Large-scale, long-term silvicultural experiments in the United States: historical overview and contemporary examples.
This paper provides a synopsis of large-scale, long-term silviculture experiments in the United States. Large-scale in a silvicultural context means that experimental treatment units encompass entire stands (5 to 30 ha); long-term means that results are intended to be monitored over many cutting cycles or an entire rotation, typically for many decades. Such studies were installed widely between 1930 and 1955 when forest rehabilitation accomplished by partial cutting dominated research and practice, but fell from favor during the profound nationwide switch to even-age silviculture during the 1960s. Concerns over the widespread use of clearcutting and the resulting even-age regimes have rekindled an interest in the use of other silvicultural systems and large-scale and long-term experiments. Contemporary studies (since 1990) from four representative forest regions of the United Statesthe Northeast, Lake States, mid-South, and Pacific Northwestare described and compared. Notable contributions of early (ca. 1925-1950) experiments, some of which remain active, are also reviewed, and contrasted to modern studies.