Recently I read a book that made me reconsider how I see my local “alien invaders”. Every bioregion has them: non-natives you wish weren’t around but are just impossible to get rid of. Here on the West Coast of Scotland we are plagued with Rhododendron ponticum and Japanese knotweed.
The picture above is of Rhododendron ponticum having formed a monocultural understorey with Mountain ash being choked out.
However, I now realise that I may have been conditioned by my background in conservation and countryside management. I’m constantly being told that the “aliens” are aggressive baddies that need eradicating – even if it means huge effort and great cost.
But what if this thinking is not only one-sided, but actually wrong? This is what Fred Pearce claims in The New Wild: Why Invasive Species will be Nature’s Salvation. He argues that the invaders are only “invading” because of the mess us humans have caused. We’ve been polluting and running amok with our chainsaws and biochemical arsenals to deplete biodiversity, but are shocked when new opportunistic species move in to fill the void we’ve created.
Pearce reckons that in many cases species actually start to clean up the mess; of the numerous examples he looks at globally a few stick out in my mind: Water Hyacinth in Lake Victoria and an introduced jellyfish in the Black Sea.
What about my two baddies: can I see them differently? I have always observed that they are filling in the gaps left by our neglect and mismanagement. Rhododendron moves into overgrazed woods lacking an understory and into clear-felled sitka spruce areas that look like battle zones. Knotweed takes on roadside verges and the edges of lochs strewn with rubbish.
Of course, they do create monocultures, but if left would they not eventually achieve a balance with other species? I suggest we concentrate our efforts on tackling two more important land management issues: overgrazing and the practice of planting dense sitka spruce monocultures, only to clear-fell them forty years later.