When planting native, following a few specific principles will maximize benefit to wildlife. So far, we've covered the importance of keystone plants and plant diversity. Next we'll cover trophic layers, which consist of the canopy layer (tall trees), the sub-canopy (understory trees and tall shrubs), the shrub and ground layers (perennials and groundcovers). This is how nature landscapes, so it should come as no surprise that it's better for nature than a solitary tree (even an oak) surrounded by an expanse of mowed grass.
Different wildlife species spend a majority of their lives in one specific trophic layer, so this type of approach also supports higher diversity. Let's look at a few examples.
The canopy layer is where katydids, walking sticks and larger birds (such as raptors) can most often be found. The canopy layer also helps protect the plants beneath from excessive sun, wind and pounding rain, and helps to hold humidity close to the ground.
Mid-sized birds, butterflies and a whole host of other insects occupy the sub canopy layer. Humans and wildlife find most of their food there, from shrubs and understory trees, and vines whose growth is supported by the sub canopy. Even those species that normally reside in the canopy layer often descend to the sub canopy for food, nesting material, and shelter when needed.
Smaller birds and mammals and some insects rely on the shrub and ground layers for food, cover and nesting sites. Most of the 800 species of butterflies and 12,000 species of moths in the US overwinter in the leaf litter that is held in place and further sheltered by shrubs and ground layer plants.
Including these trophic layer also has numerous benefits to humans. This type of landscape design creates a more stable, interconnected root system, making it less likely you'll lose a tree in high winds.
It's also a more carefree way to landscape, as the leaves that fall are held in place and hidden by the lower layers, and invasive species are less likely to settle in and create more work.
There is also a lot more visual interest to this type of plant community, as there will be flowers, fruits, nuts, and a wider variety of fall colors. And, while planting trees improves heating and cooling efficiency, including these critical trophic layers helps even more.
Be sure to check out part four for more critical principles of planting native.