In 1996, National Science Foundation began an experiment that involved augmenting two LTER sites at a funding level double to the Network standard. The sites were selected based on competitive proposals. The successful proposals contained significant commitments to involving social and economic sciences and plans for developing regional-scale research.
Over the past six years, the increased funding has provided these sites, North Temperate Lakes LTER in Wisconsin (NTL) and Coweeta LTER in the southern Appalachian mountains (CWT), the opportunity to focus on complex interactions between humans and ecological processes across a range of scales and to make significant advances in understanding the spatial, temporal, and decision-making components of land use and land-use change, and has helped build regional, national, and international collaborations.
Despite the augmentation "the bridge between natural and social sciences remains exceptionally challenging," NTL PI Steve Carpenter says, the main limitation being the cultural difference between the disciplines. "LTER can be a key bridge for the scientific community as a whole, because LTER can provide ongoing scientific interaction."
For LTER PIs to develop a collaborative style, Carpenter says, takes time— and the right conditions. "I think we are on the road to such collaboration at NTL," he says, "but it’s a journey, not a destination." In addition to the augmentation, NTL has had help from IGERT, BioComplexity, Pew, Rockefeller and Packard funds. "We have been lucky, Carpenter admits. "If LTER wants to grow some good natural-social science collaborations, each site needs sustained funding for a few students and some PI time."
The NTL LTER site augmented research in several dimensions, including the addition of a second core site in the urban Madison area, "which provides an important contrast to study lakes in the north that are much less impacted by humans," says Jim Rusak, NTL co-PI. "We have strengthened our remote sensing and landscape ecology components at multiple scales-watersheds to lake districts, to State and the western Great Lakes region." NTL has also been able to forge ongoing collaborations with Canadian sites.
Another dimension involves increasing interdisciplinary integration, including modeling and landscape analysis, "which has strengthened links among climatology, remote sensing, landscape ecology, hydrology, and limnology," Rusak says. "We have also embarked on collaborations with rural sociology and economics."
While augmentation has had its success, research and outreach accomplishments of this nature are not exclusive to augmented sites, says Ted Gragson, CWT LTER PI. "The Harvard Forest LTER site, for example, has some stellar regional-scale research, and Andrews LTER is associated with similarly stellar regional work (although with different funding)," Gragson says. "There are certainly some documents that show the value of, and highlight useful process on regionalization, but they are not specific to [this] augmentation." Gragson points out some emerging models from outside the LTER as well, including the BioComplexity program, and France’s Zones Ateliers (see The LTER Network Newsletter Vol. 14 No.1 Spring 2001, page 8).
The augmentation project at North Temperate Lakes LTER site addresses two new types of questions: one type that requires integration of natural and social sciences and another that requires understanding of regional-scale processes. For example: What ecosystem services do the lake districts of rural northern and urban southern Wisconsin provide, and what are their economic values? How do farmer behaviors vary across watersheds, and why? How do ecosystems, agencies, farmers and other lake users, respond to political processes, and how do these responses interact to affect the temporal dynamics of the lakes? What are the effects of prolonged drought on lakes throughout the upper Midwest? How has the timing and duration of ice cover changed in lakes throughout the northern Hemisphere over decadal and century time scales? Can we use satellite imagery to predict regional water quality?
Significant findings at NTL LTER
Augmentation has lead to some significant findings at NTL LTER, including: The economically optimal phosphorus input to lakes is less (often far less) than would have been estimated if the work was based on an assumption that the lakes were linear, equilibrium systems with no stochastic factors and no time delays.
By calculating the net economic value of water quality (based on the economics of farming, value of housing near the lake, and the recreational economy derived from boating, fishing and soforth), NTL researchers have shown that the economically optimal phosphorus loading (which maximizes net costs and benefits to society as a whole) is about one-third of the current loading rate to the lake. Furthermore, even economically optimal phosphorus loads may incur a high risk of shifting the lake into an irreversible eutrophic state. The model’s improved predictive capability is largely the result of including more realistic (non-linear) relationships between variables and the stochastic influence of climatic variation.
These analyses show that the total economic value generated by the Lake Mendota watershed would increase substantially if less fertilizer were used. Total economic value is the net benefit from all uses of the watershed, including agriculture, lakeshore property values, fishing and other recreation.
Another finding resulting from this effort is that the probability of cyanobacterial bloom on a given day can be reduced from about 65% to 20% by halving the phosphorus inputs. These numbers became effective public outreach tools to launch an aggressive non-point pollution control program.
A phosphorus budget we developed for Madison’s Lake Mendota watershed shows that fertilizers, supplements to dairy cattle, and natural inputs are substantially larger than the outputs of crops, meats, diary products and runoff. This excess phosphorus accumulates in soils at the rate of 450 kg per year. The accumulation of phosphorus in watershed soils poses a challenge for lake management, and is a problem of global significance. This work has inspired dialogue in community, including a popular, Web-accessible version of a scientific paper published in Issues in Ecology (see http://www.esa.org/sbi/sbi_issues/)
At the regional scale, a workshop provided researchers with common goals of examining landscape-level processes that lead to spatial and temporal patterns of lake characteristics in individual or multiple lake districts. A special issue of Freshwater Biology highlighted results from this workshop, which included 10 lake districts from North America, Europe, and Antarctica. At the global scale, records for freeze and thaw dates provide a seasonally integrated view of trends from regions where early temperature measurements are sparse. NTL investigators catalogued these records and developed a shared database for researchers around the world.
Relevant Reading
- Carpenter, S.R., D. Ludwig and W.A. Brock. 1999. Management of eutrophication for lakes subject to potentially irreversible change. Ecological Applications 9: 751-771.
- Lathrop, R. C., S. R. Carpenter, C. A. Stow, P. A. Soranno and J. C. Panuska (1998). Phosphorus loading reductions needed to control blue-green algal blooms in Lake Mendota. Canadian Journal of Fisheries and Aquatic Sciences 55(5): 1169-78.
- Kratz, T. K. and T. M. Frost (2000). The ecological organisation of lake districts: general introduction. Freshwater Biology 43: 297-99.
Significant findings resulting from augmented studies at Coweeta LTER
Permanent vegetation plots in combination with climate modeling allowed us to relate forest composition and productivity to topography over long time scales. A spatially explicit model of land-use change over a 40-year period (1950-1990) identifying physical and human factors and determining land-use patterns for representative areas across the region, shows that land-cover changes are more frequent at lower elevations and near roads. The implication is that this development is concentrated in sensitive riparian areas.
The effort has also involved studies of how plant and animal populations respond to biotic and abiotic variation at plot-to-landscape scales, as well as how biota responds to past and present land use patterns across the region. Bird diversity declined with forest patch size, which in turn influenced plant community composition. Some plant groups (e.g., Liliaceae and myrmecochores) with diaspores dispersed by ants were scarce or absent in patches subjected to intensive past land use. Land-use history was more important than patch size in explaining variation in abundance and composition of seed-dispersing ants. Fish density and diversity, in particular, are more affected by upstream than streamside deforestation. The "legacy effect" and the relative importance of upstream process point the way toward large-scale and long-term restoration given the implication that localized efforts may ultimately have little effect.
Small-scale measurements taken in 2000 at three locations in the Little Tennessee and French Broad watersheds were combined with landscape-level modeling to determine the impacts of land-use change on carbon budgets. We found that woody biomass in old growth forest is 2- to 8-fold greater than in early and mid-successional forests.
The discovery of these dramatic effects of land-use patterns and environmental heterogeneity on populations and communities led us to begin a new 30-year study in 2000 of stream regions forecast to differ over time in type and risk of development.
Intersite and Collaborative Activities
Since 1996 Coweeta researchers have led or participated in more than 30 LTER intersite or international research projects. The collaborations include comparison of organic matter budgets in streams within and outside the LTER network and a chironomid biossay technique to assess quality of fine particulate organic matter in streams from five LTER sites. It also involves examining the linkage between biodiversity of litter-inhabiting microarthropods and the decomposition of leaf litter in aquatic and terrestrial ecosystems at Coweeta, Luquillo, and La Selva. Coweeta scientists participated in a cross-site comparative mycorrhizae ecosystem function experiment at Bonanza Creek, Sevilleta, and sites in California, and participated in the 10-year LIDET (Longterm Intersite Decomposition Experiment Team) study designed to test the effects of substrate quality and macroclimate on long-term decomposition and nutrient release dynamics of fine litter at 28 participating sites.
Please review relevant literature on the Coweeta LTER Web site:
http://coweeta.uga.edu/ecology/publications_catalog.html