Original capacity: A Social History
of Restoration Efforts in the Southwestern USA
Nathan F. Sayre
Department of Geography, University of California, Berkeley, USA
[Abstract of a paper delivered at A transatlantic workshop held at the Zurich Botanical Garden, Zurich, Switzerland, organized by the Institute of Environmental Sciences, Zurich July 10-11, 2006.]
The Southwestern USA has been an important crucible for American ideas and ideologies of nature since the late 19 th century. John Van Dyke's seminal treatise on landscape aesthetics, The Desert, managed to construct a timeless apprehension of nature's beauty from observations made amidst acute ecological degradation—the great drought of 1898-1904, which followed on the heels of the worst overgrazing the region has ever seen. Around the same time, the overlapping fields of range science and plant ecology set down important roots in the Southwest at institutions such as the Santa Rita Experimental Range and the Carnegie Institution's Desert Laboratory, respectively. Over the course of the 20 th century, various regional ecological catastrophes were declared and denounced, often couched in metaphors of the fall, rapine, invasion, or immiseration. Many cases were later recognized as false alarms, but in every case, some notion of ecological restoration was implied or propounded. This paper examines three targets of major restoration efforts over the past century: perennial grasslands, riparian areas, and fire.
An estimated 84 percent of perennial grasslands in the Apachean Highlands bioregion have been invaded by shrubs; three-fifths of this area is deemed by The Nature Conservancy to be beyond restoration. Not for lack of trying, however. The field of range science came into being to combat Southwestern grassland destruction, even if its history there is one of repeated failures. The goal, at first, was recovery to "original capacity", measured in forage for livestock—it took more than fifty years of research before scientists conceded that no such thing as "carrying capacity" can be said to exist on these rangelands. In the meantime, two major interventions had already been carried out: chemical and mechanical assaults on mesquite trees, and introduction of an African lovegrass. The first was an expensive failure; the second has been deemed an ecological catastrophe in its own right. Today, rangeland ecologists have renounced restoration in favor of a more coherent notion of "remediation" that relies on measures of ecosystem processes rather than species composition.
In the case of riparian areas, restoration efforts have been still more incoherent scientifically yet in some ways more successful practically. Estimates of loss range as high as 98 percent, and intense legal and political pressure has been brought to bear in recent decades to "protect" and "restore" riparian areas. Yet historical photographs indicate that the idealized condition—cottonwood-willow canopy forests—has in fact increased dramatically since the 1890s. What has been lost, in most cases, are floodplain marshes, for which restoration would require radical alterations of current morphology.
The elimination of recurrent fires from Southwestern landscapes now appears a principal cause of both rangeland and riparian degradation, one that eluded sustained scrutiny until the 1980s. Here, finally, is a case where restoration may be a coherent, achievable goal, precisely because the goal is a process rather than a "condition", community or species. Yet despite persistent efforts by ranchers and The Nature Conservancy, fire restoration has occurred on only a few, discrete locations, due to antiquated policies and norms as well as the threat to rapidly multiplying exurban homes.[Emphases added by RNH]