environmental science – Page 2

Invasive Species on Campus

invasives-5773b — A student helps Scott Woodbury uproot an invasive bush honeysuckle.

Last Friday, we were lucky enough to have a horticulturalist, Scott Woodbury, visit the Environmental Science class. Scott teaches the Native Plant School at the Shaw Nature Reserve, and spends a lot of effort dealing with invasive species.

The extent of the problem on our campus was quite sobering. The invasive trees, shrubs, and vines displace native plants, and animals as well because the native fauna are not adapted to them. A native elm might support somewhere around 300 species of caterpillar, while an imported bradford pear might have just a few; Douglas Tallamy has a good book, Bringing Nature Home, on the subject.

invasives-5779 — This beautiful bradford pear is one of half a dozen at the front of the building. They are quite aggressive however, and their progeny can be found all the way along the creek and up the slope.

invasives-bradford_pear-5796 — A young bradford pear on the slope.

The bradford pears are quite pernicious. They were once favored by landscapers because of their beautiful spring flowers and brilliant fall colors. However, the birds spread their seeds far and wide, and now bradford pear saplings can be found all over the campus. They tend to do better in the grassy areas at the sides of the roads, as well as on the slope overlooking the school that’s still in the early stages of succession. The saplings can be cut down with hand saws, and I doubt anyone would notice that they were gone, but it’s probably going to be tricky getting permission to take down the half dozen mature trees on the front lawn that were planted when the school was built.

invasives-bittersweet-5788 — Bright orange berries on a vine of oriental bittersweet.

The dark secret about the oriental bittersweet vine that’s attacking the trees along the creek, is that they probably came from the Shaw Nature Reserve. Apparently there was a mistake at one of their sales, and one of our teachers bought the wrong species of bittersweet. Cutting the vines that are growing up the tree trunks should slow them down.

invasives-sericea-5799 — Scott Woodbury holds the long stem of a specimen of sericea lespedeza. The entire slope behind him is covered with the species.

Sericea lespedeza has pretty much taken over the slope above the school. This herb was imported for erosion control but was found to be extremely hard to control. On the plus side, while it does well in disturbed areas like the slope, since it is an early succession species, it will be succeeded by the tree species that are now growing up through it. It’s just going to take a number of years.

invasives-bush_honeysuckle-5768 — Bush honeysuckle.

invasives-bush_honeysuckle-5772 — Hand pulling a bush honeysuckle.

At least the bush honeysuckles, which can be found all along the creek, can be hand pulled if they’re small enough. However, we’ve got some pretty big specimens that are much harder to get rid of. They grow fast, leaf-out early, and crowd out the native shrubs.

Interestingly, all these four species are all from Asia. The latitude is similar to Missouri’s so species from that part of the world can thrive here where the climate is similar and they don’t have their native predators and pests. Scott did point out a couple of native species — eastern red cedars and sugar maples — that have become much more aggressive because of all the fire suppression over the last few hundred years, but that’s a story for another time.

invasives-2511 — Invasive versus native species.

Hurricane Sandy – Before and After

sandy-300 — Before and after photos from Hurricane Sandy. Via washingtonpost.com.

Above: dramatic photos from before and after Hurricane Sandy.

Below: Time-lapse video of the Hurricane from satellite.

Environmental History of St. Louis Seminar

The St. Louis Zoo is hosting a couple interesting presentations that should be relevant to my Environmental Science class. One, by Andrew Hurle from the University of Missouri, St. Louis, is on environmental history and environmental justice issues in the St. Louis (6pm on Wednesday).

The second is by the sustainability Director in the City of St. Louis Mayor’s Office, Catherine L. Werner.

Melting Permafrost and a Warming Climate: Another not-so-Positive Feedback

There’s a lot of organic matter frozen into the arctic permafrost. As the arctic has been warming much faster than the rest of the planet, the permafrost soils are thawing out quite quickly. As they unfreeze, they set up a positive-feedback loop. The warming organic matter starts to decay releasing carbon dioxide into the atmosphere, exacerbating the warming.

To generate the estimates, scientists studied how permafrost-affected soils, known as Gelisols, thaw under various climate scenarios. They found that all Gelisols are not alike: some Gelisols have soil materials that are very peaty, with lots of decaying organic matter that burns easily – these will impart newly thawed nitrogen into the ecosystem and atmosphere. Other Gelisols have materials that are very nutrient rich – these will impart a lot of nitrogen into the ecosystem. All Gelisols will contribute carbon dioxide and likely some methane into the atmosphere as a result of decomposition once the permafrost thaws – and these gases will contribute to warming. What was frozen for thousands of years will enter our ecosystems and atmosphere as a new contributor.

— Harden and Lausten (2012): Not-So-Permanent Permafrost via USGS Newsroom.

Mycorrhiza: Symbiosis Between Fungi and Plants

Symbiosis in action (specifically an example of mutualism):

Mycorhizes-02 — Fungus (white) attached to the roots of a small pine tree (brown). Image via Wikipedia User:Silk666.

The Amanita [mushroom] family also includes some of the best-known tree-partnering fungi on Earth. Many of the mushrooms in this family are mycorrhizae — fungi that coil themselves in and around the roots of trees.

The tree provides them with food it makes topside in return for a vastly improved underground absorptive network. This network, made by the many searching filaments of the fungus, brings much more water and many more minerals to the tree than it would otherwise be able to procure for itself.

— Frazer (2012): Deadly and Delicious Amanitas Can No Longer Decompose on The Artful Amoeba Blog in Scientific American.

redwood — Redwood saplings with (right) and without (left) mycorrhizae. Image by Mike Amaranthus, USDA.

In fact:

Some plants are “mycorrhizal-obligate,” meaning that they can’t survive to maturity without their fungal associate. Important mycorrhizal-obligate plants in western North America are sagebrush, bitterbrush, and some native bunchgrasses.

— BLM: Mycorrhizal Fungi

This comes from an interesting article by Jennifer Frazer on Amanita mushrooms, which are so symbiotic with their plant hosts that not only do they not decay them, they actually can’t decay them.

Human Microbiome Project: Figuring out who our Microscopic Symbiotes are, and what they do

Although we are, by number at least, 90% bacteria, only recently have scientists with the Human Microbiome Project have just begun figuring out who those bugs are.

[The] trillions of microbes that make their homes in and on us do an excellent job keeping us healthy (crowding out harmful microbes) and sated (breaking down a lot of the food we ingest).

Now that disturbances in this rich microbiome community have been linked to weight gain, inflammatory bowel disease, vaginal infections and risk for infection with harmful microbes (such as methicillin-resistant Staphylococcus aureus, or MRSA), the importance of understanding what makes up a “healthy” microbiome has become even more apparent.

— Harmon (2012): Body Count: Taking Stock of All the Bugs That Call Humans Home in Scientific American.

On the Origin of Species

Perhaps the key reason for the profound influence of Darwin’s “On the Origin of Species” is that it’s such a well written and well reasoned argument based on years of study. It is a wonderful example of how science should be done, and how it should be presented. In the past I’ve had my middle schoolers try to translate sections of Darwin’s writing into plainer, more modern English, with some very good results. They pick up a lot of vocabulary, and are introduced to longer, more complex sentences that are, however, clearly written.

Diagram and notes on the bird species P.Nanus from The Zoology of the Voyage of H.M.S. Beagle, Part 3: Birds by J. Gould and G.R. Gray (edited by C.Darwin). Image via Darwin Online.

The text of “On the Origin of Species” is available for free from the Gutenberg library. Images of the original document can be found (also for free) at the UK website, Darwin Online (which also includes the Darwin’s annotated copy). Darwin Online also hosts lot of Darwin’s other works, as well as notes of the other scientists on The Beagle, among which is included some wonderful scientific diagrams.

This year, I’m going to have the middle schoolers read the introduction, while the honors environmental science students will read selected chapters and present to the class — this will be their off-block assignment.