Ecological Processes to Guide Us
Our favorite principles for ecological landscaping follow— all deserving of greater exploration and study.
Understand Your Soil and Site
Get to know your soil, hydrology, climate through the seasons, and everything you can about the growing conditions you are working with. Choose the plants that are suited for those conditions. Do a soil test (or tests) to assess pH, percent organic matter, soluble salts, and nutrient levels. It is best to work with the soil you have to its best advantage, and not try to modify it for growing species that do not really belong there. Look for different niches and microclimates present— making it possible for a species to work very well in one particular spot but perhaps not so well 10 or 20 feet away. Landscapes with varying typography and terrain offer all kinds of opportunities.
The Importance of Leaf Litter
Leaf litter, and leaving leaves to decay naturally as part of garden management, is fundamentally important to soil health and to supporting biodiversity— to life for birds, butterflies, bumblebees, and many other faunas. The very active food web and habitat created within leaf litter supports those charismatic species along with many others, such as amphibians, reptiles, and fungi. When you leave the leaves in your woodland or perennial garden, and the dead stalks and foliage in your meadow garden, the soil regenerates itself beautifully and fertilizers are typically not needed. This wonderful organic matter, as it decays, acts as garden mulch, suppressing weeds. And it is delivered free of charge each year. Traditional lawn areas, of course, need to have leaves raked off or, better yet, mowed with a mulching mower. But managing your garden so that the vegetative material produced each year is fully recycled in place by natural processes, is a brilliant move!
Plant species grow in association with one another, in plant communities, and the makeup of species present is greatly determined by the underlying geology, hydrology, and climate of a given site. The natural communities of a dry, rocky, granite hilltop, are quite different than those of a calcareous woodland or a wetland bog. Within any given plant community there are important soil associations and many complex plant-to-plant and soil relationships that we do not yet fully understand. But observing the assemblage of species that grow together in "the wild" can be helpful in developing a landscape design. When we understand our site conditions, we can look to the natural communities, and the species that typically grow together in those conditions, to give us cues about plant selection. See more at Ecoregions of Massachusetts.
Every Garden is a Landscape in Succession
Often, when we are designing a landscape, we form an image in our heads that is a still shot of the beauty we envision. But it would be better if we thought of it as a movie instead, because plants are constantly growing and eventually dying, changing light and shade and soil all along the way. The rate of change in woody landscapes can be quite rapid from one year to the next, as trees and shrubs surprise us with their growth. And if we are creating a meadow landscape, we are trying to arrest natural successional processes by weeding, mowing, or burning to keep woody plants from getting established, but our mix of annuals and perennials will evolve as well. So when we create a plan that considers how we want our landscapes to evolve over time, we have the advantage of working with natural processes, rather than fighting them.
Trees and Shrubs are Critical to Biodiversity
The plants that give us the most "bang for the buck" in improving biodiversity overall, are native trees and shrubs. They support the highest number of Lepidopteran species (butterflies and moths), whose caterpillars are so essential to the entire food web, and especially to birds. Among the woody plants, some genera and species support far more caterpillars than others. Doug Tallamy's work is well known for giving us wonderfully specific detail about which woody plants support which Lepidoptera. Because trees and shrubs have such an impact on the health of local ecosystems, and because they form the bones of your landscape plan, it is wise to pay careful attention to species selection and plant them early in your process.
A Few More Tips
- Avoid the use of pesticides, and especially neonicotinoids that are so readily included in many off-the-shelf garden products. They are quite harmful to pollinators and to insects in general.
- Massing many specimens of the same species in your planting design will do much more to improve habitat value and support wildlife than planting isolated single specimens; this is especially true with respect to shrubs and perennials. And visually, massings and drifts of plants create more interesting effects.