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TP103
Species interactions during succession in the western Cascade Range of Oregon, 1990 to present

PRINCIPAL INVESTIGATOR: Charles B. Halpern
ORIGINATOR: Charles B. Halpern
OTHER RESEARCHER: Joseph A. Antos, Annette M. Olson, Kermit Cromack Jr.
DATA SET CONTACT PERSON: Charles B. Halpern
ABSTRACTOR: Charles B. Halpern
DATA SET CREDIT:
USDA National Research Initiative Competitive Grants Program 91-37101-6895 and 96-35101-3121
METADATA CREATION DATE:
7 Oct 1990
MOST RECENT METADATA REVIEW DATE:
24 Jul 2019
KEYWORDS:
Disturbance, Primary production, Long-Term Ecological Research (LTER), community dynamics, trophic structure, succession, primary production, species interactions, competition, disturbance, burning, timber harvest, clearcutting
PURPOSE:
To test the role of competitive interactions in shaping the early successional dynamics of understory species in Douglas-fir forests of the western Cascades.
METHODS:
Experimental Design - TP103:
Description:

The site was clearcut logged in late May/early June 1991. Slash was broadcast burned on 11 September 1991 with a moderate- to high-intensity fire. The full experiment consists of a randomized complete-block design with a control and eight treatments (A through I; see below) in which one or more species is removed from the post-disturbance community (see details in Halpern et al. 1997). Treatments were assigned randomly to nine 2.5 x 2.5 m experimental units (treatment areas) in each of 25 blocks (~11 m on a side). Within a block, treatment areas are arranged in a 3 x 3 array with ~1-m spacing (see Related Materials: Plot Layout). Species’ removal treatments were initiated in June 1992, synchronous with the first post-disturbance measurement of vegetation. For the first 7 years, removals were conducted monthly (April to June). Seedlings were pulled by hand and vegetative shoots were clipped at the ground surface (see Entity 2 for counts of seedlings and shoots removed). Subsequently, removals have been conducted at the time of vegetation measurement, but the stems removed are no longer counted. Six treatments were discontinued between 1996 and 1998 when removal or target species became uncommon. The remaining three treatments (A. Control; H. Rubus removed; and I. Berberis and Gaultheria removed) have been maintained to present.

Treatment codes (A-I), removal species, and response variables for the nine treatments include:

  • A. Control (no removal); Response = Community (all species)
  • B. Senecio sylvaticus removed; Response = Community (all other species)
  • C. Epilobium angustifolium removed; Response = Community (all other species)
  • D. Senecio sylvaticus and E. angustifolium removed; Response = Community (all other species)
  • E. Senecio sylvaticus and Community removed; Response = Epilobium angustifolium
  • F. Epilobium angustifolium and Community removed; Response = Senecio sylvaticus
  • G. Community removed; Response = Senecio sylvaticus and Epilobium angustifolium
  • H. Rubus ursinus removed; Response = Community (all other species)
  • I. Berberis nervosa/Gaultheria shallon removed; Response = Community (all other species)
Field Methods - TP103:
Description: Vegetation measurements are made in a central 1 x 1 m plot within each treatment area (see Related Materials: Plot Layout). Pre-logging measurements were made in 1990; post-harvest measurements were initiated in 1992. Between 1992 and 1996, measurements were repeated two to three times during the summer (June-Aug). Since 1997, measurements have been made annually (typically in late-June/early July). Measurements include estimates of cover (%) of ground-surface conditions (bare ground, fine litter, and logs) and of each vascular plant species (including herbs, shrubs, and trees) (see Entity 1). In addition, between 1992 and 1999, stems of each species were counted and measured for basal diameter and/or height (see Entity 1). These parameters are used in species-specific allometric equations (see Entity 5) to predict the aboveground biomass of each stem (Halpern et al. 1996). For other species, equations predict biomass in the 1 m2 plot from cover. Plot-scale estimates of biomass (summing stem estimates as needed) were generated for all species between 1990 and 1999 (see Entity 6). The remaining three treatments (A. Control; H. Rubus removed; and I. Berberis and Gaultheria removed) were maintained through 2018. Following a partial burn of the site during the Terwilliger Fire (September 2018), species' removal treatments were terminated. However, cover measurements continue.
Citation:

Halpern, Charles B., Miller, Eric A., Geyer, Melora A. 1996, Equations for predicting above-ground biomass of plant species in early successional forests of the western Cascade Range, Oregon (Pub. No: 2262)

Halpern, Charles B., Antos, Joseph A., Geyer, Melora A., Olson, Annette M. 1997, Species replacement during early secondary succession: the abrupt decline of a winter annual (Pub. No: 1890)

Models/Algorithms - TP103:
Description: Estimates of species’ biomass are from regression equations developed from dimensional measurements and destructive sampling at the study site (Halpern et al. 1996)
Permanent Plots - TP103:
Description: 1 x 1 m plots are permanently marked with rebar and uniquely numbered aluminum tags (block/plot number)
Quality Assurance - TP103:
Description: Standard QA/QC procedures, including range limits, legitimate codes, relational checks
Data Entry - TP103:
Description: Entered and checked by PI
SITE DESCRIPTION:
The 4-ha study site, Starrbright (named after nearby Starr Creek and the timber sale) lies on a gentle (<5%) east-facing slope at ~736 m elevation. Soils are mostly deep (>1.5 m), loamy Andisols (frigid typic Hapludand) formed from weathering of andesite, breccia, and volcanic ash. Prior to harvest, the site supported a mix of mature and old-growth forest dominated by Pseudotsuga menziesii with a subcanopy of Tsuga heterophylla, Thuja plicata and Taxus brevifolia. The understory was dominated by woody species, including Rhododendron macrophyllum, Gaultheria shallon and Berberis nervosa.
TAXONOMIC SYSTEM:
Garrison et al., 1976
GEOGRAPHIC EXTENT:
West of the south fork of the McKenzie River, north of Augusta Creek, western Cascades, Oregon.
ELEVATION_MINIMUM (meters):
730
ELEVATION_MAXIMUM (meters):
730
MEASUREMENT FREQUENCY:
annual
PROGRESS DESCRIPTION:
Active
UPDATE FREQUENCY DESCRIPTION:
annually
CURRENTNESS REFERENCE:
Ground condition
RELATED MATERIAL: