In an article posted on The Dirt the outlines of a new type of ecological regeneration are laid out indicating that simple recreation of pre-development “nature” according to strict biodiversity guidelines such as enforced on Table Mountain in Cape Town, is unlikely to be sustainable as the entire system has been altered by the effects of prior interventions , be they agriculture, forestry or urbanization and overuse, nor is cosmetic renovation with generic planting such as is seen in much of the developments around the Cape, rather a new restoration takes the sites context into account and attempts to remedy the natural processes of the site, taking into account the ecosystem, cultural, social and governance aspects of the site and andhopefully leading to amore sustainable restoration:
“At a Society for Ecological Restoration (SER) conference entitled, “Brave New World: Working with Emerging Ecosystems,” Jack Sullivan, FASLA, Professor and coordinator of the new landscape architecture program at the University of Maryland College Park, said ongoing deforestation and urbanization is actually a “war on nature.” Furthermore, any attempt to restore nature that has been taken over by development can’t rely on the “natural history of a site” for guidance. These “post-traumatic” landscapes have been altered too much. Ecological restorationists and landscape architects, who are at the “front lines” of the battle and are the “heroes in this brave new world,” must take better advantage of ecological research in order to restore nature. To date, a restoration approach based in ecological research has often come into conflict with the “big D” design approach to a site. The end goal shouldn’t be a place “that could be anywhere so you don’t know where you are.” A restored landscape must reflect a careful examination of the site and its natural history.
One of the front lines of this war for ecological restoration are “novel ecosystems,” which are “ecosystems that have purposefully emerged because of the presence of people,” said Margaret Palmer, Director of the Chesapeake Biological Laboratory and Professor at University of Maryland. Novel ecosystems beg questions: How do they work ecologically? Should we restore them to a more natural state? Maybe they should be left as is?
As an example, Palmer pointed to attempts at ecological restoration that have gone awry: channelized rivers that were restored and ended up turning into muddy, non-functional ditches. In other cases, large-scale power dams, which are huge interventions in natural riverine systems, are actually blocking the spread of non-native species, so keeping them in some places could be a good thing. In addition, some ecological restorationists have tried to restore to some vision of nature that didn’t really exist in an environment. Referring to well-regarded research on smaller mill dams, Palmer said once mill dams were removed on one site, new natural channels added didn’t work. Instead, “threaded channels” like a wetland were the correct application of nature.
We live in a “human-dominated world” but nature is constantly changing. “Rivers and streams are actually fixed in a state of change.” In another example, Palmer said fisheries have a changing baseline, having been depleted over time. Relating this to a forest, Palmer asked, “at what point do we chose a baseline?”
“Reference” sites are even declining. “Should we use least-impacted reference sites instead?” She argued that this approach “makes you feel like you are giving up on restoring nature.”
So “how do we restore nature if the world is changing and we can’t go back in time?” One way to restore a stream is to look at flow records, the “historical natural flow regime.” This, in fact, should be “embedded in any stream restoration.” In addition, restoration ecologists can design a channel based on what “we think it will be like,” and calculate slope, depth, and scale based on estimated flow. “This hydrologic and geo-morphologic model for change is extremely complex and multi-variate though.”
Palmer argued that restoration is “big business” these days. Lots of state and municipal governments are investing in restoring nature. In these efforts, the priority has been conservation; then “passive restoration,” or removing obstacles; then “active restoration,” like creating a new wetland from scratch; and finally, creating “designer ecosystems” – creating a wholesale new stream where there was none before.
She concluded ”maybe it’s not possible to keep everything we want. We can restore certain ecosystem service functions.” (Unless, that is, those certain functions can’t even be supported in degraded environments). In these cases, communities need to decide what is the priority, and ask “What services do we want from rivers? Communities can chose the ones they want and decide on a process to get that.” Restoration ecologists and landscape architects can then “manipulate ecological processess and biophysical structures to get services back.” Given tight budgets, communities must first make priorities when restoring nature.”
Image credit: ASLA 2009 Professional Analysis & Planning Honor Award. Brays Bayou Greenway Framework, SWA Group