June 2024 – Discover-Nature

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

This summer, the Jurica-Suchy Nature Museum is undertaking a project to get certified as an arboretum, the second one in Lisle, IL, The Arboretum Village. We will be working with summer research students, staff, and volunteers to meet the Arbnet Certification Program Level I requirements. These specify that we have a written plan, establish a governing body, have a minimum of 25 labeled tree and woody plant species, support our activities with staff or volunteers, and allow public access including at least one public or educational event each year.

While the campus is open to the public, once the accreditation is finalized, tree walks led by student or volunteer guides will be offered. Guides will be able to identify the various species and provide some fun facts about each of the more than 60 species on campus.

A new herbarium display, located in the back of the museum, will bolster these efforts and illustrate plant biology. An herbarium holds a collection of dried plant specimens that are catalogued for easy access. The display highlights some of the several thousand specimens in the museum’s plant collection, including a few of the more unique specimens. Herbaria collections methods are shown including some of our historic plant presses. The display includes slides of plant parts including many large-format slides containing paper-thin transects, or slices, of tree limbs. Transects allow the viewer to perceive structure, color, and variations of wood and bark.

Another new display shows the microscopes that have been used in Benedictine research programs during the late 1800s to the late 1900s. A couple of slide formats are presented including the popular 1″ x 3″ glass slides containing small biological specimens and large-format slides containing slices of plants that are thin enough to allow light through to highlight cell structures.

Early microscopes were “simple,” containing one piece of convex glass that provided 200-300 times magnification. Compound microscopes are the current standard, using two pieces of glass that provide 1000 times magnification. Confocal microscopes use laser light to scan dyed images, and scanning electron microscopes use specialized detectors to form an image from reflected electrons. Some scopes are back-lit, shining light through a mount to the viewer, while others may be front-lit to view 3-D surfaces in greater detail.

Another new display shows animal skulls and bones and highlights how we learn about their form and function. Many species have all the same types of bones arranged in different combinations. From these structures, we can learn which directions an animal is able to see, how the body moves, what types of food are consumed, and how a species defends itself.

Skulls and Bones – Learning about turtles

The summer period is only eight weeks long, but we have nature wellness walks scheduled for the second and fourth Wednesday mornings at 9:00am in June and July. Consider joining us to take a guided walk around Lake St. Benedict. Obtain information and sign up by clicking on the following picture:

The museum is open for everyone, by appointment, on Tuesdays, Wednesdays, and Thursdays from 10:00am to 2:00pm. If you or your group would like to visit, please sign up on our reservation system by clicking on the following picture:

Month: June 2024

Oak Tree Habitat, pt.1

What’s New at JSNM