GR: As I’ve often reported, only construction and total habitat destruction have done as much as invasive plants and animals to reduce global biodiversity and productivity. Introduction of invasive species is continuing its impact and the rate is accelerating. Global warming is gaining fast, and will combine with the others of the human impacts to push the human impact on the Earth to extremes that will require millions of years of recovery after we are gone. Here’s a report by Paul Simons on an invasion that will take years of intense labor to stop.
Invasive rhododendron ponticum spreading on the Isle of Mull, Scotland. Photograph: Mark Boulton/Alamy Stock Photo
“Rhododendrons are flowering now in a magnificent springtime spectacle – but they are thugs, invading some of our finest and most precious countryside with catastrophic impacts on wild plants and animals.
“Rhododendron ponticum was first brought to Britain, probably from Spain or Portugal, around 1763 for botanical gardens and used on big estates as cover for game birds. But the shrub has spread out of control with huge damage to many native woodlands, heaths and other wild places like the Snowdonia national park. The plant now covers 98,700 hectares, roughly 3.3 per cent of Britain’s total woodland, a report by the Forestry Commission found, and Scotland has been hit particularly hard, where it covers 53,000 hectares.
“Rhododendron grows into huge bushes with thick vegetation that blocks out sunlight and smothers most other wild plants and trees, stopping them from growing or regenerating. Its leaves are toxic to animals and repels wildlife from earthworms to birds. Many bushes have become infected with the highly pernicious tree disease called sudden oak death that threatens many types of trees and shrubs. Outbreaks of the disease in the UK, especially on larch trees, have often been linked to Rhododendron ponticum.
“Each plant can produce one million or more tiny seeds each year that spread in the wind, and it also spreads with massive tangles of branches rooting in the ground. The plant is incredibly difficult to get rid of by digging up or using herbicides. Snowdonia national park and several other sensitive areas have tried to destroy the invading rhododendron involving hundreds of people over many years digging up the plant. It’s expensive, time-consuming and takes years to completely eradicate.” –Paul Simons (Source: A spectacular thug is out of control | Science | The Guardian.)
GR: Invasive plants and animals are destroying native ecosystems. Some species that we take from their homes and release in other regions explode across the new habitat. Free from their natural competitors and diseases, the species are like Superman freed from Krypton’s light. Local species cannot compete and are replaced. I’ve studied some of the plant species that do this. You can read what I’ve learned here.
My work focuses on invasive plants, but animals can be equally destructive. The Eurasian Wild Boar is a good example of the hundreds of species impacting North American ecosystems. Here’s a brief review of the history of its introduction and spread in the U. S.
Feral Eurasian Wild Boar
Invasive species are second only to complete habitat destruction by roads and buildings as destroyers of nature. Global warming will take their place over the next few decades, but that doesn’t mean that we can ignore invasives. Protecting nature requires that we tend to all our destructive behaviors. My articles include suggestions and references to other resources for invasive plant control.
The article below from the National Geographic Society Blog reports that the invasive species problem is growing. Humans really began spreading species 500 years ago when they began crossing the oceans. It surprises me that we’ve left anything behind, but apparently we left enough invasive species behind to continue and even accelerate this form of the human impact.
“A study released this month has illustrated that the rate of species introductions to locations outside their native range is increasing faster than ever. Hanno Seebens and many others used the date of first records of introductions to plot the total number of new non-native species records every year since 1500. They show that this is not only increasing, but accelerating, with no signs of saturation. The increase was particularly marked since the 1800s. This global exchange of species is not good news, as although it increases species richness at the regional scale, globally the species richness of our planet declines as species go extinct.
Global temporal trends in first record rates (dots) for all species (a) and taxonomic groups (b–q) (Source: Nature Communications)
“New Zealand was singled out as one country whose trend was negative compared to the rest of the world. As any traveller to New Zealand will have encountered, the biosecurity importation laws and policing are rigorous and every passenger is screened. In tandem with a ‘white-list’, where only certain non-native species are automatically permitted entry, and all others must be assessed, has clearly assisted in protecting New Zealand’s biodiversity and primary industries from the global trend in accelerating species introductions.” –James Russell (Continue reading: Species Introductions Accelerating – National Geographic Society (blogs).)