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Tuesday, July 3, 2012

Transitory Places, part 2

Karori Sanctuary as a Transitory Place

I paid two brief visits to Karori Sanctuary in early 2010, in high southern summer.  My visits were about two weeks apart, and I stayed for only a few hours each time, so my direct experience of the place barely amounts to a snapshot. I did not even visit the sanctuary at night, when the kiwi would have been active, or in the early morning, when I could have heard the “dawn chorus” of resurgent native bird life.  The relevant scale of my own visit, then, was a matter of minutes and hours, rather than days and weeks.

Had I been able to stay on in New Zealand to study the sanctuary, and perhaps even volunteer there, or should I be able to go back to visit sometime soon, the relevant scale would still only be a matter of months and years. This would amount to a narrow slice of the half-millennium scope of the conservation effort Karori.  Within that narrow slice, the broader context within which the restoration effort takes place might well seem to be relatively stable: Wellington and its surrounding region seem unlikely to change very much during that time, so those carrying out the project will know what to expect: as they attempt to push the sanctuary back in time, as it were, they can at least know what they are pushing against.

And yet, a look into deep time, the domain of geologists, should give pause.  The landscape of contemporary New Zealand is renowned for its ruggedness, but when it first separated from Gondwana, the ancient southern supercontinent, 80 million years ago, the subcontinent dubbed Zealandia was flat and low lying.  During the Oligocene, 33-24 million years ago, sea levels rose and reduced the subcontinent to an archipelago of small islands. After that, in the Miocene, a plate boundary formed underneath Zealandia and geologic activity got underway in earnest, reshaping the land and lifting it above the waves, spawning volcanoes and raising mountains (Gibbs, 2006, pp. 80-81).  It would seem that, at the scale of geological time, the changes that can be worked in a landscape are linear and unidirectional: Zealandia today bears scant resemblance to what it was 25 million years ago.  Presumably, it bears scant resemblance to what it will be 25 million years from now, assuming it remains above sea level and separate from other land masses. 

The geologic time scale is relevant to the conservation project at Karori mainly because 80 million years of isolation, out of the “evolutionary mainstream of the larger continents”, have made the biota of New Zealand quite distinctive, including species, genera, and even orders not found anywhere else (Gibbs, 2006, p. 13).  While the aim of the Karori Sanctuary is to restore and protect that distinctiveness, it is pitched at a scale that is more practical for the purposes of conservation work, less remote from a human time scale. It is, after all, neither possible nor especially desirable to restore the landscape to what it was 25 million (or even 100,000) years ago, nor can we expect the landscape to remain in its restored state for the next 100,000 or 25 million years.  Instead, the project is conceived at a scale of hundreds of years: 500 years from now, with patient and diligent effort, the Karori valley will be much as it would have been 1000 years ago.

In the context of recent literature on restoration ecology, it should be clear that the 1000-year baseline is a choice conditioned by human values, rather than the pure reflection of an objective ecological criterion (Davis and Slobodkin, 2004; see also Higgs, 2003, pp. 162-163).  Even in the absence of anthropocentric disruption, biogeographic conditions on New Zealand would have changed over time, and would continue to change, through the ordinary working of ecological, evolutionary and geological processes (see Choi, 2007). To select the moment just before the first Polynesian canoes made landfall is still to make a choice that is, in ecological terms, arbitrary: there is nothing particular more “natural” about the New Zealand landscape as it was then as compared to what it was 1000 years previously, or would have been 1000 years hence, had humans never arrived.

The most that can be said for the 1000-year baseline is that it is less obviously arbitrary than it would be in a North American context, where anthropogenic change has been underway since the Pleistocene; here, a baseline set to 13,000 years ago would not capture “pristine” nature, and would seriously exacerbate the problem of incomplete information in determining what the “original state” was (Toledo, Agudelo, and Bentley, 2011).  At least, at Karori, three loose and common ways of talking about ‘naturalness’ in restoration ecology converge, giving some cultural heft and resonance to the selection of the baseline (following Hull and Robertson, 2000, pp. 100-104): it is an effort to restore a landscape to a previous point in time on the scale of a few thousand years, a point at which there would have been minimal human modification to the landscape and, related to that, a slower rate of change compared to what would happen after humans arrived.

To emphasize this, part of what makes New Zealand distinctive is that, prior to the arrival of Polynesians about 800 years ago, there were virtually no land mammals at all. Birds, including two endemic orders of ratites – moa and kiwi – dominated the fauna.  Four endemic species of flightless wren, now extinct, were like “highly athletic mice that could flit around the forest floor and scale tree trunks looking for insects” (Gibbs, 2006, pp. 14-16). Many of New Zealand’s bird species were flightless, and many of those that could fly were weak flyers, nested on the ground, or both.

James Lynch, who first conceived of a sanctuary at Karori, appealed directly to this avian past in a vision statement in 1992. Looking ahead to what the sanctuary could become, he also looked back to what might once have been:
the most noticeable difference in the forest is the birdlife. Like the forests of old, this forests rings with the whistles and coughs of the tui, the beautiful chimes of the bellbird, the chatter of the saddleback and kakariki and the booms of the weka. Noisy flocks of whitehead and silvereye pass into view. The trill of the grey warbler is always in earshot. At night can be heard the eerie call of the morepork and the haunting cry of the kiwi.

Noting that the sanctuary is also “a place for people,” he describes the experience of future visitors, including those who “return for the ‘Dawn Chorus’ tour at 6am to hear the real sound of old New Zealand” (quoted in Campbell-Hunt, 2002, pp. 36-37).

The arrival of humans from Polynesia marked the end of New Zealand’s 80-million-year isolation and the beginning of a rapid biogeographic upheaval that continues even now. Human activities did have a direct impact on the biota, of course, including the likely extinction of the moa at the hands of human hunters.  More important, perhaps, were the organisms humans brought with them. The first wave included kiore, a Polynesian rat, which spread across the islands and exerted pressure on the breeding success of ground-nesting birds. With the arrival and settlement of Europeans a few hundred years later, the upheaval accelerated and intensified as more and more organisms from elsewhere were introduced.  The Norway rat, introduced in 1830, swiftly took over the range of the kiore, which the Maori at the time took as symbolic of their own decline in the face of European encroachment (Crosby, 1986, p. 266).

In addition to plants, animals, and pathogens, Europeans strove to impose on New Zealand their own ideas of what a good, productive, and attractive landscape should be. The land did not always submit easily or respond as expected. In recounting his own decades-long effort to establish and maintain a sheep station on the North Island, Herbert Guthrie-Smith documented the difficulties and frequent reversals in the process of establishing useful pasture land, working against both native and introduced plant species (Guthrie-Smith, 1999, pp. 177-178).

Much of the Wellington region was burned over, destroying the native vegetation on which endemic nectar-feeding birds were dependent, to make way for farmland and, later, urban development. The Karori Valley itself was not developed because, for 120 years, it was protected as the catchment for Wellington’s water supply (Campbell-Hunt, 2002, p. 13). The dams and their reservoirs are still in place, but the opportunity to convert the valley to other uses arose because they were decommissioned and Wellington’s water supply located elsewhere, for reasons that will become clear shortly.

Set against the broader context of biogeographic upheaval, the Karori Sanctuary works mainly by exclusion. The entire sanctuary is surrounded by a fence specially designed to keep out all mammals: stoats, brush-tail possum, cats, rabbits, rats and mice. Once the fence was closed, in 1999, a systematic process of predator eradication got underway, in several stages, using traps and poison bait.  The process targeted 13 species at once, including rats, mice, cats, stoats, and others; perhaps most dramatically, the effort yielded 3 tonnes of brush-tailed possum carcasses (Karori Sanctuary Trust, 2008b).  The longer-term project of replacing non-native with native vegetation and re-introducing native animals, continues now and into the future.  By these means, the Trust is attempting to create and maintain a "mainland island" on the fringes of a busy urban area. (Campbell-Hunt, 2002, p. 14)

This, I think, gets to the heart of why Karori struck me as fragile: it is a small island protected only by a continuous and, it must be said, variably effective effort to push back a rising tide.  Or, to shift metaphors, it is a small place being pulled back in time, to the extent such a thing is even possible, while the broader place in which it rests and, really, the whole of New Zealand seems to be surging forward to some new and uncertain biogeographic future (regarding which see Higgs, 2003, pp. 173-177).  

As David Lowenthal (2010, p. 15) would have it, the thought of restoration is conditioned by a circular sense of time, “the recurrent cycles of nature’s constancies.” Somehow, the linear path of change to which Karori has been subjected is to be wiped away so ancient cycles resume.  And yet we also sense time as linear, and “time’s arrow subverts and denies restoration. The arrow flies only once from the irrecoverable past toward the foreign future, never again the same”.  Human life, writes Lowenthal, is shaped by “the interplay of circle and arrow”; so, I would suggest, is the prospect of restoration at Karori.

Any ecological restoration would face the challenge of time’s arrow, to one degree or another, but there is something particular to Karori that accentuates its fragility.  Stepping back once more to take in a wider sweep of time and space, there is one way in which the geological time scale is still relevant here, intruding into the scale of centuries and, it may well be, years; at some point, the slow working of geological processes will take on immediate urgency.  New Zealand rides atop a continental plate boundary, and geological activity is to be expected. Karori Valley is part of the Wellington Fault, which continues north through Wellington itself and follows the harbor up into the Hutt Valley.  This precarious position is, in a sense, no accident: it’s precisely because the valley is part of an active strike-slip fault that the reservoirs were decommissioned: it seemed imprudent to have the capital city of New Zealand dependent for its water supply on two reservoirs subject to catastrophic failure in an earthquake. 

A major quake may be expected along the Wellington Fault every 500-1000 years, with the last one having occurred some 300 -500 years ago (GNS Science, 2011).  At some point in the future, perhaps within the time scale of the Karori restoration plan, a major rupture in the fault is to be expected.  Displacement along the fault of even a few meters would make a mockery of the otherwise very fine fence that now holds back the biogeographic tide.  Should the Karori Sanctuary and, indeed, Wellington itself still be going concerns when that happens, the people of the region will have more pressing matters to attend to than mending fences to keep stoats away from kiwi eggs.

Sources
Campbell-Hunt, D. (2002). Developing a Sanctuary: The Karori Experience. Wellington, NZ: Victoria Link Ltd.

Choi, Y. D. (2007). Restoration Ecology to the Future: A Call for New Paradigm. Restoration Ecology, 15(2), 351-353. doi: 10.1111/j.1526-100X.2007.00224.x

Crosby, A. W. (1986). Ecological imperialism : the biological expansion of Europe, 900-1900. Cambridge: Cambridge University Press.

Davis, M. A., and Slobodkin, L. B. (2004). The Science and Values of Restoration Ecology. Restoration Ecology, 12(1), 1-3. doi: 10.1111/j.1061-2971.2004.0351.x

Gibbs, G. W. (2006). Ghosts of Gondwana: The History of Life in New Zealand. Nelson, N.Z.: Craig Potton Publishing.

GNS Science. (2011). How do we know which fault is most likely to rupture next in Wellington? Retrieved September 2, 2011, from http://www.gns.cri.nz/Home/Learning/Science-Topics/Earthquakes/New-Zealand-s-Fault-Lines/Major-Faults-in-New-Zealand/Wellington-Fault/How-do-we-know-which-fault-is-most-likely-to-rupture-next-in-Wellington

Guthrie-Smith, H. (1999). Tutira: The Story of a New Zealand Sheep Station. Seattle: University of Washington Press.

Higgs, E. (2003). Nature by Design: People, Natural Process, and Ecological Restoration. Cambridge, Mass.: MIT Press.

Hull, R. B., and Robertson, D. P. (2000). The Language of Nature: We Need a More Public Ecology. In P. H. Gobster and R. B. Hull (Eds.), Restoring Nature: Perspectives from the Social Sciences and Humanities (pp. 97-118). Washington, D.C.: Island Press.

Karori Sanctuary Trust. (2008b). A pest-free sanctuary  Retrieved September 5, 2011, from http://www.sanctuary.org.nz/Site/Conservation_and_Research/Restoration/Pest_eradication.aspx

Lowenthal, D. (2010). Reflections on Humpty-Dumpty Ecology. In M. Hall (Ed.), Restoration and History: The Search for a Usable Environmental Past. New York: Routledge.

Toledo, D., Agudelo, M. S., and Bentley, A. L. (2011). The Shifting of Ecological Restoration Benchmarks and Their Social Impacts: Digging Deeper into Pleistocene Re-wilding. Restoration Ecology, 19(5), 564-568. doi: 10.1111/j.1526-100X.2011.00798.x

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