Designing long-term large-scale forestry experiments with research objectives at multiple scales

Abstract

ABSTRACT. A number of large-scale manipulative studies (LSMEs) have been installed in recent decades. They were designed to test opera tionally practical silvicultural treatments on large tracts of forest land and over long periods of time. The interdisciplinary nature of LSMEs and the associated variety of research objectives provide special chal lenges in study design and implementation that usually do not occur in the setup of traditionally smaller-scaled research studies. We present and discuss these issues, including the development of a prioritized list of objectives with explicit spatial and temporal scales and clear defi nitions of the scope of inference for each objective. In this context we discuss the variation within large experimental units; the choice of replications; treatment definitions, including multiple manipulations over time; and the choice, scale, and timing of measurements. Above all, it appears that agreeing on a clear hierarchy of study objectives will prevent future conflicts between different study components and will provide guidance for the evaluation of treatment and measurement choices