SCRIBER LAKE PARK HABITAT MANAGEMENT PLAN - MAY 2021 - EARTHCORPS
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
May 2021 Scriber Lake Park Habitat Management Plan
-This page left intentionally blank-
Scriber Lake Park Habitat Management Plan
Prepared for:
Lynwood Parks
19100 44th Ave W
Lynnwood WA
Prepared by:
Nelson Salisbury, Senior Ecologist
EarthCorps
6310 NE 74th Street, Suite 201E
Seattle, WA 98115
May 2021
1|Scriber Lake Park Habitat Management Plan - 2021
-This page left intentionally blank- 2|Scriber Lake Park Habitat Management Plan - 2021
Table of Contents
1. INTRODUCTION ....................................................................................................5
2. HABITAT MAPPING AND NATURAL AREA ASSESSMENT .......................................5
2.1. Management Units.......................................................................................................... 6
Table 1. Scriber Lake Park Habitat Types ..........................................................................................7
Map 1: Habitat Management Units ...................................................................................................9
Map 2: Dominant Invasive Species Locations .................................................................................. 11
Map 3: General Invasive Species Locations ..................................................................................... 13
2.2. Assessment Procedures ................................................................................................ 15
3. SCRIBER LAKE PARK VEGETATION OVERVIEW ..................................................15
Figure 1. Proportion of general land cover types present throughout Scriber Lake Park...................... 16
Figure 2. Total acres of each habitat type present at Scriber Lake by general land cover. .................. 16
3.1. North Pacific Maritime Dry-Mesic Douglas-fir- Hemlock Forest (Units 1, 6, and 7) .... 18
3.2. North Pacific Lowland Riparian Forest and Shrubland (Units 2, 5 and 7) .................... 20
3.3. North Pacific Shrub Swamp (Units 3, 4, and 8) ............................................................ 21
3.4. Temperate Pacific Freshwater Emergent Marsh (parts of Units 3 and 4) .................... 22
4. MANAGEMENT RECOMMENDATIONS ..................................................................22
4.1. Overall Priority Restoration Checklist .......................................................................... 23
4.1.1. Targeted Restoration priorities: ....................................................................................... 23
4.2. Priority Volunteer Restoration ..................................................................................... 24
4.2.1. Zone Summaries for Volunteer Stewardship and General Vegetation Management .............. 24
4.3. Contractor Recommended Invasive Species Management .......................................... 27
Table 2. Listed noxious weeds found in Scriber Lake Park ................................................................ 27
5. GENERAL PLANTING RECOMMENDATIONS ........................................................28
6. WETLAND RESTORATION CONSIDERATIONS .....................................................29
7. REFERENCES .......................................................................................................31
8. APPENDIX A: SELECTED INVASIVE SPECIES BEST MANAGEMENT PRACTICES ..32
9. APPENDIX B: SPECIES REFERENCE LIST ............................................................43
All photos and maps in this report by Nelson Salisbury (unless otherwise noted) - EarthCorps 2020
3|Scriber Lake Park Habitat Management Plan - 2021
-This page left intentionally blank- 4|Scriber Lake Park Habitat Management Plan - 2021
1. Introduction
The City of Lynwood contracted with EarthCorps in 2020 to provide vegetation assessments and
habitat management recommendations for Scriber Lake Park. The primary goals of these
efforts were to assess the composition of the natural areas located throughout the park and
provide recommendations for improving their overall structure and function.
Increasing understanding of the existing conditions will help make informed management
decisions and provide baseline conditions that can be used to track and monitor changes to the
park over time. Through these efforts, EarthCorps mapped the natural areas based on
forest/ecological types, existing vegetation communities, and topography and created habitat
management zones to aid in planning and restoration efforts. In addition, the presence of
invasive plant species concerns were mapped and priority recommendations for control were
established. The following report summarizes these findings and describes the management
recommendations for Scriber Lake Park.
Developing a long-term habitat management plan is an important part of the City’s efforts to
protect, enhance, and maintain the forests, wetlands, and associated natural areas on the
property. Active habitat restoration and vegetation management will help to increase and
improve the natural, social, and economic services the park provides. These services include
storm water mitigation, flood and erosion control, improved air quality, carbon sequestration,
enhanced wildlife habitat, public education, passive and active recreation, as well as the many
other documented benefits to the health and well-being of the community. Scriber Lake Park
offers a unique and highly valuable resource to the community with its expansive wetlands and
the important storm water mitigation and habitat value. In addition, the park provides
extensive opportunities for recreation and experiencing nature with more than a mile of
maintained trails.
2. Habitat Mapping and Natural Area Assessment
This analysis evaluated the existing structure and condition of the natural areas present on the
property. The purpose of the forest assessment and analysis was to:
• Create Management Units to prioritize and track habitat restoration and
management efforts
• Provide baseline data on the existing structure and composition of the
vegetation communities
• Assess for dominant invasive species locations and extents
• Develop specific recommendations to restore and increase the health and structure of
existing vegetation communities
5|Scriber Lake Park Habitat Management Plan - 2021
2.1. Management Units Initial mapping efforts for Scriber Lake Park involved dividing the natural areas into similar habitat types based on soil moisture, dominant plant species associations, topography, or other existing features during GPS (global positioning system) assisted field surveys. The natural areas were divided into general Management Units generally based on habitat types, the location of existing trails, and other topographical features (Map 1). These Management Units (MUs) can be used to plan and prioritize restoration priorities and to monitor and track changes over time. However, the linear nature of these habitat types and wetland systems make the creation and classification of management units somewhat difficult. The intent of the MUs was to group similar habitat types together based on proximity in order to help direct and prioritize management and restoration. The natural areas were delineated into generally similar habitat types based on dominant plant species associations, topography, or other existing features during the GPS assisted field surveys (Map 1). Map 2 and Map 3 showing invasive species distributions are also included below, see Management Recommendations beginning on page 22 for more information regarding these maps. These habitat types include five different broadly defined ecological systems (Table 1) adapted from the ecological classification approach developed by NatureServe and utilized by the Washington Dept. of Natural Resources (WADNR) (Rocchio and Crawford 2015). Four of the dominant habitat types were adapted directly from the WADNR classifications, while one type was based on the early successional descriptions within these types. The “Shrub Swamp” habitat type includes areas related to, and often referred to, as bogs and fens. While the slow-moving water and peat formations present at Scriber Lake share characteristics of bogs, the year-round input of freshwater and resulting nutrients creates a less acidic environment compared to traditional bog habitats. The resulting vegetation communities are therefore more representative of the Shrub Swamp communities described by WADNR. Three other park areas that represent open canopy lacustrine, developed, or landscaped habitat types were also mapped and quantified. These areas include predominantly open water and portions within the property boundaries that are made up of parking lots, trails, landscaped grass, and paved streets. Table 1 shows a summary of these broad habitat types found throughout the property. These general habitat types and Management Unit delineations can be used to plan, prioritize, and track management and restoration efforts throughout the property. 6|Scriber Lake Park Habitat Management Plan - 2021
Table 1. Scriber Lake Park Habitat Types
Map Label Habitat Type* Acres % of Total
Forested (41% - 10.6 Acres)
Conifer Mixed Forest North Pacific Maritime Dry-Mesic Douglas-fir-Western Hemlock Forest* 6.2 24%
Riparian Forest North Pacific Lowland Riparian Forest and Shrubland* 3.7 14%
(Early Successional) North Pacific Maritime Dry-Mesic Douglas-fir-
Deciduous Forest 0.8 3%
Western Hemlock Forest*
Open Canopy (52% - 13.5 Acres)
Shrub Swamp North Pacific Shrub Swamp* 8.8 34%
Open Water Lacustrine Low Elevation Lake 4.4 17%
Emergent Marsh Temperate Pacific Freshwater Emergent Marsh* 0.3 1%
Developed (7% - 1.9 Acres)
Trails and Parking Lots 1.2 5%
Landscaped Grass 0.7 3%
Grand Total 26.0
*Indicates a WNHP Ecological System Classification type
The WNHP Ecological Systems describe the general characteristics of forests and natural areas
occurring within our region. These typings were developed primarily to describe relatively
undisturbed natural areas and therefore do not always correspond to our fragmented and
disturbed urban open spaces. These systems also describe different forest types that represent
a gradient of characteristics that transition from one type to another over the landscape. This
can be especially evident in areas where there are changes in soil moisture as is evident at
Scriber Lake. Despite the potential ambiguity around categorization and boundaries, these
broad classifications can help us describe both the existing conditions as well as make
inferences as to how active management could affect the future trajectory of the natural areas.
Ultimately, comparing these more disturbed habitats to the reference habitats described in the
WNHP can provide valuable information and guidance on how active management can work
towards shifting away from the current trajectory of disturbance and degradation. While some
disturbances (such as fragmentation and invasive species pressures) and continually changing
conditions (due to climate disruption etc.) may be persistent, fostering healthy and diverse
species assemblages can help increase resiliency and reduce the need for overall management
intervention over time.
The WNHP ecological system classifications descriptions (that can be found in the Natural
Heritage Report “Ecological Systems of Washington State - A Guide to Identification” (Rocchio
and Crawford, 2015)) also include listings for recognized U.S. National Vegetation Classification
Groups and Associations for each system. These associations could be used in the future to
further describe, classify, or create more specific target forest type systems or species
associations for restoration objectives.
7|Scriber Lake Park Habitat Management Plan - 2021
-This page left intentionally blank- 8|Scriber Lake Park Habitat Management Plan - 2021
Map 1 Map 1: Habitat Management Units 9|Scriber Lake Park Habitat Management Plan - 2021
-This page left intentionally blank- 10 | S c r i b e r L a k e P a r k H a b i t a t M a n a g e m e n t P l a n - 2 0 2 1
Map 2: Dominant Invasive Species Locations
Map 2
11 | S c r i b e r L a k e P a r k H a b i t a t M a n a g e m e n t P l a n - 2 0 2 1-This page left intentionally blank- 12 | S c r i b e r L a k e P a r k H a b i t a t M a n a g e m e n t P l a n - 2 0 2 1
Map 3: General Invasive Species Locations Map 3 13 | S c r i b e r L a k e P a r k H a b i t a t M a n a g e m e n t P l a n - 2 0 2 1
-This page left intentionally blank- 14 | S c r i b e r L a k e P a r k H a b i t a t M a n a g e m e n t P l a n - 2 0 2 1
2.2. Assessment Procedures Each Management Unit was inventoried using a rapid visual assessment procedure to provide a general understanding of the composition of the existing vegetation present throughout the park. Information collected for each area included dominant native plant species (trees, shrubs, groundcovers), presence of dominant non-native invasive plant species, and the presence of other habitat features or general site characteristics. All field surveys were conducted in June and August of 2020 by an EarthCorps ecologist. Overall, more than 26 acres of natural areas were mapped and rapidly surveyed using these general qualitative observations. This survey was intended to provide a broad understanding of the structure and composition of the vegetation present on site and did not consist of a comprehensive species inventory. The management units and habitat type delineations could be used in future efforts to develop a more rigorous or objective survey or analysis. 3. Scriber Lake Park Vegetation Overview At the center of Scriber Lake Park is the open water of Scriber Lake, a 2.4 acre perennial body of water that is fed by Scriber Creek flowing into the property from the southeast (Map1). Water flows north out of the property through a culvert beneath 196th Street SW. There is a smaller complex of two smaller bodies of water in the northeast portion of the property and another linear area of ponded water along the norther boundary of the park adjacent to 19th Street SW (the “North Lagoon”). These smaller waterbodies which include the slow-moving stream channel leading into Scriber Lake combine for an additional 2 acres of open water throughout the park (Figure 2). In winter and in times of heavy or sustained rainfall all of these bodies of water can become connected with overland flow. A vast network of scrub-shrub wetlands, swamps, and riparian forests link the standing water together in a complex matrix of wetlands that cover the majority of the property (Map 1, Figures 1 & 2). Areas of higher elevation transition into remnants of upland coniferous forests concentrated mostly along the southern and western portions of the park. A smaller elevated portion of the park in the northeast is also comprised of a generally upland deciduous forested habitat that shows signs of past significant disturbance (categorized as an early successional mixed conifer forest type – Table 1 & Figure 2). 15 | S c r i b e r L a k e P a r k H a b i t a t M a n a g e m e n t P l a n - 2 0 2 1
Figure 1. Proportion of general land cover types present throughout Scriber Lake Park Figure 2. Total acres of each habitat type present at Scriber Lake by general land cover. 16 | S c r i b e r L a k e P a r k H a b i t a t M a n a g e m e n t P l a n - 2 0 2 1
The upland forests are dominated by mature conifer trees and typical Pacific Northwest shrub assemblages. These forests transition to bands of riparian forests that flank the wetland systems providing a buffer to the scrub-shrub swamp habitats. The low-lying areas of the park along the stream and open water are made up of a thick native shrub complex exhibiting a striking diversity of species and providing abundant habitat for birds and other wildlife. These shrub-swamp habitats are comprised of an intricate matrix of plant species that are tolerant of frequent flooding and saturated soil conditions, with most areas not able to support tree establishment. Because of the persistent high water levels, the areas surrounding the lake exhibit bog-like characteristics with patches of dense emergent vegetation adapted to these very wet conditions. While patches of herbaceous dominated marsh vegetation are scattered through the shrub swamp habitat, a narrow but consistent band of this habitat was mapped along the northern portion of the main lake area (Map 1). Plant species here are well adapted to persistent flooding and transition into floating vegetation in some areas. More detailed information on species associations are presented below for each Ecological System type. Appendix B includes a list of all native and non-native species noted in Scriber Lake Park during the survey. The greatest threat to the health and function of these natural areas is the continued spread and establishment of non-native invasive plant species. Many areas of the park have become substantially invaded with a variety of species of invasive plants common in our area. Maps 2 and 3 show the approximate locations of selected invasive species concerns throughout the park. The primary invasive species threats include hybrid Bohemian knotweed, Himalayan blackberry, English ivy, English holly, and cherry laurel. Limited amounts of poison hemlock, a King County Class B noxious weed required for control, are also present in MU 7 (Map2). Other concerns include smaller infestations of bittersweet nightshade and yellow flag iris in the shrub swamp habitats and around the lake (MUs 3, 4, and 8). See Table 2 on page 26 for all listed noxious weeds noted in the park. The control and eradication of invasive plant species should be considered a high management priority for Scriber Lake Park. Other concerns include water quality issues such as eutrophication and sedimentation resulting from the highly urbanized nature of the surrounding watershed. While water quality is not directly addressed in this report, maintaining healthy riparian habitat can help mitigate the negative effects of ongoing pollution and contamination. Overall, the park consists of unique natural areas that exemplify a high level of ecological diversity. The wetlands and surrounding habitats serve important stormwater detention functions and provide vital wildlife habitat in an increasingly urbanized environment. These types of wetlands (especially of this size and complexity) are also rare in western Washington due to their sensitivity to disturbance and the degradation and loss from historical filling and development. Combined with the adjacent mature upland forested habitats, these natural areas offer a valuable resource to Lynnwood’s community and provide important recreational and educational opportunities. Maintaining and enhancing the structure and function of these natural areas will ensure that Scriber Lake Park will continue to provide these important resources to the Lynwood community. 17 | S c r i b e r L a k e P a r k H a b i t a t M a n a g e m e n t P l a n - 2 0 2 1
3.1. North Pacific Maritime Dry-Mesic Douglas-fir-Western Hemlock Forest (Units
1, 6, and 7)
Approximately
6.2 acres (24%)
of Scriber Lake
Park consists of
generally upland
forest types and
were categorized
as the North
Pacific Maritime
Dry-Mesic
Douglas-Fir
Western Hemlock
Forest Ecological
System
classification Photo 1: Douglas fir and salal understory in MU 1.
(Table 1). Units 1 and 6 are primarily conifer-dominated generally upland forests. Dominant
trees are Douglas fir (Pseudotsuga menziesii) and western red cedar (Thuja plicata) with lesser
amounts of western white pine (Pinus monitcola), bigleaf maple (Acer macrophyllum), and red
alder (Anus rubra). Some areas have regenerating western red cedar and cascara (Frangula
purshiana) in the understory. Shrub cover is somewhat patchy and open in Unit 1 and
generally more developed in Unit 6. Native shrub cover in drier areas is dominated by beaked
hazelnut (Corylus cornuta), salal (Gaultheria shallon), oso-berry (Oemleria cerasiformis),
Cascade Oregon grape (Mahonia nervosa), and bald-hip rose (Rosa gymnocarpa) with wetter
areas also with red huckleberry (Vaccinium parvifolium) and salmonberry (Rubus spectabilis).
The herbaceous layer is relatively sparse and dominated by sword fern (Polystichum munitum)
especially in drier areas. Wood fern (Dryopteris expansa), bracken fern (Pteridium aquilinum),
and some patches of vanilla leaf (Achlys triphylla) area also scattered throughout, especially in
Unit 6. Unit 7 has a mostly upland area (described as Deciduous Forest on Map 1) that is
included in this general habitat type.
Unlike Units 1 and 6, Unit 7 is dominated by mature deciduous trees made up predominantly of
red alder with black cottonwood (Populus trichocarpa) and bigleaf maple in lesser amounts.
This unit was categorized as an early successional representation of the overarching Douglas
fir/western hemlock forest type. Shrub cover is moderate and comprised of generally upland
associated shrubs including ocean spray (Holodiscus discolor), oso-berry, and red elderberry
(Sambucus racemosa). The herbaceous layer here is relatively sparse and comprised of sword
fern and trailing blackberry (Rubus ursinus).
18 | S c r i b e r L a k e P a r k H a b i t a t M a n a g e m e n t P l a n - 2 0 2 1Invasive species
are generally well
established
throughout these
forest types.
Portions of the
forests are heavily
invaded with large
patches of
Himalayan
blackberry (Rubus
bifrons) and English
ivy (Hedera helix)
with small patches
of hybrid Bohemian
knotweed (Fallopia
x bohemica) in Unit
1 (Map 2). Much of
Photo 2: MU 6 showing intact upland forest with mixed overstory and the understory is
Cascade Oregon grape/sword fern in the understory. dominated with
invasive tree species dominated by English holly (Ilex aquifolium), cherry laurel (Prunus
laurocerasus), and Portugal laurel (Prunus lusitanica) with lesser amounts of bird cherry (Prunus
avium), common hawthorn (Crataegus monogyna), horse chestnut (Aesculus hippocastanum),
and European mountain ash (Sorbus aucuparia). Other invasive species include spurge laurel
(Daphne laureola), hedge-false bindweed (Calystegia sepium), herb Robert (Geranium
robertianum), and bittersweet nightshade (Solanum dulcamara).
Reduction of invasive species would greatly increase the health and structure of these forests.
Minimal planting would be needed due to the relatively high cover of native species and the
existing canopy although some areas of heavy invasive cover will require substantial effort to
clear and revegetate.
19 | S c r i b e r L a k e P a r k H a b i t a t M a n a g e m e n t P l a n - 2 0 2 13.2. North Pacific Lowland Riparian Forest and Shrubland (Units 2, 5 and 7)
The forested areas that transition towards
the wetter areas of the park are primarily
comprised of moisture tolerant deciduous
forests dominated by red alder with some
black cottonwood trees. These units make
up approximately 3.7 acres or 14% of the
park (Table 1). Some large western red
cedar trees are present near the transition
to the wetter shrub-dominated interior
habitats. Drier portions of these areas
have relatively high shrub cover made up
of beaked hazelnut and oso-berry while
wetter areas are dominated by
salmonberry, red-osier dogwood (Cornus
sericea) and black twinberry (Lonicera
involucrata). The herbaceous layer
includes giant horsetail (Equisetum
telmateia), stinging nettle (Urtica dioica),
and lady fern (Athyrium filix-femina) with
some patches of false lily-of-the-valley
(Maianthemum dilatatum).
Invasive species are prevalent in these
Photo 3: MU 5 showing mature western red cedar
areas, especially bordering the trail. These
tree with false lily-of-the-valley groundcover
species include non-target invasive species
such as creeping buttercup (Ranunculus repens) and reed canary grass (Phalaris arundinacea)
as well as targeted species including hybrid Bohemian knotweed (Units 5 and 7), English ivy,
and spotted jewelweed (Impatiens capensis). The riparian forested portion of Unit 7 in
particular is heavily invaded with non-native species including Himalayan blackberry, English ivy,
knotweed, poison hemlock (Conium maculatum), hedge-false bindweed, and English holly (Map
2). Unit 2 along 196th Street SW is also heavily disturbed and invaded with Himalayan
blackberry and evergreen clematis (Clematis vitalba).
20 | S c r i b e r L a k e P a r k H a b i t a t M a n a g e m e n t P l a n - 2 0 2 13.3. North Pacific Shrub Swamp (Units 3, 4, and 8)
The majority of the
natural areas located at
Scriber Lake Park were
classified as the North
Pacific Shrub Swamp
habitat type (Map 1),
making up 8.8 acres or
34% of the park. These
areas are dominated by
dense stands of tall and
spreading shrubs that
are able to tolerate the
saturated soil
conditions. Prominent
species include Pacific
willow (Salix lasiandra),
Sitka willow (Salix
sitchensis), and coastal
Photo 4: Trail in west MU 4 adjacent to dense willow and hardhack
willow (Salix
shrubs. Note non-native creeping buttercup along trail opening.
hookeriana), red-osier
dogwood, twinberry, salmonberry, hardhack (Spiraea douglasii), Pacific crabapple (Malus
fusca), and Labrador-tea (Rhododendron groenlandicum). These systems are generally too wet
for persistent tree establishment, although some red alder trees are sporadically present.
Openings in the shrub canopy provide opportunities for herbaceous annual and perennial
species to proliferate including skunk cabbage (Lysichiton americanus), lady fern (Athyrium filix-
femina), musk-flower (Erythranthe moschata), false lily-of-the-valley, American brooklime
(Veronica americana), marsh bedstraw (Galium palustre), leafy beggar-ticks (Bidens frondosa),
mad-dog skullcap (Scutellaria lateriflora), and fowl manna grass (Glyceria striata).
These Units share characteristics with the Vancouverian Lagg Shrub Swamp and the
Vancouverian Shrub Basin Swamp wetland and riparian subgroup types (WADNR has a
forthcoming guide to these wetland types for Washington State: Wetland and Riparian
Vegetation Types | WA - DNR). Much of the current vegetation is typical of Puget Lowland
scrub-shrub wetlands and also share many characteristics of the shrub types described in the
North Pacific Lowland Riparian Forest and Shrubland system.
These habitats overlay extensive peat deposits that have accumulated over thousands of years
in the poor nutrient conditions created in these types of glacial depressional landforms. Scriber
Lake could technically be described as a fen (as opposed to a bog) due to the year-round input
of freshwater form Scriber Creek. The high water table results in saturated bog-like conditions
although the input of freshwater and resulting nutrients creates a less acidic environment
21 | S c r i b e r L a k e P a r k H a b i t a t M a n a g e m e n t P l a n - 2 0 2 1compared to traditional bog habitats. These conditions allow for more typical freshwater
wetland and riparian shrub, herb, and graminoid communities. More acidic bogs would be
dominated by Ericaceous shrubs while only limited amounts of Labrador tea were noted at
Scriber Lake Park.
Invasive species concerns are predominantly associated with the trails and include creeping
buttercup, reed canary grass, spotted jewelweed, and Himalayan blackberry. Some limited
patches of bittersweet nightshade and yellow flag iris were also noted (Map 2). A large patch
of hybrid Bohemian knotweed extends into the eastern portion of Unit 4 from the adjacent
riparian forest.
3.4. Temperate Pacific Freshwater Emergent Marsh (parts of Units 3 and 4)
The Shrub Swamp wetland
transitions towards more
emergent vegetation along the
lake edge including freshwater
emergent marsh species such
as spreading rush (Juncus
effusus), small-fruited bulrush
(Scirpus microcarpus), sedges
(Carex spp. Including awlfruit
sedge: C. stipata), Pacific water
parsley (Oenanthe
sarmentosa), and marsh
cinquefoil (Comarum palustre).
The margins of the lake itself
Photo 5: North edge of Scriber Lake showing spatterdock and are ringed with native broad-
cattails in the emergent marsh. leaf cattails (Typha latifolia)
with spatterdock (Nuphar polysepala) extending into the open water. Only relatively narrow
bands were mapped along the lake shores although pockets of emergent marsh vegetation can
be found as a matrix within the Shrub Swamp wetland complex.
Yellow flag iris is the predominant invasive species concern in this habitat type although reed
canary grass is also present in some areas along the lake shore (Map 2).
4. Management Recommendations
Much of the natural areas at Scriber Lake Park have been heavily invaded with non-native and
invasive plant species (Map 2 & 3). The highest priority should be to reduce the pressure of
these species in the vicinity of designated wetlands and to work to incrementally remove them
from the park over time. High priority consideration should be given to King County listed
invasive species and those species that are directly compromising the function of the riparian
and wetland habitats.
22 | S c r i b e r L a k e P a r k H a b i t a t M a n a g e m e n t P l a n - 2 0 2 1The following is a summary of general restoration management recommendations that are
intended to provide overarching guidance towards improving the health and structure of the
natural areas. Management recommendations are separated by overall parkwide priorities
(4.1), Volunteer recommended tasks (4.2), and Contractor recommended tasks (4.3). See Map
2 for general invasive species locations and Map 3 for volunteer and contractor recommended
restoration areas. In general, English ivy areas in upland habitats were considered the most
accessible for volunteer restoration efforts. Areas of knotweed, contiguous blackberry, and all
work on steep slopes or directly in the wetlands are recommended for initial contractor
designated work.
4.1. Overall Priority Restoration Checklist
The following list is intended to show the overall recommended management priorities across
the entire park. Tasks are generally listed in order of decreasing priority although many actions
could be undertaken concurrently depending on resource availability and seasonality.
4.1.1. Targeted Restoration priorities:
• Herbicide treatment and removal of poison hemlock (King County Class B noxious weed
control required) in Unit 7. Recommend foliar spray (2% triclopyr) in spring
(March-May).
• Herbicide treatment of Bohemian knotweed (King County non-regulated Class B noxious
weed) in Units 1, 4, 5, and 7. Recommend foliar spray (2% glyphosate or triclopyr, or
1% imazapyr) in late summer (July-September).
• Herbicide treatment of yellow flag iris (King County non-regulated Class C noxious weed)
in Units 3 and 4. Recommend foliar spray in summer (May-June with 1% imazapyr) or
fall (September with 1% imazapyr or 5% glyphosate). Manual control could be
considered for smaller isolated populations.
• Manual control of bittersweet nightshade (King County weed of concern) in Units 3 and
4 before seed set (before October).
• Manual control of evergreen clematis (King County non-regulated Class C noxious weed)
from the northeast corner of Unit 2.
• Manual control of spotted jewelweed to reduce seed production (King County non-
regulated Class C noxious weed) from Units 3, 5, and 8 (Volunteer friendly) before seed
set (before October).
• Initial sweep for all invasive tree species (English holly, cherry laurel, common
hawthorn, European mountain ash, and Portugal laurel – King County weeds of concern)
throughout Units 1, 2, 6, and 7. Recommend stem injection with EZ-Ject lance
herbicide shells
23 | S c r i b e r L a k e P a r k H a b i t a t M a n a g e m e n t P l a n - 2 0 2 1• Targeted reduction of smaller populations of English ivy and Himalayan blackberry (King
County non-regulated Class C noxious weeds) from Units 1, 3, 5, and 6. Focus on
isolated patches or areas adjacent to existing restoration. See volunteer recommended
areas on Map 3.
• Targeted and phased efforts to reduce larger populations of English ivy and Himalayan
blackberry from Units 1, 2, 5, 6, and 7. See contractor recommended areas on Map 3.
o Consider targeted herbicide applications of English ivy in areas of heavy
monocultures especially in Unit 6.
o Consider a combination of mechanical and herbicide treatments of contiguous
blackberry. Recommend brush cutting blackberry in spring/summer and then
targeted herbicide applied to regrowth 4 to 6 weeks following knockdown.
• Manual and chemical control of relatively small population of bamboo, hedge false
bindweed, periwinkle, and other non-native invasive plants throughout the park.
4.2. Priority Volunteer Restoration
Overall primary restoration efforts (suitable for volunteers) should focus on the following
general themes:
1. Existing site maintenance and restoration efforts within previously cleared areas
including targeted invasive species management of priority noxious weeds;
2. Increasing the structural diversity of the forest with park-wide native tree and shrub
planting focused on increasing overall conifer canopy in upland areas where appropriate;
3. Incremental reduction of predominant invasive plant species that are currently
widespread or occupy large or dense portions of the park (as time and resources
become available).
Primary restoration efforts should focus on maintaining existing areas that have previously been
cleared of invasive species. It is important to provide continued resources towards supporting
these efforts before instigating new projects in unconnected areas of the park. New projects
should only be implemented when enough investment (both labor and capitol) can be expected
to sustain maintenance on both existing and planned efforts.
4.2.1. Zone Summaries for Volunteer Stewardship and General Vegetation
Management
The following recommendations are provided as suggested volunteer appropriate restoration
objectives for each general ecological system type and Management Unit.
A general approach to stewardship should follow these overarching guidelines:
• Remove isolated or small patches of invasive plants first before initiating removal of
large or dense infestations.
• When dealing with larger or dense infestations, consider the following:
24 | S c r i b e r L a k e P a r k H a b i t a t M a n a g e m e n t P l a n - 2 0 2 1o Work in small, manageable sections and consider the level of follow-up
maintenance efforts that will be required for long-term success.
o Sheet-mulch in upland areas if practical for invasive species suppression and
plant hardy trees and shrubs for initial establishment. Sheet mulching with
burlap or cardboard and 6-8 inches of woodchip mulch is recommended in
relatively small areas of recently cleared or bare ground for weed suppression
and moisture retention.
▪ Be mindful of spreading mulch on rare or sensitive plants. Make sure to
only use clean material free of weeds to avoid introducing additional
invasive species. Hedge-false bindweed and creeping buttercup can
quickly establish on newly mulched areas.
▪ Mulch provides weed suppression, retains moisture, and adds organic
content to the soil. However, it also obstructs ground nesting pollinators
and can smother herbaceous plants and bryophytes. Either plan to phase
out mulching after your plant stock becomes fully established, only mulch
in certain areas (e.g. mulch rings around installed plants), or do without.
If you do without, more vigilant weeding will be necessary
o Only initiate new clearing if resources are available to maintain existing active
restoration sites.
• Consider late summer or early fall for initial clearing activities to plan for favorable fall
plant installation timing.
• Plan for infill-planting one to two years after initial planting occurs. Generally plan for
an additional 20% of initial planting density.
• Document and report on restoration efforts in order to track progress and coordinate
follow-up maintenance activities.
• Consider establishing photo-points in areas where repeat photographs can be taken
prior to initial clearing and again once or twice a year for the first 3-5 years during site
establishment. This information can be useful in tracking progress and employing
adaptive management.
• Target plant species prioritized for removal should include Himalayan blackberry, English
ivy, bittersweet nightshade, spotted jewelweed, hedge-false bindweed, and manageable
sprouts of all invasive tree species (English holly, cherry laurel, Portugal laurel, common
hawthorn, and European mountain-ash). Small or isolated patches of creeping
buttercup and herb Robert may also be considered in areas where manual control is
feasible.
o Larger trees (that cannot be removed by manual digging) should be flagged for
treatment by a Park’s contracted licensed herbicide applicator.
o Trees can be limbed up to facilitate access but should not be cut which will result
in aggressive re-sprouting.
25 | S c r i b e r L a k e P a r k H a b i t a t M a n a g e m e n t P l a n - 2 0 2 1General recommendations for each Management Unit:
Conifer Mixed Forest - Units 1 & 6: These Management Units are predominantly upland
forested areas with patches of dense Himalayan blackberry and English Ivy. See Map 3 for
areas of English ivy that should be targeted for removal. Areas that have seen recent
restoration should receive follow-up removal efforts to ensure thorough control.
Short-term management goals for the Conifer Mixed Forest Management Units include:
• Target maintaining and continuing stewardship efforts in existing restoration sites.
• Hand-remove isolated patches of English ivy throughout Units 1 and 6, focusing on
volunteer recommended areas (Map 3).
• Consider phased stewardship of areas where initial contractor work (mechanical and/or
chemical treatments) could be followed by volunteer stewardship, maintenance, and
planting
Riparian Forest - Units 2, 5 & 7: These Management Units are comprised of relatively linear
habitats along the edges of the park and wetlands. Unit 5 offers the best opportunities for
volunteer stewardship (Map 3) while Units 5 and 7 include steep slopes and heavy invasive
species cover.
Short-term management goals for the Riparian Forest Management Units include:
• Hand removal of English ivy and Himalayan blackberry from MU 5
• Possibility for manual removal of ivy and blackberry on the “plateau” of MU 7 avoiding
steep slope areas (Map 3).
• Efforts to control English ivy and evergreen clematis in MU 2 could be considered,
although initial contractor directed work is generally recommended.
Shrub Swamp and Emergent Marsh - Units 3, 4 & 8: These areas are primarily wetlands
surrounding the stream and open water areas of the park. Because of the saturated soil
conditions and dense plant cover, only limited access should be considered and most shot term
management should focus on areas directly adjacent to the trails. In general, these areas are
relatively intact and do not require direct management action at this time.
Short-term management goals for the Shrub Swamp and Emergent Marsh Management Units
include:
• Manual removal of small patches of Himalayan Blackberry directly adjacent to the trail
(Maps 2 and 3).
• Manual removal of spotted jewelweed along trail corridors. Spotted jewelweed is an
herbaceous annual that can be effectively controlled by hand removal before the plant
goes to seed.
26 | S c r i b e r L a k e P a r k H a b i t a t M a n a g e m e n t P l a n - 2 0 2 14.3. Contractor Recommended Invasive Species Management
It is recommended that new clearing efforts focus on expanding and connecting existing active
restoration sites. More intensive efforts should only be considered if there are enough
resources to actively maintain these areas during the site establishment phase that will require
follow-up invasive species control, planting, and ongoing invasive species management for
several years. A combination of contracted crew work followed by volunteer planting and
maintenance can be an effective approach in accessible areas. Work on steep slopes will
require ongoing contractor crew work. High priority noxious weeds should be addressed as an
initial priority. Some high priority management considerations involve tasks that are not
recommended for volunteer activities. These priorities primarily represent tasks that involve the
use of restricted chemical herbicides or include projects occurring in designated wetland areas
or steep slopes. Herbicide is only recommended for targeted use on invasive plant species that
have been given a legal definition by Washington State and King County Noxious Weed Control
Boards or specific weeds that are difficult and costly to control using manual methods. High
priority weeds of concern present on the property include the following Class B and C regulated
and non-regulated noxious weeds and select weeds of concern that pose a substantial threat to
the health and function of the natural areas:
Table 2. Listed King County noxious weeds found in Scriber Lake Park
Common Name Scientific Name King County Designation
Poison hemlock Conium maculatum Class B – regulated
Bohemian knotweed Polygon x bohemica Class B – non-regulated
Herb Robert Geranium robertianum Class B – non-regulated
Spurge laurel Daphne laureola Class B – non-regulated
Yellow flag iris Iris pseudacorus Class C – non-regulated
Common hawthorn Crataegus monogyna Class C – non-regulated
Bittersweet Nightshade Solanum dulcamara Weed of Concern
Cherry Laurel Prunus laurocerasus Weed of Concern
English holly Ilex aquifolium Weed of Concern
European mountain-ash Sorbus aucuparia Weed of Concern
Hedge-False Bindweed Calystegia sepium Weed of Concern
Horse-Chestnut Aesculus hippocastanum Weed of Concern
For more information on controlling these weeds see Appendix A.
• High priority noxious weed control with targeted herbicide applications are
recommended for these projects as the most cost effective and efficient treatment
option. If use of herbicide is not desired, manual efforts could be employed but will
require substantial and sustained efforts over many years.:
o Chemical control of known locations of poison hemlock from MU 7. While only
limited instances of this plant were noted, repeat efforts will likely be required to
completely eradicate.
27 | S c r i b e r L a k e P a r k H a b i t a t M a n a g e m e n t P l a n - 2 0 2 1o Chemical control of all known locations of bohemian knotweed from MUs 1, 4, 5,
7 and 8. Priority locations include the area where control efforts have already
begun in Units 4 and 5 that extend into the shrub swamp habitat (Maps 2 and
3).
▪ The infestations in Unit 7 will require substantial efforts and should
overlap with initial blackberry and ivy reduction efforts in this zone.
o Chemical and manual control of yellow flag iris from Units 3 and 4. While current
populations of this species appear to be relatively sparse, this plant can rapidly
spread in riparian areas and should be considered a priority for control at this
time.
• Long-term invasive species restoration considerations:
o Control of heavy blackberry in MUs 1 and 6.
o Control of large infestations of English ivy in MUs 1 and 6. Initial herbicide
treatments should be considered, especially for heavy cover in Unit 6.
o Full park sweep of all invasive tree species. This effort will require follow-up
retreatment for several years.
o Targeted control of evergreen clematis, English ivy and Himalayan blackberry
form the northeast corner of MU 2 near the park entrance along 196th Street SW.
o Large-scale reduction of Himalayan blackberry and English ivy from MU 7. Initial
efforts should focus on areas adjacent to knotweed control and avoiding steep
slopes.
o Treatment of Himalayan blackberry from Unit 2. Initial efforts should focus on
the area in the southwest directly adjacent to shrub swamp habitat (south of the
culvert access trail).
o Targeted treatment of Himalayan blackberry from MU 2 on slopes and adjacent
to 196th Street SW.
o Phased control of Himalayan blackberry on steep slopes adjacent to the
northeast pond in MU 7. These efforts will require rope work and slope
stabilization measures.
5. General planting recommendations
Overall goals should focus on amending and increasing future conifer canopy cover where
appropriate. Short term goals should work towards creating a dense native understory that will
limit the potential for invasive species re-establishment. Vegetation planting of the upland and
riparian forested natural areas on the site should be guided by the following general goals and
objectives:
1. Increase evergreen canopy cover (where applicable).
2. Increase structural diversity by creating multiple layers of vegetation using a variety of
tree, shrub, and groundcover species.
3. Increase overall native species richness (number of species) of vegetation, especially in
upland and riparian areas.
28 | S c r i b e r L a k e P a r k H a b i t a t M a n a g e m e n t P l a n - 2 0 2 1• Species selection should focus on hardy native plant species that are suited for the
particular conditions at each site location (soil moisture, sun exposure, etc.).
• General spacing guidelines should consider shrubs placed at approximately 4-6 feet on
center and trees placed approximately 10-15 feet on center (considering existing plants
as appropriate). Herbaceous plants (such as annuals or perennial wildflowers) are not
generally recommended until site is well established or in limited areas where regular
maintenance is no longer necessary.
• Any plant species native to the lower Puget Sound ecoregion may be considered for
planting, although hardy species well adapted to existing site conditions should be
prioritized. See Appendix B for a list of all native and non-native species noted in
Scriber Lake Park during the survey.
o Recommended species for generally upland areas (MUs 41, 6, and 7) could
include (but should not be limited to): Douglas fir and grand fir (sunny and
generally dry areas), western hemlock and western red cedar (shady or moist
areas), Sword fern, oso-berry, vine maple, beaked hazelnut, red-flowering
current, serviceberry, thimbleberry, snowberry, Cascade Oregon grape, bald-hip
rose, evergreen huckleberry, and Pacific ninebark.
o Wetter site locations could also consider red-twig dogwood, twinberry, willow
species, Nootka and cluster rose, red elderberry, salmonberry, Pacific crabapple,
black hawthorn, hardhack (Spiraea douglasii), Labrador-tea, western red cedar,
Sitka spruce, or other trees and shrubs adapted to moist conditions.
o Additional deciduous trees could include Oregon ash, red alder, black
cottonwood, bitter cherry, and cascara.
• When possible, plants should be installed from mid-October through April (prioritize fall
planting where possible) to ensure adequate root development and to minimize the
need for irrigation or supplemental watering. Planting can occur outside this window in
wetter areas of the park.
6. Wetland restoration considerations
Special consideration must be taken when working in and around designated wetlands. In most
cases, it is recommended that only limited stewardship activities take place directly in any of the
delineated wetlands found throughout the park. Restoration work taking place in the vicinity of
these areas (especially MUs 3, 4, and 8) should take extra precautions to ensure that these
sensitive areas are not disturbed. These precautions include (but are not limited to) the
following:
• Limit access and restoration to the summer months in order to minimize soil disturbance
and damage to sensitive vegetation. It is also advisable to conduct most work after
August 1st to minimize disturbance to nesting and breeding birds. Non-nesting season
in our region is generally considered to occur from August 1st through January 31st.
29 | S c r i b e r L a k e P a r k H a b i t a t M a n a g e m e n t P l a n - 2 0 2 1• Limit the size of volunteer restoration work parties within wetlands and their buffers.
Reducing the number of individuals in sensitive areas at a given time will help limit
disturbance.
• Avoid leaving weed fragments or composting invasive plants in or around wetlands as
the wet or moist soils may promote re-rooting. Plant material should be removed from
the area or placed on cardboard or dry debris piles (avoid letting the plants come in
contact with moist soil) and checked throughout the year for growth or re-
establishment.
• Planting in wetter areas can often occur in late-spring or summer if the root zone
remains moist.
30 | S c r i b e r L a k e P a r k H a b i t a t M a n a g e m e n t P l a n - 2 0 2 17. References Rocchio, F.J. and R.C. Crawford. 2015. Ecological Systems of Washington State: A Guide to Identification. Washington State Department of Natural Resources. http://file.dnr.wa.gov/publications/amp_nh_ecosystems_guide.pdf http://www.dnr.wa.gov/NHPecologicalsys 31 | S c r i b e r L a k e P a r k H a b i t a t M a n a g e m e n t P l a n - 2 0 2 1
8. Appendix A: Selected Invasive Species Best Management Practices
See Table 2 on page 26 for a list of noxious weeds found in the park.
Bohemian knotweed (Fallopia x bohemica)
Bohemian knotweed (aka Polygonum x bohemicum) is the most common invasive knotweed in
western Washington and is a is a hybrid between giant and Japanese knotweed. This species is
a large, clump forming perennial, forming canes up to 12 feet tall. This highly invasive plant
spreads by seed and vegetatively by rhizome and root fragments. In the Pacific Northwest it
colonizes wetlands and riparian areas as rhizome fragments are dispersed by flowing water.
Small infestations can be
controlled by manual means.
Digging up the roots including
all root fragments can be
effective if the plant material is
removed off-site. Do not
compost the plant as it can root
in the compost pile. This
method of control will take
several years of careful
monitoring and removal of any
root fragments that are
sprouting. Covering the
infestation with a heavy geo-
textile fabric or black plastic for
three to five growing seasons
can also be effective.
However, with both of these
Hybrid knotweed. Photo courtesy King County Noxious Weed
methods it is important to
Control
monitor up to 20 feet outside
the original infestation for other canes that can spread below ground.
For large infestations, chemical application is the most effective control of this plant. Chemicals
such as glyphosate and imazapyr have been shown to be effective for bohemian knotweed. It
is important to select an herbicide that is appropriate for the particular site, either aquatic or
terrestrial. Herbicides can only be purchased and applied to aquatic systems in Washington
State by a licensed pesticide applicator. In addition, federal, state and local restrictions apply to
herbicide use in critical areas. Refer to King County Noxious Weed Regulatory Guidelines for a
summary of current restrictions and regulatory compliance issues.
Foliar application can be conducted early in the season when the plants are three to six feet tall
and the spray can be effectively applied over the leaf surfaces. Although spray is most
effectively taken up in June or July, most knotweed plants can be over 15 tall at that point in
the season. The canes can be cut down to the ground in early spring and will re-grow to an
acceptable height for treatment by mid-summer. Treatments over two or more years will be
necessary to adequately control the plant. If the canes are cut down, they should be removed
off-site and disposed of properly so they do not re-root.
32 | S c r i b e r L a k e P a r k H a b i t a t M a n a g e m e n t P l a n - 2 0 2 1Another method to apply chemicals is the stem-injection method, which has been proven to be very effective (over 90% control rate in the first year) and greatly reduces drift to non-target plants. A stem injection gun is a specially designed syringe that applies a carefully calibrated amount of herbicide directly into each cane. To successfully use this method, each individual cane greater than ½ inch in diameter must be injected. Follow-up injections over several years are important to catch canes that were two small to inject the first year or ones that were not successfully controlled. When large areas of plants are removed, it is necessary to replant with native vegetation. No biological control methods are approved at this time for control of bohemian knotweed. Hybrid knotweed resprouting along the access road in Scriber Lake Park MGMT Unit 5 Best Management Practices for this plant can be found at: http://www.kingcounty.gov/environment/animals-and-plants/noxious-weeds/weed- identification/invasive-knotweeds/bohemian-knotweed.aspx 33 | S c r i b e r L a k e P a r k H a b i t a t M a n a g e m e n t P l a n - 2 0 2 1
Poison hemlock (Conium maculatum) Poison-hemlock is a Class B Noxious Weed on the Washington State Noxious Weed List that is selected for required control on public lands and public rights-of-way by the King County Noxious Weed Control Board. Poison-hemlock stems have reddish or purple spots and streaks, are not hairy, and are hollow. Leaves are bright green, fern-like, finely divided, toothed on edges and have a strong musty odor when crushed. Flowers are tiny, white and arranged in small, umbrella-shaped clusters on ends of branched stems. Manual control can be effective for small or isolated populations. Wear gloves or long sleeves to avoid contact with the toxic sap. Pull or dig up plants making sure to remove entire root. Wash your hands thoroughly after handling plants. To be fully effective, all mature plants need to be removed so no new seeds are produced. Adding a layer of mulch to the area after it has been cleared, or replanting with desirable vegetation, will reduce germination of poison hemlock seeds present in the soil. Remove all flowers and seed heads from the site to reduce reestablishment. Chemical control is recommended for larger sites or hard to access areas. Herbicides should only be applied at the rates specified on the label. Spray foliage (leaves and stems) in the spring, followed by another application later in the summer for late sprouts. Spray plants before they flower for best results. Spraying may not prevent seed Poison hemlock in flower. Photo courtesy King County production in mature plants. Seeds Noxious Weed Control germinate throughout the season, so repeat treatment is necessary to eliminate all plants. For more information, contact the Noxious Weed Control Program. Best Management Practices for this plant can be found at: https://kingcounty.gov/services/environment/animals-and-plants/noxious-weeds/weed- identification/poison-hemlock.aspx https://your.kingcounty.gov/dnrp/library/water-and-land/weeds/Brochures/Poison- Hemlock_factsheet.pdf 34 | S c r i b e r L a k e P a r k H a b i t a t M a n a g e m e n t P l a n - 2 0 2 1
English Ivy (Hedera helix) English ivy is one of the most invasive species in the Pacific Northwest. This evergreen climbing vine is capable of forming dense mats in the forest understory and excluding all other understory species. It can also climb up trees, preventing light from reaching the leaves and adding weight to the tree canopy, causing trees to weaken and fall during windstorms. The most effective method for controlling English ivy is manual removal. Because English ivy can impact tree health and flower more prolifically by growing vertically, the priority is to remove any vines growing on tree trunks and in the canopy. Install "survival rings" around trees by cutting or prying vines at shoulder height with the aid of a hand tool, killing any upper vines and leaving them to decompose on the tree. Lower vines then need to be cleared, along with roots and vines found within at least a five-foot radius of the base of the tree. For ivy growing along the ground, use hands or a small tool such as a hand tiller to pull or dig out the leaves and vines growing above the soil, as well as the woody roots growing just below the surface of the soil. Chemical control of large monocultures of extensive English ivy can also be effective. For disposal of hand-removed English ivy, several options are available. Disposal at a municipal vegetation waste facility is preferred. If the site will be monitored regularly, ivy can be piled on site on top of raised debris hummocks, a paved area or tarp to prevent stems from re-rooting. Allow the pile to dry out, flipping periodically to ensure English ivy at Scriber Lake Park along access road in MGMT complete decomposition. Unit 6. Best Management Practices for this plant can be found at: http://www.kingcounty.gov/environment/animals-and-plants/noxious-weeds/weed- identification/english-ivy.aspx 35 | S c r i b e r L a k e P a r k H a b i t a t M a n a g e m e n t P l a n - 2 0 2 1
English holly (Ilex aquifolium) and Cherry laurel Prunus lauroceracus)
English holly and Cherry laurel are
evergreen trees that can reach up to 50
feet in height, although are usually shorter
and often shrub-like when present in the
forest understory. Portugal laurel is also a
similar invasive species that does not have
a legal designation in King County. These
species can form thickets in the forest
understory, reproducing in low-light
conditions and excluding native plant
species. These trees can be difficult to
control as they form extensive root sprouts
after being cut down. The most effective
method of control is to remove the entire
root while the plant is small and can be
pulled. If the plant is larger, it is possible
to remove it using a weed wrench. If the
tree is too large to be either hand pulled or English holly with berries. Photo courtesy King
removed with a weed wrench, cutting the County Noxious Weed Control
stem at or above ground level and applying
an herbicide concentration directly to the cut portion of the stem as soon as possible is
effective. Other methods of herbicide application include frilling (cutting into the cambium and
applying herbicide to the wounds) and stem injection where time-release dosages are placed
directly into the stem. These methods kill the trees in place which can be left to fall and
naturally decompose or can be cut once the tree has died.
A study by EarthCorps in
2013 (see link below)
found that triclopyr
formulations were more
effective than glyphosate
for cut stump and frilling
applications. Treatment
with imazapyr stem
injection was found to be
very effective and should
be the method of choice
where plants can be left
standing until they are
dead. Because these trees
tend to root sprout and
have many seedlings,
monitoring around the
infested areas on a regular
basis will be necessary for
English holly at Scriber Lake Park in MGMT Unit 6. several years after removal.
36 | S c r i b e r L a k e P a r k H a b i t a t M a n a g e m e n t P l a n - 2 0 2 1You can also read
