CONTENTS

Introduction...... 1

The City Woodland: Nature Next Door...... 1

Life in the Leaf Litter Layer ...... 5 Some of the You Might Find in Your City Woodlands ...... 7

Slugs and Snails ...... 7

Roundworms ...... 7

Worms ...... 7

Water Bears...... 9

Animals with Jointed Legs (Arthropoda) ...... 9

Sowbugs...... 10 , Harvestmen, Pseudoscorpions, ...... 10 Acknowledgements: , , and Symphylans ...... 12 Thanks to our many helpful reviewers: Regina Alvarez (Central Park Conservancy) Proturans, Double-Tails, and ...... 14 Dennis Burton (Schuylkill Center, Philadelphia) Margaret Carreiro (University of Louisville) ...... 15 Robert DeCandido (Linnaean Society of New York) ...... David Grimaldi (American Museum of Natural History) Conserving Leaf Litter 20 Richard Kruzansky (Central Park Conservancy) Human Impact on Leaf Litter Invertebrates...... 20 Mariet Morgan (American Museum of Natural History) Richard Pouyat (USDA Forest Service) Park Managers to the Rescue ...... 22 Katalin Szlavecz (The Johns Hopkins University) And the CBC staff and volunteers What You Can Do to Help ...... 23

Written by: Elizabeth A. Johnson (Center for Biodiversity and Conservation, AMNH) and Resources and Recommended Reading ...... 24 Kefyn M. Catley (Rutgers, the State University of New Jersey) Background research and writing: Raul Hernandez Index...... 25 Edited by: Marc Le Card Artwork by: Patricia J. Wynne Designed by: James Lui

This booklet was produced by the Center for Biodiversity and Conservation. Partial funding was provided by a grant from the New York City Environmental Fund.

Copyright 2002 by the American Museum of Natural History.

Printed on 100% post-consumer recycled paper.

ISBN: 1-930465-11-4 LIFE IN THE LEAF LITTER 1

Introduction think of biodiversity as some- thing remote from their daily lives, but it is just as important hen you think of urban to conserve the biodiversity in animals, rats, roaches, W our city environments as it is to pigeons, or squirrels might save distant rainforests. come to mind. But an astonish- ing variety of species live in cities, some native, others The City Woodland: introduced from other regions Nature Next Door of the world. Many of them live right under our feet. he woodlands in city parks are Timportant to urban dwellers for This booklet will introduce you many reasons. The trees provide to some of the tiny animals (all cooling shade in the summer. They of them invertebrates or animals are beautiful to look at and restful to Life wander through, providing a in the with no backbones) with which we share our city. We will focus break from the high energy of the city. Park woodlands Leaf on the ones that live in the are also home to many woods, on the forest floor; the species of plants and ani- invisible creatures you walk mals. Some animals past unknowingly every time live in the Litter woods all year, you visit one of our city parks. while others, These small animals, along with such as certain songbirds, stop in all the rest of the plants, animals, the woods to rest and feed during and habitats in the city, make their long spring and fall migrations. up the region’s biodiversity. For people who live in the city, the woodlands can be a good place to Biodiversity includes all life on learn about nature. earth and the processes that Woodlands are important in other sustain it. People sometimes ways. Trees and other green plants LIFE IN THE LEAF LITTER 3

produce the oxygen in our called leaf litter. This layer of litter atmosphere. Tree roots hold the provides nesting material for birds in place, helping to prevent soil and squirrels, hiding places for small erosion (wearing away) by wind and woodland mice and salamanders, and water. The leaves and branches protected spots for seeds to escape shield the ground from the impact of notice by hungry birds. It also heavy rain, allowing the rainwater to enriches the soil and keeps it moist filter more slowly into the ground, so new plant seedlings can grow. rather than running off. Equally The leaf litter layer is full of life: it important, woodland vegetation provides both food and shelter to helps filter out air pollutants such as bacteria, fungi, and tiny inverte- soot and some heavy metals. brates — an amazing community of The woods are made up of many living creatures. Some of these ani- layers — trees, understory shrubs, mals (such as earthworms, snails, and and the smaller plants on the ground. millipedes) feed on the litter, break- The soil beneath them is made up of ing it up into smaller pieces. This tiny bits of weathered rock, humus makes it easier for other organisms (decayed leaves, sticks, and other like bacteria and fungi to decompose organic matter), moisture, and small (chemically convert) the tiny litter pockets of air. Healthy forest soil can pieces into soluble chemicals and take hundreds of years to form and minerals, such as various forms of provides both nutrients and support nitrogen, calcium, and sulfur. These for plants and their networks of roots. nutrients are then recycled and used again as food by the trees and other Each year, the woodlands go plants growing in the woods. through seasonal cycles. With the start of spring, trees grow leaves, According to Richard H. Yahner in flower, and produce seeds; with the Eastern Deciduous Forest: Ecology coming of winter, most trees and and Wildlife Conservation, the trees smaller plants lose their leaves. The in a hectare (more than 2 acres) of fallen leaves, small twigs, seeds, and temperate woodland can produce other woody debris that accumulate between 1,500 and 5,000 kilograms on the ground are a natural part of (more than 5 tons!) of leaves, twigs, our forests and make up what is frass (excrement) and other debris every year. Imagine what woodlands might look like if this The process of leaf breakdown, decomposition, were not “taken andEach soil formation spring can the take woodland many years. trees put care of” by these out leaves. New plants sprout from decomposers and the nutrient-rich soil. The cycle allowed to accumu- begins again. Without the richly late undisturbed! diverse community of invertebrates 4 LIFE IN THE LEAF LITTER 5

providing ecological services like and decaying plant matter in which Life in the Leaf found in most environ- nutrient cycling, the soil would soon they live, the plants that grow in the Litter Layer ments — from the be depleted of nutrients and plants soil, and the larger animals living in of forests and deserts, to could not grow. the forest all make up the woodland ince plants and larger ani- boiling hot springs and in ecosystem. (An ecosystem is the sum mals are familiar to most of Not only are these tiny leaf litter S mountain-top ice, and of all the living organisms in a par- us, in this booklet we are going animals valuable in creating good even inside the bodies of ticular environment and their inter- to introduce you to the smallest woodland soil, they themselves plants and animals. actions with each other, as well as creatures (the ones some consid- become food for other forest animals. Although some bacteria with the physical environment er the most important), the In other words, they become part of can produce their own food around them — the rocks, soil, microorganisms and invertebrate the forest food web. Salamanders, by photosynthesis or other weather, and landscape.) animals that live in the leaf litter turtles, and mice feed on earthworms chemical means, most feed on other beneath the forest trees. Scientists and insects, and they, in turn, are Each component of the ecosystem organisms, including other bacteria. throughout the world are making eaten by birds or larger mammals. has a role to play in the environment. Bacteria secrete enzymes that chem- new efforts to study these organ- Larvae (the immature forms of Plants, algae and some bacteria are ically dissolve their food, making it isms, and there is still much to be some insects) that are eaten by producers, able to convert the sun’s easier to absorb. learned about them. forest birds also live in the leaf litter. energy into food — a process called Fungi include mushrooms and Together, these leaf litter microor- photosynthesis. Consumers are those The smallest of these are the bacteria, yeasts. They get their food by ganisms and invertebrates, the soil animals that feed on producers or fungi, protozoans, algae, and viruses. absorbing nutrients from the envi- other animals to sur- Most are so tiny we need a micro- ronment around them, similar vive. Of consumers, scope to see them. Although each is to the way bacteria feed. The the animals that eat important in the soil ecosystem, fungal body is made only plants are called bacteria and fungi are the primary up of many slen- . organisms capable of decomposition, der threads Predators are those the chemical breakdown and cycling (hyphae) that grow animals that hunt of nutrients. In fact, 80 to 90 percent together in a other animals to eat. of the decomposition of dead plant mycelium. Each of Scavengers eat dead and animal matter is accomplished these individual filaments can plants and animals. by bacteria and fungi. absorb nutrients. Fungi are one of the The decomposers Bacteria are the most numerous most important components in our are mainly bacteria living things on the planet. They are forest soils, since they are the only and fungi that feed organisms capable of decomposing on dead plants and the tough lignin in logs and fallen animals and break branches. They also serve as food for them down chemi- creatures that inhabit the soil, such cally into nutrients.

Top: Nitrogen-fixing bacteria live on The forest ecosystem: Energy the root nodules of some plants from the sun passes from (legumes such as peas, for instance). plant to animal, and from These bacteria help convert nitrogen animal to animal. As each is There are many kinds of bacteria from the air into a chemical form the eaten in turn and ultimately in soil and leaf litter. plants can use. decomposed, their nutrients are returned to the soil. Above: Fungal mycelium with repro- ductive cells. 6 LIFE IN THE LEAF LITTER LIFE IN THE LEAF LITTER 7

as mites, springtails, shapes many beetles and and sizes. The Here are some of the more common leaf litter animals nematodes. ones that live on the you might find in your city woodlands. surface of the ground Mycorrhizal fungi have well-developed eyes are a special group of fungi acid soils prevent them from devel- and legs and readily move about SLUGS AND SNAILS that live in close associa- Mushrooms release oping shells, whereas slugs can be spores which will among the leaves in search of Phylum Mollusca Gastropoda tion with plant roots. They soon develop into | | | common there. food and shelter. Often, they are very important to life in new mycelia. There are approximately a thousand will move deeper into the litter the forest, since they help plant snail species within North America ROUNDWORMS during the drier summer months. In roots absorb vital nutrients such as alone. Snails have coiled shells into Phylum Nematoda contrast, those animals living deeper | phosphorus and nitrogen from the which they retreat for protec- in the soil tend to be smaller and soil. In fact, many plants could not tion, whereas slugs have no Most roundworms, also more worm-like. Since they live in live without mycorrhizae. In return, shell. Both produce a thick called nematodes, are an environment without light, many the plant gives the fungus the nutri- layer of slime to help microscopic, worm-shaped have no eyes. ents it makes by photosynthesis in a them travel from animals found in a variety of process called mutualism, a “you Some animals, such as springtails leaf to leaf. Most environments. Many are aquatic scratch my back, I’ll scratch yours” (Collembola), spend their entire species are found in environments (living in water) rather than arrangement. lives in soil and litter. However, that can provide them with a plenti- terrestrial (living on land). Some many groups of are ful food source, moisture, shelter roundworms live in the guts of Most of the animals in the woodlands found in the leaf litter only at certain and usually a source of lime, which other animals, while still others are invertebrates, those animals with- times in their lives. Some bees use provides the calcium snails need to live inside the roots of plants. out a backbone. These the litter and soil habitat for nesting. develop their shells. For these rea- The ones that live in soil have include earthworms, Cicadas spend their sons, many snails and slugs are a critical role to play in recy- slugs and snails, and entire larval stage under- common in leaf litter, where they cling dead organic materials. arthropods. Arthropods ground, feeding on plant hide by day, emerging to feed on Generally, they feed on bacteria are invertebrates with rootlets. Other leaves and fungi at night. The leaf and fungi, on small earthworms, and an exoskeleton (a hard insects, such as litter provides just the food and other roundworms. Nematodes supporting outer certain moths moisture they need to survive. can occur in staggering covering) and and bees, Snails are rare in ever- numbers, sometimes jointed legs, such as spend the green forests millions per spiders and insects. winter hiber- because the square meter Most of these small, nating under the (about a square yard). generally unseen animals protective leaf dwell in the top organic layer. When the adult layers of soil. Loose leaf litter insects emerge from the lit- WORMS provides hollow spaces ter in spring, they often move Phylum Annelida Class Oligochaeta | | | between the leaves where into other nearby habitats to find a This group of invertebrates is repre- many such creatures live. mate, food, or new nesting sites. sented in the leaf litter community These invertebrates by earthworms and potworms. come in many Earthworms (Lumbricidae) are long and slender. Some, such as night- crawlers, can grow to be quite large, Slug eggs, shown here with newly emerged and many are capable of burrowing young, are commonly deep into the soil. They have no found in leaf litter. 8 LIFE IN THE LEAF LITTER LIFE IN THE LEAF LITTER 9

casting

eyes and instead use the 8,000 enchytraeids and 700 lumbri- bristles on the surface of cids found in a square meter of their skin to feel their way meadow soil. moisture they dry out completely around in their under- and shrivel up; they remain in this The earthworms you might find in ground environment. state, alive but motionless, until they an urban park in the Northeast again have access to water. In dry Earthworms are very today are all recent immigrants from leaf litter they are only found as important in maintaining Europe and Asia. They were warty eggs and cysts. Water bears healthy soil, especially in brought here accidentally in ship are very sensitive to lack of oxygen, agricultural areas. As they ballast and in the soil of potted soil compaction, and soil particle eat their way through the plants. Although earthworms were size, which restricts the depth to soil, the tunnels they create make once native to the northeastern which they are found (5-10 cm). Soil it easier for water and air to move United States, the glaciers of the Ice species feed on algae, bacteria, pro- cocoons into the soil. This is essential for Ages pushed the range of the origi- containing tozoa, rotifers, nematodes, and earthworm plant growth and also increases the nal worms further south. Our “latest organic detritus. They in turn serve eggs activity of microbes, which in turn arrivals” thrive in our city park as food for a variety of predators. promotes decomposition and nutri- woodlands, feasting on leaf litter. In ANIMALS WITH JOINTED LEGS ent cycling. As earthworms eat the fact, they are consuming so much Phylum Arthropoda leaves at the surface and excrete that they are removing the leaves | bristles waste (called castings), they also before other decomposers, like Arthropods, the largest and most help to mix and move nutrients fungi, can feed on them. This is diverse group of animals on earth, through the soil, and their fecal resulting in a thinner organic layer are characterized by a hard material provides additional sites for in some city parks and less food and exoskeleton and jointed legs. microbial activity. The famous evolu- shelter for other Arthropods tionary biologist, Charles Darwin, forest floor was so impressed by the collective inhabitants. City “power” of earthworms that he park managers wrote his last book about are now studying this commonly them. problem to find a way to balance the found in leaf litter include earthworm populations. (sowbugs), chelicerates (such as spiders and pseudoscorpi- gizzard ons, daddy longlegs, and mites), Potworms myriapods (millipedes, centipedes, segment (Enchytraeidae) are WATER BEARS and symphylans), and hexapods small, whitish worms more tolerant Phylum Tardigrada (proturans, double-tails, springtails, than earthworms of acidic soils with | and insects). high organic matter content. They Water bears are microscopic animals are usually confined to the top few with four pairs of clawed, stumpy The fauna of leaf litter inches of soil and feed primarily on legs and a conical snout. and soil is so incredibly diverse, and decomposed plant remains and Tardigrades, even terrestrial occurs in such enormous numbers, species, are aquatic and are crop fungal mycelia. that it is difficult to describe, and unable to function with- should be experienced first- Both groups of worms can out a film of water hand. Howard Ensign occur in vast numbers, with over surrounding Evans, in his book Life on them. Without mouth 10 LIFE IN THE LEAF LITTER LIFE IN THE LEAF LITTER 11

a Little and, in adult males, doubling as a Known Planet, reproductive organ. they are the only crustaceans adapted Pseudoscorpions can be found in says of those who for life on land. They use gills Because their diet consists mostly a variety of habitats: in soil, would explore this (pleopods) to breathe; these need to of insects, spiders are very impor- ground litter, under tree bark, in world that “they will be be kept moist, so sowbugs are mostly tant in controlling insect popula- caves, in host nests of larger rewarded with an array of active at night and in damp environ- tions. Web-spinning spiders that organisms, on rock or mud animals a good deal stranger than ments. One group of isopods, the live on the ground use the dried surfaces. From time to time those to be found in books on pre- pill bugs, will curl into a tight ball leaves in leaf litter to anchor their they engage in a unique historic life.” In terms of sheer when disturbed. webs. Free-hunting spiders also form of transportation called numbers of individuals, springtails SPIDERS, HARVESTMEN, thrive on small invertebrates that phoresy. In this behavior, the are impressive; 40,000 to 50,000 PSEUDOSCORPIONS, MITES live in the leaf litter. Some com- pseudoscorpion attaches itself to individuals typically occur in a square Subphylum | mon families which occur a larger animal host and allows meter of leaf litter and soil. Species Class | Arachnida in leaf litter include jumping spi- itself to be transported around richness is also impressive, with ders (Salticidae), line weaving spi- (a great way to save energy!). more than 40 species of Collembola Spiders ders (Linyphiinae) dwarf spiders occurring in temperate deciduous Order | Araneae (Erigoninae), Hahniidae, wolf spi- Harvestmen woodland or undisturbed grassland. Order | Opiliones Spiders are a domi- ders (Lycosidae), sac spiders Mites are found in even larger These animals are sometimes nant predatory (Clubionidae), and crab spiders numbers and with similar species called daddy longlegs because group in the leaf (Thomisidae). Many spiders over- richness. If we scale up these num- most have extremely long, stilt-like litter. They have four winter in the litter layer, sheltered bers, Evans (1993) estimates an legs and a small, rounded, compact pairs of legs and a body divided from cold and wet. acre of English pasture supports into two parts, the cephalothorax body. The kind you are most likely to find on the surface of 666,300,000 mites, 248,375,000 and . Although all spiders Pseudoscorpions springtails, 17,825,000 beetles and 135 produce silk, only some use it to the ground have long legs that Pseudo- enable them to crawl over and million other assorted arthropods! build webs to catch their food, scorpion, Order | Pseudoscorpiones which consists mainly of insects. life size through the thick leaf litter. Animals in this order have Other spiders sit in hiding and Harvestmen living deeper in four pairs of walking legs like SOWBUGS wait for their prey to pass by. Even the litter have much shorter legs. spiders, but they superficially These animals are predators, Subphylum | Crustacea with eight eyes, most spiders still resemble scorpions or feeding on both live and dead ani- Order Isopoda don’t see very well. To help sense | very small lobsters, their environment for moving mal matter, unlike spiders that This group is composed hence their name. prey, they have specialized hairs take only live prey. They have stink of what we know as sowbugs. Unlike scorpions, (setae) on their legs. Spiders also glands for protection, and can Sowbugs have hard, flattened they do not have a possess special called secrete toxic substances to deter exoskeletons, and seven stinging tail. However, pedipalps, used for handling prey, predators, but are not known to be pairs of legs. They are pseudoscorpions do poisonous to people. In desperate mostly dull brown or slate have powerful “jaws” situations, harvestmen can gray in color. Characteris- MALE and pincer-like claws for “release” part of a leg to escape. tically, they have two pairs of SPIDER pedipalps grabbing prey, which they The wound heals quickly, but the antennae, one long, one short. subdue with help from the poison lost leg will Sowbugs are scavengers, cephalothorax glands in their jaws. They feed never grow eating mostly dead or decaying on springtails, mites and back. plant material like rotting wood. A abdomen any smaller inverte- distant relative of crabs and crayfish, spinnerets brate they can catch. 12 LIFE IN THE LEAF LITTER LIFE IN THE LEAF LITTER 13

Mites fungi and rotting segment. Most of the more Soil centipedes (Geophilomorpha)

Order | wood. than 10,000 species of millipedes are slender and worm-shaped, and currently known in the world are tend to be found deeper in the soil. Common in leaf litter, mites are Mesostigmatid mites are herbivores or scavengers. They They have no eyes but rely on many small (less than 1 millimeter) but free-living predators in the soil and consume decaying plant matter, sensory hairs to help them find prey, very abundant. In fact, there can litter, eating other small inverte- , and fungi, contributing typically small earthworms. Stone be several hundred thousand brates like springtails, other mites, significantly to the production centipedes (Lithobiomorpha), in individual mites in a square bacteria, and fungi. They are of humus. Long-lived, they contrast, live on the leaf litter sur- meter of woodland soil. lighter-colored than oribatids have the potential to sur- face. Active and efficient hunters, They have short legs and and are distinguishable from vive 10 years. Millipedes they eat small insects, which unsegmented bodies. Slow- the third group, the prostig- live in the upper soil layer they catch with poison pincers. moving, they eat decaying plant matids, by having their stigmata, and in leaf litter, under material, mold, or other or breathing holes, on the MESOSTIGMATID rocks, logs or bark in moist Symphylans smaller soil organisms, sides of their bodies. The environments, and are usually active thus playing an important prostigmatids have their breath- at night. Generally, they are found Class | role in the leaf litter food web. ing holes at the base of their most abundantly in soils rich in These invertebrates are often Mites in turn are fed upon by a mouthparts. They eat calcium, which they need for building mistaken for either centipedes or variety of predators such as larger nematodes, other smaller their exoskeletons. As a protective millipedes. They do look like small mites, spiders, and centipedes. arthropods and algae, mechanism, many millipedes can centipedes, and in fact are often fungi, and bacteria. There are three categories of soil exude a smelly, cyanide-based referred to as “garden centipedes.” Some prostigmatids live on and leaf litter mites: liquid that can burn skin Symphylans are other animals as parasites. tiny, colorless, The oribatid mites are best repre- if handled. Their thick Female symphylan and well-suited sented by the moss and beetle exoskeletons also pro- depositing fertilized to life under- eggs on moss. mites. Oribatids live in soil and PROSTIGMATID vide protection from ground in the are very numerous. They are predators, and some MILLIPEDES, CENTIPEDES, soil pore dark-colored with hard, shiny millipedes can roll themselves AND SYMPHYLANS spaces around “shells.” They eat a variety of into a ball for extra protection. Subphyla | plant rootlets. They have no eyes, leaf litter material, Centipedes but instead have many sensory cells including bacteria Millipedes at the tips of their antennae and at the and yeast, algae, Class Diplopoda | base of the third to last pair of legs. Adult millipedes have long, segmented Class | Chilopoda Unlike centipedes and millipedes, bodies with two pairs of legs per Centipedes can be found in leaf litter ORIBATID and soil, under rocks and logs. They are voracious predators of other How to Tell single leg invertebrates, especially small Millipedes from earthworms. Centipedes Centipedes have pincers just behind their heads on the first Look closely! body segment, which they Millipedes usually use to pierce their prey have two pairs of and inject their poison. legs for each body pair of legs segment; centipedes always have only Stone centipede in pursuit of a one pair. pseudoscorpion. 14 LIFE IN THE LEAF LITTER LIFE IN THE LEAF LITTER 15

their terminal body segments carry and long, well-developed a pair of silk-producing spinnerets, springing organs. Those Incomplete life cycles, as which spin silken threads used to that live deeper in the soil typified by crickets, occur deter predators. Most species are are smaller, colorless, with when the insect egg develops into a omnivorous and can feed on either reduced eyes or no eyes, short minute version of head plant or animal matter, preferably antennae, and no springing organ. the adult (called a live organisms and finer plant Springtails live about a year, feed- nymph) and grows rootlets, which explains why some ing on fallen leaves, other detritus, through successive species are considered serious crop Above: algae, and fungi, converting them moults into a full-size thorax pests. They are capable of consum- Diplurans fighting. Below: into humus. Some eat the fecal adult. Many well-known ing 20 times their own weight of Japygid guarding pellets of other soil animals, while groups of insects, vegetable matter in 24 hours. eggs underground. still others eat small nematodes. including flies, bee- Proturans, Double-tails, Together with mites, springtails tles, bees, and and Springtails under stones, or in deeper litter make up the most abundant group butterflies and and moist soil pore spaces. Of the of leaf litter invertebrates. moths, have complete life cycles in which eggs Subphylum | 70 species present in North America, most are herbivorous, develop into larvae that abdomen Proturans eating decaying vegetation. One do not usually resem- Order | , the Japygidae, has pincer- 3 ble the adults. These larvae in turn Proturans are very small, delicate shaped appendages called cerci, develop into pupae (a growth stage between the larva and the full-grown animals (0.5-2 mm) lacking eyes which make them look like imma- 2 and antennae. Instead, their fore- ture . Despite being blind, adult) from which the reproductive legs, which have many sensory adults finally emerge. japygids are very efficient preda- 1 structures, function as antennae. tors of other small soil animals, Crickets They require moist soil and using their antennae to locate prey. How a jumps. humus, feeding on decaying Insects Order | organic vegetation, fungal mycelia Springtails Field crickets of the Order Collembola family Gryllidae are some- and spores. | Class Insecta | times found hiding in leaf litter. Known for the forked springing Insects are characterized by having Double-tails organs on their that They construct burrows in the soil three body parts, the head, thorax where they store and later consume allow them to jump away from and abdomen. The head bears Order | their enemies, springtails play green plant material. Occasionally This is a group of wingless sensory and food-gathering structures. young cave crickets of the family an important role in the Typically, the thorax has wings and hexapods (animals decomposition process. can also be found. with six legs) without six walking legs; the abdomen holds Crickets are well-known for the They have six legs, are the reproductive, digestive and eyes or scales. They wingless, and seldom grow chirping sounds made by males are whitish or yellow- excretory systems. The life to attract a mate. bigger than one centimeter. cycles of most insects fall ish, with long, slender, There are several groups of beaded antennae and a into two distinct groups; Termites springtails: some live on the sur- those with incomplete pair of “tails” often face of the leaf litter, others deep- and those with com- adult with Order Isoptera used as feelers; hence er down in the soil. Springtails | plete metamorphosis. ball of dung Termites play a vital they are often called found on the surface are larger, “double-tails.” Most pupa egg laid role in the decomposi- richly pigmented, with dense in dung Diplura live in moss, tion of wood, both on the scales or hairs, compound eyes, Life cycle of a dung beetle— complete metamorphosis. cerci larva 16 LIFE IN THE LEAF LITTER LIFE IN THE LEAF LITTER 17

forest floor and in stand- mycelia. True bugs found in the ing but decaying trees. While leaf litter are: jumping ground Beetles undergo com- some termites live above in leaf litter mostly feed bugs (Schizopteridae) which are plete metamorphosis and ground in dry locations, on fungal spores and active jumpers when disturbed; many of their larvae are encoun- many live in moist underground hyphae, or on small lace bugs (Tingidae) which, tered in the leaf litter. All beetle habitats in wood buried or lying on arthropods. Some are wing- although plant feeders, are often larvae have jointed legs on the the soil. They are able to convert less, but if winged the wings found in the litter; minute pirate thorax and they will have some the cellulose in dead plant material are fringed with long hairs. Many bugs (Anthocoridae), which prey parts which are soft, while other with the help of microorganisms species are pests of plants and are on other small arthropods; seed parts are covered by hard plates (protists) that live in their gut. often found in flower blossoms. bugs (Lygaeidae), which feed on (or sclerites). Larvae of ground These small protists secrete the seeds, and flat bugs (Aradidae), beetles (Carabidae) and rove bee- Order Psocoptera enzymes that digest the cellulose. Book Lice| which feed on the sap of fungi. tles (Staphylinidae) are elongated, Book lice feed on algae, lichen, white to yellowish with well-devel- Earwigs organic detritus, fungal spores Beetles oped plates on the back of the and mycelia. Most outdoor species head, thorax, and abdomen, with Order | Dermaptera are winged, while indoor species Order | Coleoptera exposed membranous sections in Nocturnal creatures, earwigs hide are wingless and often found Beetles are a very diverse group between. Often the abdomen ends by day, coming out at night to feed. among old books and papers, of insects, accounting for more in two “tails” (or urogomphi). They have shortened, leathery feeding on molds and known species than any other Scarab beetle larvae (Scarabaeidae) wings, and pincers on their abdo- fragments of dead living thing on the planet. There are whitish, grub-like and usually mens that they use for defense insects. Sixty species are are more than 300,000 described comma-shaped, but have jointed or predation. Many earwigs eat found in leaf litter in the species of beetles in the world, legs on the thorax. United States. dead plant matter in the leaf litter. with over 30,000 in North America The beetle families most common Others eat fresh plant fragments, alone. Like other insects, adult in leaf litter are described below. or fungal spores, algae, lichen, True Bugs beetles have three pairs of jointed and moss. Some species are even legs and one pair of antennae. Ground Beetles (Carabidae) are Order Heteroptera carnivorous, feeding on insects | However, unlike other insects, a very diverse group, with more and spiders. Earwigs, in turn, are Being primarily plant feeders, true adult beetles have a pair of special than 1,700 species known from preyed upon by many other bugs are not often found in leaf front wings called elytra. North America. Most active at animals, such as beetles, spiders, litter. Of those that are, however, These wings, along night, the adults are predaceous centipedes, birds, and some families, like stink bugs with a hard exoskele- or omnivorous, feeding on any lizards. (Pentatomidae), may only be over- ton, form a strong protective invertebrates they can catch. wintering there, while others are armor for this insect. predators, feeding on other Rove Beetles arthropods with their stylus-like Beetles are found in almost (Staphylinidae) make up beaks. A few feed on fungal every terrestrial habitat, and many the largest family of beetles in are even aquatic. Their chewing North America, with 3,100 species mouthparts are well developed, and known. Staphylinids play an beetles feed in a number of ways. important role in the litter eco- system as agile predators feeding Thrips Some feed on a large variety of plant parts, both living and dead. on mites, nematodes, Others are predators, many are Collembola, and Order | Thysanoptera scavengers, some are fungal feed- insect larvae. Thrips are very small insects with ers, and some are even parasitic. Some species are sucking mouthparts. Those found Adult stink bug with nymphs. 18 LIFE IN THE LEAF LITTER LIFE IN THE LEAF LITTER 19

also known to feed on decompos- worms and are found in rotting True Flies feed on decaying organic

ing organic matter and fungi. wood. Because wood is so nutri- Order | Diptera material (both plant and Rove beetles can be recognized ent-poor, click beetles take five to One of the largest groups animal) and fungi, some are by their very short elytra. seven years to mature from larvae of insects (25,000 species also predators. In general, fly to adult. Featherwing beetles (Ptiliidae) known from North larvae are elongated, cigar- or integu- are the smallest known beetles, Two other families of beetles often America), flies are extremely grub-shaped. The skin (or ment being 1 millimeter or less in encountered in the leaf litter are abundant and are found in almost ) is usually soft, pliable, and size. They feed on fungal hyphae carrion and dung every habitat, even, occasionally, often whitish in color. All fly lar- and spores. beetles, both of in leaf litter. Adult flies found vae lack jointed legs on the tho- which can play there are likely to be laying eggs, rax, unlike most beetle larvae. Short-winged mold beetles important or perhaps have just emerged Some may have fleshy prolegs (Pselaphidae) are small beetles roles in the from pupae. There are also some (but not jointed legs), while oth- (0.7- 4.5 millimeters) that prey on litter ecosystem. leaf litter flies that are parasitic on ers have raised ridges or creeping worms, Collembola, insect larvae, Carrion, or burying other insects. Best known are the welts along their bodies that allow mites, and symphylans. There are beetles (Silphidae) dig beneath humpbacked them to move about. over 700 known species, found the bodies of small dead animals, flies, the mainly in leaf litter. burying the carcasses before lay- Phoridae. Weevils (Curculionidae). Almost ing their eggs on them. Both all weevils in this very large family adults and larvae feed on We tend to are plant feeders, and some are such carrion. Dung think of flies as a nuisance, Bees, Wasps, and Ants serious pests of cultivated crops. beetles (Scarabaeinae, or be concerned about how some Those found in leaf litter are Aphodiinae) lay their eggs species transmit diseases, but fly Order | Hymenoptera mostly nut or acorn weevils on pieces of animal dung, larvae play an essential role in Many species of bees and wasps of the subfamily Curculioninae, which they often roll large decomposition. Fly larvae of many build their nests in the ground, and have very long snouts. distances and then bury, ensuring different families live in the leaf beneath the litter layer. Of these, a food supply for their larvae. This Click beetles (Elateridae) are litter and soil, including fungus most of the native bees are solitary behavior is also important in also commonly found on gnats and other families of tiny and do not build large hives as do returning nutrients to the soil. the forest floor. They are midges, crane flies, dance flies, the honey bees that were intro- called click horse flies, house flies, hover flies, duced from Europe. The thick litter beetles fruit flies and many others with- layer also provides protection because of the out common names. While most from the winter cold for hibernat- sound they How a click beetle jumps. ing wasps and bees. Wasps are make when important insect predators, and they flip their native bees are responsible for bodies over. pollinating many of our woodland They are able to arch wildflowers. and snap their bodies There are numerous to right themselves if families of parasitic wasps turned upside-down which are parasites of or if attacked by insect eggs, larvae, pupae predators. The larvae or adults. Some are even are called wire hyperparasites (parasites of 20 LIFE IN THE LEAF LITTER LIFE IN THE LEAF LITTER 21

parasites!) and have fascinating the some trees could be more easily life cycles. Though not regular CONSERVING soil, so uprooted in a strong wind, and roots inhabitants of the leaf litter, when LEAF LITTER that plants near the surface can be more easily found there they will have been and animals have damaged. Soil compaction from looking for hosts to lay their eggs Human Impact on Leaf trouble getting the human foot traffic also increases soil on, or perhaps have just emerged Litter Invertebrates water they need to survive. erosion by increasing surface from the egg themselves. The City habitats are also subject runoff. most common family found in leaf to warmer air temperatures, healthy layer of leaves on the The use of pesticides and other litter is the Trichogrammatidae. which affect soil temperature and A forest floor is a vital component poisons, as well as the introduction The Trichogramma has been the amount of moisture in the soil. of every woodland. The leaf layer of non-native plants, can change the used successfully as a biological protects and nourishes the soil, Users of park and city woodlands, chemistry of the soil, which will control agent for insect pests. enables rainwater to filter into the wittingly or not, have a large impact eventually affect life in the leaf litter. Ants (Formicidae) are true social ground, harbors seeds, and provides on the fascinating, diverse and frag- Native plants are those that have animals; they live in highly organ- hiding places for woodland animals. ile community of largely unseen litter originated in a particular habitat. ized colonies and communicate by Without it, the woodlands would be invertebrates. People destroy habitat Non-native invasive species were chemical means. Depending on unable to exist and reproduce. (if not the animals themselves) by brought or spread from somewhere species, ants can be farmers, What creates a good litter layer? compacting the soil when they walk else. In addition to their effects on hunters, collectors or even Plenty of litter — the natural kind — on the leaf litter. Worse still, some soil chemistry, the leaf litter produced slaves of other ants. They feed leaves, sticks, and seeds, and a people ride their bicycles and other by these non-native plants may be on a variety of food, including healthy population of leaf litter vehicles over it. When soil is com- unpalatable to soil organisms. dead plants and insects. animals (without too many earth- pacted, the pore spaces in the soil Invasives can also out-compete and Ants play a very important worms), and loose, moist soil. collapse, making it difficult for water crowd out native plant species from role in soil ecology by aerating to penetrate and making air less an area. and enriching the soil as they build Sometimes these ingredients are available to the roots of plants. This Fortunately, even in a city environ- their colonies. In addition, many hard to find in a city park. Environ- inhibits plant growth and affects the ment, there is much that we can do forest plants such as violets and mental pollutants and acid rain are root growth of trees. The root sys- to protect this fragile community of wild ginger depend on ants for known to affect the terrestrial tems become shallower, with greater creatures. seed dispersal. As the ants collect world of leaf litter invertebrates. lateral growth. This means that seeds to eat, they may accidentally Some pollutants are making city drop some on soils more “water repellent.” the return Scientists still do not know why this trip to their nest, is occurring, but it means that it is thus spreading the difficult for rainwater to filter into seeds around.

Scientists have identified 38 species of ants in New York City’s Central Park. 22 LIFE IN THE LEAF LITTER LIFE IN THE LEAF LITTER 23

stay on the trail. Put up signs • Don’t drop litter on the litter. decompose where they fall. where people might otherwise go Keep parks and woodlands free “Leaving” leaves and other organic off-trail and trample on the leaf from trash. Materials such as matter around and under trees litter and all the invertebrates plastics and glass disrupt the allows them to become part of that live in it. normal functioning of the soil. the soil and provide nutrients for Minimize use of pesticides or other plants and the trees them- • • Clean up after your dog and keep chemicals such as lawn and garden selves in the coming year. Fallen dogs away from trees. Because fertilizers that could disrupt the trees also provide habitat for many their urine is acidic and very chemical balance of the soil. of the animals and microorganisms concentrated, it can burn through tree bark. Dog droppings also that live in the leaf litter. • Use deicing salts sparingly; these Minimize soil disturbance in pollute the soil. • salts may melt pavement ice woodlands. Cultivating the soil in winter, but pollute the soil. Use could harm plant and animal life • When fishing near woodland other deicers like CaCl(calcium Park Managers because it disturbs soil formation 2 areas, take any extra bait home. to the Rescue and the natural layering of the chloride) rather than NaCl Please don’t release worms into leaf litter. Soil disturbance may (sodium chloride). the wild. Park managers work to keep the also allow the seeds of non-native • Encourage restoration projects • Plant native species in your own park healthy and natural, safe and invasive plant that use native plants and control garden; this will encourage the enjoyable. Here are some techniques species to non-native invasive species. proliferation of the native leaf litter used by park managers to maintain become invertebrates. Avoid introducing dynamic woodland ecosystems and established. Foster research and education • invasive species (which might protect the variety of life that about the complex relationship of colonize nearby parklands) into depends on the forest for survival. soil and the living organisms in • Encourage your garden. park visi- the woodland. Let fallen leaves and branches • tors to (and even whole fallen trees) • When possible, minimize your driving. Cars and other machinery What You Can Do to Help contribute to air pollution. Auto emissions contribute to acid rain, A decaying log is Park visitors can also help protect the which leaches some of the impor- full of life. amazing diversity of life in our city tant nutrients needed for plant woodlands in the following ways: growth out of the soil. These emissions stimulate plants to • Appreciate the natural, unmani- produce a protective waxy layer cured look of your woodlands on their leaves, which may make and parks. Leave the organic the leaves less digestible to soil materials, fallen foliage, twigs and animals. The pollutants may also branches around and under trees cause the soil surface to become undisturbed. water repellant, thus affecting seed • Avoid unnecessary trampling on germination and seedling survival. the fragile soil. Stay on designated trails. • Volunteer. Support park activities that help protect biodiversity. 24 LIFE IN THE LEAF LITTER INDEX 25

References and Recommended Reading INDEX Barnes, R. D. Invertebrate Zoology, fourth edition. Saunders College, Philadelphia. 1980. A abdomen, 10, 14, 15, 16, 17; Borror, D. J. and R. E. White. A Field Guide to the Insects of North America cicadas, 6 illustration–spider, 10 North of Mexico. Peterson Guide. Houghton Mifflin Co., NY. 1970. city parks, 20, 21 acid rain, 20; and soil nutrients, 23 click beetles (Elateridae), 18; Borror, D.J., C.A. Triplehorn, and N.F. Johnson. An Introduction to the Study of acid soil, 7, 8 illustration, 18 Insects, sixth edition. Saunders College, Philadelphia. 1989. air pollution, 2, 23 Collembola (springtails), 6, 10, 14-15, algae, 4, 5, 9, 12, 15, 16 Darwin, C. The Formation of Vegetable Mould Through the Action of Worms, 17 antennae, 10, 13, 14, 15, 17 with Observations on Their Habits. 1881. Reprint. Vol. 028, The Complete Works crab spiders (Thomisidae), 11 ants, 19, 20; illustration, 20 of Charles Darwin. New York University Press, NY. 1990. crane flies, 19 aquatic, 7, 9, 17 crickets (Orthoptera), 15 Evans, H.E. Life on a Little Known Planet. Lyons and Burford, NY. 1993. arthropods, 6, 12, 16, 17; diversity in crop pests, 14, 18 leaf litter, 9, 10; Kricher, J. Peterson Field Guide to Eastern Forests. Houghton Mifflin Co., crustaceans, 9, 10 auto emissions, 23 NY. 1998. cryptostigmatid mites, 12 cycling of nutrients, 3, 4, 5, 8 Levi, H. A Golden Guide to Spiders. Golden Press, NY. 1987. B cysts, 9 D Sauer, L. J. The Once and Future Forest. Island Press, Washington, DC. 1998. bacteria, 5, 7, 9, 12; as producers, 3, 4; illustration, 5 daddy longlegs (harvestmen) Silver, D. M. One Small Square: Backyard. McGraw Hill, NY. 1993. bees, wasps, and ants (Hymenoptera), (Opiliones), 9, 11 19 dance flies, 19 Yahner, R. H. Eastern Deciduous Forest: Ecology and Wildlife Conservation. bees, hibernating, 6, 15; life cycle of, Darwin, Charles, 8 University of Minnesota Press, Minneapolis. 1995. 15; native, 19 decomposers, 3, 4, 9 Zim, H. S. and C. Cottam. A Golden Guide to Insects. Golden Press, NY. 1956. beetles (Coleoptera), 6, 15, 16, 17; decomposition, 5, 8, 14, 15, 15, 18, 19 larvae, 17; families, common in leaf deicing salts, and soil, 23 litter, 10, 17-18 double-tails (Diplura), 9, 14; biodiversity, 1, 23 illustration, 14 birds, 1, 3, 4, 16 dung beetles (Scarabaeinae, book lice (Psocoptera), 16 Aphodiinae), 15, 18; illustration, 15 dwarf spiders (Erigoninae), 11 C E calcium, 3, 7, 13 calcium chloride, 23 earthworms (Annelida), 3, 4, 6, 7-9, 13, carnivorous, 16 20; native vs. exotic, 9; illustration, 8 carrion beetles (Silphidae), role in earwigs (Dermaptera), 16; Diplura nutrient cycling, 18 mistaken for, 14 castings, 8 Eastern Deciduous Forest: Ecology and cave crickets, 15 Wildlife Conservation, 3 cellulose, 16 ecological services, 4 centipedes (Chilopoda), 9, 12, 13, 16; ecosystem, 4, 5,17,18, 22; illustration,4 illustration, 12, 13 elytra, 17, 18 enzymes, 5, 16 (The classification used in this book is based on the Integrated Taxonomic cephalothorax, 10; illustration–spider, 10 erosion, 2, 21 Information System. See the ITIS web site at http://www.itis.usda.gov.) cerci, 14 chelicerates, 9, 10 Evans, Howard Ensign, 9, 10 exoskeleton, 6, 9, 10, 13, 17 26 INDEX INDEX 27

F J nitrogen, 3, 6 S featherwing beetles (Ptiliidae), 18 Japygidae, 14; illustration, 14 nitrogen-fixing bacteria, illustration, 5 sac spiders (Clubionidae), 11 fecal material, 8, 15 jumping ground bugs non-native plants, 21, 22, 23 salamanders, 3, 4 fertilizers, 23 (Schizopteridae), 17 nutrients, 5, 6, 8; nutrient cycling, 3, 4, scarab beetle larvae (Scarabaeidae), 17 fishing worms, 23 jumping spiders (Salticidae), 11 5, 8; nutrient leaching, 23 scavengers, 4, 10, 13, 17 flat bugs (Aradidae), 17 nymph, 15; illustration, 16 sclerites, 17 flies, 15, 19; fly larvae, 19 L seeds, 3, 20, 22; seed dispersal, 20 food web, 4, 12 lace bugs (Tingidae), 17 O seed bugs (Lygaeidae), 17 frass, 3 larvae, 4, 6, 15, beetle larvae, 17, 18; omnivorous, 14, 17 setae, 10 fruit flies, 19 fly larvae, 19 organic materials, recycling of, 7, 23 short-winged mold beetles fungal mycelia, 5, 8, 14, 16-17; leaf litter, 6, 7, 12, 13, 19, 20; 21, 22, 23 oribatid mites, 12 (Pselaphidae), 18 illustration, 5 composition of, 3-4;earthwormsin, 9; oxygen, 2, 9 silk; spider, 10; symphylan, 13-14 fungi, as decomposer, 3, 4, 5-6, 9; numbers of invertebrates in, 10 slugs (Mollusca: Gastropoda), 3, 6, 7; as food for invertebrates, 7-8, 12, 13, lichen, 16 P illustration, 7 14, 15, 16-17, 18, 19 lifecyclesofinsects,15,20;illustration,15 parasites, 12, 17, 19-20 snails (Mollusca: Gastropoda), 3, 6, 7 fungus gnats, 19 Life on a Little Known Planet, 9 park managers, 9, 22 soil, 5; chemistry, 21, 23; disturbance, 22; lignin, 5 park visitors, 23 dog droppings and urine on, 23; G lime, as source of calcium, 7 pedipalps, 10; illustration–spider, 10 erosion, 2, 4, 21; formation, 2, 3, 22; “garden centipedes” (symphylans), 13 line weaving spiders (Linyphiinae), 11 pesticides, 21, 23 illustration, 4; layers, 6; native plants gills, 10 phoresy, 11 and, 21; nutrients, 6,18,23; pollutants, ground beetles (Carabidae), 17 M phosphorus, 6 20; soil comapaction, 9, 21 mesostigmatid mites, 12 photosynthesis, 4, 5, 6 soil centipedes (Geophilomorpha), 13 H metamorphosis, 15, 17; illustration, 15 pill bugs, 10 soot, 2 habitat, 6, 16, 17, 19, 21, 22 mice, 3, 4 plastics, 23 sowbugs (Crustacea: Isopoda), 9, 10 Hahniidae (spider family), 11 microbes, 8 pleopods, 10 spiders (Araneae), 6, 9, 10-11, 12, 16 harvestmen (Opiliones), 10, 11 microorganisms, 4, 5, 16, 22 pollination, 19 spinnerets, of symphylans, 13; heavy metals, 2 midges, 19 pollutants, 2, 20, 23 illustration–spider, 10 hectare, 3 millipedes (Diplopoda), 3, 9, 12-13; potworms (Enchytraeidae), 7-9 spores, 14, 16, 18 herbivores, 4, 13, 14 illustration, 12 predators, 9, 10, 11,12,13, 14, 16, 17, 18, springtails (Collembola), 6, 9, 11, 12, hexapods (Hexapoda), 9, 14 minute pirate bugs (Anthocoridae), 17 19; defined, 4 14-15; numbers of, 10 honey bees, 19 mites (Acari), 6, 9, 10, 11, 15, 17, 18; in prostigmatid mites, 12; illustration, 12 squirrels, 2 horse flies, 19 leaf litter, 12 protists, 16 stigmata, of mites, 12 hover flies, 19 moths, 6, 15 protozoans, 5, 9 stink bugs (Pentatomidae), 16; illustra- house flies, 19 moults, 15 Protura (Protura), 9, 14 tion, 16 humpbacked flies (Phoridae), 19 mushrooms, 5; illustration, 6 pseudoscorpions (Pseudoscorpiones), stink glands; in harvestmen, 11; humus, 2, 13, 14, 15 mutualism, 6 9, 10, 11, 13; illustration, 11 in millipedes, 13 hyperparasites, 19 mycelium,mycelia,5,16,17;illustration,5 pupae, 15, 19 stone centipedes (Lithobiomorpha), 13; hyphae, 5, 16, 18 mycorrhizal fungi, 6 illustration, 13 myriapods (Myriapoda), 9, 12-14 sulfur, 3 I R symphylans (Symphyla), 9, 12-14, 18; insects, 4, 6, 9, 10, 11, 15-20 restoration projects, 23 illustration, 13 integument, 19 N roots, 2, 6, 21; root nodules illustration, 5 invasive species, 21, 23 native plants, 21; and restoration rootlets, 6, 13 invertebrates, 1, 3-4, 5, 6, 7, 11, 13, 15, projects, 23 rotifers, 9 17, 20, 21; prey of spiders, 11; prey nematodes (roundworms) roundworms (nematodes) T of mites, 12; native, 23 (Nematoda), 6, 7, 9, 12, 15, 17 (Nematoda), 7 tardigrades (water bears) isopods (Isopoda), 10 nightcrawlers, 7 rove beetles (Staphylinidae), 17-18 (Tardigrada), 9 28 INDEX

termites (Isoptera), 15-16 terrestrial, 7, 9, 17, 20 thorax, 15, 17, 19 thrips (Thysanoptera), 16 trash and soil function, 23 true bugs (Heteroptera), 16-17 true flies (Diptera), 19 turtles, 4

U understory, 2 urogomphi, 17 V viruses, 5 W wasps, 19-20; parasitic (microhy- menoptera), 19 water bears (tardigrades) (Tardigrada), 9 weevils (Curculionidae), 18 wolf spiders (Lycosidae), 11 woodlands, 1, 2, 3, 6, 21, 23; woodland ecosystem, 4, 22 worms; earthworms (Lumbricidae), 3, 7-9, 23; role in healthy soil, 6; (see also: nematodes, potworms, roundworms)

Y Yahner, Richard H., 3 yeasts, 5, 12