Monday, February 27, 2012

The irony of protecting homes from invasion by planting invasive species

  image from: 
                From the mother-country comes a remarkable example of the quicksand nature of invasive species issues. When two reasonable ideas intersect the domain of invasion biology and ecosystem services, we get a collision of desires arising from the wicked inconvenience of the complexities involved. Simply put, sometimes good ideas have unexpected outcomes. And most of the time, though not all of the time, the unexpected outcomes have a negative impact. Many times the unseen outcome arises because the initial idea or action takes place in the near term while the unintentional outcome shows up later. For example, planting running bamboo, Phyllostachys aurea Carrière ex A. Rivière & C. Rivière, golden bamboo, or Phyllostachys aureosulcata McClure, yellow grove bamboo, will enable fulfillment of short term expectations, and will, in the long run, surely destroy driveways, foundations, patios and neighborly love. 

               So the Metropolitan Police Force in the United Kingdom bravely set out to speak of things of which it knows little in the wrappings of that which it knows much. The Police force set out to offer landscaping solutions to personal security by presenting a list of 30 ornamental plants that will deter criminal intent. And from a pure security point of view they did a good job. The list is a mugger's hell of thorns and entrapment barriers and living barbed wire, and even some poisonous species for good measure.  "Most burglars are lazy. They look for easy ways of getting into a house or garden (and) by taking a few simple precautions you can reduce the risk of being burgled and make your house and garden more secure", the Tribune report notes.[1]  

                When it comes to the invasive species part of the article, there is silence on the issue of invasion biology which is ironic given the topic is defense of the home(land). Perhaps bamboo does not run in England, but for unwary Americans, and loyal Canadian subjects of the Queen, the list is a minefield of ecosystem challenges.  Many of the 30 species are indeed appropriate and useful as ornamental defense of hearth and home, but some are Trojan horses that should remind would be landscapers of Virgil's immortal line:  "Timeo Danaos et dona ferentis".
            First on the list is number 5  "Golden Bamboo - Phyllostachys aurea- Very graceful, forming thick clumps of up to 3.5m high. Less invasive than other bamboos. Hardy. Young shoots in spring." While it is very true that this extremely quick growing indestructible species will create a grove so dense nothing can move within or through it, it is also important to remember that this species also quickly moves across adjoining properties into parks and natural areas as well as the neighbors' manicure gardens. The American Bamboo Society provides a 4 + 4 step plan for removal cheerfully suggesting how easy this will be by assuming you are removing a small patch of say less than one acre. It should go without saying that buyers should beware for some bamboos can form dense, mono-cultural thickets that displace both native and ornamental species. Once bamboo is established, it is difficult and expensive to remove.

               Next up is number 11 - "Purple Berberis - Berberis thunbergii 'Atropurpurea'- Rich purple foliage. Thorny stem. Medium-sized deciduous. Any soil sunny position." Barberries are quickly establishing in eastern North American changing the ecosystems in which they establish themselves. Barberries are Nature's barbed wire and excellent defense against human and animal incursions but Japanese barberry does not stay put. Rather it is dispersed by wildlife and,  "...forms dense stands in natural habitats including canopy forests, open woodlands, wetlands, pastures, and meadows and alters soil pH, nitrogen levels, and biological activity in the soil. Once established, barberry displaces native plants and reduces wildlife habitat and forage. White-tailed deer apparently avoid browsing barberry, preferring to feed on native plants, giving barberry a competitive advantage. In New Jersey, Japanese barberry has been found to raise soil pH (i.e., make it more basic) and reduce the depth of the litter layer in forests."[2]

               Way down the list we find genus only recommendations such as Aralia with no species designation. Here the problem is one of imprecision for there are invasive Aralias such as Japanese Angelica Tree, Aralia elata (Miq.)Seem which can trap the uninformed gardener as well as the unsuspecting burglar.[3]  There is also mention of Mahonia some species of which may be showing signs of invasiveness in the US in certain circumstances. The unintentional irony is the ending statement, however: "Although they will take some time to grow, the end result justifies the effort. They should deter even the most determined burglar." Almost certainly selecting bamboo will disavow you of any thoughts of sluggish establishment and final solution through landscape domination. It is always worth remembering that when it comes to complex systems, simple solutions beget unexpected outcomes; there are no simple problems, no simple answers and no simple solutions.

[1] The 30 plants that can help protect your home against burglary. Telegraph Media Group Limited. February 27, 2012. [accessed February 27, 2012]

[2] Alien Plant Working Group. Berberis thunbergii Barberry family (Berberidaceae). Plant Conservation Alliance. July 7, 2009. [accessed February 27, 2012]

[3] Central Jersey Invasive Species Strike Team (CJISST). Japanese Angelica Tree (Aralia elata). Invasive Plant Fact Sheet. [accessed February 27, 2012]

1 comment:

John said...

They left out Japanese knotweed. This works by decreasing your property value so you're less attractive to thieves. See