Restoration of a heavily degraded ecosystem

In this post Associate Editor David Moreno Mateos discusses a paper he recently handled by Andrea Borkenhagen and David Cooper ‘Creating fen initiation conditions: a new approach for peatland reclamation in the oil sands region of Alberta

Go to Google Earth and adjust the screen so you can see the whole of North America from about 7,000 km from the ground. You will see Alberta, one of the large Canadian provinces, which is about three times the size of Great Britain. At that distance, in the upper right corner you will see two light brown spots, the upper one is Lake Claire which is about 1,400 km2 and the lower one is the tar sand opencast mines.

At the moment the surface area of the mines is still below 1,000 km2 but it seems that it will not take much time to reach that size. There have been a number of initiatives to rehabilitate and restore the heavily degraded lands that remain after the tar is extracted. Some of them have been concerned with completely different things than peatlands including lake marshes or upland forest, others have aimed at restabilising a layer of organic matter from surrounding peatlands to facilitate the establishment of moss species found in mature peatlands. What is relevant about the new study by Borkenhagen and Cooper is that rather than recreating the conditions of mature peatlands, and of course creating new habitats, like marshes and forests, instead they focus on the natural succession of peatlands. That is, peatlands at some point start to become fens on mineral soils, but what happens next?

Mined area getting ready for rehabilitation
Mined area getting ready for rehabilitation in Alberta, Canada. Photo credit: Andrea Borkenhagen.

Borkenhagen and Cooper dug the peat to find out and found a bunch of herbs, woody shrubs and mosses that were pioneers a few thousand years ago on the sterile lands. They pick a few peat-forming moss species commonly present in fens, but not bogs, in the area and chose several water depths to test the effects of those initial conditions on moss establishment. Their findings are highly context dependent, which is the usual, overall feature of restoration. The more we know about one place the higher will be our success. They found that different moss species were adapted to different water depths which reflects that their approach is consistent with real-world conditions, and mosses grew better when those herbs and woody species found under the peat were present. A great lesson from paleoecology! Although an actual bog will take just a few years to form – about 5,000 – the early fens from this study show surprisingly fast growth in only three seasons.

Core used to sample moss biomass
Core used to sample moss biomass in one of the experimental treatments. Photo credit: Andrea Borkenhagen.

An important feature of the findings of Borkenhagen and Cooper is that their approach is cheap (I mean cheap once the stockpiles, channels, road-marks, and other physical leftovers from tar extraction are removed). But in any event, it does not involve bringing large amounts of peat from somewhere else or creating large basins to retain water; although the large-scale hydrology of a rehabilitation project on a former tar sand area is a whole new story to be written.

In brief, before restoring heavily degraded lands, in former tar sands and beyond, that sometimes resemble the Earth after the retreat of the glaciers, it may be a good idea to go back to those initial times and learn what was there and what conditions existed. Then, try to simulate those conditions, although you may need to wait for a few thousand years.

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