Our involvement in the LTER program (LTER I 1982-1986) began with spatially explicit ideas and questions about the importance of landscape structure, particularly the classic soil catena model, in the long-term development and maintenance of shortgrass steppe ecosystems. In the second phase of the project (LTER II 1987-1990) we expanded our concept of long-term processes to include the origin and persistence of spatial patterns at a range of spatial scales (Fig 1). This work included substantial questioning of the generality of the catena model at the CPER and in the shortgrass steppe region. Our work for LTER III builds upon LTER I and II and expands the depth of our investigations into interactions between spatial and temporal patterns in ecosystem structure and function.
LTER IV will expand our understanding of SGS ecosystem structure and function, by continuing a substantial suite of long-term experiments and initiating new long-term monitoting, long- and short-term experiments, and simulation analyses. Our work will focus on the key biotic responses and feedbacks as influenced by humans, natural disturbances, physiography, and climate. Our work includes: 1) new studies of invasive species, the prairie dog and its biology, and cactus; 2) new studies of control by landscapes over biogeochemical cycling, new studies of the N balance of SGS ecosystems, and 3) new studies of carbon balance over landscape to regional scales, and the interactions between landuse and regional climate. We are also expanding experiments associated with our past work in paleoecology and pedology, plant community dynamics, and biogeochemistry. We plan to continue our 60 long-term experiments, and to initiate 14 new long-term experiments and 10 new short-term, synthesis and cross site experiments over the next six years.