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.)
A modified or ‘rapid’ version of an existing wetland assessment tool can accurately assess the quality of wetlands, according to researchers. Using the rapid version of the tool, known as the Floristic Quality Assessment Index, can save time and improve upon wetland monitoring strategies. www.sciencedaily.com
GR: This article gives citizen naturalists tools for assessing the health of their neighboring wetlands.
“It’s easy to think of plants as passive features of their environments, doing as the land prescribes, serving as a backdrop to the bustling animal kingdom.
“But what if the ecosystems of the world take their various forms because plant “decisions” make them that way? A new theory presented by Princeton University researchers in the journal Nature Plants suggests that in some cases that may be exactly what happens. In one of the first global theories of land-biome evolution, the researchers write that plants may actively behave in ways that not only benefit themselves but also determine the productivity and composition of their environs.
“Our theory explains biomes based on the new idea that we must consider plants to be smart and strategic,” said senior author Lars Hedin, a Princeton professor of ecology and evolutionary biology and department chair. “This is a global theory that explains why biomes differ in nutrient conditions and in their abilities to respond to disturbances and to absorb carbon dioxide from the atmosphere.” From: phys.org
GR: This article by reputable scientists and published by a reputable journal troubles me. Thinking back to J.P. Grime’s book “Plant Strategies and Vegetation,” I wonder if the authors simply overlooked relevant literature when the proposed and then interpreted their research. Adding more life-history variations to Grime’s work would be preferable to striking out on an independent course to rediscover Grime’s ideas. This interpretive remark by one of the authors is especially troubling: “Tropical nitrogen-fixing plants are smart enough to know when to use costly nitrogen fixation to compete with neighboring plants, and when to turn it off, as if they are sentient beings,” Hedin said.
Frederick E. Clements had edged toward the idea that vegetation behaved as an organism as it matured. I believe H. A. Gleason demolished this idea quite well in his 1926 paper: “The Individualistic Concept of the Plant Association” (Bulletin of the Torrey Botanical Club).
“Tropical tree species could be in much bigger trouble than scientists had thought: A new study, which involved collaboration from dozens of researchers, suggests that at least 36 percent and up to 57 percent of all Amazon tree species are likely at risk of extinction, depending on future deforestation rates. If true, this information would raise the number of threatened plant species on Earth by about 22 percent.
“The research, which was published Friday in the journal Science Advances, combined spatial distribution models of the Amazon with both historical and projected data on deforestation to determine the conservation status of more than 15,000 Amazonian tree species, about two-thirds of which the authors considered rare species. The researchers used listing criteria from the International Union for Conservation of Nature (IUCN), which maintains a “red list” of threatened species on Earth, to decide which species should be considered in danger of extinction.” From: www.washingtonpost.com
GR: With the expected growth of our population and demand for meat and other products from forest soils, the threatened extinctions discussed in this article seem virtually inevitable.