The project transcends history without neglecting its importance: the park will function like a Pleistocene grassland yet without a truly Pleistocene species compositions. There are many aspects of this region that may not be reconstructed through restoration. Firstly, paleoclimatic reconstructions suggest that though the precipitation would be similar to present patterns, the Pleistocene climate of north eastern Russia was 2⁰-5⁰C colder in summer, and 10⁰- 20⁰C colder in winter than present temperatures, which resulted in a shorter growing season (Zimov et al. 1995). Secondly, because some species from the original mammoth steppe ecosystem have now gone extinct, the goal of this project is not to restore the historical composition of the ecosystem, but rather to create an ecosystem with similar function, levels of diversity, and productivity. In this way, replacements are used to fill the necessary functional role for species that have gone extinct (Pleistocene Park, n.d.).
It is hoped that introduced megafauna will return the ecosystem to its Pleistocene state by interacting with the landscape in multiple ways. The grazing activity of megaherbivores is essential to achieving a novel mammoth steppe-like ecosystem Large herbivorous vertebrates have strong interactions with their landscape and vegetation, which directly affects the structure, composition, and dynamics of plant communities within these animals’ range (Johnson, 2009). In an experiment which took place in the African Savanna, it was shown that there was a 9% woody cover increase over a 36 year period when fauna (<5kg) were excluded from the landscape. Further, it was found that the low woody cover is mainly driven by elephants, which uproot 1500 trees per elephant, per year (Doughty, 2010). Doughty (2010) compares the current grazing systems in Africa to the Mammoth steppe of the Pleistocene and states that the two systems may have functioned in a very similar manner; “abundant herbivores maintaining productivity by enhancing the rate of nutrient cycling through more labile biomass pools”. Moreover, examination of recovered mammoths has shown that they had a very similar diet to African elephants. Both of their diets contained grasses as well as multiple tree species that were also found in the Pleistocene era such as willow, birch, larch, and alder (Doughty, 2010).
With the extinction of many of the Pleistocene megafauna herbivores, which consumed a significant net primary production, there would be a reactive increase in size of both grasses and trees. However, trees would eventually grow overtop these grasses and dominate the ecosystem (Doughty, 2010). Simply put, the megafauna that inhabited this ecosystem prevented forest growth and tundra vegetation by various direct and indirect influences. Similar to the summer grazing which enabled the predominance of grasses and herbs, the trampling of snow by megafauna in the winter also led to multiple facilitations that other smaller and predatory species along with vegetation relied upon (Putshkov, 2003).
Mammoths and the hooves of various other ungulates moved and created paths through snow during feeding of the various herds. These areas, connected by multiple paths allowed for the easy grazing of smaller species but also the easy passage through what would have been very deep snow. This allowed for the easy predation by species such as the cave lion (Panthera leo spelaea) who could use these pathways to catch prey (Putshkov, 2003). A recent study from Pleistocene Park showed an increase of protein content in winter feeds where heavy grazing has taken place or where animals had been digging in the snow disturbing the mosses and soils below (Zimov, 2007).
The disturbance of the mosses by these new species will allow grasses to grow in between the moss. This will reduce the soil moisture much more effectively than the mosses through high rates of evapotranspiration, which, in turn, will purportedly transition the land to a mammoth steppe ecosystem. Furthermore, based on the plant competition for water, light, nutrient supply, and plant sensitivity to grazers, a grass dominated tundra could exist under current climate conditions (Zimov et al., 1995). The living plant communities that inhabit these ecosystems need to be re-imagined with the megafauna that complement them in order for Pleistocene Park to be a success. “This insight should also provide the foundation for ecological restoration, which should aim to reinstate interactions between large herbivores and vegetation where that is still possible” (Johnson, 2009).
The association that herbivorous grazing and soil fertilization have with tundra/grassland ecosystem transitions is not only associated with Pleistocene rewilding, but also with transformations of modern arctic ecosystems (Croll, 2005; McNaughton, 1984). This project is valuable to the field of restoration as it furthers our understanding of tundra rangeland stability and the important roles that interconnected trophic levels play in maintaining system function in the arctic. Implications from this research may assist in restoration in areas that are affected by declining herbivore populations, such as caribou (Rangifer tarandus) or bison (Bison bison) here in Canada using novel ecosystem theories and practice.
Implications for the field of Restoration
In her book, Rambunctious Gardens, Emma Marris describes how some restoration ecologists are abandoning the idea of restoring ecosystems to a historic baseline. Instead, ecosystems are frequently being “design[ed] or engineer[ed]” for “specific measurable goals” (Marris, 2011). Although it does have a historic, albeit prehistoric goal, Pleistocene Park is an example of a restoration project where the ecosystem is being engineered to mitigate the effects of climate change.
Arctic soils contain approximately 14% of the global soil carbon (Anisimov & Reneva, 2006: p. 174). Northern Siberia’s soil is especially carbon rich, often dozens of meters thick compared to other regions which only have a carbon-rich layer of 0.5 meters (Zimov, 2007). This carbon remains in the soil because freezing temperatures and the resulting permafrost, defined as “any subsurface material that remains below 0oC for at least two consecutive years,” prevent all but the slowest decomposition of organic material (Anisimov & Reneva, 2006; p. 169). Zimov’s Pleistocene Park is a progressive response to years of observed permafrost decline in the Northern Hemisphere, where permafrost regions account for 25% of the terrestrial surface (Anisimov & Reneva, 2006: p. 169). In their 2014 paper, “Warming-Induced Shrub Expansion and Lichen Decline in the Western Canadian Arctic,” scientists Robert H. Fraser et al., observed that increasing temperatures in the Tuktoyaktuk Coastal Plain in Canada’s Low was causing permafrost to thaw. As they write, “air temperature increases likely promoted growth of Arctic shrubs indirectly,” by warming the soil and thus increasing soil productivity (Fraser et al., 2014: p.1163). This allows vegetation composition to shift from lichens to shrubs, making the landscape greener and reducing its ability to reflect solar energy, measured as albedo (Fraser et al., 2014). Similarly, studies by M. Torre Jorgenson and colleagues in Alaska’s Arctic found that permafrost degradation in Alaska had greatly increased since 1982 due to “record warm temperatures (Jorgenson et al., 2006: p. 1). They predicted that:
If trends continue, 10-30% of the terrestrial landscape may be directly affected, greatly altering local biodiversity, plant communities, and wildlife use; modes of soil respiration and organic matter accumulation; and sinks and sources of trace gases (p. 4) [emphasis added].
As anthropogenic climate change causes temperatures to rise, the fear is that a positive feedback loop will occur in which permafrost thaw will cause soil nutrient cycles to speed up, releasing gases such as carbon or methane into the atmosphere, which will raise temperatures further (Zimov, 2005: p. 798). If the soil is beneath water, a likely scenario in the case of rapidly melting ice, microbial activity will transform stored carbon into methane gas – a highly potent greenhouse gas (Wolf, 2008: p. 67). Some have described this as Siberia’s “Carbon Bomb” (Wolf, 2008).
By recreating the pasture ecosystem of the mammoth era, scientists hope to “contribute to global cooling” by returning the system to back to a negative feedback relationship with the climate in which greenhouse gases are (and remain) sequestered in the soil rather than being released into the atmosphere (Zimov, 2007: p. 112). In fact, the park has had some success in cooling. The presence of animals in the park has effectively compacted snow during peak wintertime which has lowered ground surface temperatures to as much as 20oC cooler than in similar places without pastures (Zimov, 2007). By halting further permafrost decline, the project hopes to prevent the “runaway warming” that is predicted if significant thawing of permafrost occurs in the Arctic (Zimov, 2007: p. 112; Wolf, 2008: p. 68)
As a project that is engineering a landscape through the process of rewilding, Pleistocene Park challenges previous notions of what ecological restoration is. Both ‘Pleistocene rewilding’ and ‘designer ecosystem’ have become controversial topics among restoration and conservation ecologists. Some scientists are critical that rewilding projects like Pleistocene Park will not be able to meet their intended trajectory. Critics of Pleistocene rewilding argue that it is unrealistic to assume that communities and climatic conditions today are functionally similar to their state in the past, and that success in rewilding programs will be unpredictable (Caro, 2007; Nicholls, 2006; Rubenstein et al. 2006). They suggest significant time has passed for these communities to evolve in the absence of megafauna, and the reintroduction of large mammals could disturb ecosystem dynamics and lead to the destruction of the fragile native tundra ecosystem already present. In terms of intentionally engineered or designed ecosystems, critics are most fearful that accepting such ecosystems will result in a lack of commitment to the conservation and restoration of existing ecosystems (Hobbs et al., 2014). As Hobbs et al. (2014) write, “accepting novel ecosystems leads to the recognition that some ecosystems may be effectively managed for goals other than a return to the ecosystem’s historic trajectory” (p. 562). Is Pleistocene Park a legitimate intervention? Is it appropriate to create landscapes for specific goals, such as the mitigation of climate change? These questions are difficult to answer and the project’s success or failure will certainly spark further debate as to the trajectory of future restoration projects in the era of climate change.