Awareness of the problematic nature of invasive species has greatly increased over the past few years. These organisms are defined quite loosely, but are characterised by their rapid spread and the ability to out-compete communities of native and endemic wildlife.
Many invasive species have their origins in other countries, but most species have the potential to become invasive should climatic conditions change or the natural balance of an ecosystem be disrupted.
Non-native wildlife is that which has been introduced – by accident or design – to a location outside its native range.
Some of the best-loved plants in Britain, such as the cricket bat willow, were first introduced in this way. Problems start to occur when organisms from elsewhere start to thrive disproportionately well because of the absence of the usual natural competitors or controls.
Although it should be noted that some of them are also a nuisance in their native ecosystems!
The Nature of the Problem
The rampant expansion of introduced invasive species, especially plant species, is a particular issue in landscape, residential and commercial architecture.
Many of these, like the deciduous tree of heaven, grow in a weed-like fashion and are well nigh impossible to eradicate. Some invasive plants, such as giant hogweed, are equipped with the ability to secrete poisonous compounds, and these can cause severe health problems for humans.
Disrupting established communities of these plants often has the paradoxical effect of making them grow with renewed vigour, so their presence on a development site should immediately raise a red flag.
In fact, the American Society of Landscape Architects (ASLA) recommends that its members work with biologists to survey any area earmarked for development, purely for the purpose of identifying invasive plants. If they are found, attempts at eradication should be carried out before the ground is disturbed, to prevent their accidental propagation.
Avoid Harming Invasive Species
Ironically, most non-native invasive species were originally introduced by horticulturalists and gardeners. The ASLA advises architects to remain aware of native, non-invasive alternatives when designing planting schemes, and to use those where possible.
And it is certainly necessary for all professionals in the construction industry to remain current with the state of knowledge concerning invasive plants, if only to avoid accidentally making matters worse.
Eradication and Containment
When invasive plants are known to be present, it isn’t enough to try and get rid of them by simply slashing and burning.
Sometimes – as with Japanese knotweed – legal restrictions apply to the disposal of waste that may contain fragments of the plant.
Quite often, control measures include the targeted and systematic application of herbicides over an extended period of time. Sometimes the plants are best left totally undisturbed, since attempts to control their growth just prompt them to spread.
After the site has been surveyed and the invasive species identified, research must be undertaken to find out the best approach to their eradication.
It’s obvious that the presence of non-native invasives has the potential to delay a project, sometimes by a considerable period.
It may even be wise for architects to assume a worst-case scenario when planning a project and budget for delays of this kind: at the very least, the possibility of disruptive vegetation should always be allowed for, and resources for a biological survey factored into the budget.
Non-native invasive species have the potential to cause devastating harm to the ecology of a region, and to the health of its human inhabitants.
The presence of invasive species on a site earmarked for development can delay a project’s progress, and if such delays are unanticipated they can result in heavy financial penalties.
It therefore makes excellent sense for architects to allow for the presence of disruptive plant species when drawing up plans.
Forewarned is forearmed, and provided construction professionals keep abreast of the current thinking on invasives, their presence need not necessarily create an insurmountable problem.
If you are unsure if your property has an invasive plant species, such as Japanese Knotweed, contact us today by calling 0800 389 1911 or contact us online.