A network of 17 sites (Fig.1) with individual research programs has been founded in the United States to study ecology at extended time and space scales (Callahan 1984; Brenneman 1989; Franklin et al. 1990; Magnuson and Bowser 1990). Long-term or sustained research is necessary to understand many important ecological phenomena such as those characterized by slow processes; those affected by disturbance from rare or episodic events; and those driven by highly variable, subtle or complex process operating at a variety of temporal and spatial scales (Likens 1989). Long-term ecological research also will be essential in addressing ecological questions related to global change issues. The need .for study at broad spatial scales or at least nested sets of spatial scales goes hand in hand with extending the temporal scale of ecological research (Magnuson et al. 1990c; Swanson and Sparks 1990). Environments are spatially heterogeneous at many spatial scales. Interactions, not only within patches, but also between and among patches are ecologically significant. Patches are not independent; ecosystems by any definition have boundaries, and interactions occur across those boundaries. Similarly, the response of ecosystems to change depends on their position in environmental gradients; the position in the gradient, for example altitudinal position in the landscape, can provide the spatial context for an ecosystem (Magnuson et al. 1990c, Krat.z et al. manuscript). Clearly, an ability to understand the function and structure of an ecological system depends both on its temporal context (Magnuson 1990) and its spatial context (Swanson and Sparks 1990). Long-term ecology and landscape ecology become natural partners at this time when we wish our science to be relevant to the issues of global change. The recognition of these concerns led to the formation of a network of long-term ecological research sites in the United States. The same concerns must have driven your thinking as you developed a program for ecosystem research in the Bornhoved Lakes region of FRG. Long-term ecological research is relevant to current issues such as deforestation, acid deposition, C02 induced climate warming, the introduction of synthetic chemicals and the invasions of non-native plants and animals. Without the temporal context that long-term research provides, scientists and environmental managers misinterpret their observation of the present. Causative factors are hidden because the lags between cause and effect are greater than a year and because some of the changes occur so slowly that they are imperceptible over short time scales. In a sense the present is invisible to us if the present is all we have to observe (Magnuson 1990). Because of this, good environmental management depends on a new ’partnership between environmental managers and long-term or sustained ecological researchers (Likens 1989). The purposes of our paper are to (1) describe briefly the Long-Term Ecological Research (L TER) network in the United States and (2) provide an example of the role LTER sites can play in global change research by describing the capabilities and perspectives of one site, the North Temperate Lakes LTER site. I (Magnuson) have enjoyed your hospitality and your science and thank you for including me in your sessions. We thank our colleagues for helping prepare the materials, namely: David E. Armstrong, Carl J. Bowser, Thomas M. Frost, Timothy K. Kratz, John E. Kutzbach, Mark D. McKenzie and Mary L. Smith of the University of Wisconsin-Madison. The research in Wisconsin is funded by the Division of Biotic Systems and Resources of the National Science Foundation, Grant Number BSR 85 14330.