Why Site Networks?

Summary

Long term experiments reveal the dynamics of ecosystems over relatively long time periods and agricultural field experiments comprise probably the largest long-term spatial data base of ecosystem experiments available. Networks of these long-term sites have a greater value than the individual sites alone for the following reasons. Networks can increase our understanding of ecosystems by combining data from a range of sites so allowing investigators to increase numbers of observations and examine how well the data can be generalized. Furthermore, a comparison of differences between experimental designs and locations may lead to new insight about agroecosystems and fundamental knowledge about ecosystem distributions can be tested and used to address important practical problems. Another advantage of site networks is that responses can be summed for a region based upon the distribution of driving variables and they also allow us to test our understanding embodied in ecosystem models and determine the level of confidence in the ability of the model to reproduce ecosystem behavior. Networks also provide data to support defensible regional projections and additional testing power is gained when time series of model output is compared with field data obtained over a period of years. It should be noted that responses of ecosystem components include interactions and feedbacks inherent in whole system dynamics. Currently, extensive networks are organized, or being organized in the U.S., Australia, Western and Eastern Europe (see this volume) and, to a lesser extent, in Africa. Additional efforts should be mounted, especially in the tropics.