Native plants are adapted to the climate of Portland. Native plants attract and provide food/shelter for native insects, animals that are predators, like birds, have more to feed on over time. By planting natives in a garden, a more supportive environment is created, allowing more insects to live and breed, increasing food supply for birds to feed on. Ornamental plants typically have little insect damage, since they are usually not palatable to insects: however, even ornamental plants harbor arthropods that need a pace to hang out. By providing habitat, we may be increasing food resources for birds, birds will be able to continue to live in our area, and we might be supporting other native wildlife as well, such as salamanders.
As cities grow, native habitat becomes more fragmented. Where once a naturally occurring forest ecosystem once existed, we now have only patches of forest habitat. The areas in between the forest patches are usually not supportive of a complex forest ecological processes. Once abundant species can become endangered or extinct within the urban boundaries. The growth of cities also contributes to the introduction of non-native species that compete for resources that are already scarce.
With dwindling natural areas and a lack of sufficient green spaces, what we plant in our gardens and yards could help provide little stepping stones of habitat for our dwindling insects, spiders, birds, pollinators, and wildlife species.
You can help in the effort to understand how garden habitat influences wildlife in the city, You could measure the shrubs and other plants in the garden and see how wildlife species observations change over time as your garden matures. Percent cover is an efficient means of understanding the relative abundance and contribution to the ecosystem made by different plants. Percent cover is a measure of influence. Since plants may be persisting, or dropping out, or coming in to the system, we monitor over time.