Canopy coverage and dry weight of understory vegetation from two silvicultural experiments in southeast Alaska

Metadata:
Identification_Information:
Citation:
Citation_Information:
Originator: Barnard, Jeffrey C.
Originator: Nelson, Kellen N.
Originator: Crotteau, Justin S.
Publication_Date: 2025
Title:
Canopy coverage and dry weight of understory vegetation from two silvicultural experiments in southeast Alaska
Geospatial_Data_Presentation_Form: tabular digital data
Publication_Information:
Publication_Place: Fort Collins, CO
Publisher: Forest Service Research Data Archive
Online_Linkage: https://doi.org/10.2737/RDS-2025-0017
Description:
Abstract:
This data publication contains understory vegetation canopy coverage and dry weight data collected from 2007 to 2019 as part of the Tongass Wide Young Growth Studies (TWYGS) and Prince of Wales Commercial Thinning (POW-CT) silviculture experiments on young growth stands on the Tongass National Forest, Alaska. Data include vegetation cover information such as plant scientific name, species percent cover and dry weight of vegetation.
Purpose:
Data were collected as part of two long-term silvicultural experiments, TWYGS and POW-CT. These studies analyze the effects of these experiments on wildlife habitat and understory vegetation (a key component of wildlife habitat). These data have been used to develop allometric equations to estimate vegetation biomass for publications of these studies.
Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 2007
Ending_Date: 2019
Currentness_Reference:
Ground condition
Status:
Progress: Complete
Maintenance_and_Update_Frequency: None planned
Spatial_Domain:
Description_of_Geographic_Extent:
Data were collected in North and Central Prince of Wales Island, Alaska, USA.
Bounding_Coordinates:
West_Bounding_Coordinate: -133.3457591
East_Bounding_Coordinate: -132.5339544
North_Bounding_Coordinate: 56.28881807
South_Bounding_Coordinate: 55.32113356
Bounding_Altitudes:
Altitude_Minimum: 7.8
Altitude_Maximum: 488.7
Altitude_Distance_Units: meters
Keywords:
Theme:
Theme_Keyword_Thesaurus: ISO 19115 Topic Category
Theme_Keyword: biota
Theme:
Theme_Keyword_Thesaurus: National Research & Development Taxonomy
Theme_Keyword: Ecology, Ecosystems, & Environment
Theme_Keyword: Plant ecology
Theme:
Theme_Keyword_Thesaurus: None
Theme_Keyword: silviculture
Theme_Keyword: understory vegetation
Theme_Keyword: plant production
Place:
Place_Keyword_Thesaurus: None
Place_Keyword: Alaska
Place_Keyword: Price of Wales Island
Place_Keyword: Tongass National Forest
Access_Constraints: None
Use_Constraints:
These data were collected using funding from the U.S. Government and can be used without additional permissions or fees. If you use these data in a publication, presentation, or other research product please use the following citation:

Barnard, Jeffrey C.; Nelson, Kellen N.; Crotteau, Justin S. 2025. Canopy coverage and dry weight of understory vegetation from two silvicultural experiments in southeast Alaska. Fort Collins, CO: Forest Service Research Data Archive. https://doi.org/10.2737/RDS-2025-0017
Point_of_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: USDA Forest Service, Pacific Northwest Research Station
Contact_Person: Jeffrey Barnard
Contact_Position: Fish Biologist
Contact_Address:
Address_Type: mailing and physical
Address: Forestry Science Lab
Address: 11175 Auke Lake Way
City: Juneau
State_or_Province: AK
Postal_Code: 99801
Country: USA
Contact_Voice_Telephone: 907-586-8838
Contact_Electronic_Mail_Address: jeffrey.barnard@usda.gov
Contact Instructions: This contact information was current as of original publication date. For current information see Contact Us page on: https://doi.org/10.2737/RDS.
Data_Set_Credit:
Funding for this project was provided by the USDA Forest Service, Pacific Northwest Research Station.


Author Information:

Jeffrey C. Barnard
USDA Forest Service, Pacific Northwest Research Station
https://orcid.org/0009-0003-0049-2682

Kellen N. Nelson
USDA Forest Service, Pacific Northwest Research Station
https://orcid.org/0000-0002-2532-4656

Justin S. Crotteau
USDA Forest Service, Rocky Mountain Research Station
https://orcid.org/0000-0001-8889-822X
Cross_Reference:
Citation_Information:
Originator: Alaback, Paul B.
Publication_Date: 1986
Title:
Biomass regression equations for understory plants in coastal Alaska: Effects of species and sampling design on estimates
Geospatial_Data_Presentation_Form: journal article
Series_Information:
Series_Name: Northwest Science
Issue_Identification: 60(2)
Cross_Reference:
Citation_Information:
Originator: Crotteau, Justin S.
Originator: D’Amore, David V.
Originator: Barnard, Jeffrey C.
Originator: Lawton, Gary
Originator: McFarland, Jessika
Publication_Date: 2022
Title:
Commercial thinning strategies in southeast Alaska: establishment and effects of the Prince of Wales Commercial Thinning Study
Geospatial_Data_Presentation_Form: document
Series_Information:
Series_Name: General Technical Report
Issue_Identification: PNW-GTR-1012
Publication_Information:
Publication_Place: Portland, OR
Publisher: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station
Other_Citation_Details:
77 p.
Online_Linkage: https://doi.org/10.2737/PNW-GTR-1012
Cross_Reference:
Citation_Information:
Originator: Crotteau, Justin S.
Originator: Rue-Johns, Annelise Z.
Originator: D’Amore David V.
Originator: Barnard, Jeffrey C.
Publication_Date: 2020
Title:
Effects on understory biomass and forage 8–10 years after precommercial thinning of Sitka spruce – western hemlock stands in southeast Alaska
Geospatial_Data_Presentation_Form: journal article
Series_Information:
Series_Name: Canadian Journal of Forest Research
Issue_Identification: 50(2): 215–225
Online_Linkage: https://doi.org/10.1139/cjfr-2019-0268
Online_Linkage: https://research.fs.usda.gov/treesearch/59541
Cross_Reference:
Citation_Information:
Originator: Hanley, Thomas A.
Originator: Spalinger, Donald E.
Originator: Mock, Kenrick J.
Originator: Weaver, Oran L.
Originator: Harris, Grant M.
Publication_Date: 2012
Title:
Forage resource evaluation system for habitat—deer: an interactive deer habitat model
Geospatial_Data_Presentation_Form: document
Series_Information:
Series_Name: General Technical Report
Issue_Identification: PNW-GTR-858
Publication_Information:
Publication_Place: Portland, OR
Publisher: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station
Other_Citation_Details:
64 p.
Online_Linkage: https://doi.org/10.2737/PNW-GTR-858
Cross_Reference:
Citation_Information:
Originator: Hanley, Thomas A.
Originator: McClellan, Michael H.
Originator: Barnard, Jeffrey C.
Originator: Friberg, Mary A.
Publication_Date: 2013
Title:
Precommercial thinning: implications of early results from the Tongass-Wide Young-Growth Studies experiments for deer habitat in southeast Alaska
Geospatial_Data_Presentation_Form: document
Series_Information:
Series_Name: Research Paper
Issue_Identification: PNW-RP-593
Publication_Information:
Publication_Place: Portland, OR
Publisher: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station
Other_Citation_Details:
64 p.
Online_Linkage: https://doi.org/10.2737/PNW-RP-593
Cross_Reference:
Citation_Information:
Originator: Nelson, Kellen N.
Originator: Barnard, Jeffrey C.
Originator: Massingham, Preston
Originator: Crotteau, Justin S.
Publication_Date: 2022
Title:
Effect of pruning in Sitka spruce-western hemlock forests in the Pacific Temperate Rainforest
Geospatial_Data_Presentation_Form: conference proceedings
Other_Citation_Details:
4 p.
Online_Linkage: https://research.fs.usda.gov/treesearch/64717
Larger_Work_Citation:
Citation_Information:
Originator: Jain, Theresa B. (comp.)
Originator: Schuler, Thomas M. (comp.)
Publication_Date: 2022
Title:
Foundational concepts in silviculture with emphasis on reforestation and early stand improvement-2022 National Silviculture Workshop
Geospatial_Data_Presentation_Form: conference proceedings
Series_Information:
Series_Name: Proceedings
Issue_Identification: RMRS-P-80
Publication_Information:
Publication_Place: Fort Collins, CO
Publisher: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station
Online_Linkage: https://research.fs.usda.gov/treesearch/64530
Cross_Reference:
Citation_Information:
Originator: Nelson, Kellen N.
Originator: Barnard, Jeffrey C.
Originator: Massingham, Preston
Originator: Crotteau, Justin S.
Publication_Date: 2024
Title:
Tree pruning improves tree form but not understory plant production in mixed stands of Sitka spruce and western hemlock, USA
Geospatial_Data_Presentation_Form: journal article
Series_Information:
Series_Name: Forestry: An International Journal of Forest Research
Issue_Identification: 97(2): 309-318
Online_Linkage: https://doi.org/10.1093/forestry/cpad042
Online_Linkage: https://research.fs.usda.gov/treesearch/67009
Cross_Reference:
Citation_Information:
Originator: Rue-Johns, Annelise Z.
Originator: Crotteau, Justin S.
Originator: D'Amore, David V.
Originator: Barnard, Jeffrey C.
Publication_Date: 2022
Title:
Biomass regressions for understory species in young growth Sitka Spruce–Western Hemlock forests of southeast Alaska
Geospatial_Data_Presentation_Form: journal article
Series_Information:
Series_Name: Northwest Science
Issue_Identification: 95(1): 114-124
Online_Linkage: https://doi.org/10.3955/046.095.0108
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Data_Quality_Information:
Attribute_Accuracy:
Attribute_Accuracy_Report:
There is a high degree of consistency in the data collection methods. Prior to sampling, crews received one month of training involving calibration of sampling (crew members checking each other’s species identifications and methods against the protocol). A single individual provided crew training and supervised data collection across all years.

Several methods were used to record data across the study timeframe. Field data were collected using paper, (transcribed) allegro data recorders, and iPads. Following collection, field data are uploaded to computer on Forest Service Network. Lab sample data were collected on paper. Paper data were transcribed into Excel. Data were checked using filters in excel to identify duplicates, incorrect dates, weights, species, incorrect locations and omissions.
Logical_Consistency_Report:
Conducted sorts and filters of data in Excel for duplicates, missing data, incorrect locations, species, dates. Where possible data were corrected. No known errors in the data.
Completeness_Report:
Calculated dry weights below 0.1 gram were discarded because of the low confidence in the results which are at the limits of scales for field and lab weight measurements. Data were removed for duplication, incorrect species id, as well as omission or incorrect sample dates, locations, canopy cover and weight data if corrections could not be made.
Lineage:
Methodology:
Methodology_Type: Field
Methodology_Description:
STUDY DESIGN

Measurements and samples were collected during the course of two experimental silviculture research projects in southeast Alaska, the Tongass-Wide Young Growth Studies (TWGYS) and the Prince of Wales Commercial Thinning (POW-CT) experiments. Data in this archive were collected from experimental sites located on Prince of Wales Island, Alaska. TWYGS consists of four replicated silviculture experiments that tested silvicultural prescriptions following conifer reinitiation of harvested areas. Experiment 1 included three treatments implemented at 0-5 years stand age: untreated, red alder planted at 20 trees per acre (TPA), and red alder planted at 80 TPA. Experiment 2 included two precommercial thinning treatments implemented at 15-25 years stand age: thinning to 134 TPA, thinning to 222 TPA, and untreated. Experiment 3 implemented at 25-35 years stand age included three thinning treatments to 170 TPA and untreated. Two treatments had additional tree pruning, one on 25% of trees, and one on 50% of trees. Experiment 4 included thinning and slash mitigation treatments implemented at greater than 35 years stand age: thinning to 82 TPA, thinning plus bucking of slash to 15 feet lengths, thinning plus bucking of slash to 5 foot lengths, and a girdling treatment which was thinning plus girdling and untreated.

The POW-CT experiment included five treatments implemented in stands ranging from 50 to 63 years stand age. POW-CT treatments included unthinned, thin from above, crown thinning, thin from below, and a hybrid treatment called “strip” thinning.

A list of all treatment type codes used in the data and associated descriptions:
20-TPA = red alder planted at 20 trees per acre (TPA)
80-TPA = red alder planted at 80 TPA
14x14 = thinned to 14 foot (ft) spacing (222 TPA)
16x16 = thinned to 16 ft spacing (170 TPA)
16x16 1:2 = thinned to 16 ft spacing + 50% of trees pruned
16x16 1:4 = thinned to 16 ft spacing + 25% of trees pruned
18x18 = thinned to 18 ft spacing (134 TPA)
23x23 = thinned to 23 ft spacing (82 TPA)
23x23-15buck = thinned to 23 ft spacing logs cut in 15 ft pieces
23x23-5buck = thinned to 23 ft spacing logs cut in 5 ft pieces
Above = thinning from above
Below = thinning from below
Crown = crown thinning
Girdle = thinned to 23 ft spacing + girdling
Strip = strip thinning
Control = untreated

For more information on the experiments and treatments associated with these data, see Hanley (2013) for the TWYGS study and Crotteau (2022) for the Prince of Wales Commercial Thinning study.


FIELD SAMPLING (DATA COLLECTION)

Tongass-Wide Young Growth Studies (TWYGS) Experiment 1 (2011, 2016): Understory vegetation sampling was conducted systematically in 1 square meter (m²) quadrats along three parallel transects within each treatment, run perpendicular to slope with predetermined start and end points located with GPS. Transects were of variable length due to treatment area and shape. Transects were designed to sample each stand as widely as possible. Quadrats (20 per transect, 60 per treatment) were spaced at 3- to 7-meter (m) intervals, depending on transect length. Plant sample handling methods follow methods below.

TWGYS Experiments 2, 3, and 4 (2007, 2008, 2010, 2012, 2013, 2014, 2018): The basic sampling design employed four or five permanent fixed-area plots within each treated stand. From plot center, transects were run out in the cardinal directions (North, South, East, West) Three or four 1 m² quadrats were measured on each transect per plot for a total of 12 per permanent plot (60 per treated stand). At each quadrat, canopy coverage was estimated for each plant species and harvested for biomass sampling. Species included vascular plants including all tree seedlings and branches, shrubs, and herbs (forbs, grasses, grasslike plants, ferns, clubmosses, and horsetails). Bryophytes or lichens were excluded. The percentage of understory plant canopy cover (vertical projection of outer perimeter of plant canopy to ground) was assessed visually with the following levels of precision: 0 to 1 percent (estimated to nearest 0.1 percent); 1 to 10 percent (estimated to nearest 1 percent); 10 to 30 percent (estimated to nearest 5 percent); 30 to 100 percent (estimated to nearest 10 percent). Because of inefficiencies in the double-sampling design used in 2007-2008, a different sampling protocol was implemented for all experiments beginning in 2009 and continuing through 2019. Samples were collected from quadrats along transects run through each treatment. Specific species and canopy coverage amounts were targeted until sufficient samples were obtained throughout the full range of potential canopy coverage for each species.(This systematic sampling provided a sufficiently wide range of values to calculate a meaningful regression equation for each species.

Regardless of experiment and sample year, target species within a quadrat were assessed for percent cover, harvested, weighed (fresh weight) using a Pesola spring scale, oven dried at 100 degrees Celsius (°C) for 24 hours, and reweighed (dry weight) using a digital lab scale. Ferns, forbs, and graminoids were harvested, weighed, and processed whole. Shrubs and deciduous trees were separated into leaves, annual growth twigs, and older woody stems, weighed and processed separately. Conifers over 10 cm tall were separated into current year’s annual growth (needles and twigs) and prior years wood, needles, and branches.

Prince of Wales Commercial Thinning Experiment (2007, 2014, 2019): Treatments and permanent plots were laid out similarly to the TWYGS study above. Five systematically located permanent sampling plots were located within each treatment. One meter quadrats were sampled at intervals along cardinal direction transects originating from the center of the permanent plots. All species within each quadrat were assessed for percent cover. Targeted species were processed as above.
Methodology_Citation:
Citation_Information:
Originator: Hanley, Thomas A.
Originator: Spalinger, Donald E.
Originator: Mock, Kenrick J.
Originator: Weaver, Oran L.
Originator: Harris, Grant M.
Publication_Date: 2012
Title:
Forage resource evaluation system for habitat—deer: an interactive deer habitat model
Geospatial_Data_Presentation_Form: document
Series_Information:
Series_Name: General Technical Report
Issue_Identification: PNW-GTR-858
Publication_Information:
Publication_Place: Portland, OR
Publisher: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station
Other_Citation_Details:
64 p.
Online_Linkage: https://doi.org/10.2737/PNW-GTR-858
Process_Step:
Process_Description:
No process steps have been described for this data set.
Process_Date: Unknown
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Entity_and_Attribute_Information:
Overview_Description:
Entity_and_Attribute_Overview:
Below you will find a list and description of the files included in this data publication.

VARIABLE DESCRIPTION FILE (1)

1. \Data\_variable_descriptions.csv: Comma-separated values (CSV) file containing a list and description of variables found in all data files. (A description of these variables is also provided in the metadata below.)

Columns include:

Filename = name of data file
Variable = name of variable
Units = units (if applicable)
Precision = precision (if applicable)
Description = description of variable


DATA FILES (2)

1. \Data\vegetation_cover_weight_sample_data.csv: CSV file containing a compendium of vascular understory plant data collected from 2007-2019 as part of the Tongass Wide Young Growth Studies (TWYGS) and Prince of Wales Commercial Thinning (POWCT) silviculture experiments on young growth stands on the Tongass National Forest, Alaska. These data are intended for calculating cover/biomass allometric equations.

Variables include:

Experiment = Name of silviculture experiment for which data were collected (POWCT, TWYGS1, TWYGS2, TWYGS3, and TWYGS4)

Site = Geographic location of experiment replicate

Treatment = Experimental treatment within the silviculture experiments (treatments defined in methods section)

Year = Year (summer field season) data were collected (2007, 2008, 2010, 2011, 2012, 2013, 2014, 2016, 2018, 2019)

Species = Scientific name (genus and species) for plant from which data were collected

Plant Part = Specific part of plant processed (A = all or whole, CAG = current annual growth, L = leaf, O =Old (woody stem), T = Twig (current year))

Cover % = Percent canopy coverage of a given plant within a one meter area quadrat (1-100)

CalcdryWt (g) = Oven dry weight of plant material sampled (grams)

Height cm = Total height of shrubs and trees sampled (centimeters)



2. \Data\vegetation_sample_long_lati.csv: CSV file containing longitudes and latitudes for vegetation samples collected. Location approximates centerpoint of treatment.

Variables include:

Experiment = Name of silviculture experiment for which data were collected (POWCT, TWYGS1, TWYGS2, TWYGS3, and TWYGS4)

Site = Geographic location of experiment replicate

Treatment = Experimental treatment within the silviculture experiments (treatments defined in methods section)

Latitude = Latitude (decimal degrees)

Longitude = Longitude (decimal degrees)
Entity_and_Attribute_Detail_Citation:
none provided
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Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: USDA Forest Service, Research and Development
Contact_Position: Research Data Archivist
Contact_Address:
Address_Type: mailing and physical
Address: 240 West Prospect Road
City: Fort Collins
State_or_Province: CO
Postal_Code: 80526
Country: USA
Contact_Voice_Telephone: see Contact Instructions
Contact Instructions: This contact information was current as of April 2025. For current information see Contact Us page on: https://doi.org/10.2737/RDS.
Resource_Description: RDS-2025-0017
Distribution_Liability:
Metadata documents have been reviewed for accuracy and completeness. Unless otherwise stated, all data and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. However, neither the author, the Archive, nor any part of the federal government can assure the reliability or suitability of these data for a particular purpose. The act of distribution shall not constitute any such warranty, and no responsibility is assumed for a user's application of these data or related materials.

The metadata, data, or related materials may be updated without notification. If a user believes errors are present in the metadata, data or related materials, please use the information in (1) Identification Information: Point of Contact, (2) Metadata Reference: Metadata Contact, or (3) Distribution Information: Distributor to notify the author or the Archive of the issues.
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Format_Name: CSV
Format_Version_Number: see Format Specification
Format_Specification:
Comma-separated values file
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
Network_Resource_Name: https://doi.org/10.2737/RDS-2025-0017
Fees: None
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Metadata_Reference_Information:
Metadata_Date: 20250402
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: USDA Forest Service, Pacific Northwest Research Station
Contact_Person: Jeffrey Barnard
Contact_Position: Fish Biologist
Contact_Address:
Address_Type: mailing and physical
Address: Forestry Science Lab
Address: 11175 Auke Lake Way
City: Juneau
State_or_Province: AK
Postal_Code: 99801
Country: USA
Contact_Voice_Telephone: 907-586-8838
Contact_Electronic_Mail_Address: jeffrey.barnard@usda.gov
Contact Instructions: This contact information was current as of original publication date. For current information see Contact Us page on: https://doi.org/10.2737/RDS.
Metadata_Standard_Name: FGDC Biological Data Profile of the Content Standard for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001.1-1999
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