Many ecosystems have been degraded or modified, and these are the sorts of systems you target for restoration. But when a system has been altered so much the original species might not be the best choice to bring it back to health. Therefore, says Thomas Jones, you need to look at alternative species.
A paper from BioScience has caught my eye. In Ecologically Appropriate Plant Materials for Restoration Applications Thomas Jones argues that restoration might go better sometimes if you bring in some novel species to a site. What I find interesting is that it tackles the question what does it mean to ‘restore’ an ecosystem? My initial reaction is put it back as it was, but the ecosystem that was there was the product of centuries of interactions. Perhaps putting the final ingredients into a place and expecting a working ecosystem is like expecting some eggs, sugar and flour to spontaneously become a cake.
Bringing in novel species might sound like giving up on restoration and replacing the ecosystem instead. Jones shows that it’s not the case. The abstract includes this section which explains:
Ecologically appropriate plant materials are those that exhibit ecological fitness for their intended site, display compatibility with other members of the plant community, and demonstrate no invasive tendencies. They may address specific environmental challenges, rejuvenate ecosystem function, and improve the delivery of ecosystem services. Furthermore, they may be improved over time, thereby serving to ameliorate the increasingly challenging environments that typify many restoration sites.
In the paper Jones says that, for some ecosystems, local has value rather than local is best. Following this way of thinking, you introduce novel plants so that you can support the local material. If you think of an ecosystem as a whole system, instead of a collection of parts, then this extra support is a success rather than an intrusion. It also helps acknowledge that ecosystems are rarely oases isolated from anywhere else. The restored system might well have novel neighbours. The new species could help make the restored system more robust to challenges from outside.
Another factor is ecosystems aren’t binary between natural and broken. They change with human activity. The longer they’ve been exposed to human activity the farther from natural they move. If the ecosystem you’re restoring isn’t strictly natural then how do you work out what natural is? Jones points out ecosystems are dynamic and not always in stasis.
If Jones is right then restoration is not the same as preservation.
This thought may be disturbing to preservationists, who may view anything less than entirely local plant material as an unwise exchange of restoration orthodoxy for a “slippery slope.” Nevertheless, one cannot continue to rely solely on local genotypes simply because they are local and theoretically best adapted if experience demonstrates otherwise.
It certainly bothers me. The question then becomes do you do what works, or what you wish would work? It’s a good paper and, as I write, free access so definitely worth a visit to read.
Jones T. (2013). Ecologically Appropriate Plant Materials for Restoration Applications, BioScience, 63 (3) 211-219. DOI: 10.1525/bio.2013.63.3.9