Permanent tree measurement plots were installed (1.5 ha) within 27 seven-hectare experimental units in the Rogue River-Siskiyou National Forest between 1992 and 1995. Plots were established with very wide buffers to follow long-term development of trees as a stand, to protect a central measurement plot, and to allow for destructive sampling in buffers. Vegetation treatments were implemented in 1997. The Biscuit complex wildfire burned about half the plots in 2002. Standard measurements on all live trees (dbh > 3.5 cm) were collected 10 times between 1992 and 2010 including species, dbh, and treetop and base of live-crown heights. Additional measurements of sapwood thickness and rings in sapwood on all trees > 20 cm dbh were made and a subsample of live trees was cored for breast-height age. Biomass was determined from both derived and existing equations. Douglas-fir is the primary conifer species.
Bernard T. Bormann, Brett A Morrissette, David V. D'Amore, Kylie M. Meyer, Peter S. Homann, Robyn L. Darbyshire, S. Mark Nay
The question that drives LTEP studies is: What factors, influenced directly or indirectly by management, most affect the long-term productivity of the land? Maintaining the "productivity of the land, " which includes producing commodities as well as other resources, is required by law for managing federal land. A dominant effect of forest management has been to shorten the time and space that early- and late-successional plant assemblages occupy sites. The first factor chosen for study was the sustained, day in and day out effects of different species and their litter on soil properties particularly the relative effects of early successional, pioneering plants, late-successional plants and structure, and conifer monocultures. We also hypothesized that removing biomass and woody debris can affect the site nutrient capital and soil properties. Ecosystem responses and the processes underlying them are being studied in short- and long-term experiments.