Novel ecosystems are new combinations of species and result from the influence of people, said Marilyn Jordan, Senior Conservation Scientist, The Nature Conservancy at a conference organized by the Society for Ecological Restoration (SER). Starting in the 1700′s, classic “biomes” started to reflect human changes. Now, more than half of natural wilderness has been impacted by people, with just 22 percent of the original wild left relatively untouched. Within this new human-dominated globe, some 37 percent of all ecosystems are novel. These could be former agriculture sites or new forms of urban ecosystems. In terms of biodiversity, this has meant a shift from native to non-native. For land-use, this process has meant a shift from functional uses for nature to simply ornamental ones. Both these trends need to stop and be rolled back.
To ensure people can continue to use nature for common benefit and gain from nature’s many ecosystem services, genes found in nature’s diversity must be maintained. Genetic richness is also needed for climate change — future adaptations can’t happen without a wide gene pool. As Jordan put it bluntly, “you can’t evolve if you’re dead.” Conservationists, however, are still debating whether it’s important to “save the stage and lose the actors” or focus on the ”place, which is more important than any species there.” Instead, Jordan thinks it’s about ecosystem stability and productivity.
Ecosystems are fragile. She explained that an ecosystem is like a plane. “If you start taking parts of out of the plane, it may continue to fly, but eventually it will crash.” Ecosystems all have breakpoints. “We can remove species but when we hit a certain point, there’s a rapid decline.” For example, many insect species – even “generalists” – are able to eat only a few plant species. If the native plants they rely on are pushed out of the way by non-native invasives, the insect species die. Looked at another way: in its native range, one plant may support 170 species, but outside its normal range, only supports five species. In ecosystems where 90 percent is non-native, there is no functioning food web left. Jordan says “butterflies can’t be supported by non-native species.” In these instances where native habitat has been taken over by non-native invasives, “we may need thousands of years to return to previous levels of diversity.”
To prevent ecosystem change, restoration ecologists focus on “early detection and rapid response.” To manage inevitable change, they focus on “eradication, containment, exclusion, and suppression.” Managing involves creating refuges for native species and genotypes. In these instances, “we’ll have to accept novel ecosystems.” Still, Jordan argued for not giving up. “We can take an ecosystem-level approach” or a wide view of restoration. “Eventually, this means we’ll need to manage that complex matrix though.”
Residential homes are a central part of novel ecosystems and homeowners can take some positive action on their own in the near-term. She made a pitch to homeowners: shrink lawns, remove non-native plants in favor of native ones, and leave leaf litter, which is habitat for bugs. These steps are actually crucial because lawns now make up more habitat in the U.S. than native land. Furthermore, to make novel ecosystems more amenable to biodiversity, “we actually need to make it illegal to sell non-native invasives” in the residential landscape marketplace.
Image credit: Example of sustainable residential design with use of native plants. ASLA 2008 Residential Design Honor Award, San Juan Island Residence, San Juan Islands, Washington. Paul Broadhurst & Associates, Seattle, Washington