will be better in every sense – visually, ecologically, and economically. I am always concerned with the thought that, one day, all the poplars will either have died or be in a state of decline, and suddenly there are very few trees of any stature. Thus, I agree with Helliwell when he suggests that, gradually, new trees must be planted in their place. Continuous-cover industrial estate arboriculture, if you will.