Leaf Litter bk - Weebly€¦ · in soil and leaf litter. Top: Nitrogen-fixing bacteria live on the root nodules of some plants (legumes such as peas, for instance). These bacteria

C O N T E N T S

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

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

Life in the Leaf Litter Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Some of the Animals 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

Spiders, Harvestmen, Pseudoscorpions, Mites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Millipedes, Centipedes, and Symphylans . . . . . . . . . 12

Proturans, Double-Tails, and Springtails . . . . . . . . . . 14

Insects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Conserving Leaf Litter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Human Impact on Leaf Litter Invertebrates. . . . . . 20

Park Managers to the Rescue . . . . . . . . . . . . . . . . . . . . . . . . . 22

What You Can Do to Help . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Resources and Recommended Reading . . . . . . . . . . . . . . . . . 24

Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Acknowledgements:

Thanks to our many helpful reviewers:Regina Alvarez (Central Park Conservancy)Dennis Burton (Schuylkill Center, Philadelphia) Margaret Carreiro (University of Louisville)Robert DeCandido (Linnaean Society of New York)David Grimaldi (American Museum of Natural History)Richard Kruzansky (Central Park Conservancy)Mariet Morgan (American Museum of Natural History)Richard Pouyat (USDA Forest Service)Katalin Szlavecz (The Johns Hopkins University)And the CBC staff and volunteers

Written by: Elizabeth A. Johnson (Center for Biodiversity and Conservation, AMNH) andKefyn M. Catley (Rutgers, the State University of New Jersey)Background research and writing: Raul Hernandez Edited by: Marc Le CardArtwork by: Patricia J. WynneDesigned 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

L I F E I N T H E L E A F L I T T E R 1

Int roduct ion

When you think of urbananimals, rats, roaches,

pigeons, or squirrels mightcome to mind. But an astonish-ing variety of animal species livein cities, some native, othersintroduced from other regionsof the world. Many of them liveright under our feet.

This booklet will introduce youto some of the tiny animals (allof them invertebrates or animalswith no backbones) with whichwe share our city. We will focuson the ones that live in thewoods, on the forest floor; theinvisible creatures you walkpast unknowingly every timeyou visit one of our city parks.

These small animals, along withall the rest of the plants, animals,and habitats in the city, makeup the region’s biodiversity.Biodiversity includes all life onearth and the processes thatsustain it. People sometimes

think of biodiversity as some-thing remote from their dailylives, but it is just as importantto conserve the biodiversity inour city environments as it is tosave distant rainforests.

The Ci ty Woodland:Nature Next Door

The woodlands in city parks areimportant to urban dwellers for

many reasons. The trees providecooling shade in the summer. Theyare beautiful to look at and restful towander through, providing abreak from the high energyof the city. Park woodlandsare also home to manyspecies of plants and ani-mals. Some animalslive in thewoods all year,while others,such as certain songbirds, stop inthe woods to rest and feed duringtheir long spring and fall migrations.For people who live in the city, thewoodlands can be a good place tolearn about nature.

Woodlands are important in otherways. Trees and other green plants

Lifein the

LeafLitter


called leaf litter. This layer of litterprovides nesting material for birdsand squirrels, hiding places for smallwoodland mice and salamanders, andprotected spots for seeds to escapenotice by hungry birds. It alsoenriches the soil and keeps it moistso new plant seedlings can grow.

The leaf litter layer is full of life: itprovides both food and shelter tobacteria, fungi, and tiny inverte-brates — an amazing community ofliving creatures. Some of these ani-mals (such as earthworms, snails, andmillipedes) feed on the litter, break-ing it up into smaller pieces. Thismakes it easier for other organismslike bacteria and fungi to decompose(chemically convert) the tiny litterpieces into soluble chemicals andminerals, such as various forms ofnitrogen, calcium, and sulfur. Thesenutrients are then recycled and usedagain as food by the trees and otherplants growing in the woods.

According to Richard H. Yahner inEastern Deciduous Forest: Ecologyand Wildlife Conservation, the treesin a hectare (more than 2 acres) oftemperate woodland can producebetween 1,500 and 5,000 kilograms(more than 5 tons!) of leaves, twigs,insect frass (excrement) and otherdebris every year. Imagine whatwoodlands might look like if this

were not “taken care of” by these

decomposers andallowed to accumu-late undisturbed!

Each spring the woodland trees putout leaves. New plants sprout fromthe nutrient-rich soil. The cyclebegins again. Without the richlydiverse community of invertebrates

The process of leaf breakdown, decomposition,and soil formation can take many years.

produce the oxygen in ouratmosphere. Tree roots hold the soil in place, helping to prevent soilerosion (wearing away) by wind andwater. The leaves and branchesshield the ground from the impact ofheavy rain, allowing the rainwater tofilter more slowly into the ground,rather than running off. Equallyimportant, woodland vegetationhelps filter out air pollutants such assoot and some heavy metals.

The woods are made up of many layers — trees, understory shrubs,and the smaller plants on the ground.The soil beneath them is made up oftiny bits of weathered rock, humus(decayed leaves, sticks, and otherorganic matter), moisture, and smallpockets of air. Healthy forest soil cantake hundreds of years to form andprovides both nutrients and supportfor plants and their networks of roots.

Each year, the woodlands gothrough seasonal cycles. With thestart of spring, trees grow leaves,flower, and produce seeds; with thecoming of winter, most trees andsmaller plants lose their leaves. Thefallen leaves, small twigs, seeds, andother woody debris that accumulateon the ground are a natural part ofour forests and make up what is

Li fe in the LeafL i t te r Layer

Since plants and larger ani-mals are familiar to most of

us, in this booklet we are goingto introduce you to the smallestcreatures (the ones some consid-er the most important), themicroorganisms and invertebrateanimals that live in the leaf litterbeneath the forest trees. Scientiststhroughout the world are makingnew efforts to study these organ-isms, and there is still much to belearned about them.

The smallest of these are the bacteria,fungi, protozoans, algae, and viruses.Most are so tiny we need a micro-scope to see them. Although each isimportant in the soil ecosystem, bacteria and fungi are the primaryorganisms capable of decomposition,the chemical breakdown and cyclingof nutrients. In fact, 80 to 90 percentof the decomposition of dead plantand animal matter is accomplishedby bacteria and fungi.

Bacteria are the most numerous living things on the planet. They are

found in most environ-ments — from the soils

of forests and deserts, toboiling hot springs and inmountain-top ice, and

even inside the bodies ofplants and animals.Although some bacteria

can produce their own foodby photosynthesis or other

chemical means, most feed on otherorganisms, including other bacteria.Bacteria secrete enzymes that chem-ically dissolve their food, making iteasier to absorb.

Fungi include mushrooms andyeasts. They get their food byabsorbing nutrients from the envi-ronment around them, similarto the way bacteria feed. Thefungal body is madeup of many slen-der threads(hyphae) that growtogether in amycelium. Each ofthese individual filaments canabsorb nutrients. Fungi are one of themost important components in ourforest soils, since they are the onlyorganisms capable of decomposingthe tough lignin in logs and fallenbranches. They also serve as food forcreatures that inhabit the soil, such

There are many kinds of bacteriain soil and leaf litter.

Top: Nitrogen-fixing bacteria live onthe root nodules of some plants(legumes such as peas, for instance).These bacteria help convert nitrogenfrom the air into a chemical form theplants can use.

Above: Fungal mycelium with repro-ductive cells.

54 L I F E I N T H E L E A F L I T T E R

providing ecological services likenutrient cycling, the soil would soonbe depleted of nutrients and plantscould not grow.

Not only are these tiny leaf litter animals valuable in creating goodwoodland soil, they themselvesbecome food for other forest animals.In other words, they become part ofthe forest food web. Salamanders,turtles, and mice feed on earthwormsand insects, and they, in turn, areeaten by birds or larger mammals.Larvae (the immature forms ofsome insects) that are eaten by forest birds also live in the leaf litter.Together, these leaf litter microor-ganisms and invertebrates, the soil

and decaying plant matter in whichthey live, the plants that grow in thesoil, and the larger animals living inthe forest all make up the woodlandecosystem. (An ecosystem is the sumof all the living organisms in a par-ticular environment and their inter-actions with each other, as well aswith the physical environmentaround them — the rocks, soil,weather, and landscape.)

Each component of the ecosystemhas a role to play in the environment.Plants, algae and some bacteria areproducers, able to convert the sun’senergy into food — a process calledphotosynthesis. Consumers are thoseanimals that feed on producers or

other animals to sur-vive. Of consumers,the animals that eatonly plants are calledherbivores.Predators are thoseanimals that huntother animals to eat.Scavengers eat deadplants and animals.The decomposersare mainly bacteriaand fungi that feedon dead plants andanimals and breakthem down chemi-cally into nutrients.

The forest ecosystem: Energyfrom the sun passes fromplant to animal, and fromanimal to animal. As each iseaten in turn and ultimatelydecomposed, their nutrientsare returned to the soil.


SLUGS AND SNAILSPhylum | Mollusca | Class | Gastropoda

There are approximately a thousandsnail species within North Americaalone. Snails have coiled shells intowhich they retreat for protec-tion, whereas slugs have noshell. Both produce a thicklayer of slime to helpthem travel fromleaf to leaf. Mostspecies are found in environmentsthat can provide them with a plenti-ful food source, moisture, shelterand usually a source of lime, whichprovides the calcium snails need todevelop their shells. For these rea-sons, many snails and slugs arecommon in leaf litter, where theyhide by day, emerging to feed onleaves and fungi at night. The leaflitter provides just the food andmoisture they need to survive.Snails are rare in ever-green forestsbecause the

acid soils prevent them from devel-oping shells, whereas slugs can becommon there.

ROUNDWORMSPhylum | Nematoda

Most roundworms, alsocalled nematodes, are

microscopic, worm-shapedanimals found in a variety of

environments. Many are aquatic(living in water) rather than terrestrial (living on land). Someroundworms live in the guts ofother animals, while still otherslive inside the roots of plants.The ones that live in soil havea critical role to play in recy-cling dead organic materials.Generally, they feed on bacteriaand fungi, on small earthworms, andother roundworms. Nematodes

can occur in staggeringnumbers, sometimes

millions persquare meter

(about a square yard).

WORMS Phylum | Annelida | Class | Oligochaeta

This group of invertebrates is repre-sented in the leaf litter communityby earthworms and potworms.Earthworms (Lumbricidae) are longand slender. Some, such as night-crawlers, can grow to be quite large,and many are capable of burrowingdeep into the soil. They have no

Here are some of the more common leaf l itter animalsyou might f ind in your city woodlands.

Slug eggs, shown herewith newly emergedyoung, are commonlyfound in leaf litter.

as mites, springtails,many beetles andnematodes.

Mycorrhizal fungiare a special group of fungithat live in close associa-tion with plant roots. Theyare very important to life inthe forest, since they help plantroots absorb vital nutrients such asphosphorus and nitrogen from thesoil. In fact, many plants could notlive without mycorrhizae. In return,the plant gives the fungus the nutri-ents it makes by photosynthesis in aprocess called mutualism, a “youscratch my back, I’ll scratch yours”arrangement.

Most of the animals in the woodlandsare invertebrates, those animals with-

out a backbone. Theseinclude earthworms,slugs and snails, and

arthropods. Arthropodsare invertebrates with

an exoskeleton (a hardsupporting outer

covering) and jointed legs, such as spiders and insects.

Most of these small, generally unseen animalsdwell in the top organic layers of soil. Loose leaf litterprovides hollow spacesbetween the leaves wheremany such creatures live.These invertebratescome in many

shapesand sizes. The

ones that live on thesurface of the ground

have well-developed eyesand legs and readily move aboutamong the leaves in search offood and shelter. Often, theywill move deeper into the litter

during the drier summer months. Incontrast, those animals living deeperin the soil tend to be smaller andmore worm-like. Since they live inan environment without light, manyhave no eyes.

Some animals, such as springtails(Collembola), spend their entirelives in soil and litter. However,many groups of arthropods arefound in the leaf litter only at certaintimes in their lives. Some bees usethe litter and soil habitat for nesting.Cicadas spend theirentire larval stage under-ground, feeding on plant

rootlets. Otherinsects, such as

certain mothsand bees,spend thewinter hiber-nating under the

protective leaflayer. When the adult

insects emerge from the lit-ter in spring, they often move

into other nearby habitats to find amate, food, or new nesting sites.


Mushrooms releasespores which willsoon develop intonew mycelia.


8,000 enchytraeids and 700 lumbri-cids found in a square meter ofmeadow soil.

The earthworms you might find inan urban park in the Northeasttoday are all recent immigrants fromEurope and Asia. They werebrought here accidentally in shipballast and in the soil of pottedplants. Although earthworms wereonce native to the northeasternUnited States, the glaciers of the IceAges pushed the range of the origi-nal worms further south. Our “latestarrivals” thrive in our city parkwoodlands, feasting on leaf litter. Infact, they are consuming so muchthat they are removing the leavesbefore other decomposers, likefungi, can feed on them. This isresulting in a thinner organic layerin some city parks and less food andshelter for otherforest floorinhabitants. Citypark managersare now studying thisproblem to find a way to balance theearthworm populations.

WATER BEARSPhylum | Tardigrada

Water bears are microscopic animalswith four pairs of clawed, stumpylegs and a conical snout.Tardigrades, even terrestrialspecies, are aquatic and areunable to function with-out a film of watersurroundingthem. Without

moisture they dry out completelyand shrivel up; they remain in thisstate, alive but motionless, until theyagain have access to water. In dryleaf litter they are only found aswarty eggs and cysts. Water bearsare very sensitive to lack of oxygen,soil compaction, and soil particlesize, which restricts the depth towhich they are found (5-10 cm). Soilspecies feed on algae, bacteria, pro-tozoa, rotifers, nematodes, andorganic detritus. They in turn serveas food for a variety of predators.

ANIMALS WITH JOINTED LEGSPhylum | Arthropoda

Arthropods, the largest and mostdiverse group of animals on earth,are characterized by a hardexoskeleton and jointed legs.Arthropods

commonlyfound in leaf litter include

crustaceans (sowbugs), chelicerates(such as spiders and pseudoscorpi-ons, daddy longlegs, and mites),myriapods (millipedes, centipedes,and symphylans), and hexapods(proturans, double-tails, springtails,and insects).

The arthropod fauna of leaf litterand soil is so incredibly diverse, andoccurs in such enormous numbers,

that it is difficult to describe, andshould be experienced first-

hand. Howard EnsignEvans, in his book Life on

eyes and instead use thebristles on the surface of

their skin to feel their wayaround in their under-ground environment.

Earthworms are veryimportant in maintaining

healthy soil, especially inagricultural areas. As they

eat their way through thesoil, the tunnels they create make

it easier for water and air to moveinto the soil. This is essential forplant growth and also increases theactivity of microbes, which in turnpromotes decomposition and nutri-ent cycling. As earthworms eat theleaves at the surface and excretewaste (called castings), they alsohelp to mix and move nutrientsthrough the soil, and their fecalmaterial provides additional sites formicrobial activity. The famous evolu-tionary biologist, Charles Darwin,was so impressed by the collective“power” of earthworms that he

wrote his last book aboutthem.

Potworms(Enchytraeidae) aresmall, whitish worms more tolerantthan earthworms of acidic soils withhigh organic matter content. Theyare usually confined to the top fewinches of soil and feed primarily ondecomposed plant remains and fungal mycelia.

Both groups of worms can occur in vast numbers, with over


bristles

cocoonscontainingearthworm

eggs

casting

crop

mouth

segment

gizzard

L I F E I N T H E L E A F L I T T E R 1 1

and, in adult males, doubling as areproductive organ.

Because their diet consists mostlyof insects, spiders are very impor-tant in controlling insect popula-tions. Web-spinning spiders thatlive on the ground use the driedleaves in leaf litter to anchor theirwebs. Free-hunting spiders alsothrive on small invertebrates thatlive in the leaf litter. Some com-mon spider families which occurin leaf litter include jumping spi-ders (Salticidae), line weaving spi-ders (Linyphiinae) dwarf spiders(Erigoninae), Hahniidae, wolf spi-ders (Lycosidae), sac spiders(Clubionidae), and crab spiders(Thomisidae). Many spiders over-winter in the litter layer, shelteredfrom cold and wet.

PseudoscorpionsOrder | Pseudoscorpiones

Animals in this order havefour pairs of walking legs like spiders, but they superficially

resemble scorpions orvery small lobsters,hence their name.Unlike scorpions,

they do not have astinging tail. However,

pseudoscorpions dohave powerful “jaws”

and pincer-like claws forgrabbing prey, which they

subdue with help from the poisonglands in their jaws. They feedon springtails, mites andany smaller inverte-brate they can catch.

Pseudoscorpions can be found ina variety of habitats: in soil,ground litter, under tree bark, incaves, in host nests of largerorganisms, on rock or mudsurfaces. From time to timethey engage in a uniqueform of transportation calledphoresy. In this behavior, thepseudoscorpion attaches itself toa larger animal host and allowsitself to be transported around (a great way to save energy!).

Har vestmenOrder | Opiliones

These animals are sometimescalled daddy longlegs becausemost have extremely long, stilt-likelegs and a small, rounded, compact

body. The kind you are mostlikely to find on the surface ofthe ground have long legs thatenable them to crawl over andthrough the thick leaf litter.Harvestmen living deeper in

the litter have much shorter legs.These animals are predators,feeding on both live and dead ani-mal matter, unlike spiders thattake only live prey. They have stinkglands for protection, and cansecrete toxic substances to deterpredators, but are not known to bepoisonous to people. In desperatesituations, harvestmen can“release” part of a leg to escape.The wound heals quickly, but the

lost leg willnever grow

back.

Pseudo-scorpion,life size

a LittleKnown Planet,

says of those whowould explore this

world that “they will berewarded with an array of

animals a good deal stranger thanthose to be found in books on pre-historic life.” In terms of sheer numbers of individuals, springtailsare impressive; 40,000 to 50,000 individuals typically occur in a squaremeter of leaf litter and soil. Speciesrichness is also impressive, withmore than 40 species of Collembolaoccurring in temperate deciduouswoodland or undisturbed grassland.Mites are found in even larger numbers and with similar speciesrichness. If we scale up these num-bers, Evans (1993) estimates an acre of English pasture supports666,300,000 mites, 248,375,000springtails, 17,825,000 beetles and 135million other assorted arthropods!

SOWBUGS

Subphylum | CrustaceaOrder | Isopoda

This group is composedof what we know as sowbugs.

Sowbugs have hard, flattenedexoskeletons, and seven

pairs of legs. They aremostly dull brown or slategray in color. Characteris-tically, they have two pairs ofantennae, one long, one short.Sowbugs are scavengers,

eating mostly dead or decayingplant material like rotting wood. A

distant relative of crabs and crayfish,

they are the only crustaceans adaptedfor life on land. They use gills(pleopods) to breathe; these need tobe kept moist, so sowbugs are mostlyactive at night and in damp environ-ments. One group of isopods, thepill bugs, will curl into a tight ballwhen disturbed.

SPIDERS, HARVESTMEN,PSEUDOSCORPIONS, MITES

Subphylum | ChelicerataClass | Arachnida

SpidersOrder | Araneae

Spiders are a domi-nant predatorygroup in the leaflitter. They have fourpairs of legs and a body dividedinto two parts, the cephalothoraxand abdomen. Although all spidersproduce silk, only some use it tobuild webs to catch their food,which consists mainly of insects.Other spiders sit in hiding andwait for their prey to pass by. Evenwith eight eyes, most spiders stilldon’t see very well. To help sensetheir environment for movingprey, they have specialized hairs(setae) on their legs. Spiders alsopossess special appendages calledpedipalps, used for handling prey,

1 0 L I F E I N T H E L E A F L I T T E R

cephalothorax

abdomen

pedipalps

spinnerets

M A L E S P I D E R

Female symphylandepositing fertilized

eggs on moss.


segment. Most of the morethan 10,000 species of millipedescurrently known in the world areherbivores or scavengers. Theyconsume decaying plant matter,moss, and fungi, contributingsignificantly to the productionof humus. Long-lived, theyhave the potential to sur-vive 10 years. Millipedeslive in the upper soil layerand in leaf litter, underrocks, logs or bark in moistenvironments, and are usually activeat night. Generally, they are foundmost abundantly in soils rich in calcium, which they need for buildingtheir exoskeletons. As a protectivemechanism, many millipedes can

exude a smelly, cyanide-basedliquid that can burn skin

if handled. Their thickexoskeletons also pro-vide protection from

predators, and some millipedes can roll themselves

into a ball for extra protection.

CentipedesClass | Chilopoda

Centipedes can be found in leaf litterand soil, under rocks and logs. Theyare voracious predators of otherinvertebrates, especially smallearthworms. Centipedeshave pincers just behindtheir heads on the firstbody segment, which theyuse to pierce their preyand inject their poison.

Stone centipede in pursuit of apseudoscorpion.

Soil centipedes (Geophilomorpha)are slender and worm-shaped, andtend to be found deeper in the soil.They have no eyes but rely on manysensory hairs to help them find prey,typically small earthworms. Stonecentipedes (Lithobiomorpha), in

contrast, live on the leaf litter sur-face. Active and efficient hunters,they eat small insects, whichthey catch with poison pincers.

SymphylansClass | Symphyla

These invertebrates are often mistaken for either centipedes ormillipedes. They do look like smallcentipedes, and in fact are oftenreferred to as “garden centipedes.”Symphylans aretiny, colorless,and well-suitedto life under-ground in thesoil porespaces aroundplant rootlets. They have no eyes,but instead have many sensory cellsat the tips of their antennae and at thebase of the third to last pair of legs.Unlike centipedes and millipedes,


MitesOrder | Acari

Common in leaf litter, mites aresmall (less than 1 millimeter) butvery abundant. In fact, there canbe several hundred thousandindividual mites in a squaremeter of woodland soil.They have short legs andunsegmented bodies. Slow-moving, they eat decaying plantmaterial, mold, or othersmaller soil organisms,

thus playing an importantrole in the leaf litter food web.

Mites in turn are fed upon by avariety of predators such as largermites, spiders, and centipedes.

There are three categories of soiland leaf litter mites:

The oribatid mites are best repre-sented by the moss and beetlemites. Oribatids live in soil andare very numerous. They aredark-colored with hard, shiny“shells.” They eat a variety ofleaf litter material,including bacteriaand yeast, algae,

fungi and rottingwood.

Mesostigmatid mites arefree-living predators in the soil andlitter, eating other small inverte-brates like springtails, other mites,

bacteria, and fungi. They arelighter-colored than oribatids

and are distinguishable fromthe third group, the prostig-matids, by having their stigmata,

or breathing holes, on thesides of their bodies. The

prostigmatids have their breath-ing holes at the base of theirmouthparts. They eatnematodes, other smallerarthropods and algae,fungi, and bacteria.Some prostigmatids live onother animals as parasites.

MILLIPEDES, CENTIPEDES, AND SYMPHYLANS

Subphyla | Myriapoda

MillipedesClass | Diplopoda

Adult millipedes have long, segmentedbodies with two pairs of legs per

How to TellMillipedes fromCentipedes

Look closely!Millipedes usuallyhave two pairs oflegs for each bodysegment; centipedesalways have onlyone pair.

C E N T I P E D E

M I L L I P E D E pair of legs

single leg

M E S O S T I G M A T I DM I T E

P R O S T I G M A T I D

O R I B A T I D


and long, well-developedspringing organs. Thosethat live deeper in the soilare smaller, colorless, withreduced eyes or no eyes, shortantennae, and no springing organ.

Springtails live about a year, feed-ing on fallen leaves, other detritus,algae, and fungi, converting theminto humus. Some eat the fecalpellets of other soil animals, whilestill others eat small nematodes.Together with mites, springtailsmake up the most abundant groupof leaf litter invertebrates.

InsectsClass | Insecta

Insects are characterized by havingthree body parts, the head, thoraxand abdomen. The head bears sensory and food-gathering structures.Typically, the thorax has wings andsix walking legs; the abdomen holdsthe reproductive, digestive andexcretory systems. The lifecycles of most insects fallinto two distinct groups;those with incompleteand those with com-plete metamorphosis.

Incomplete life cycles, as typified by crickets, occur

when the insect egg develops into aminute version ofthe adult (called anymph) and growsthrough successivemoults into a full-sizeadult. Many well-knowngroups of insects,including flies, bee-tles, bees, andbutterflies andmoths, have completelife cycles in which eggsdevelop into larvae thatdo not usually resem-ble the adults. These larvae in turndevelop into pupae (a growth stagebetween the larva and the full-grownadult) from which the reproductiveadults finally emerge.

CricketsOrder | Orthoptera

Field crickets of thefamily Gryllidae are some-times found hiding in leaf litter.They construct burrows in the soilwhere they store and later consumegreen plant material. Occasionallyyoung cave crickets of the familyGryllacrididae can also be found.Crickets are well-known for thechirping sounds made by males

to attract a mate.

TermitesOrder | Isoptera

Termites play a vitalrole in the decomposi-

tion of wood, both on the

1

2

3

head

thorax

abdomen

How a springtail jumps.

Life cycle of a dung beetle—complete metamorphosis.

adult withball of dung

egg laidin dung

larva

pupa


their terminal body segments carrya pair of silk-producing spinnerets,which spin silken threads used todeter predators. Most species areomnivorous and can feed on eitherplant or animal matter, preferablylive organisms and finer plantrootlets, which explains why somespecies are considered serious croppests. They are capable of consum-ing 20 times their own weight ofvegetable matter in 24 hours.

Proturans, Double-tails, and Springtails Subphylum | Hexapoda

ProturansOrder | Protura

Proturans are very small, delicateanimals (0.5-2 mm) lacking eyesand antennae. Instead, their fore-legs, which have many sensorystructures, function as antennae.They require moist soil andhumus, feeding on decayingorganic vegetation, fungal myceliaand spores.

Double-tailsOrder | Diplura

This is a group of winglesshexapods (animalswith six legs) withouteyes or scales. Theyare whitish or yellow-ish, with long, slender,beaded antennae and apair of “tails” oftenused as feelers; hencethey are often called“double-tails.” MostDiplura live in moss,

under stones, or in deeper litterand moist soil pore spaces. Of the70 species present in NorthAmerica, most are herbivorous,eating decaying vegetation. Onefamily, the Japygidae, has pincer-shaped appendages called cerci,which make them look like imma-ture earwigs. Despite being blind,japygids are very efficient preda-tors of other small soil animals,using their antennae to locate prey.

SpringtailsOrder | Collembola

Known for the forked springingorgans on their abdomens that

allow them to jump away fromtheir enemies, springtails play

an important role in thedecomposition process.They have six legs, are

wingless, and seldom growbigger than one centimeter.There are several groups of

springtails: some live on the sur-face of the leaf litter, others deep-er down in the soil. Springtailsfound on the surface are larger,richly pigmented, with densescales or hairs, compound eyes,

cerci

Above:Dipluransfighting. Below:Japygid guardingeggs underground.


mycelia. True bugs found in theleaf litter are: jumping groundbugs (Schizopteridae) which areactive jumpers when disturbed;lace bugs (Tingidae) which,although plant feeders, are oftenfound in the litter; minute piratebugs (Anthocoridae), which preyon other small arthropods; seedbugs (Lygaeidae), which feed onseeds, and flat bugs (Aradidae),which feed on the sap of fungi.

BeetlesOrder | Coleoptera

Beetles are a very diverse groupof insects, accounting for moreknown species than any other living thing on the planet. Thereare more than 300,000 describedspecies of beetles in the world,with over 30,000 in North Americaalone. Like other insects, adultbeetles have three pairs of jointedlegs and one pair of antennae.However, unlike other insects,adult beetles have a pair of specialfront wings called elytra.These wings, alongwith a hard exoskele-ton, form a strong protectivearmor for this insect.

Beetles are found in almostevery terrestrial habitat, and manyare even aquatic. Their chewingmouthparts are well developed, andbeetles feed in a number of ways.Some feed on a large variety ofplant parts, both living and dead.Others are predators, many arescavengers, some are fungal feed-ers, and some are even parasitic.

Beetles undergo com-plete metamorphosis andmany of their larvae are encoun-tered in the leaf litter. All beetlelarvae have jointed legs on thethorax and they will have someparts which are soft, while otherparts are covered by hard plates(or sclerites). Larvae of groundbeetles (Carabidae) and rove bee-tles (Staphylinidae) are elongated,white to yellowish with well-devel-oped plates on the back of thehead, thorax, and abdomen, withexposed membranous sections inbetween. Often the abdomen endsin two “tails” (or urogomphi).Scarab beetle larvae (Scarabaeidae)are whitish, grub-like and usuallycomma-shaped, but have jointedlegs on the thorax.

The beetle families most commonin leaf litter are described below.

Ground Beetles (Carabidae) area very diverse group, with morethan 1,700 species known fromNorth America. Most active at

night, the adults are predaceousor omnivorous, feeding on any

invertebrates they can catch.

Rove Beetles(Staphylinidae) make up

the largest family of beetles inNorth America, with 3,100 speciesknown. Staphylinids play animportant role in the litter eco-system as agile predators feedingon mites, nematodes,Collembola, andinsect larvae.Some species are


forest floor and in stand-ing but decaying trees. While

some termites live aboveground in dry locations,

many live in moist undergroundhabitats in wood buried or lying onthe soil. They are able to convertthe cellulose in dead plant materialwith the help of microorganisms(protists) that live in their gut.These small protists secrete theenzymes that digest the cellulose.

Ear wigsOrder | Dermaptera

Nocturnal creatures, earwigs hideby day, coming out at night to feed.They have shortened, leatherywings, and pincers on their abdo-mens that they use for defenseor predation. Many earwigs eatdead plant matter in the leaf litter.Others eat fresh plant fragments,or fungal spores, algae, lichen,and moss. Some species are evencarnivorous, feeding on insectsand spiders. Earwigs, in turn, arepreyed upon by many other animals, such as beetles, spiders,centipedes, birds, andlizards.

ThripsOrder | Thysanoptera

Thrips are very small insects withsucking mouthparts. Those found

in leaf litter mostly feedon fungal spores andhyphae, or on smallarthropods. Some are wing-less, but if winged the wingsare fringed with long hairs. Manyspecies are pests of plants and areoften found in flower blossoms.

Book LiceOrder | Psocoptera

Book lice feed on algae, lichen,organic detritus, fungal sporesand mycelia. Most outdoor speciesare winged, while indoor speciesare wingless and often foundamong old books and papers,

feeding on molds andfragments of dead

insects. Sixty species arefound in leaf litter in the

United States.

True BugsOrder | Heteroptera

Being primarily plant feeders, truebugs are not often found in leaf litter. Of those that are, however,some families, like stink bugs(Pentatomidae), may only be over-wintering there, while others arepredators, feeding on otherarthropods with their stylus-likebeaks. A few feed on fungal

Adult stink bugwith nymphs.


True FliesOrder | Diptera

One of the largest groupsof insects (25,000 speciesknown from NorthAmerica), flies are extremelyabundant and are found in almostevery habitat, even, occasionally,in leaf litter. Adult flies foundthere are likely to be laying eggs,or perhaps have just emergedfrom pupae. There are also someleaf litter flies that are parasitic onother insects. Best known are thehumpbackedflies, thePhoridae.

We tend tothink of flies as a nuisance,

or be concerned about how somespecies transmit diseases, but flylarvae play an essential role indecomposition. Fly larvae of manydifferent families live in the leaflitter and soil, including fungusgnats and other families of tinymidges, crane flies, dance flies,horse flies, house flies, hover flies,fruit flies and many others with-out common names. While most

feed on decaying organicmaterial (both plant and

animal) and fungi, some arealso predators. In general, fly

larvae are elongated, cigar- orgrub-shaped. The skin (or integu-ment) is usually soft, pliable, andoften whitish in color. All fly lar-vae lack jointed legs on the tho-rax, unlike most beetle larvae.Some may have fleshy prolegs(but not jointed legs), while oth-ers have raised ridges or creepingwelts along their bodies that allowthem to move about.

Bees, Wasps, and AntsOrder | Hymenoptera

Many species of bees and waspsbuild their nests in the ground,beneath the litter layer. Of these,most of the native bees are solitaryand do not build large hives as dothe honey bees that were intro-duced from Europe. The thick litterlayer also provides protectionfrom the winter cold for hibernat-ing wasps and bees. Wasps areimportant insect predators, andnative bees are responsible forpollinating many of our woodland

wildflowers.

There are numerousfamilies of parasitic waspswhich are parasites of

insect eggs, larvae, pupaeor adults. Some are evenhyperparasites (parasites of


also known to feed on decompos-ing organic matter and fungi.Rove beetles can be recognizedby their very short elytra.

Featherwing beetles (Ptiliidae)are the smallest known beetles,being 1 millimeter or less in size. They feed on fungal hyphaeand spores.

Short-winged mold beetles(Pselaphidae) are small beetles(0.7- 4.5 millimeters) that prey onworms, Collembola, insect larvae,mites, and symphylans. There areover 700 known species, foundmainly in leaf litter.

Weevils (Curculionidae). Almostall weevils in this very large familyare plant feeders, and some areserious pests of cultivated crops.Those found in leaf litter are mostly nut or acorn weevilsof the subfamily Curculioninae,and have very long snouts.

Click beetles (Elateridae) arealso commonly found onthe forest floor. They arecalled clickbeetlesbecause of thesound theymake whenthey flip theirbodies over.

They are able to archand snap their bodiesto right themselves ifturned upside-downor if attacked bypredators. The larvaeare called wire

worms and are found in rottingwood. Because wood is so nutri-ent-poor, click beetles take five toseven years to mature from larvaeto adult.

Two other families of beetles oftenencountered in the leaf litter arecarrion and dungbeetles, both ofwhich can playimportantroles in thelitter ecosystem.Carrion, or buryingbeetles (Silphidae) dig beneaththe bodies of small dead animals,burying the carcasses before lay-ing their eggs on them. Both

adults and larvae feed onsuch carrion. Dung beetles (Scarabaeinae,

Aphodiinae) lay their eggson pieces of animal dung,

which they often roll largedistances and then bury, ensuringa food supply for their larvae. Thisbehavior is also important inreturning nutrients to the soil.

How a click beetle jumps.


thesoil, sothat plantsand animals havetrouble getting thewater they need to survive.City habitats are also subjectto warmer air temperatures,which affect soil temperature andthe amount of moisture in the soil.

Users of park and city woodlands,wittingly or not, have a large impacton the fascinating, diverse and frag-ile community of largely unseen litterinvertebrates. People destroy habitat(if not the animals themselves) bycompacting the soil when they walkon the leaf litter. Worse still, somepeople ride their bicycles and othervehicles over it. When soil is com-pacted, the pore spaces in the soilcollapse, making it difficult for waterto penetrate and making air lessavailable to the roots of plants. Thisinhibits plant growth and affects theroot growth of trees. The root sys-tems become shallower, with greaterlateral growth. This means that

some trees could be more easilyuprooted in a strong wind, and rootsnear the surface can be more easilydamaged. Soil compaction fromhuman foot traffic also increases soilerosion by increasing surfacerunoff.

The use of pesticides and other poisons, as well as the introductionof non-native plants, can change thechemistry of the soil, which willeventually affect life in the leaf litter.Native plants are those that haveoriginated in a particular habitat.Non-native invasive species werebrought or spread from somewhereelse. In addition to their effects onsoil chemistry, the leaf litter producedby these non-native plants may beunpalatable to soil organisms.Invasives can also out-compete andcrowd out native plant species froman area.

Fortunately, even in a city environ-ment, there is much that we can doto protect this fragile community ofcreatures.


parasites!) and have fascinatinglife cycles. Though not regularinhabitants of the leaf litter, whenfound there they will have beenlooking for hosts to lay their eggson, or perhaps have just emergedfrom the egg themselves. Themost common family found in leaflitter is the Trichogrammatidae.The genus Trichogramma has beenused successfully as a biologicalcontrol agent for insect pests.

Ants (Formicidae) are true socialanimals; they live in highly organ-ized colonies and communicate bychemical means. Depending onspecies, ants can be farmers,hunters, collectors or evenslaves of other ants. They feedon a variety of food, includingdead plants and insects.Ants play a very importantrole in soil ecology by aeratingand enriching the soil as they buildtheir colonies. In addition, manyforest plants such as violets andwild ginger depend on ants forseed dispersal. As the ants collectseeds to eat, they may accidentally

drop some onthe return

trip to their nest,thus spreading the

seeds around.

Human Impact on LeafL i t te r Inver tebrates

A healthy layer of leaves on theforest floor is a vital component

of every woodland. The leaf layerprotects and nourishes the soil,enables rainwater to filter into theground, harbors seeds, and provideshiding places for woodland animals.Without it, the woodlands would beunable to exist and reproduce.

What creates a good litter layer?Plenty of litter — the natural kind —leaves, sticks, and seeds, and ahealthy population of leaf litter animals (without too many earth-worms), and loose, moist soil.

Sometimes these ingredients arehard to find in a city park. Environ-mental pollutants and acid rain areknown to affect the terrestrial world of leaf litter invertebrates.Some pollutants are making citysoils more “water repellent.”Scientists still do not know why thisis occurring, but it means that it isdifficult for rainwater to filter into

CONSERVINGLEAF L ITTER

Scientists have identified 38 species of ants inNew York City’s Central Park.


stay on the trail. Put up signswhere people might otherwise gooff-trail and trample on the leaf litter and all the invertebratesthat live in it.

• Minimize use of pesticides orchemicals such as lawn and gardenfertilizers that could disrupt thechemical balance of the soil.

• Use deicing salts sparingly; thesesalts may melt pavement ice in winter, but pollute the soil. Useother deicers like CaCl2 (calcium chloride) rather than NaCl (sodium chloride).

• Encourage restoration projectsthat use native plants and controlnon-native invasive species.

• Foster research and educationabout the complex relationship ofsoil and the living organisms inthe woodland.

What You Can Do to He lp

Park visitors can also help protect theamazing diversity of life in our citywoodlands in the following ways:

• Appreciate the natural, unmani-cured look of your woodlands and parks. Leave the organicmaterials, fallen foliage, twigs andbranches around and under treesundisturbed.

• Avoid unnecessary trampling onthe fragile soil. Stay on designatedtrails.

• Don’t drop litter on the litter.Keep parks and woodlands freefrom trash. Materials such asplastics and glass disrupt the normal functioning of the soil.

• Clean up after your dog and keepdogs away from trees. Becausetheir urine is acidic and very concentrated, it can burn throughtree bark. Dog droppings alsopollute the soil.

• When fishing near woodlandareas, take any extra bait home.Please don’t release worms intothe wild.

• Plant native species in your owngarden; this will encourage theproliferation of the native leaf litterinvertebrates. Avoid introducinginvasive species (which might colonize nearby parklands) intoyour garden.

• When possible, minimize yourdriving. Cars and other machinerycontribute to air pollution. Autoemissions contribute to acid rain,which leaches some of the impor-tant nutrients needed for plantgrowth out of the soil. Theseemissions stimulate plants to produce a protective waxy layeron their leaves, which may makethe leaves less digestible to soilanimals. The pollutants may alsocause the soil surface to becomewater repellant, thus affecting seedgermination and seedling survival.

• Volunteer. Support park activitiesthat help protect biodiversity.


Park Managers to the Rescue

Park managers work to keep thepark healthy and natural, safe andenjoyable. Here are some techniquesused by park managers to maintaindynamic woodland ecosystems andprotect the variety of life thatdepends on the forest for survival.

• Let fallen leaves and branches(and even whole fallen trees)

decompose where they fall.“Leaving” leaves and other organicmatter around and under treesallows them to become part ofthe soil and provide nutrients forother plants and the trees them-selves in the coming year. Fallentrees also provide habitat for manyof the animals and microorganismsthat live in the leaf litter.

• Minimize soil disturbance inwoodlands. Cultivating the soilcould harm plant and animal lifebecause it disturbs soil formationand the natural layering of theleaf litter. Soil disturbance mayalso allow the seeds of non-nativeinvasive plantspecies tobecomeestablished.

• Encouragepark visi-tors to

A decaying log isfull of life.

I N D E X 2 5

Aabdomen, 10, 14, 15, 16, 17;

illustration–spider, 10acid rain, 20; and soil nutrients, 23acid soil, 7, 8air pollution, 2, 23algae, 4, 5, 9, 12, 15, 16antennae, 10, 13, 14, 15, 17ants, 19, 20; illustration, 20aquatic, 7, 9, 17arthropods, 6, 12, 16, 17; diversity in

leaf litter, 9, 10;auto emissions, 23

Bbacteria, 5, 7, 9, 12; as producers, 3, 4;

illustration, 5bees, wasps, and ants (Hymenoptera),

19bees, hibernating, 6, 15; life cycle of,

15; native, 19beetles (Coleoptera), 6, 15, 16, 17;

larvae, 17; families, common in leaflitter, 10, 17-18

biodiversity, 1, 23birds, 1, 3, 4, 16book lice (Psocoptera), 16

Ccalcium, 3, 7, 13calcium chloride, 23carnivorous, 16carrion beetles (Silphidae), role in

nutrient cycling, 18castings, 8cave crickets, 15cellulose, 16centipedes (Chilopoda), 9, 12, 13, 16;

illustration, 12, 13cephalothorax, 10; illustration–spider, 10cerci, 14chelicerates, 9, 10

cicadas, 6city parks, 20, 21click beetles (Elateridae), 18;

illustration, 18Collembola (springtails), 6, 10, 14-15,

17crab spiders (Thomisidae), 11crane flies, 19crickets (Orthoptera), 15crop pests, 14, 18crustaceans, 9, 10cryptostigmatid mites, 12cycling of nutrients, 3, 4, 5, 8cysts, 9

Ddaddy longlegs (harvestmen)

(Opiliones), 9, 11dance flies, 19Darwin, Charles, 8decomposers, 3, 4, 9decomposition, 5, 8, 14, 15, 15, 18, 19deicing salts, and soil, 23double-tails (Diplura), 9, 14;

illustration, 14dung beetles (Scarabaeinae,

Aphodiinae), 15, 18; illustration, 15dwarf spiders (Erigoninae), 11

Eearthworms (Annelida), 3, 4, 6, 7-9, 13,

20; native vs. exotic, 9; illustration, 8earwigs (Dermaptera), 16; Diplura

mistaken for, 14Eastern Deciduous Forest: Ecology and

Wildlife Conservation, 3ecological services, 4ecosystem, 4, 5, 17,18, 22; illustration, 4elytra, 17, 18enzymes, 5, 16erosion, 2, 21Evans, Howard Ensign, 9, 10exoskeleton, 6, 9, 10, 13, 17

INDEX


References and Recommended Reading

Barnes, R. D. Invertebrate Zoology, fourth edition. Saunders College,Philadelphia. 1980.

Borror, D. J. and R. E. White. A Field Guide to the Insects of North AmericaNorth of Mexico. Peterson Guide. Houghton Mifflin Co., NY. 1970.

Borror, D.J., C.A. Triplehorn, and N.F. Johnson. An Introduction to the Study ofInsects, sixth edition. Saunders College, Philadelphia. 1989.

Darwin, C. The Formation of Vegetable Mould Through the Action of Worms,with Observations on Their Habits. 1881. Reprint. Vol. 028, The Complete Worksof Charles Darwin. New York University Press, NY. 1990.

Evans, H.E. Life on a Little Known Planet. Lyons and Burford, NY. 1993.

Kricher, J. Peterson Field Guide to Eastern Forests. Houghton Mifflin Co., NY. 1998.

Levi, H. A Golden Guide to Spiders. Golden Press, NY. 1987.

Sauer, L. J. The Once and Future Forest. Island Press, Washington, DC. 1998.

Silver, D. M. One Small Square: Backyard. McGraw Hill, NY. 1993.

Yahner, R. H. Eastern Deciduous Forest: Ecology and Wildlife Conservation.University of Minnesota Press, Minneapolis. 1995.

Zim, H. S. and C. Cottam. A Golden Guide to Insects. Golden Press, NY. 1956.

(The classification used in this book is based on the Integrated TaxonomicInformation System. See the ITIS web site at http://www.itis.usda.gov.)

I N D E X 2 7

nitrogen, 3, 6nitrogen-fixing bacteria, illustration, 5 non-native plants, 21, 22, 23nutrients, 5, 6, 8; nutrient cycling, 3, 4,

5, 8; nutrient leaching, 23nymph, 15; illustration, 16

Oomnivorous, 14, 17organic materials, recycling of, 7, 23oribatid mites, 12oxygen, 2, 9

Pparasites, 12, 17, 19-20park managers, 9, 22park visitors, 23pedipalps, 10; illustration–spider, 10pesticides, 21, 23phoresy, 11phosphorus, 6photosynthesis, 4, 5, 6pill bugs, 10plastics, 23pleopods, 10pollination, 19pollutants, 2, 20, 23potworms (Enchytraeidae), 7-9predators, 9, 10, 11,12,13, 14, 16, 17, 18,

19; defined, 4prostigmatid mites, 12; illustration, 12protists, 16protozoans, 5, 9Protura (Protura), 9, 14pseudoscorpions (Pseudoscorpiones),

9, 10, 11, 13; illustration, 11pupae, 15, 19

Rrestoration projects, 23roots, 2, 6, 21; root nodules illustration, 5rootlets, 6, 13rotifers, 9roundworms (nematodes)

(Nematoda), 7rove beetles (Staphylinidae), 17-18

Ssac spiders (Clubionidae), 11salamanders, 3, 4scarab beetle larvae (Scarabaeidae), 17scavengers, 4, 10, 13, 17sclerites, 17seeds, 3, 20, 22; seed dispersal, 20seed bugs (Lygaeidae), 17setae, 10short-winged mold beetles

(Pselaphidae), 18silk; spider, 10; symphylan, 13-14slugs (Mollusca: Gastropoda), 3, 6, 7;

illustration, 7snails (Mollusca: Gastropoda), 3, 6, 7soil, 5; chemistry, 21, 23; disturbance, 22;

dog droppings and urine on, 23; erosion, 2, 4, 21; formation, 2, 3, 22;illustration, 4; layers, 6; native plantsand, 21; nutrients, 6,18,23; pollutants,20; soil comapaction, 9, 21

soil centipedes (Geophilomorpha), 13soot, 2sowbugs (Crustacea: Isopoda), 9, 10spiders (Araneae), 6, 9, 10-11, 12, 16spinnerets, of symphylans, 13;

illustration–spider, 10spores, 14, 16, 18springtails (Collembola), 6, 9, 11, 12,

14-15; numbers of, 10squirrels, 2stigmata, of mites, 12stink bugs (Pentatomidae), 16; illustra-

tion, 16stink glands; in harvestmen, 11;

in millipedes, 13stone centipedes (Lithobiomorpha), 13;

illustration, 13sulfur, 3symphylans (Symphyla), 9, 12-14, 18;

illustration, 13

Ttardigrades (water bears)

(Tardigrada), 9

2 6 I N D E X

Ffeatherwing beetles (Ptiliidae), 18fecal material, 8, 15fertilizers, 23fishing worms, 23flat bugs (Aradidae), 17flies, 15, 19; fly larvae, 19food web, 4, 12frass, 3fruit flies, 19fungal mycelia, 5, 8, 14, 16-17;

illustration, 5fungi, as decomposer, 3, 4, 5-6, 9;

as food for invertebrates, 7-8, 12, 13,14, 15, 16-17, 18, 19

fungus gnats, 19G“garden centipedes” (symphylans), 13gills, 10ground beetles (Carabidae), 17

Hhabitat, 6, 16, 17, 19, 21, 22Hahniidae (spider family), 11harvestmen (Opiliones), 10, 11heavy metals, 2hectare, 3herbivores, 4, 13, 14hexapods (Hexapoda), 9, 14honey bees, 19horse flies, 19hover flies, 19house flies, 19humpbacked flies (Phoridae), 19humus, 2, 13, 14, 15hyperparasites, 19hyphae, 5, 16, 18Iinsects, 4, 6, 9, 10, 11, 15-20integument, 19invasive species, 21, 23invertebrates, 1, 3-4, 5, 6, 7, 11, 13, 15,

17, 20, 21; prey of spiders, 11; preyof mites, 12; native, 23

isopods (Isopoda), 10

JJapygidae, 14; illustration, 14jumping ground bugs

(Schizopteridae), 17jumping spiders (Salticidae), 11

Llace bugs (Tingidae), 17larvae, 4, 6, 15, beetle larvae, 17, 18;

fly larvae, 19 leaf litter, 6, 7, 12, 13, 19, 20; 21, 22, 23

composition of, 3-4;earthwormsin, 9;numbers of invertebrates in, 10

lichen, 16lifecyclesof insects,15,20; illustration,15 Life on a Little Known Planet, 9lignin, 5lime, as source of calcium, 7line weaving spiders (Linyphiinae), 11

Mmesostigmatid mites, 12metamorphosis, 15, 17; illustration, 15mice, 3, 4microbes, 8microorganisms, 4, 5, 16, 22midges, 19millipedes (Diplopoda), 3, 9, 12-13;

illustration, 12minute pirate bugs (Anthocoridae), 17mites (Acari), 6, 9, 10, 11, 15, 17, 18; in

leaf litter, 12moths, 6, 15moults, 15mushrooms, 5; illustration, 6mutualism, 6mycelium,mycelia, 5,16,17; illustration, 5 mycorrhizal fungi, 6myriapods (Myriapoda), 9, 12-14

Nnative plants, 21; and restoration

projects, 23nematodes (roundworms)

(Nematoda), 6, 7, 9, 12, 15, 17nightcrawlers, 7

2 8 I N D E X

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

Uunderstory, 2urogomphi, 17

Vviruses, 5

Wwasps, 19-20; parasitic (microhy-

menoptera), 19water bears (tardigrades)

(Tardigrada), 9weevils (Curculionidae), 18wolf spiders (Lycosidae), 11woodlands, 1, 2, 3, 6, 21, 23; woodland

ecosystem, 4, 22worms; earthworms (Lumbricidae), 3,

7-9, 23; role in healthy soil, 6; (see also: nematodes, potworms,roundworms)

YYahner, Richard H., 3yeasts, 5, 12

Documents

Leaf Litter bk - Weebly€¦ · in soil and leaf litter. Top: Nitrogen-fixing bacteria live on the root nodules of some plants (legumes such as peas, for instance). These bacteria