Habitat – Woodland – Discover-Nature

Forest Floor

Two main types of forests grow in the regions between the tropics and the poles, deciduous forest and coniferous forest. A majority of energy from sunlight is captured by the canopy vegetation, with little leftover to reach the forest floor. And yet, the lowest level of the forest has an abundance of food and organisms.

Deciduous species are mainly hardwoods including oak, birch, maple, ash, beech, and hickory. These trees have leaves that are broad and flat, designed to catch sunlight. Conifer forests are made up mostly of softwood tree species from the pine and fir families. Most conifers have leaves that are long, thin, and needle-like, a compact form of leaf that is often waxy and designed to withstand the rigors of an environment that is cold and dry for long periods.

^{Green ash tree leaf in summer & autumn by Alain de Maximy}

Chlorophyll is a chemical that is synthesized by plants and gives leaves and needles their characteristic green color. Plants use chlorophyll to absorb energy from sunlight and use that energy to power the process of photosynthesis which creates carbohydrates, providing food for the rest of the plant. Senescence, the process that occurs when a plant stops making chlorophyll, happens as seasons change and day length shortens while temperatures fall. As chlorophyll is removed, leaves and needles lose their green hues and show their underlying colors of browns, reds, and oranges even as they die and fall to the forest floor.

^{Black beetle on forest floor by Undefined, Getty Images; Forest floor fungi cluster in Autumn woods by Vladimir Srajber, Pexels; Springtail on fallen log by Henrik L, Getty Images; Lush moss covering the forest floor by Doina Gherban}

Fallen leaves create a thick layer of litter, broken down by a rich variety of decomposers including mosses, fungi, insects, and other invertebrates. Decaying vegetation releases nutrients back into the soil to be used once more as food for other forest plants. The annual leaf fall adds an estimated 2,600 pounds of vegetation per acre back into forest habitats worldwide.

In deciduous forests, all of the leaves typically fall in late autumn opening up the forest floor to sunlight in early spring. A group of plants known as spring ephemerals take advantage of this sunlight to quickly flower, bloom, and reproduce before leaves re-appear and shade once more rules the forest floor. In conifer forests, where shade is ever-present, flora is restricted to shade-loving species such as ferns and fungi. In addition, fir and pine tree needles are high in acid content and their leaf litter is only broken down by a relatively few fungi species over long periods of time.

All forest floors are rich with many organisms present throughout the year. Invertebrates including insects, fungi, and small mammals spend their entire lives living in the leaf litter. Detritus from leaf fall provides food and nutrients throughout the year to the plants and other organisms living in these wonderful habitats. As you walk the forests, no matter what the season, think about all of the life going on around you each day on the rich woodland floor.

Autumn Foods

Meteorological fall began September 1st, marking the beginning of cooling temperatures that lead into winter, the coldest time of the year in the northern hemisphere. As the days begin to cool, many plant species are producing ripe fruits and seeds and starting the process of going dormant until next spring’s warming temperatures and longer days signal a beginning of the next growing cycle. Some animals, especially birds, travel long distances, migrating to areas that stay warm throughout the year. Those who stay through the coldest months depend on having food sources available even while plants are dormant.

_{Grey-headed coneflower seed head by Laura Fischer Photography}

The best winter food sources for wildlife are native plants with berries and seeds available throughout the colder months. Birds including woodpeckers, robins, waxwings, bluebirds, thrushes, chickadees, quail, and thrashers rely on robust insect populations in summer. In winter, when insects are no longer available, having another food source such as seed heads and berries left standing in your garden fulfills this need while adding visual interest and wildlife watching opportunities for you.

^{Food items shown above: Acorns on forest floor by Liz West, Oct 2006; Shellbark hickory nuts by HeikeRau, Getty Images; Pine cones with seeds by GordonImages, Getty Images}

Several tree families including pine, hickory, oak, and cherry offer fruit and nuts lasting through the winter. Along with grass and wildflower stems, trunks and branches also provide habitat for insect eggs and larva that will emerge in the spring. Over winter, insects in these stages are available as food for foraging species that use beaks and claws to dig them out. Stems growing close together provide additional benefits as thickets that provide protection against cold winds and harsh weather and hiding places that are safe from other predators.

^{Berries & Seeds above: Aster seeds by David Hansche, Getty Images; Sunflower at sunset by Hazal Ak, Getty Images; Wild elderberries by StargateChris, Getty Images; Thistle seeds by JTCanada, Getty Images}

Sunflowers, elderberries, and serviceberries are important food sources for fall migrators and winter inhabitants, providing fat and energy to stay warm and active. Aster, thistle, and conifer seeds released throughout the colder months are a favorite food source for finches and other small perching birds. Oak acorns, beechnuts, and hickory nuts are eaten by many woodland animals including squirrel, chipmunk, deer, wild turkey, fox, and quail.

^{Wildlife enjoying an offering: Blue tit on suet by Hedera.Baltica, Dec 2022; Lunch by Audrey, Feb 2008; Pine siskins on thistle by Yooperann, May 2015; Purple finches by Stan Lupo, Oct 2016}

Some of these animals also forage through our backyards in winter as many berry producing plants in the wild are stripped bare during late autumn and early winter. Backyard plantings and feeders provide important supplementary food sources for these animals. A variety of species to consider planting include American persimmon, blackberry, blueberry, elderberry, raspberry, cranberry, paw-paw , and prickly pear cactus, holly, sumac, hackberry, viburnum, hawthorn, bayberry, red cedar, and juniper. You can learn more under Garden For Wildlife on the National Wildlife Federation website at https://www.nwf.org/Garden-for-Wildlife/Food.

Nature journaling is a great way to track your observations and learn more through later research

Opportunities to observe wildlife in your own backyard can be an exciting way to learn. Try tracking which plants are being eaten and at what times during the changing seasons. Record the weather conditions during those periods to learn what foods are relied upon during colder, harsher winter weather. Try a variety of suet, seed and nut varieties in feeders to attract a range of animals to your backyard for fun wildlife watching and education.

Oak Tree Habitat, pt.3

In the past couple of blogs, we learned that oak trees are a keystone species in their habitat, especially for the vast network of relationships between oaks and insects.

^{Ladybug on oak tree leaf by EMFA16, Getty Images}

^{Leaf litter and under-bark room for rent, by Wayne S. Grazio, Nov 2013}

^{Insect holes & homes on cork oak, Quercus suber, by Bloor4ik, Getty Images}

Oak trees and their surroundings provide shelter and food from leaves, wood, bark, sap, flowers, pollen, and acorns to thousands of species of insects and other invertebrates. Shelter is provided on the tree, inside cavities or other fissures, among the leaf litter, and around the root systems. As oaks age, there are more opportunities for shelter and food, including after branches or the whole tree dies and falls to decay on the forest floor.

^{Chickadee nest by Jack VandenHeuval, Getty Images}

^{Chickadee eating a caterpillar by Bettina Arrigoni, May 2018}

Over 900 caterpillar species have been identified in oak habitats, more than three times the number found in forests dominated by maple trees. Canopy leaves and branches provide shelter and nesting opportunities for dozens of bird species who find a ready source of food within the insect populations. Ninety percent of bird species feed insects, especially caterpillars, to their young. The Carolina Chickadee feeds four to six chicks for 16 days before they fledge. Mealtimes require 400 to 500 caterpillars each day.

^{Aphids and ants by oday222, Getty Images Pro}

^{Philodromus praedatus spiders live mainly in mature oak trees, by Nikk, May 2016}

^{Oak gall by Michael Boubin, Getty Images}

Several species of flies and wasps lay their eggs on oak trees, stimulating a growth hormone in the tree to grow a gall, an outgrowth of bark, around the eggs. When the larvae hatch, secretions from the gall feed the larvae, and the gall provides protection to the developing insects. The abundance of insects attracts other invertebrates from higher up on the food chain. Spiders frequently inhabit mature oak trees hunting and feeding on many of the insect species. Aphid colonies are often found on oak trees, but cause little damage to the tree. Aphids feed on the sap from the tree and secrete a sticky, sugary substance called honeydew, a favorite food for ants. The ants protect the aphid colonies, keeping them underground during inclement weather and herding them up the tree in summer to ensure the aphids are well fed to keep producing more honeydew.

^{Fall webworm, Hyphantria cunea, by Anita Gould, Sep 2015; Polyphemus moth caterpillar, Antheraea polyphemus, by Ed Uthman, Sec 2018; Speckled wood caterpillar, Pararge aegeria, by Dean Morley, May 2013; Linden looper caterpillar, Erannis tillaria, by sankax, Jun 2009}

Insects and oak trees have created an environment rich in food for many of its inhabitants. According to Doug Tallamy, a leading entomologist at the University of Delaware, “caterpillars transfer more energy from plants to other animals than any other type of creature.” The loss of habitat for insects puts considerable strain on all other environments, including ones supporting ourselves. Insects do most of the work of pollination, allowing plants to reproduce. They also provide for quick decomposition and the return of nutrients to the soil for growing new plants. Insects are a driving force of the world’s food webs and are necessary for a healthy environment.

There are over 400 species of oaks worldwide, with about one quarter found in North America. As we have briefly touched upon in this series of blogs, oak trees provide opportunities for healthy habitats for many other species. For information and further discussion on the relationships between caterpillars and oak trees, please see The Nature Of Oaks, by Doug Tallamy.

Oak Tree Habitat, pt.2

In the last blog, we discussed oak trees as a keystone species, substantially affecting the types and abundance of other species in their habitat. There are 400-500 species of oaks worldwide, supporting an extraordinary 2,300 wildlife species not including fungi, bacteria, and other microorganisms. Oak trees in all stages of life and death have numerous biotic relationships with wildlife.

^{Badger in tree cavity by Byrdyak, Getty Images||Golden millipede in Lagos by efeghali, Getty Images||Neanura springtail by Henrik_L, Getty Images||Pileated woodpecker in oak tree by mtruchon, Getty Images||Slug & rollie pollies by Sonya Kate Wilson, Getty Images||Wood Mouse in tree cavity by byjohn, Getty Images}

Fungi are often identified as attacking oak trees, but they can have very beneficial relationships. Fungi growing in the ground assist an oak tree in getting nitrogen, phosphorous, and other nutrients out of the soil, and in return get carbon and energy from the sugars in the tree’s sap. Oaks provide a place to live for over 700 species of lichens, plus uncounted liverworts and mosses. Lichens covering the oak’s surface help to keep them free of fungal infections and invasive insects. Liverworts and mosses help oaks to retain water and release it into the soil over a long period of time. As oak limbs fall and decay, water retention softens the wood providing food and habitat for decomposers.

Green moss on oak tree by tntemerson, Getty Images

Lichen & peat moss on oak by Sean Gardner, Getty Images

Fallen oak leaves are slow to decompose due to their tannin and lignin content, both preservative compounds. Leaf litter, composed of several layers of fallen leaves, becomes habitat for many millions of species including millipedes, springtails, woodlice, slugs, beetles, ants, and other organisms that feed on decaying plants. Through their activities, the creatures of the leaf litter help to return nutrients to the trees.

Oak forest leaf litter by Tina_C_Olsen, Getty Images

Acorns, with high amounts of fats, proteins, and carbohydrates, are one of the healthiest and most sought after foods in the woodland. White oaks, living between 200 and 300 years, will produce about 3 million acorns during their lifetime. Many bird species eat acorns, but oak trees enjoy a special relationship with blue jays, whose beaks are strong enough to pry an acorn open. In autumn, blue jays enjoy feeding on acorns, but also cache them for winter, burying several at a time under a few inches of soil in various locations up to a mile from the originating tree. Although blue jays cache large quantities of acorns, they can only remember and retrieve about 25% of them, allowing many new oak trees to grow and spread into new areas.

Blue jay with red oak acorn by mirceaux, Getty Images

Oak trees support 31 mammal species who consume acorns for food, use the tree for shelter, or use the surrounding habitat for hunting. Gray squirrels and red squirrels favor acorns in the autumn and throughout the winter from caches hidden in nearby locations. They remember far more cache locations than blue jays, but there are still uneaten acorns that will germinate in spring to start new trees. Acorns are also a favorite food for badger, deer, wild board, and wood mouse.

^{Gray squirrel eating acorn by viktor2013, Getty Images}

^{Red squirrel with acorn by Neil_Burton, Getty Images}

Oak trees offer shelter for many species. Squirrels often build their nests high up among the leaves that provide protection from weather and predators. Dead branches, especially those with cavities, may remain on the tree for many years, providing excellent roost sites for bats. Open limbs, leafed areas, and cavities all provide nest sites for a variety of birds. In addition, the many insects drawn to oak trees provide a ready source of food for all of these nesters. Humans have been acorn consumers for millennia. Raw acorns, high in tannin content, can be toxic in larger quantities; but, properly prepared, acorns are high in calories, vitamin C, starch, magnesium, calcium, phosphorous, and antioxidants. They have been a food staple in many cultures and can be found in the records of ancient Greeks, Iberians, Japanese, and English.

Oak trees have many direct and indirect relationships with insects, which we will explore in the next blog.

Beat The Heat

This week, the weather has been hot for the upper Midwestern U.S. with temperatures topping out above 100°F. Combined with high dew points in the mid-70s, the heat index temperature was upwards of 110°F. Here are some ways that plants and animals keep cool in the extreme heat.

^{Mojave Desert by LezusRocks, Getty Images}

^{Kit fox at entrance to desert den by Stevelenzphoto, Getty Images}

Desert environments, where hot conditions exist daily, are home to numerous animal species that live underground. Heat from the sun penetrates soils and sand layers for several inches, but at 20″ below the surface of the sand in the Mojave Desert, temperatures are fairly constant around 86°F while the surface may be over 110°F. Few large mammals are known to use burrows, although kit foxes and humans are two examples. Basements and lower levels in buildings are often preferred areas on hotter days.

^{Shaded walk in the woods by Felixmizioznikov, Getty Images}

Shade from trees is highly effective in creating cooler areas. Leaves are lighter in color than most soils and paved areas, and leaves reflect much of the sun’s radiation upwards, away from the shady area underneath. Denser foliage and rough leaf textures enhance the cooling effect. Under a shade tree, temperatures may drop up to ten degrees and other surfaces no longer exposed to direct sunlight, including our skin, may be 20 to 40 degrees cooler.

^{African elephant by Petr Polak, Getty Images: Black-tailed jackrabbit by Rancho_Runner, Getty Images; Fennec fox by Nattanan726, Getty Images}

Vasodilation occurs when blood vessels near the skin’s surface expand so more blood flows next to the skin. Many animals living in hotter climates, including fennec foxes, black-tailed jackrabbits, and African elephants, have large ears with broad, flat surfaces devoid of hair, fur, or other insulation. The ear’s large surface area is covered by a thin layer of skin and blood vessels. During hot weather, heat carried in the blood through the ear is readily lost to the outside environment, providing a cooling effect for the rest of the body.

^{Large crowd by Shaunl, Getty Images Signature}

Evaporative cooling is another method through which heat can be dissipated from a body. Trees use this method by losing water vapor through their leaves during photosynthesis, cooling the air under the leaves. Humans employ this method in a process called sweating. We lose warm water through skin pores directly to the air around us. Sweating also moistens our skin’s surface, indirectly providing additional cooling as air moves across the skins surface and wicks away additional heat. An important aspect enhancing the effectiveness of this method is our posture. Being supported by two legs, rather than four, exposes much less surface area to the direct rays of the sun, and much more surface area to air currents.

^{Forest path by Inga Nielsen, Getty Images}

While sweating is good for cooling, it is removing water from the body, which must be replaced for the process to continue. Exposure to today’s temperature extremes may result in a loss of three gallons of water or more from an average-sized human. As you are out enjoying nature during hot days, remember to keep hydrating to stay cool and keep other bodily systems healthy.

Oak-Hickory Forest

Oak-hickory forests makeup one-fourth of all the woodlands in the eastern United States. At the end of the last ice age, oaks were only found in the Appalachian Mountains and the driftless section where glaciers did not form in southwestern Wisconsin. In the last 15,000 years they have repopulated the land from the Mississippi River to the Atlantic coastline.

Clockwise from top left: Quercus alba, white oak by Chris Andrei, Getty Images; Quercus palustris, northern pin oak by Michel VIARD, Getty Images; Quercus rubra, northern red oak by ValerijaP, Getty Images; Fraxinus pennsylvanica, green ash by Garsya, Getty Images; Carya ovata, shagbark hickory by Elmar Langle, Getty Images; Prunus serotina, black cherry tree by Ina Hensel, Getty Images

Oak-hickory forests are an open woodland community where trees make up less than 10% of the plant life. Species of both the red oak and the white oak groups dominate these wood including Northern red oak, Quercus rubra, black oak, Quercus velutina, white oak, Quercus alba, and bur oak, Quercus macrocarpa. Two members of the hickory family, shagbark hickory, Carya ovata, and bitternut hickory, Carya cordiformis, are also found in abundance. These forests are rich with several other tree species most notably red maple, Acer rubrum, sugar maple, Acer saccharum, black cherry, Prunus serotina, black walnut, Juglans nigra, and green ash, Fraxinus pennsylvanica.

^{Arisaema triphyllum berries by ES3N, Getty Images}

^{Arisaema triphyllum, jack-in-the-pulpit by Holcy, Getty Images}

The open structure of the forest supports a large variety of other plants that offer food, shelter from predators and weather, and places to raise a family. Food sources are plentiful including fruit-bearing plants of the genus Vaccinium, which includes blueberries and raspberries, and vines from the genus Vitis, which includes several species of wild grape. Bloodroot, Sanguinaria canadensis, and Jack-in-the-pulpit, Arisaema triphyllum, along with several clovers, attract birds and insects that attract larger predators, creating a rich forest community. It is estimated that oak-hickory forests support over 300 animal species including birds, mammals, insects, reptiles and amphibians.

^{Oak woodland by fotoVoyager, Getty Images Signature}

Oak trees provide a haven for wildlife. Acorns, the fruit of an oak tree, are large and heavy, so they do not spread far from the tree. They offer good nutrition and are a favorite of many wildlife species, whether eaten immediately or cached and eaten over time. Oak trees retain their dead leaves throughout the winter, not letting them fall until early spring. The leaves provide shelter from wind and rain, as well as hiding many smaller birds and mammals from airborne predators. Oak trees have craggy bark providing shelter for insects and other small animals including many amphibian species that overwinter under the bark.

After dying, oak leaves retain tannin, a chemical that slows down their decay. As leaves build up on the forest floor year after year, they create thick layers used by amphibians, reptiles, small mammals, and insects for shelter from predators and weather. In winter, the leaf layer provides insulation from the snow and cold, allowing small animals to move around under the snow, hunting for food, or moving to other sites. However, the leaves can be advantageous to some predators, as well. Owls, and other nighttime hunters, have excellent hearing and can easily detect the sounds from crackling leaves as prey attempts to hide and flee.

^{Gnarled tree with large cavity from wepix, Getty Images Signature}

^{Nature lives forever in fallen trunks by Oleksiy Brunets, Getty Images}

Many tree species are susceptible to dry rot of their interior wood, and none more-so than members of the red oak family. This provides natural cavities for woodland species. Woodpeckers, owls, chickadees, and nuthatches, plus squirrels, raccoons, bats, amphibians, and reptiles all use cavities for shelter and protection. Almost 40% of animal species inhabiting oak-hickory forests will use cavities at some point in their lifetimes. As trunks and branches decay and fall to the forest floor, they create opportunities for food and shelter. In addition, animals drawn to these spaces provide food for larger predators.

As you walk through forested areas over the summer, take note of the tree species and the overall structure you observe Can you spot holes in trees, logs laying on the forest floor, and thicker layers of leaf cover? Are the woods open where you can see possible lanes of movement? What plants have fruit or seeds? Keeping a journal of observations helps us to identify the changes and enjoy these rich habitats.

^{Dry oak forest in springtime by Meinzahn, Getty Images}

^{Swamp oak forest in springtime by Aleksander, Getty Images}

Boreal Forest in Winter

The boreal forest is the largest tract of woodland on earth covering 11% of all land area, half again as large as the Amazon rainforest. It stores 30% of the sequestered carbon on earth. The area also contains a mosaic of wet meadows, ponds, lakes, marshes, and bogs interlaced among the trees. Tree species include many conifers, dominated by spruce, plus aspen, birch, willow and alder. The animal life is abundant, with every species that was there before European settlement still remaining.

^{Boreal Forest panorama by Mliberra, getty Images}

The boreal forest is distinguished by short, hot, wet summers and long, dry, cold winters. When the last glaciers retreated northward, many holes and fissures were left behind. As the ice melted, all of these depressions were filled with water. The underlying geology is mostly granite shield, a rock layer that holds the water in and contains few minerals that dissolve in water, yielding very clear water that does not promote algae or bacteria growth. Most lake life is found in the shallow, warmer edges which also provide support to nearly all of the land-based fauna.

^{From upper left clockwise: Alder tree by Mantonature, Getty Images Signature; Spruce trees by Hannu Koskela, Getty Images; Willow tree by smarko , Pixabay; Aspen trees by Adamisovitsch, Getty Images}

Winter time presents many challenges including less sunlight, colder temperatures, less available water, less food and shelter, and increased severe storms. Animals that are active daily have higher energy requirements in winter. They must often change their dietary sources to whatever is available in winter. Grey squirrels and beavers cache food during warmer periods. Birds eat foods higher in calories such as nuts, seeds, dried fruit, and insects found under tree bark. When changes are consistent from year to year, species develop adaptations to meet the requirements of each season and are able to live comfortably throughout the year.

Shelter becomes not only a place to hide from predators, but also provides protection from weather extremes. Snow of different thicknesses and weight covers the landscape. Snow is also a great insulator, keeping cold winds away from exposed skin. There is normally a layer of air between the ground and the snow cover immediately above. Temperatures in this space are warmer than the exposed air above the snow creating a winter habitat that is vitally important for many species. Mice and voles create burrows under the snow where they can huddle together for added warmth. Similarly, air pockets surrounded by a heavy growth of conifer needles create spaces above the snow cover for birds and some larger mammals to shelter. And many larger species will nestle into the snow pack to shelter from storms and wind.

^{Spruce grouse by Impr2003, Getty Images}

^{Willow ptarmigan by Alex Berger, Mar 2022}

Spruce grouse, Canachites canadensis, and willow ptarmigan, Lagopus lagopus, are not able to fly more than several yards. They grow feathers on their feet to insulate them and aid in traction. Grouse use the air layer at ground level to shelter in.

^{Portrait of a snowshoe hare by Jim Cumming, Getty Images}

^{Canada lynx by Carol Gray, Getty Images}

Ptarmigan, along with snowshoe hares, Lepus americanus, and short-tailed weasels, Mustela erminea, all change color to pure white to hide from predators. Snowshoe hare and Canada lynx, Lynx canadensis, have very large feet that aid in walking on snow without sinking in. Arctic fox, Vulpes lagopus, are winter specialists with compact bodies and short legs and ears that limit their exposure to cold, and large, furry paws that enable them to walk on top of the snowpack. With their long, bushy tails wrapped around their heads, they can withstand winds and temperatures to fifty below zero.

^{Stayin’ warm, Arctic fox by PEDRE, Getty Images Signature}

You can learn more about this cold but wondrous habitat by searching online for boreal forest, referring to the southern portions of the habitat, or taiga, referring to the northern portions. Also, look for information concerning seasonal adaptations for species in your own area, or visit a local natural history museum such as the Jurica-Suchy Nature Museum in Lisle, Illinois.

Forest Litter, Hand Lens Views

This week we take a look at one other group of species found in the forest litter, those that we can best observe using a hand lens. Springtails are tiny insects colored gray, brown, and white. They are wingless with a worm-like body, and are named for a unique abdominal structure that allows them to suddenly jump. They are extremely numerous, ranging from 500 to 50,000 individuals per square meter. Springtails may form dense groups that come out in winter on top of new fallen snow earning them the nickname “snow fleas.” They are an important species of decomposer feeding on fungi, decaying vegetation, and live vegetation.

Springtail, genus *Isotoma*, by Ryszard, Aug 2009

Springtails, aka Snow Fleas, by mwms1916, Mar 2015

Soil mites are members of the arachnid family, the same as spiders. When viewed up close, they may look like tiny spiders having four pairs of legs, and a rounded, glossy abdomen in a variety of dark earth tones. Soil mites are decomposers, as well as predators. They feed mostly on decaying vegetation, but also eat springtails, round worms, and fungi.

Red velvet soil mite, *Trombidium sp*, by Alexey Nikodimov, Apr 2018

Pseudoscorpions, also called false scorpions, look like real scorpions without the dagger-like abdomen. They carry no poison, but have two large claw-like appendages in front. They are predators of springtails, soil mites, and certain worm species. Pseudoscorpions have no eyes or ears, living in the dark soil just below the leaf litter. Almost as numerous as springtails and soil mites, they depend on scent and vibration to locate their prey.

Pseudoscorpion by Philippe Garcelon, Mar 2021

Pseudoscorpion by Philippe Garcelon, Oct 2018

Other animal species that can be observed with either your eyes or a hand lends include ants and beetles. These two groups are quite diverse and can be found in all habitats and soil types.

Eastern Bess beetle larva, by Katja Schultz, Jul 2014

Ground beetles by Bernard DuPont, Feb 2006

Beetles make up the largest order of insects with over 300,000 known species. They can be found under decaying logs, under loose bark, and in the leaf litter. They are especially attracted to light sources at night. The larval stage of a beetle is called a grub, often found in shallow soil layers both on the forest floor as well as in our own backyards. Beetles feed on decaying vegetation, live roots, and other plant parts. They are a major food source for a variety of birds, mammals, arachnids, and other predatory insects.

Ants in bark by Michael Jefferies, Mar 2010

Ants are another insect group, forming vast colonies organized into social castes. There is a single queen in each colony plus thousands of workers and soldiers. Each individual has an appointed job serving the colony. Ants provide several ecological functions in any habitat: predators, scavengers, pollinators, recyclers, and soil aerators. Ant species are split into four groups identified as carpenter ants, little black ants, red ants and fire ants.

Forests are stopping grounds for many migrating species of birds, mammals, and insects. Forest litter is an excellent layer of insulation, and many of the species we have reviewed are active throughout the year, providing food for migrators and ecological services to the other year-round inhabitants. I encourage you to get out and observe this exciting habitat as you hike the forest paths this autumn.

Forest Litter, Critters to See

Last week, we started to look at the forest floor and the litter covering it, composed of leaves, dead wood, animal carcasses and other organic waste. A complex community of organisms thrives in this habitat, working to return the nutrients from the litter back to the soil to be used again as food for green plants. The first layer of this community consists of decomposers. This week, we investigate several other layers.

Forest floor & rotten log by DonArnold, Sep2022

Many species can be spotted among the litter, but observing them takes patience. Carefully sorting through leaf litter is a skill learned through practice. Overturning decomposing logs and probing through rotting bark will yield great results if done slowly and without great disturbance to the animals present. Animals can be observed with your eyes, a hand lens, or a microscope.

Using your eyes, there are several species that like moist conditions and are easily found under decaying logs. Many are very active after an autumn rain. Some of the more abundant species are:

Slugs are a type of mollusk with a soft, slimy body that leave a slime trail wherever they go on their nighttime feeding excursions. They eat decomposing leaf litter and animal remains.

Snail, Maple Grove by DonArnold, Sep2022

Snails, another mollusk, are covered with a hard shell for protection from predators and to help retain moisture. They also eat decomposing vegetation and animal remains.

Isopods, also known as wood lice or pillbugs, must have moist conditions because they breathe using gills. Often found under logs after a rainfall, they move quickly using their 14 pairs of legs. There are several hundred species found in field and forest habitats.

Pillbug, *Armadillidium vulgare*, by Dann Thombs, Dec 2010

Millipedes are segmented and covered by an exoskeleton. Feeding on litter and animal remains, they can be found in any slightly wet area. Millipedes protect themselves when threatened by rolling up into a tight ball.

Millipede, Maple Grove by DonArnold, Sep2022 (3)

Millipede defense, Maple Grove by DonArnold, Sep2022

Several species can be found in any litter conditions. Many are predators, hunting and feeding on other animals. Some often found in our forests include:

Centipedes may look like millipedes, but are predators, eating many smaller insects. The first pair of legs by their head are modified into sharp, poisonous claws used to capture and stun their prey.

Spiders have four pairs of legs, no antenna, simple eyes, and powerful jaws with poison glands. The injected toxin liquifies the soft tissues inside the victim’s body, allowing the spider to suck them out. Many species, including the popular wolf spider, are ground dwelling, digging burrows and hunting by night.

Paperbark spider, *Maratus pavonis* by Jean&Fred Hort, Sep 2015

Harvestmen, also known as daddy long legs, are similar to spiders. They have four pairs of very long legs. When disturbed, they will wave the front two pair around to ward off another predator. They feed on small insects and decaying plants and tend to hunt in groups, mostly at night.

Harvestmen, *Phalangium opilio*, by Dann Thombs, Sep 2007

Next we will investigate what a hand lens can reveal about some of the most numerous inhabitants.

Forest Litter

Autumn is a time of year when many changes take place in forests in northern Illinois. Leaves change color and fall off the trees; numerous species start their annual migration; and other species get ready to overwinter here. The forest floor forms a rich habitat, covered with several layers of litter including fallen leaves, dead wood, plant debris, exposed roots, and other organic matter.

Forest leaf litter by DonArnold, Sep 2022

Very few of the leaves that grow in a forest during spring and summer are eaten before they fall off the trees. A majority of the forest biomass litters the forest floor in autumn, providing a large amount of potential food for bacteria, fungi, and other decomposers living in the forest litter.

The top layer of forest litter contains newly fallen leaves. At lower levels, leaves and other debris become wetter. Small holes appear in leaves and around their edges, made by minute insects and mites. These allow bacteria and fungi to enter the interior of the leaves and begin the process of decomposition. As vegetation breaks down it becomes darker in color, and surfaces feel slimy due to the large number of microorganisms living on them.

Leaf litter with holes by DonArnold, Sep 2022

Skeletonized leaf by DonArnold, Sep 2022

Deeper in the litter, leaves have lost much of their soft tissue, leaving only veins and petioles. In bottom layers, leave are often unrecognizable. The organic matter has changed into dark, gritty, moist humus. Complex organic matter, once living, has been broken down to simple, non-organic chemicals and nutrients that are absorbed into the soil. Calcium, potassium, nitrogen, phosphorous, magnesium, and sodium are recycled from decomposing vegetation and animal remains.

Various fungi on rotting log by DonArnold, Sep 2022

Fungi feed on organic matter. Fungi are often not visible, either living underground or are microscopic in size. They produce fruiting bodies in the form of mushrooms, mold, and yeast. Fungal fruits are at the peak of their showiness after autumn rains. Fungi reproduce from spores, grown in the fruit, and released by wind, water, or contact with passing animals, to be spread throughout their habitat.

The most recognized fruits are the many mushroom varieties that appear in autumn. Mushrooms are most often grouped by physical characteristics. Some found in our area include:

Gilled mushrooms are pale white to highly colorful. They tend to grow from the ground or from decomposing stumps and logs, and may be poisonous. They are important field and forest decomposers by DonArnold, Sep 2022

Fleshy pore mushrooms come in many varieties, all having close relationships with specific tree root systems. They have pores instead of gills, loaded with spores under the edges of their caps.

Bolete mushroom by Jon D. Anderson, Oct 2014

Stinkhorns are pale white to red and sharply pointed. They produce a rotten odor to attract beetles and other bugs to spread the spores. They are commonly found among wood chips and decaying vegetation.

Stinkhorn by Yooperann, Jul 2012

Brackets grow by attaching to decomposing logs or tree trunks. They are dark red to deep brown and may grow singly or in clusters. They are hard and woody allowing them to a long time. Brackets by DonArnold, Sep 2022

Puffballs are round and light tan, tending to explode into a cloud of spores when hit by raindrops or falling debris.

Puffball by DonArnold, Sep 2022

Water-cup mushroom by Peter Stevens, Oct 2015

Orange-peel fungus by John Munt, Oct 2014

Cup fungi are brightly colored with upturned edges or deep furrows, such as morel.

Coral fungi grow mostly on logs and stumps. These appear as many branching structures with spores located in each branch.

Coral mushroom by Jim Bahn, Nov 2011

Chanterelles are light colored with wavy, upturned edges holding their spore.

Chanterelle by Sandra Cohen-Rose, Aug 2007

Jelly fungi are brightly colored, pale white to red. Although they appear to be shiny and slimy, they have a dry surface and a rubbery texture. They look like a clump of jelly or laid out in ribbons on branches and logs. Following a wetting from rain, spores appear on the surface to be lifted away by the wind.

On your next forest walk, be sure to watch for mushrooms along the trail, on fallen logs, and on tree trunks and branches. Next week we will take a closer look at what else may be living in the rich habitat beneath your boots!