NATIVE PLANTS: An Introduction

Transcription

1 NATIVE PLANTS: An Introduction What do we mean when we say a plant is NATIVE? Why should we care about native plants? Presented by Louisa Rogoff Thompson Master Gardener, Howard County MD March 20, 2002 What can we do to preserve them? What do we mean when we say a plant is NATIVE? Indigenous it got here without being introduced by humans (directly or indirectly) OR It has been here a long time since before European colonization (might have been introduced by Native Americans) OR It grows here when the climate and other conditions are appropriate Native to where? Different plants are adapted to different conditions Plants are indigenous to particular Regions (Coastal Plain, Piedmont, Mountains) Habitats (forests, meadows, wetlands) Stages of Succession (Pioneer plants on cleared sites, then progress to Climax plant community) What do we mean when we say a plant is NOT native? EXOTIC = from another place INTRODUCED Brought by humans intentionally, for agricultural, horticultural, or other purposes Brought by humans unintentionally, e.g. as a crop contaminant Spread here as a result of changed conditions, e.g. roads through mountains, increased deer population INVASIVE [EXOTIC] Once introduced, it spreads widely, & displaces native plants in natural areas AGGRESSIVE NATIVE Because of human-caused changes, some native plants act like invasive exotic plants, out-competing plants that used to be more common Virginia Pine Virginia Creeper Poison Ivy 1

2 Why should we care about native plants? Because they are disappearing as habitat disappears as invasive plants threaten to out-compete them as invasive insects and diseases, and natives released from natural controls, threaten their continued existence Because native wildlife depends on them Native wildlife evolved with native plants they are adapted to each other Plants, animals, & other organisms grow together in interdependent COMMUNITIES Extinction of a few species can lead to CASCADES OF EXTINCTIONS Because healthy ECOSYSTEM FUNCTIONING depends on them Ecosystems provide a life-support system for all living things, including ourselves Food production Maintenance of correct level of atmospheric oxygen Maintenance of water cycle Enough rain Enough groundwater Nutrient cycling (N, P, Sulfur, etc.) Erosion control & soil building Temperature control Habitat for living creatures Native plants are more effective than introduced plants at providing ecosystem services because: They are well adapted to local conditions They are adapted to local pests and predators They are exactly what is needed by local wildlife However, we are changing local conditions. Native Plants Foundation of the Web of Life Fruits, Seeds & Nuts Tubers, Corms, Bulbs Plants Provide Food: Black Haw Viburnum 2

3 Nectar & Pollen Eastern Tiger Swallowtail nectaring on New York Ironweed Buds, Leaves, &Twigs & the Insects that feed on them! Spicebush leaves browsed by a leaf-cutter bee or Rhabdopterus beetle Red Admiral laying eggs on nettle from Fruits Dew Sap Even leaves Highbush Blueberry Plants Supply Liquid: Plants Create Structure: A Place to Build a Nest Or other home for young Oak Bullet Gall a wasp lays its egg in a leaf, and the leaf creates a benign tumor in response to the irritation, protecting the wasp s offspring An old growth forest has a diverse vertical structure, and is home to different creatures at each level Many insects shelter in bark crevices Cover from Predators Shelter from Weather The herbaceous layer of the forest floor provides cover, too Native Plants Provide the RIGHT food Adult butterflies can sip nectar from many plants, but their larvae may only be able to live on specific plants The Pawpaw Sphinx Moth & the Zebra Swallowtail Butterfly larvae eat only Pawpaw leaves. This Fritillary must lay its eggs on Violets; Monarch butterfly larvae feed only on Milkweeds 3

4 & the RIGHT structures Some birds nest high in trees, some on the ground, others at specific heights. Some feel more secure in a crotch, others at the tip of a branch that will sway wildly under a predator s weight. for native insects, birds, and other species, Turtles eat mayapple fruits at the RIGHT times. The fat-rich fruits of spicebush provide calories to fuel the long migratory flights of neotropical songbirds Healthy Ecosystems Serve Us All: Capture the sun s energy Recycle nutrients & water Maintain oxygen levels Filter air & water Native witch hazel blooms in fall, just in time to feed its pollinator, a cold-tolerant night-flying moth. Fungi decompose fallen trees, creating humus and returning nutrients to the food web Moderate temperature (shade, evaporation-transpiration, windbreaks, carbon sinks) Hold & build soil This Red Maple is one of many canopy trees that provide shade and evaporative cooling to the forest interior, rivers & streams, homes & yards Chestnut oak s roots can penetrate crevices in rock formations, holding soil on the steepest slopes. 4

5 Native birds & other animals need native plant communities. All living things need healthy ecosystems. But there are very few undisturbed plant communities left! In Maryland, most is farmed or developed. Master Gardener Roles: Support preservation of natural areas Help clients create gardens for humans AND wildlife Use native plants in the landscape, to provide ecosystem services Stop the spread of invasive species CREATE WILDLIFE GARDENS Replace lawn with native grasses Wild Columbine attracts hummingbirds, likes limey soil Big Bluestem Grass provides larval food for several butterflies, cover for ground-nesting meadow birds and wildflowers Cardinal Flower needs rich, moist soil great for perennial beds & rain gardens attracts hummingbirds Plant or preserve shade trees, grow forest plants beneath them Yellow Violets and Star Chickweed bloom in spring, in shady places, provide food for insects Wild Geranium likes partial shade, attracts insect pollinators in spring 5

6 Plant native shrubs to provide fruit, cover, & nest sites for birds, food for insects Plant flowering trees some provide fruit all provide leaves! Red Chokeberry likes sun & moist to wet soil; fruits are famine food for birds Blueberries grow in sun or shade, tolerate thin soil, need low ph, produce fruit in early summer Black Haw Viburnum Redbud Fringetree PLANT NATIVES TO PROVIDE ECOSYSTEM SERVICES Control erosion on steep slopes under flowing water Hold poor soil, build humus Wild sedum needs moist soil and partial shade, wonderful cascading over rocks or walls. Elderberry holds river & stream banks, can hold soil in a drainage ditch or under a downspout Black huckleberry can grow on the poorest soil, in sun or shade. Mountain Laurel tolerates thin, acidic soil; Holds soil on steep slopes Resist deer browsing - Deer dislike many Ferns aromatic plants hairy plants Pawpaw s pungent smell makes it our most deer-resistant tree Christmas Fern is evergreen, needs light shade & moderately rich, moist soil rarely eaten by deer, it holds soil where deer-browsing has wiped out native wildflowers Use native plants in your garden to create a sense of place Maryland should look like Maryland That s how we know we are home 6

7 Let your garden harmonize with natural areas nearby KEEP INVASIVES FROM SPREADING Don t buy invasive plants Ask your community not to plant them Ask your nursery not to stock them Check for information Lesser Celandine Remove the most invasive non-native landscape plants Volunteer to remove them from parks Norway Maple English Ivy Bush Honeysuckles Review Plants are native to specific regions & habitats They are adapted to local conditions They form an interdependent community with native wildlife They provide ecosystem services We, too, rely on those services We benefit from living in harmony with nature The survival of native plants is threatened by Loss of habitat Displacement by invasive exotic plants Destruction by introduced pests and native species released from natural controls General changes such as global warming 7

8 For all these reasons, we should do all we can to preserve native species and plant/animal communities, through: Land preservation Habitat restoration & maintenance Prevention of introduction & spread of invasives Gardens for wildlife, ecosystem services, sense of place Using Nature as a model 8