savannah – Discover-Nature

American Asters

As we enter early autumn, it is late in the growing season for the central United States, and many insect species are still actively looking for pollen and nectar as they get ready for winter. Migrating birds and species that overwinter here are also seeking daily meals. Fall flowering plant species are much fewer in number than summer blooming species, but include varieties of American asters, Symphyotrichum spp.; goldenrod, Solidago spp.; black-eyed Susans, Rudbeckia spp.; coneflower, Echinacea spp.; sedum, Sedum spp.; and anise hyssop, Agastache spp.

^{American Aster by Andrew McKinlay, Aug 2013; Anise hyssop by Steve Guttman, Oct 2011; Black-eyed Susan by Jodi Grundig, Aug 2009; Coneflower by Bonnie Leer, Jul 2008; Goldenrod by Cathy Baird, Aug 2013; Sedum by Eleanor Martin, Jul 2009}

In this blog, we take a look at American asters, which make up a genus of over 100 species of perennial plants, all of which are native to North America. Asters like full or partial sun and reach heights of between one and six feet. They display a variety of colors from white to blue to purple. They do best in wet soils. Asters are often grown in pots or used in borders, as well as being found in a variety of wild habitats including forests, savannas, prairies, and wetlands.

^{American painted lady on Pacific aster by TJ Gehling, Oct 2023; Gulf fritillary on white aster by Vicki DeLoach, Ot 2012; Leaf cutter bee, Megachile spp, on New England aster, by GreenRavenPhotography, Sep 2016; Metallic green bee on white aster by Jacqui Trump, Oct 2021; Pecks skipper, Polites peckius, on smooth blue aster, Symphyotrichum laeve, by Tom Potterfield, Sep 2016}

These asters are an excellent source of nectar and pollen sought by both long-tongued and short-tongued bees, butterflies, wasps, and beetles. All parts of the plant are edible, although some species may contain mild toxins, making the animal eating it ill. Leaves and stems are eaten by grouse, turkey, chipmunks, mice, and deer. The abundant seeds are available long after most other flower seeds have been consumed or buried. Large quantities of seeds are eaten by migrating bird species including dark-eyed junco, Junco hyemalis; indigo bunting, Passerina cyanea; American tree sparrow, Spizelloides arborea; and American goldfinch, Spinus tristis.

^{American goldfinch, Spinus tristis, by F Delventhal, Jul 2022; American tree sparrow, Spizelloides arborea, by Tom Benson, Nov 2018; Dark-eyed junco, Junco hyemalis, by Stan Lupo, Mat 2020; Indigo bunting, Passerina cyanea, by Mitchell McConnell, Apr 2013}

Asters are sometimes referred to as a keystone species. Keystone species can be either plants or animals that are essential to maintaining the health and functions of the entire ecosystem to which they belong. The introduction or loss of a keystone species may significantly affect an entire ecosystem in either positive or negative ways. Populations of other organisms may be altered, habitat changes can be observed, and biodiversity can rapidly change. American asters, along with the other late blooming flower species, are an important food source late in the growing season for maintaining a healthy population of pollinators, migrating birds, and over-wintering wildlife.

To learn more about seasonal changes and how our native species are adapted to handle these conditions, consider a visit to the Jurica-Suchy Nature Museum or a nature center near you.

Oak Tree Habitat, pt.1

Oak trees, genus Quercus, have over 400 species worldwide, but almost one-third are threatened with extinction. They are a keystone species, playing a central role in supporting the entire habitat in which they live. They maintain the structure and stability within their ecosystem, substantially affecting the types and abundance of other species. Oaks make up only 2% of plant species, but they directly support more than 30% of all plants and animals.

^{A great oak in Nottingham Forest by Peter Shaw, Getty Images}

Oak trees live from a few decades to several centuries. The Great Oak, Quercus agrifola, a species of Coast Live oak in California, is estimated to be over 2,000 years old. Oaks clean the air by absorbing pollution and sequestering carbon. They provide shelter, food, shade, and help to reduce erosion. Humans get food from the acorns, dyes from the tannin, and wood for construction, ships, and barrels, plus cork for stoppers and oak chips for smoking meat, fish, and cheese.

^{Red oak with new leaves, Quercus rubra, by aleroy4, Getty Images}

^{Oak forest leaf litter in winter by Whiteway, Getty Images Signature}

In spring, tender new leaves containing fresh sap are consumed by a variety of insects. In fall, older leaves will fall to the ground, but are slow to decompose, building up many layers of leaves over time which provide shelter for small woodland ground dwellers and food for decomposers.

^{Branches of red oak with catkins, Quercus rubra,}
^{by anmbph, Getty Images}

^{Texas Red Oak female flowers, Quercus buckleyi by Doug Goldman, USDA-NRCS National Plants Data Team}

Oak trees have both male and female flowers. Male flowers grow in early spring in long clusters hanging from tree limbs. The pollen is a favorite food for a large variety of insects, especially bees. Pollen is released slowly, over several weeks, to be blown by the wind to the female flowers, which appear as tiny, red flowers near the tips of twigs and new shoots. Female flowers are eaten by insects and are a favorite of red and gray squirrels. Oak flowers are one of the earliest food sources for animals in spring, and must be abundant on every tree so that some are able to survive to produce acorns, the seeds of the oak tree.

^{Bur Oak acorns, Quercus macrocarpa; Northern Red Oak acorns, Quercus rubra; Live Oak acorns, Quercus virginiana by Steve Hurst, ARS Systematic Botany and Mycology Laboratory, USDA-NRCS PLANTS Database;}

In late summer, after pollination, the female flower will produce a large, green nut called an acorn, which will mature in autumn, turn brown, and fall from the tree. Acorns are a nutritious food source for many animals, being high in energy, carbohydrates, and fat. In the eastern U.S., many species are dependent on acorn production, and the amount of available acorns significantly influences population sizes. Some acorns will find suitable ground for sending out a root and starting a new tree, but most will be eaten. Masting, an over-abundance of acorns, occurs every few years. It is thought that masting creates a better chance for new oak trees to grow by overwhelming the animal populations’ need for food. As a secondary result, animal populations may expand immediately following a mast year, only to have higher than normal mortality when food resources return to normal for the following years.

^{Bur Oak bark, Quercus macrocarpa by Herman, D.E., ND State Soil Conservation Committee, USDA-NRCS PLANTS Database}

^{Dead oak log in Bialowieza Forest by Nirian, Getty Images Signature}

Oak roots grow close to the ground’s surface and extend well beyond the circumference of the tree’s crown. A complex network of fungi live on the roots and provide additional nutrients to the tree, keeping both species healthy. As the trees grow and age, roots and bark develop crevices and holes in their surfaces, or chunks may become loose, providing niches for plants and animals to shelter and grow. Exposed wood gradually dies and decays providing even more habitat and food for decomposers and the other wildlife that live on them.

In our next post, we will take a look at some of the many species that oak trees directly and indirectly support with shelter, food, and breeding opportunities.

The Woodlands at the Turning, an Illinois oak savannah, by Justin Kern, Nov 4, 2013

A Big, Cool One

Elephants are the largest land mammals and they live in a variety of habitats in tropical and subtropical regions. Their native habitat is often savanna, grassland or forest although they can also be found in desert, swamp, and highlands. These areas get twelve hours of sunlight each day, with warm, daily temperatures averaging from the lower 70s to above 100˚F for animals living in the desert. Heat and gravity are two natural factors that affect all large animals, and elephants have some unique methods and body design to compensate for both.

^{Walking in Kruger National Park by Simone Eman, simoneemanphotos}

Elephants have a massive skeleton with solid bones in their feet, legs, hips, and ribs that provide excellent support for all of their weight. Lots of muscles, both large and small, allow easy movement while still protecting their vital organs. But not all of the bones are solid. The skull is honeycombed throughout, so it is light enough that the neck can support the head and allow for many small and precise movements of the trunk, the ears, and the tusks. The brain is small for an animal of this size, but elephants are quick learners, have an excellent memory, and are one of the smartest animals.

^{Elephant’s foot by sboofek, Getty Images}

^{Elephants foot tread by skynavin, Getty Images}

While small animals, such as ants, can hang on to a vertical surface, elephants require a solid set of legs to stand and walk on. They actually stand on the tips of their toes, located along the front edge of the foot. The center and back of the foot is one large pad behind and under the toes that cushions each step and helps to carry their weight. The large, round flat of the foot spreads the weight evenly over a larger area, and their soles have treads to provide traction on slippery or uneven surfaces.

^{Elephant ears by Harvey Sapir, Pexels}

Heat from the sun, and from the exertion of the muscles performing under the tremendous weight of the body, must be dissipated efficiently. This task is handled by the elephant’s ears, which are very large and very thin. Hundreds of blood vessels run through each ear close to the skin to radiate heat away from the body. The blood, now cooled, can be circulated throughout the body. Skin over the rest of the body is thicker, but there is little to no fat underneath, nor is there any fur or hair covering the outside to trap heat. The skin also has many wrinkles creating much more surface area than smooth skin, allowing more heat to be lost to cooler air and water.

^{Celery anyone…by eugen_z, Getty Images}

An elephant’s trunk is a nose-arm-hand all wrapped into one. They can pick up large and heavy objects as well as being able to manipulate the sensitive tip to grab tiny and delicate objects. To help control the heat, they often will suck in a trunkful of water and using the end of the trunk like a shower head, spray all of the water across their body to wet down and cool off. Similarly, they can snuffle up a load of dust to spray across dry or wet skin to create a coating to help keep away biting insects and provide protection from the sun.

Elephants are built to move easily and efficiently in their environment, and they have several methods and adaptations to deal with their size and the heat. Next week we will discover more about family life and the lands they live in.

The Elephant Trunk

An elephant’s trunk is an amazing body part. It is a 300 pound nose-arm-hand about seven feet long. It contains 50,000 muscles, but no bones or cartilage, making it strong and flexible. A vast array of nerves controls it. Elephants use their trunks for a variety of tasks including:
• smelling an approaching rainstorm from 150 miles away
• locating food by smell including grass, branches, and fruit
• lifting objects up to 400 pounds
• reaching food 20 feet off the ground
• using it as a snorkel when swimming underwater
• using the top and bottom lip to pick up a single seed off the ground
• sucking up to 2.5 gallons of water and squirting it into their mouths
• sucking up water to squirt over their backs to cool off
• curling it around large quantities of food to place in their mouths
• controlling the shape and size of the nostril to modulate sounds
• snorting dirt to spray over their backs
• picking up and throwing objects in defense
• entwining with another’s trunk for a friendly hug