tagged trees in permanent sample plot, Butte, WA

Overview

History

Experimental
Design

Treatment Implementation

Study Areas

Photos of Study Areas

 

  

D E M O
Demonstration of Ecosystem Management Options Study

A Large-Scale Experiment in Structural Retention Harvests in Pacific Northwestern Forests
Experimental Design

The DEMO study consists of a randomized complete block design, consisting of six, 13-ha structural retention treatments (see descriptions and photos below), including a control, replicated at each of six blocks (geographic locations). Treatment units are square or slightly rectangular in shape. Within each unit, sampling is integrated around a permenent grid system (8 x 8 or 7 x 9 points at 40-m spacing). For a detailed treatment of the DEMO experimental design and harvest prescriptions see:

Aubry, K.B., M.P. Amaranthus, C.B. Halpern, J.D. White, B.L. Woodard, C.E. Peterson, C.A. Lagoudakis, and A.J. Horton. 1999. Evaluating the effects of varying levels and patterns of green-tree retention: experimental design of the DEMO study. Northwest Science 73 (Special Issue): 12-26.

schematic diagram of the 6 retention treatments

Descriptions of Treatments

1. 100% retention: a 13-ha control that provides a baseline for assessing the effects of harvest treatments on ecosystem composition, structure, and function.

control treatment, Capitol Forest
2. 75% aggregated retention: Three circular, 1-ha patches are harvested in a triangular array, removing 25% of the original stand area. The pattern and distances between "gaps" are consistent among experimental blocks.
aerial photo of 75% treatment
3. 40% dispersed retention: a proportion of the dominant and co-dominant trees are retained in a relatively even distribution throughout the treatment unit. The total basal area retained is equivalent to that of the corresponding aggregated retention treatment (40% aggregated retention).
aerial photo of 40% dispersed treatment
4. 40% aggregated retention: five undisturbed, 1-ha circular aggregates are retained at fixed distances from each other; all merchantable trees in the surrounding area are cut and removed.
aerial photo of 40% aggregated treatment
5. 15% dispersed retention: a proportion of the dominant and co-dominant trees are retained in a relatively even distribution throughout the treatment unit. The total basal area retained is equivalent to that of the corresponding aggregated retention treatment (15% aggregated retention).
aerial photo of 15% dispersed treatment
6. 15% aggregated retention: two undisturbed, 1-ha circular aggregates are retained at fixed distances from each other; all merchantable trees in the surrounding area are cut and removed.
aerial photo of 15% aggregated treatment