|Landscape ecologist M.L. Cadenasso, architect Phanat Xanamane, and landscape architect Victoria Marshall (L-R) work on the "periodic table" of urban land covers for Baltimore using the HERCULES methodology.|
First, there was the need to understand ecological systems over the long term. Since 1980, Long-Term Ecological Research “sites,” as they are still most often called, had been funded to conduct research in specific places over the long term. This was a reaction to the fact that most scientific ecological studies funded before then had been of short duration, generally 1 to 3 years. That situation limited ecological understanding because many ecological processes take many years or even decades to play out. Succession, natural disturbance, the accumulation or loss of nutrients, the change in soil and climate, or the effects of colonization of a new species, for example, are processes that require long times to occur, and thus, similarly long times to evaluate. Of course, simulation modeling can take existing data and, making careful assumptions about dynamics, make reasonable projections through time. But at some point the validity of such projections is most securely evaluated against real data. In 1997, the network of 18 sites included such extremes as moist deciduous forest, and a northern hardwoods mountain transect-- both in the eastern US -- temperate coniferous forest in the Pacific Northwest, coastal sites, a high alpine site, a forest and a tundra site in Alaska, a tropical forest, desert grassland, shrub desert, short grass prairie, an agricultural site, northern and southern lakes, and so on. (See www.lter.edu for the complete roster and history of sites.) The urban sites would add a new kind of ecosystem in which long-term changes were undoubtedly important, to the existing roster of LTER sites.
The second goal was to add sites that explicitly examined the role of people as components of the ecosystems to be studied. Except for the agricultural site in Michigan, usually people were not thought to be of great significance to the structure and functioning of LTER sites. But beginning in the early 1980s, when more and more ecologists began to look seriously at the history and distant connections of their sites, the conclusion became clear, that people – both present and absent – could no longer be ignored in understanding the ecology of North America. So NSF acted on this second goal in choosing a focus on systems where people and their actions could never be ignored – urban ecosystems.
The final goal, according to the 1997 Request for Proposals, was “to enhance the interdisciplinary breadth of the Long-Term Ecological Research (LTER) Network.” Obviously, to understand urban areas as ecosystems, the skills, talents, theories, and methodologies of experts in various social sciences would have to be integrated with the familiar work of biological ecologists and the physical scientists they were used to working with. Urban ecological research would necessarily be interdisciplinary. Not only the technical expertise of social and economic scientists would be required, but also their experience in dealing with social structures and human institutions would be needed for working in urban systems. It turned out in Baltimore that we also recognized the need to borrow their “social capital” and trust built up over decades of working with communities, organizations, and governments in the Baltimore region.
Putting all this together resulted in seven explicit goals that an urban LTER would have to satisfy. Five were required of all LTER sites, and had been in place since 1980:
· Primary Production: pattern and control of primary production,
· Population Studies: spatial and temporal distribution of populations selected to represent trophic structure,
· Movement of Organic Matter: pattern and control of organic matter accumulation in surface layers and sediments,
· Movement of Inorganic Matter: patterns of inorganic inputs and movements of nutrients through soils, groundwater, and surface waters, and
· Disturbance: patterns and frequency of disturbance to the research site.
But in addition, urban LTERs would have to deal with:
· Land Use and Land Cover Change: examine the human impact on land use and land-cover change in urban systems and relate these effects to ecosystem dynamics,
· Human-Environment Interactions: monitor the effects of human-environmental interactions in urban systems, develop appropriate tools (such as GIS) for data collection and analysis of socio-economic and ecosystem data, and develop integrated approaches to linking human and natural systems in an urban ecosystem environment, and
· School Systems: integrate research with local K-12 educational systems.
So it turns out that the Urban LTERs, our Baltimore Ecosystem Study and the Central Arizona-Phoenix LTER have seven core areas of accomplishment. These seven core requirements can be considered the charter of the Urban LTERs. Integration of social and biophysical approaches to understand the feedbacks in urban ecosystems as complex, spatially heterogeneous mosaics, is thus a multidimensional pursuit in satisfying the founding charter.