HomeMy WebLinkAboutSuWa223sec11-9ptAAlaska Resources Library & Information Services
Susitna-Watana Hydroelectric Project Document
ARLIS Uniform Cover Page
Title:
Invasive plant study, Study plan Section 11.9 : Initial study report -- Part A:
Sections 1-6, 8-10
SuWa 223
Author(s) – Personal:
Author(s) – Corporate:
ABR, Inc.-Environmental Research & Services
AEA-identified category, if specified:
Initial study report
AEA-identified series, if specified:
Series (ARLIS-assigned report number):
Susitna-Watana Hydroelectric Project document number 223
Existing numbers on document:
Published by:
[Anchorage : Alaska Energy Authority, 2014]
Date published:
June 2014
Published for:
Alaska Energy Authority
Date or date range of report:
Volume and/or Part numbers:
Final or Draft status, as indicated:
Document type:
Pagination:
iii, 17, 3 p.
Related work(s):
The following parts of Section 11.9 appear in separate files:
Part A ; Part B ; Part C.
Pages added/changed by ARLIS:
Notes:
Contents: Part A. Sections 1-6, 8-10 -- Appendix A. Photos of selected invasive species, 2013 field
survey, Susitna-Watana Hydropower Project.
All reports in the Susitna-Watana Hydroelectric Project Document series include an ARLIS-
produced cover page and an ARLIS-assigned number for uniformity and citability. All reports
are posted online at http://www.arlis.org/resources/susitna-watana/
Susitna-Watana Hydroelectric Project
(FERC No. 14241)
Invasive Plant Study
Study Plan Section 11.9
Initial Study Report
Part A: Sections 1-6, 8-10
Prepared for
Alaska Energy Authority
Prepared by
ABR, Inc.—Environmental Research & Services
June 2014
INITIAL STUDY REPORT INVASIVE PLANT STUDY (11.9)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page i June 2014
TABLE OF CONTENTS
1. Introduction............................................................................................................................ 1
2. Study Objectives .................................................................................................................... 1
3. Study Area .............................................................................................................................. 2
4. Methods and Variances in 2013 ............................................................................................ 2
4.1. Field Surveys .................................................................................................................. 2
4.1.1. Variances................................................................................................................. 3
4.2. Ecological Risk Assessment .......................................................................................... 4
4.2.1. Variances................................................................................................................. 4
5. Results ..................................................................................................................................... 4
5.1. Field Survey ................................................................................................................... 4
5.2. Ecological Risk Assessment .......................................................................................... 5
6. Discussion ............................................................................................................................... 6
7. Completing the Study ............................................................................................................ 7
8. Literature Cited ..................................................................................................................... 7
9. Tables ...................................................................................................................................... 9
10. Figures .................................................................................................................................. 12
INITIAL STUDY REPORT INVASIVE PLANT STUDY (11.9)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page ii June 2014
LIST OF TABLES
Table 4.1-1. Invasive Vascular Plant Species Previously Found in the Vicinity of the Susitna-
Watana Hydroelectric Project Area.1 ....................................................................................... 9
Table 5.1-1. Invasive Species Found During the August 2013 Field Survey, Susitna-Watana
Hydroelectric Project. ............................................................................................................ 10
Table 5.1-2. Number of Observations (Survey Sites) of Invasive Plants in Six Cover-value
Categories, Susitna-Watana Hydroelectric Project Area, 2013. ............................................ 11
LIST OF FIGURES
Figure 3-1. Invasive Plant Survey Plot Locations in the Vicinity of the Susitna-Watana
Hydroelectic Project Area, 2013. ........................................................................................... 13
Figure 5.2-1. Locations and Degree of Infestation of Melilotus alba in the Invasive Plant Survey
Area, Susitna-Watana Hydroelectric Project, 2013. .............................................................. 14
Figure 5.2-2. Locations and Degree of Infestation of Viccia cracca and Linaria vulgaris in the
Invasive Plant Survey Area, Susitna-Watana Hydroelectric Project, 2013. .......................... 15
Figure 5.2-3. Locations and Degree of Infestation of Hordeum jubatum in the Invasive Plant
Survey Area, Susitna-Watana Hydroelectric Project, 2013. .................................................. 16
Figure 5.2-4. Locations and Degree of Infestation of Bromus inermus, Leucanthemum vulgare,
and Tanacetum vulgare in the Invasive Plant Survey Area, Susitna-Watana Hydroelectric
Project, 2013. ......................................................................................................................... 17
APPENDICES
Appendix A. Photos of Selected Invasive Species, 2013 Field Survey, Susitna-Watana
Hydropower Project
INITIAL STUDY REPORT INVASIVE PLANT STUDY (11.9)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page iii June 2014
LIST OF ACRONYMS, ABBREVIATIONS, AND DEFINITIONS
Abbreviation Definition
AEA Alaska Energy Authority
AKEPIC Alaska Exotic Plants Information Clearinghouse
AKNHP Alaska Natural Heritage Program
ATV all-terrain vehicle
CIRWG Cook Inlet Region Working Group
FERC Federal Energy Regulatory Commission
GPS Global positioning system. A system of radio-emitting and -receiving satellites used for
determining positions on the earth.
ILP Integrated Licensing Process
ISR Initial Study Report
ORV off-road vehicle
PM&E protection, mitigation and enhancement
Project Susitna-Watana Hydroelectric Project
RSP Revised Study Plan
SPD study plan determination
UAF University of Alaska
USDA United States Department of Agriculture
INITIAL STUDY REPORT INVASIVE PLANT STUDY (11.9)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 1 June 2014
1. INTRODUCTION
On December 14, 2012, Alaska Energy Authority (AEA) filed with the Federal Energy
Regulatory Commission (FERC or Commission) its Revised Study Plan (RSP) for the Susitna-
Watana Hydroelectric Project No. 14241 (Project), which included 58 individual study plans
(AEA 2012). Section 11.9 of the RSP described the Invasive Plant Study. On February 1, 2013,
FERC staff issued its study plan determination (February 1 SPD) for 44 of the 58 studies,
approving 31 studies as filed and 13 with modifications. RSP Section 11.9 was one of the 31
studies approved with no modifications.
In this study, disturbed habitats in and near the Project area that could serve as sources of
invasive vascular plant species are being identified, and field surveys are being conducted in
those disturbed areas to locate populations of invasive species that have some potential to spread
into, or farther into, the Project area in association with development activities. An ecological
risk assessment will be conducted for the invasive species identified during the field surveys to
evaluate the risk of the continued spread of those species because of Project development
activities. RSP Section 11.9 provided goals, objectives, and proposed methods for data collection
regarding invasive plants.
Following the first study season, FERC’s regulations for the Integrated Licensing Process (ILP)
require AEA to “prepare and file with the Commission an initial study report describing its
overall progress in implementing the study plan and schedule and the data collected, including an
explanation of any variance from the study plan and schedule” (18 CFR 5.15(c)(1)). This Initial
Study Report (ISR) on the Invasive Plant Study has been prepared in accordance with FERC’s
ILP regulations and details AEA’s status in implementing the study, as set forth in the FERC-
approved RSP (referred to herein as the “Study Plan”).
2. STUDY OBJECTIVES
The study objectives are established in RSP Section 11.9.1. The overall goals of the Invasive
Plant Study are to determine the current prevalence of invasive vascular plants in the Project area
and nearby disturbed areas, and to assess the risk of the continued spread of invasive species as a
result of Project development. Invasive plant species are defined as non-native species that pose
a serious ecological threat to natural systems and whose populations are difficult to control
(Carlson et al. 2008). Currently, 164 of the 284 non-native plant species that occur in Alaska are
considered invasive (Nawrocki et al. 2011).
The specific objectives of the Invasive Plant Study are to:
• Identify the locations at which invasive plant species have already become established in
the Project area and in nearby disturbed areas;
• Estimate population sizes for invasive species and map their current distributions; and
• Determine whether any of the species found could pose a substantial ecological threat if
populations were to spread into the Project area.
INITIAL STUDY REPORT INVASIVE PLANT STUDY (11.9)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 2 June 2014
3. STUDY AREA
The study area for the Invasive Plant Study is set forth in RSP Section 11.9.3. As discussed
therein, since invasive vascular plant species are generally confined to disturbed areas and the
Project area is primarily undeveloped, the 2013 field survey for this study was focused on
disturbed areas near the Project area that could act as potential pathways for invasive species to
enter and establish in the Project area. Sections of the George Parks (Parks) and Denali highways
that are relatively close to the three possible alignments for the access road and transmission
lines, primitive roads and off-road vehicle (ORV) trails emanating from the Denali Highway that
currently provide access into the Project area, and other disturbed areas near the Parks and
Denali highway corridors were surveyed (Figure 3-1).
Sites not within the Project area but that could serve as sources for invasives during construction
(e.g., Stephan Lake Lodge, High Lake Lodge, Gold Creek Camp, and the Talkeetna airport) will
be surveyed in the next year of study. Additionally, as engineering design for the Project
proceeds, potential gravel material sources will be identified and any existing gravel mine sites
being considered for support of Project construction and operations also will be surveyed for
invasive plant species.
4. METHODS AND VARIANCES IN 2013
The invasive plant survey included a review of the Alaska Exotic Plants Information
Clearinghouse (AKEPIC) database, maintained by the Alaska Natural Heritage Program
(AKNHP), to identify invasive species previously documented in the study area; a field survey of
previously surveyed sites and new areas identified as potentially harboring invasive species; and
a preliminary assessment of the ecological risk of the invasive species found during the field
survey. The field survey focused on roads and trails that could be used to access the Project area
and that had site characteristics that would likely encourage the establishment of invasive plants.
These include well-drained, typically gravelly soils that are frequently disturbed. The ecological
risk assessment involves an examination of plant species life-history traits and a set of ecological
and plant management/control factors that influence the degree to which an invasive species can
establish and threaten native plant communities.
4.1. Field Surveys
The field surveys for this study were conducted as set forth in Section 11.9.4.1 of the RSP with
no variances. Prior to the 2013 field survey, recent aerial imagery for portions of the Parks and
Denali highway corridors near the Project area was reviewed to identify disturbed sites that could
harbor invasive species or were at risk for colonization by invasive species. These included ORV
trails, gravel roads, quarry sites, and other disturbed areas. The current records in the AKEPIC
database also were reviewed to identify survey locations in the vicinity of the Project area that
could be resurveyed to determine if invasive species are still present and whether the populations
(in cases in which population estimates are available) are contracting, expanding, or are
relatively unchanged since previous surveys. Based on a search of collection localities in the
AKEPIC database, which included data from invasive plant surveys conducted along road
systems near the Project area (Parks and Denali highways) and from other plant surveys in the
INITIAL STUDY REPORT INVASIVE PLANT STUDY (11.9)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 3 June 2014
Susitna River Basin upstream of Gold Creek, 21 invasive plant species were found to occur in
areas relatively near the Project area (Table 4.1-1).
The invasive plant field survey was conducted with a 2-person team from August 19–28, 2013
following guidelines in the AKEPIC User Manual (AKNHP 2012). For ORV trails, two
observers walked up the trail for at least 200 m (656 ft), or 200 m (656 ft) beyond the last
invasive plant sighting. If an established campsite or clearing was observed on aerial photos
farther up the trail, the trail was surveyed up to that disturbance. The highway roadsides on either
side of a trail junction and on both sides of the road for approximately 100 m (328 ft) in each
direction (total of approximately 400 linear m [1,312 ft]) also were surveyed. The trail and
adjacent roadside surveys were recorded as one sample location.
For paved and gravel pullouts/waysides, the entire graveled area and brushed (disturbed)
perimeter was surveyed. Trails and campsites associated with pullouts were also surveyed.
Adjoining roadsides were surveyed for approximately 50 m (164 ft) beyond pullouts if invasives
were discovered at pullouts. Creek sides near pullouts also were surveyed, and natural
(undisturbed) plant communities adjacent to pullouts were periodically checked for the presence
of invasive species. If pre-selected sample points at pullouts were > 5 km (3.1 miles) apart, the
intervening road segments were periodically surveyed for invasives.
Suspected invasive species were collected for identification and the locations of populations
encountered were recorded with a hand-held global positioning system (GPS) receiver. Digital
photographs of the sample site and invasive species present were taken at each sampled location.
Non-native species that are not considered invasive also were noted when encountered. If
possible, population estimates for invasive species were made by visually enumerating or
estimating the number of plants in the area. If enumeration or estimation of the number of
individual plants was not possible, the degree of infestation at each location was ranked
qualitatively as low (1–10 percent cover of assessment area), medium (10–40 percent cover), or
high (> 40 percent cover). Because the distribution and size of the areas where invasive species
were present was highly variable, the use of a standard assessment-area size (e.g., a 10-m [33-ft]
radius plot) was not appropriate for evaluating the degree of infestation. Instead, the geographic
limits of an infested area were used to define the assessment-area boundaries (these areas may be
as small as 0.01 acre or as large as 2 acres).
Invasive species were identified in the field using Hultén (1968), Cody (1996), Skinner et al.
(2012), and (AKNHP 2013), but the final taxonomic nomenclature used in this report is based on
the Natural Resources Conservation Service’s PLANTS database (NRCS 2013). Voucher
specimens of invasive species were collected and submitted to the University of Alaska in
Fairbanks (UAF) Herbarium for final identification. All field data were entered into a Microsoft
Access database and will be made available for entry into the AKEPIC database upon
completion of the study.
4.1.1. Variances
In 2013, there were no variances from the methods for field data collection described in RSP
Section 11.9.4.1. While field data collection did not occur on Cook Inlet Regional Working
Group (CIRWG) lands because land-access permits were not available, this was not considered a
INITIAL STUDY REPORT INVASIVE PLANT STUDY (11.9)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 4 June 2014
variance because this study was designed so that the disturbed areas comprising the study area
would be surveyed over the two study years. A sufficient number of disturbed sites outside of
CIRWG lands were accessible for assessment in 2013.
4.2. Ecological Risk Assessment
The methodologies for ecological risk assessment in this study were conducted as set forth in
Section 11.9.4.2 of the RSP with no variances. To assess the ecological risk of invasive plant
species found in and near the Project area, the invasiveness ranking system developed for non-
native vascular plant species in Alaska by the AKNHP in association with the U.S. Forest
Service, U.S. Department of Agriculture, U.S. Geological Survey, National Park Service, and the
UAF Cooperative Extension Service (Carlson et al. 2008; Nawrocki et al. 2011) was used. In this
ranking system, the overall invasiveness scores for each species are based on sub-scores for
ecological impact, biological characteristics (e.g., life history, potential for spread, allelopathy),
distribution, and feasibility of control. The higher the overall score (ranging from 1–100), the
greater the risk that a species will have negative ecological effects and the lower the likelihood it
can be controlled effectively. A preliminary assessment of the local ecological risk of invasive
species being spread because of Project development activities was assessed by taking into
account the invasiveness score for each species found; evaluating the number, size, and location
of each population; and considering the species’ possible mode(s) of dispersal into the Project
area based on likely construction and operations scenarios. To the extent possible, the potential
impact of invasive species on ecologically important native plant species in the Project area also
was assessed.
4.2.1. Variances
In 2013, there were no variances from the methods for the ecological risk assessment described
in RSP Section 11.9.4.2.
5. RESULTS
Data generated in support of this study are available for download at
http://gis.suhydro.org/reports/isr. The data are in the file: ISR_11_9_INPL_FieldData.accdb.
5.1. Field Survey
In 2013, 107 field sites were surveyed, 23 of which had previously been surveyed in 2004, 2006,
or 2012 (Figure 3-1). At those 23 locations, no invasive species were observed at two locations
in previous surveys or by Project researchers. Additionally, no invasive species were found at 6
of the other sites surveyed in this study. A total of 28 invasive plant taxa were recorded on the
remaining 99 sites (Table 5.1-1), including 10 additional species that were not found in previous
surveys as recorded in the AKEPIC database. Four species that were previously recorded at the
AKEPIC sites, however, were not found in 2013: Bromus tectorum (cheatgrass or downy
brome), Leontodon hirtus (rough hawkbit), Melilotus officinalis (yellow sweetclover), and
Sonchus asper (spiny sowthistle). Individual species were found at a variable number of survey
sites, ranging from 1 to 76, with most (22) species occurring at 10 or fewer sites. In general, the
INITIAL STUDY REPORT INVASIVE PLANT STUDY (11.9)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 5 June 2014
cover of invasive plants at the surveyed sites was modest, with 439 (95%) of the 463 cover-value
observations across all 107 sites recorded as either trace (< 1%) or low (1–5%) cover (Table 5.1-
2). Observations of moderate cover values (11–25% and 26–40%) for invasive species were
recorded for only 13 (3%) of the cover-value observations. High cover (95%) was observed only
for Stellaria media (common chickweed) at a single site; this species is considered weakly
invasive, with an invasiveness rank of 42.
With few exceptions, populations of invasive species were confined to road rights-of-way and
other sites with gravelly, well-drained substrates. Invasive plants were uncommon along
undeveloped roads and trail networks, but were sometimes present at trailheads and adjacent
roadsides. In a few cases, invasive species were found farther up trails at campsites or other
disturbed locations, typically where the substrate was sandy or gravelly. An exception was at
field plot suwa-inv-028 at a trailhead near the eastern end of the study area; at this site several
individuals of Taraxacum officinalis (common dandelion) had established in undisturbed
vegetation (Low Open Alder–Willow Scrub) adjacent to the trail.
No information is available on the survey boundaries for the infestation areas assessed during the
previous AKEPIC field studies, so comparing differences in percent cover of invasive species
between those surveys and this study was not possible. Nevertheless, the levels of infestation
found in both the AKEPIC surveys and this study were generally categorized as low, based on
the canopy-cover estimates for the four survey years (2004, 2006, 2012, and 2013). Perhaps most
notable when comparing the previous surveys to the 2013 data was that, for many of the sites
revisited, new invasive species were recorded in 2013; thus, the overall number of invasive
species associated with at least the revisited survey sites has increased over the past 9 years. This
is notwithstanding the fact that four species (see above), which were recorded in the earlier
AKEPIC surveys, were not found in this study. Populations of invasive species still appear,
however, to be confined primarily to heavily disturbed areas along the margins of main roadways
and trail entrances. This may be due largely to soil substrates in undisturbed areas being
unsuitable for promoting the expansion of populations of invasive species. At some locations, it
was likely that invasive plant populations had been eliminated or reduced considerably by
management practices (e.g., road-corridor maintenance and expanded paved areas, including
parking lots).
5.2. Ecological Risk Assessment
Because the populations of most invasive species found during the 2013 survey were negligible
to small in size, the current ecological risk of invasive plants in the vicinity of the Project area is
relatively low. However, 7 of the 28 species (25 percent) have U.S. Department of Agriculture
(USDA) rankings of moderately (60–69) to extremely (> 80) invasive (Table 5.1-1; Figures 5.2-1
through 5.2-4). The two species of greatest concern are probably Hordeum jubatum (foxtail
barley) and Melilotus alba (white sweetclover). H. jubatum (invasiveness rank: 63) is able to
colonize a wide range of disturbed habitats, from well drained, gravelly substrates to relatively
wet, silty soils. This species is difficult to eradicate and is potentially harmful to wildlife,
although it can be controlled with herbicides. Although H. jubatum is palatable to grazers early
in the season, later in the summer the mature awns (bristles on flower heads) can be irritating to
the eyes, mouths, and skin of grazing mammals. H. jubatum was present at 50 (47%) of the 107
sites surveyed in 2013, although cover levels were relatively low.
INITIAL STUDY REPORT INVASIVE PLANT STUDY (11.9)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 6 June 2014
The AKEPIC research group has identified M. alba (invasiveness rank: 81) as one of Alaska’s
most problematic invasive species, due to its propensity to form dense stands on river bars. In
addition, M. alba serves as a host for nitrogen-fixing bacteria, which means its establishment is
likely to alter soil-nutrient composition and could help promote the establishment of other
species, native or non-native. Recent studies of several Alaska rivers found that low to moderate
densities of M. alba are associated with the establishment of other exotic species, while high
densities can negatively affect the establishment of both native and non-native species (Conn et
al. 2011; Spellman and Wurtz 2011). Native species that were shown to be negatively affected
by the presence of M. alba included the often dominant riparian shrub, Salix alaxensis (feltleaf
willow), and the forb, Lathyrus japonicus var. maritimus (beach pea). During the 2013 field
study, M. alba was present at 7 (7%) of the 107 sites surveyed.
Both H. jubatum and M. alba were found mostly at trace (< 1%) and low (1–5%) cover values
(48 and 5 locations, respectively) during the 2013 survey; H. jubatum was found at 6–10% cover
at only 2 sites (Table 5.1-2). Nevertheless, they are aggressive colonizers and can pose
ecological threats if larger populations establish.
6. DISCUSSION
The Invasive Plant Study is a 2-year study that was initiated in 2013. Results from the first year
of study, along with observations of invasive plants made in the other botanical studies being
conducted for the Project, especially the Vegetation and Wildlife Habitat Mapping Study in the
Upper and Middle Susitna Basin (Study 11.5) and the Wetland Mapping Study in the Upper and
Middle Susitna Basin (Study 11.7), will be used in planning for the next year of field surveys for
invasive species.
Results from the 2013 field survey provided important baseline data on the extent to which
invasive plants are currently associated with areas along the Parks and Denali highways where
each of the three alternative road corridors for the Project are planned to originate. The data
document the occurrence of invasive species along the margins of these highway corridors and
along the initial sections of trails and unimproved roads that enter the Project area from those
highways. Repeat visits to the AKEPIC survey sites in 2013 provided insight into changes in
invasive species occurrence and their population sizes over time. The characterization of
conditions at sites that support invasive species now will be useful in preparing appropriate
protection, mitigation and enhancement measures, as those data will help in determining the
appropriate risk-management protocols and identifying which Project activities are most likely to
promote the establishment of invasive species. For example, based on a review of previous
invasive plant surveys in Alaska, 70% of infestations of invasive plants were associated with fill
importation (Nawrocki et al. 2011).
The invasive plant study team is working with the study teams for the Wetlands Mapping Study
(Study 11.7), Vegetation and Wildlife Habitat Mapping Study (Study 11.5), and Riparian
Vegetation Study (Study 11.6) to identify potential high-risk locations for invasive plants within
the Project area. Casual observations in 2012 and 2013 by other botanical studies field crews
indicated that invasive plants (primarily Taraxacum officinalis) were present at the Talkeetna
Airport; in the Susitna River corridor between Willow and Talkeetna (near human disturbances)
INITIAL STUDY REPORT INVASIVE PLANT STUDY (11.9)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 7 June 2014
along a section of the Upper River near Sherman; and in the vicinity of both Stephan Lake Lodge
and Gold Creek Camp. The Upper River location near Sherman was in a relatively pristine area,
although it was close (70–100 m [230–330 ft]) to the Alaska Railroad corridor. The other Upper
River locations (near Gold Creek Camp) were associated with all-terrain vehicle trails or river
gravel bars. This information will be used to help guide field survey efforts in the next year of
study.
7. COMPLETING THE STUDY
[Section 7 appears in the Part C section of this ISR.]
8. LITERATURE CITED
AEA (Alaska Energy Authority). 2012. Revised Study Plan: Susitna-Watana Hydroelectric
Project FERC Project No. 14241. December 2012. Prepared for the Federal Energy
Regulatory Commission by the Alaska Energy Authority, Anchorage, Alaska. Available
on-line at http://www.susitna-watanahydro.org/study-plan. Accessed September 2013.
AKNHP (Alaska Natural Heritage Program). 2012. Alaska Exotic Plants Information
Clearinghouse (AKEPIC) User's Manual. Alaska Natural Heritage Program, University
of Alaska, Anchorage, AK. 18 pp. Available on-line at
http://aknhp.uaa.alaska.edu./botany/akepic. Accessed May 2013.
AKNHP (Alaska Natural Heritage Program). 2013. Identification of Non-native Plants in Alaska.
Alaska Natural Heritage Program, University of Alaska, Anchorage, AK. 251 pp.
Carlson M.L., I.V. Lapina, M. Shephard, J. Conn, R. Densmore, P. Spencer, J. Heys, J. Riley,
and J. Nielsen. 2008. Invasiveness ranking system for non-native plants of Alaska.
Technical Report R10-TP-143. U.S. Dept. of Agriculture and U.S. Forest Service, Alaska
Region, Anchorage, Alaska. 218 pp.
Cody, W. J. 1996. Flora of the Yukon Territory. Second Edition. NRC Research Press, National
Research Council of Canada. Ottawa, Ontario, Canada. 669 pp.
Conn, J. S., N. R. Werdin-Pfisterer, K. L. Beattie, and R V. Densmore. 2011. Ecology of
invasive Melilotus albus on Alaskan glacial river floodplains. Arctic, Antarctic, and
Alpine Research, 43(3):343-354. 2011.
Hultén, E. 1968. Flora of Alaska and neighboring territories. Stanford University Press.
Stanford, CA. 1008 pp.
Nawrocki, T. H. Klein, M. Carlson, L. Flagstad, J. Conn, R. DeVelice, A. Grant, G. Graziano, B.
Million, and W. Rapp. 2011. Invasiveness Ranking of 50 Non-native Plant Species for
Alaska. Prepared for the Alaska Association of Conservation Districts by the Alaska
Natural Heritage Program, University of Alaska, Anchorage, AK. 28 pp.
INITIAL STUDY REPORT INVASIVE PLANT STUDY (11.9)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 8 June 2014
NRCS (Natural Resources Conservation Service). 2013. PLANTS database. Available on-line at
http://plants.usda.gov/java/. Accessed 09/26/2013. Accessed September 2013.
Skinner, Q. D., S.J. Wright, R.J. Henszey, J.L. Henszey, and S.K. Wyman. 2012. Field Guide for
Alaska grasses. Education Resources Publishing, Cumming, GA. 384 pp.
Spellman, B. T. and T. L. Wurtz. 2011. Invasive sweetclover (Melilotus alba) impacts native
seedling recruitment along floodplains of interior Alaska. Biological Invasions.
doi:10.1007/s10530-010-9931-4: 12
INITIAL STUDY REPORT INVASIVE PLANT STUDY (11.9)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 9 June 2014
9. TABLES
Table 4.1-1. Invasive Vascular Plant Species Previously Found in the Vicinity of the Susitna-Watana Hydroelectric Project Area.1
Scientific Name Common Name Invasiveness Rank2
Bromus inermis smooth brome 62
Bromus tectorum cheatgrass 78
Crepis tectorum narrowleaf hawksbeard 56
Galeopsis tetrahit brittlestem hempnettle 50
Hordeum jubatum foxtail barley 63
Leontodon hirtus rough hawkbit NR
Matricaria discoidea pineappleweed 32
Melilotus alba white sweetclover 81
Melilotus officinalis yellow sweetclover 69
Phleum pratense timothy 54
Plantago major common plantain 44
Poa annua annual bluegrass 46
Poa pratensis spreading bluegrass or Kentucky
bl
52
Polygonum aviculare prostrate knotweed 45
Sonchus asper spiny sowthistle 46
Tanacetum vulgare common tansy 60
Taraxacum officinale common dandelion 58
Trifolium hybridum alsike clover 57
Trifolium repens white clover 59
Tripleurospermum inodorum scentless false mayweed 48
Vicia cracca bird vetch 73
1. Species records from the AKEPIC database of invasive species maintained by the AKNHP (see text).
2. Assigned according to the Invasiveness Ranking System for Non-native Plants of Alaska (Carlson et al. 2008) and the Invasiveness
Ranking of 50 Non-native Plant Species for Alaska (Nawrocki et al. 2011). Species are ranked on a scale of 0 to 100, with 100 being an
extremely invasive species; NR = not ranked.
INITIAL STUDY REPORT INVASIVE PLANT STUDY (11.9)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 10 June 2014
Table 5.1-1. Invasive Species Found During the August 2013 Field Survey, Susitna-Watana Hydroelectric Project.
Scientific Name Common Name
Invasiveness
Rank1
Number of
Sites2
Percent of
Sites2
Bromus inermis smooth brome 62 5 4.7
Capsella bursa-pastoris shepherd's purse 40 2 1.9
Cerastium fontanum big chickweed 36 2 1.9
Chenopodium album lambsquarters 37 9 8.4
Crepis tectorum narrowleaf hawksbeard 56 10 9.3
Galeopsis tetrahit brittlestem hempnettle 50 2 1.9
Hordeum jubatum foxtail barley 63 50 46.7
Leontodon autumnalis fall dandelion 51 1 0.9
Lepidium densiflorum common pepperweed 25 2 1.9
Leucanthemum vulgare oxeye daisy 61 2 1.9
Linaria vulgaris butter and eggs 69 2 1.9
Lolium multiflorum Italian ryegrass 41 2 1.9
Matricaria discoidea pineappleweed 32 75 70.1
Melilotus alba white sweetclover 81 7 6.5
Phleum pratense timothy 54 22 20.6
Plantago major common plantain 44 76 71.0
Poa annua annual bluegrass 46 38 35.5
Poa pratensis ssp. irrigata spreading bluegrass 52 10 9.3
Poa pratensis ssp. pratensis Kentucky bluegrass 52 10 9.3
Polygonum aviculare knotweed 45 25 23.4
Rumex acetosella sheep sorel 51 1 0.9
Stellaria media common chickweed 42 9 8.4
Tanacetum vulgare common tansy 60 1 0.9
Taraxacum officinale common dandelion 58 71 66.4
Trifolium hybridum alsike clover 57 20 18.7
Trifolium repens white clover 59 7 6.5
Tripleurospermum inodorum scentless false mayweed 48 3 2.8
Vicia cracca bird vetch 73 4 3.7
1. Assigned according to the Invasiveness Ranking System for Non-native Plants of Alaska (Carlson et al. 2008) and the Invasiveness
Ranking of 50 Non-native Plant Species for Alaska (Nawrocki et al. 2011). Species are ranked on a scale of 0 to 100, with 100 being an
extremely invasive species; NR = not ranked.
2. Number and percent of field sites (out of 107 total surveyed) on which each species was found.
INITIAL STUDY REPORT INVASIVE PLANT STUDY (11.9)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 11 June 2014
Table 5.1-2. Number of Observations (Survey Sites) of Invasive Plants in Six Cover-value Categories, Susitna-Watana Hydroelectric Project Area, 2013.
Percent Cover Categories1
Species
Trace
(< 1 %) 1–5% 6–10% 11–25% 26–40% 95%
Total No. of
Observations
Bromus inermis 1 2 1 1 5
Capsella bursa-pastoris 1 1 2
Cerastium fontanum 1 1 2
Chenopodium album 6 3 9
Crepis tectorum 5 5 10
Galeopsis tetrahit 1 1
Hordeum jubatum 30 18 2 50
Leontodon autumnalis 1 1
Lepidium densiflorum 2 2
Leucanthemum vulgare 1 1 2
Linaria vulgaris 2 2
Lolium multiflorum 2 2
Matricaria discoidea 32 40 3 75
Melilotus alba 4 1 5
Phleum pratense 11 10 21
Plantago major 38 37 1 76
Poa annua 9 25 3 1 38
Poa pratensis 6 4 10
Poa pratensis 6 4 10
Polygonum aviculare 13 7 2 3 25
Rumex acetosella 1 1
Stellaria media 2 4 1 1 1 9
Tanacetum vulgare 1 1
Trifolium hybridum 6 14 20
Taraxacum officinale 28 41 1 1 71
Trifolium repens 4 3 7
Tripleurospermum inodorum 3 3
Vicia cracca 1 1 1 3
Totals 208 231 10 9 4 1 463
1. Listed are the number of survey sites at which each species was recorded in each cover-value category.
INITIAL STUDY REPORT INVASIVE PLANT STUDY (11.9)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 12 June 2014
10. FIGURES
INITIAL STUDY REPORT INVASIVE PLANT STUDY (11.9)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 13 June 2014
Figure 3-1. Invasive Plant Survey Plot Locations in the Vicinity of the Susitna-Watana Hydroelectic Project Area, 2013.
INITIAL STUDY REPORT INVASIVE PLANT STUDY (11.9)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 14 June 2014
Figure 5.2-1. Locations and Degree of Infestation of Melilotus alba in the Invasive Plant Survey Area, Susitna-Watana Hydroelectric Project, 2013.
INITIAL STUDY REPORT INVASIVE PLANT STUDY (11.9)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 15 June 2014
Figure 5.2-2. Locations and Degree of Infestation of Viccia cracca and Linaria vulgaris in the Invasive Plant Survey Area, Susitna-Watana Hydroelectric Project, 2013.
INITIAL STUDY REPORT INVASIVE PLANT STUDY (11.9)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 16 June 2014
Figure 5.2-3. Locations and Degree of Infestation of Hordeum jubatum in the Invasive Plant Survey Area, Susitna-Watana Hydroelectric Project, 2013.
INITIAL STUDY REPORT INVASIVE PLANT STUDY (11.9)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 17 June 2014
Figure 5.2-4. Locations and Degree of Infestation of Bromus inermus, Leucanthemum vulgare, and Tanacetum vulgare in the Invasive Plant Survey Area, Susitna-Watana Hydroelectric Project, 2013.
INITIAL STUDY REPORT INVASIVE PLANT STUDY (11.9)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 June 2014
PART A - APPENDIX A: PHOTOS OF SELECTED INVASIVE SPECIES,
2013 FIELD SURVEY, SUSITNA-WATANA HYDROPOWER PROJECT.
INITIAL STUDY REPORT INVASIVE PLANT STUDY (11.9)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Appendix A - Page 1 June 2014
Taraxacum officinale Melilotus alba
Field plot: suwa-inv-004 Field plot: suwa-inv-005
Matricaria discoidea Poa annua
Field plot: suwa-inv-023 Field plot: suwa-inv-089
Chenapodium alba Hordeum jubatum
Field plot: suwa-inv-014 Field plot: suwa-inv-015
INITIAL STUDY REPORT INVASIVE PLANT STUDY (11.9)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Appendix A - Page 2 June 2014
Bromus inermis Trifolium repens
Field plot: suwa-inv-018 Field plot: suwa-inv-102
Poa pratensis ssp. pratensis Trifolium hybridum
Field plot: suwa-inv-028 Field plot: suwa-inv-103
Crepis tectorum Stellaria media
Field plot: suwa-inv-067 Field plot: suwa-inv-043
INITIAL STUDY REPORT INVASIVE PLANT STUDY (11.9)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Appendix A - Page 3 June 2014
Tanacetum vulgare Vicia cracca
Field plot: suwa-inv-068 Field plot: suwa-inv-068
Phleum pratense Taraxacum officinale
Field plot: suwa-inv-005 Field plot: suwa-inv-089