Trees and plants aid stormwater management with their root systems, which stabilize and hold the soil and help absorb water (called infiltration: the process by which water is soaked into subsurface soils, rocks and spaces). This is especially true for wet-loving trees and plants. On the surface, then, this slows and minimizes runoff, which can have severely negative repercussions including erosion, sedimentation (buildup of loose particles in streambeds and storm drains, which can degrade habitat and water quality) and even property damage.
Trees and plants also increase evaporation and transpiration—by consuming water for their own use, increasing the amount of groundwater moved into the air from the soil around them, and releasing water as vapor through leaves and as evaporation from rainwater intercepted by the tree canopy.
Trees and plants, especially woody ones, also provide filtration and removal of pollutants, including excess nutrients and contaminates, among them, metals, pesticides, solvents and oil.
In fact, trees and forests are so important for stormwater management that they’ve been identified as among the most important Best Management Practices (BMPs) in stormwater management, after years of emphasis on retention basins that have done little to help with water quality.
Native species are even more beneficial than trees and plants in general!
Native plants are those that occur naturally in an area. They’ve evolved over time, adapting to local conditions including soil, climate and rainfall. So, as opposed to more exotic varieties, they require far less water and care, and save you much time and money.
There are approximately 2,100 native plants in Pennsylvania that include trees, shrubs, vines, wildflowers, ferns, grasses, sedges, rushes and mosses.
"Wherever I go in America, I like it when the land speaks its own language
in its own regional accent."
- Lady Bird Johnson, Wildflowers Across America (1993)
Native vs. Non-Native:
· First of all, as Lady Bird Johnson alludes to, natives offer a “sense of place,” meaning that they are tied to the locale, its landscape and heritage; they are keystone species that “belong” to the area.
· Natives are part of the natural ecosystem, or community, including plants, animals and microorganisms and, so, help maintain a natural and healthy balance. They are a fundamental link in the local food chain.
· Natives attract pollinators and wildlife because they provide food sources (nectar, pollen, seeds, leaves and stems) that native butterflies, bees and other insects, birds and other animals prefer and need to survive.
· Natives are unlikely to be invasive or overly competitive, crowding out other plants. Non-natives, on the other hand, can be invasive (though many are not), spreading aggressively and creating big swaths of monoculture, supporting a smaller and smaller diversity of pollinators and predatory species.
· Natives reduce the need for herbicides and pesticides, as well as water and other care, because they are the best adapted to local conditions. This yields a healthier yard for you and your family, including pets.
· Natives provide seasonal interest, or year-round beauty, with spring and fall blooms, changing autumn leaves, interesting bark and berries in wintertime.
· Many non-natives were imported for their ornamental benefit but have gotten way out of control, such as bamboo and Japanese or Chinese (vs. American) wisteria. They are not good neighbors! They refuse to stay in our yards, or ponds and water gardens. Like their land-born cousins, the nasty invaders in our water bodies choke out others in the fight for nutrients, light and oxygen. They can cause infestations that can migrate via boat bottoms, create floating mats of vegetation and algae blooms that produce all kinds of problems, or throw off byproducts such as nuts so hard and sharp they can puncture the soles of your shoes (from the European Water Chestnut).
So, now that we’ve convinced you of the reasons to add trees and plant material to your property—especially native varieties—here are some basic principles to follow when gardening or landscaping with natives:
· “Right Plant, Right Place”—Assess your local site conditions and select compatible plants whose ultimate size and shape fit your needs. (Don’t be surprised if they decide a different place is more ideal for them. And don’t fight it; go with it!)
· Plant Diversity—Choose a variety of plants to provide a more diverse wildlife habitat and more seasonal interest and to make damage from pest and disease both more manageable and less noticeable.
· Vertical Layers—A multi-layered approach (using grass, ground cover, bushes or shrubs, and trees of different heights) creates interest at every eye level, a diverse habitat, more cooling benefit for your home and greater cover for wildlife.
For further reading:
Why Use Native Plants? (PennState Extension)
Landscaping with Native Plants in PA (DCNR)
Native Alternatives(PennState Extension, Master Gardener Program)
Mistaken Identity: Invasive Plants and their Native Look-Alikes(Delaware Dept. of Agriculture, funded by US Dept. of Agriculture Natural Resources Conservation Service)
Invasive Plant Fact Sheets (DCNR)
PA Invasive Plants list (DCNR)