The harlequin ladybird is a clever little devil

GR:  This is a good example of the unintended harm caused by human efforts to improve nature for human benefit.  Accidental and intentional introductions of plants and animals from one continent to another releases the plants and animals from their native predators and diseases. If they multiply, they can replace whole ecosystems and cause drastic reductions in biodiversity and productivity. After the immediate effects of habitat loss to construction, human-introduced invasive species are the most significant contemporary destructor of nature. As global warming effects grow, surviving humans will probably share the Earth with these species.

“Tricked out in Halloween orange and black, a harlequin moves awkwardly through a micro woodland of moss on the concrete as if it were wandering through an alien world, which in some respects it is. This is Harmonia axyridis succinea, a beetle that began its global travels somewhere in eastern Asia between Kazakhstan and Japan.

“Because its larva has an insatiable appetite for aphids and other small insects it was taken to America in the 1980s for the biological control of crop pests. It was so successful that it has been transported into European agriculture, too. To show its appreciation the beetle, called the Halloween ladybug in the US and the harlequin ladybird in Europe, has had a population explosion.

“This is such a common story of what happens when commerce controls nature for its own ends that it comes as no surprise that a creature pressed into servitude causes fear on liberation. It arrived here in 2004 and in 10 years spread throughout an area that took grey squirrels a century to colonise.

Harlequin ladybirds declared UK’s fastest invading species

“Described as a “voracious invader” with a frightening appetite for other ladybirds and the eggs of butterflies and moths, the harlequin causes understandable alarm, given the threat it poses to Britain’s beleaguered wildlife. By the time the harlequin arrived here it was far too late to do anything about it.” –Paul Evans (The harlequin ladybird is a clever little devil).

Desertification and China’s Great Green Wall

“Unlike the Great Wall of China, a 5,000-mile fortification dating back to the 7th century BC that separates northern China from the Mongolian steppe, the Great Green Wall of China-otherwise known as the Three-North Shelter Forest Program-is the biggest tree planting project on the planet. Its goal is to create a 2,800-mile long green belt to hold back the quickly expanding Gobi Desert and sequester millions of tons of carbon dioxide in the process. If all goes according to plan, the completion of the Green Wall by 2050 will increase forest cover across China from five to 15 percent overall.

“The Chinese government first conceived of the Green Wall project in the late 1970s to combat desertification along the country’s vast northwest rim. Soon thereafter, China’s top legislative body passed a resolution requiring every citizen over the age of 11 to plant at least three Poplar, Eucalyptus, Larch and other saplings every year to reinforce official reforestation efforts.

“But despite progress-according to the United Nations’ most recent Global Forest Resources Assessment, China increased its overall forest cover by 11,500 square miles (an area the size of Massachusetts) between 2000 and 2010, with ordinary citizens alone planting upwards of 60 billion trees-the situation is only getting worse. Analysts think China loses just as many square miles of grasslands and farms to desertification every year, so reforestation has proven to be an uphill battle. The encroaching Gobi has swallowed up entire villages and small cities and continues to cause air pollution problems in Beijing and elsewhere while racking up some $50 billion a year in economic losses. And tens of millions of environmental refugees are looking for new homes in other parts of China and beyond in what makes America’s Dust Bowl of the 1930s look trivial in comparison.”  Source: www.healthnewsdigest.com

GR:  A little reading in this article and its references quickly reveals that despite China’s massive commitment to reforestation, desertification is increasing.  Part of the problem is that the land-use practices that led to vegetation loss and soil instability are continuing.  Another part of the problem is that Chinese planners are making the same mistakes made in the U. S. and in other arid regions where managers used nonnative plants to replace depleted natives.

Many of you will be nodding and thinking that whenever land-use managers focus on Human benefits, they lose sight of the need for complete ecosystem health. They focus on potential benefits from foreign species that appear to be suited to growth on degraded lands.  Their goal is to continue profitable logging, livestock grazing, and water diversion.  Therefore, the desert grows.

 

Thanks to Professor Willem Van Cotthem for his efforts to provide a single Internet source for work on desertification (https://desertification.wordpress.com).

Disturbance and Invasive Plants

By Garry Rogers

Disturbance and Invasive Plants:  Introduction

Wild Horses and Weeds

Wild Horses on a Former Great Basin Shrubland Destroyed by Livestock Grazing, Invasive Plants, and Fire.

In the invasive plant literature, disturbance refers to an event that removes plants and alters the soil surface.  “Disturbance is believed to be the major factor favoring plant introductions” (Radosevich et al. 2007:  58).  Without disturbance, invasive plants would find no openings to become established and begin to spread and replace native species.

It is important to understand the nature and origin of disturbance that leads to plant invasions, because, as with global warming, it is often profitable to deny human responsibility for invasions so that a disturbance activity can continue. Continue reading