CONTENTS 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 Acknowledgements: Millipedes, Centipedes, and Symphylans .........12 Thanks to our many helpful reviewers: Regina Alvarez (Central Park Conservancy) Proturans, Double-Tails, and Springtails ..........14 Dennis Burton (Schuylkill Center, Philadelphia) Margaret Carreiro (University of Louisville) Insects..........................................................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 animal species live in cities, some native, others The City Woodland: introduced from other regions Nature Next Door of the world. Many of them live he woodlands in city parks are right under our feet. T important 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 are beautiful to look at and restful to Life of them invertebrates or animals in the wander through, providing a with no backbones) with which break from the high energy we share our city. We will focus 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 Litter live in the past unknowingly every time woods all year, you visit one of our city parks. while others, These small animals, along with such as certain songbirds, stop in the woods to rest and feed during all the rest of the plants, animals, their long spring and fall migrations. and habitats in the city, make For people who live in the city, the up the region’s biodiversity. 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 soil 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 insect frass (excrement) and other debris every year. Imagine what The process of leaf breakdown, decomposition, and soil formation can take many years. woodlands might look like if this were not “taken Each spring the woodland 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 soils 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 Smals are familiar to most of mountain-top ice, and Not only are these tiny leaf litter of all the living organisms in a par- us, in this booklet we are going even inside the bodies of animals valuable in creating good ticular environment and their inter- to introduce you to the smallest plants and animals. woodland soil, they themselves actions with each other, as well as creatures (the ones some consid- Although some bacteria become food for other forest animals. with the physical environment er the most important), the can produce their own food In other words, they become part of around them — the rocks, soil, microorganisms and invertebrate by photosynthesis or other the forest food web. Salamanders, weather, and landscape.) animals that live in the leaf litter chemical means, most feed on other turtles, and mice feed on earthworms beneath the forest trees. Scientists organisms, including other bacteria. and insects, and they, in turn, are Each component of the ecosystem throughout the world are making Bacteria secrete enzymes that chem- eaten by birds or larger mammals. has a role to play in the environment. new efforts to study these organ- ically dissolve their food, making it Larvae (the immature forms of Plants, algae and some bacteria are isms, and there is still much to be easier to absorb. some insects) that are eaten by producers, able to convert the sun’s 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- herbivores. organisms capable of decomposition, der threads Predators are those the chemical breakdown and cycling