Pacific West Region
Redwood National Park
PMIS # 56602
NRPP-Resources Management

Remove English Ivy and Other Invasive Shade-Tolerant Plants from Old-Growth Redwood Forests

 
PROBLEM STATEMENT

English ivy is a shade-tolerant perennial vine which, once established in old-growth redwood forests, covers the forest floor and spreads into the canopy. On the forest floor, ivy forms a thick mat that displaces and suppresses native understory plants, and endangers recruitment of redwood seedlings. In the forest canopy, ivy grows high into the trees where it shades out native mosses and lichens and causes limb breakage due to its additional weight. Once in the canopy the ivy sets fruit. Birds eat the berries, disperse the seed, and thereby spread the problem much more widely and rapidly than spread by the vines on the ground. The aerial vines may infest nesting cavities that may otherwise be suitable for the federally threatened northern spotted owl and other cavity nesting birds and rodents. This project removes known ivy infestations from the Hiouchi/Jedediah Smith area, Del Norte County, California, which serves as the northern gateway to the redwood parks. English ivy was assigned high-priority for control in the park’s Exotic Plant Management Plan because of its great potential to disrupt the redwood ecosystem.

 
DESCRIPTION OF RECOMMENDED PROJECT OR ACTIVITY

Background – Redwood National Park (REDW) was established in 1968 by PL 90-545, "to preserve significant examples of the primeval coast redwood forests"; REDW included Jedediah Smith State Park within the legislative boundaries of the park. The congressional intent was to preserve the resources of the three State Parks within the boundaries of the National Park by adding the State Parks to the system. The National Park Service (NPS) and California Department of Parks and Recreation (CDPR) formed a partnership to accomplish the preservation mission, and the parks and are now collectively managed as "Redwood National and State Parks" (RNSP).

Previous Work – The park has completed a large, successful pilot project. RNSP treated an 18-acre infestation of English ivy that threatened redwood forests in the Marshall Pond area. Native plants quickly rebounded and now flourish in areas cleared of English ivy. Park staff now annually visit the site to ensure that ivy does not reestablish in the area. The park intends to continue these maintenance visits as a part of its long-term management commitment.

A second, shade-tolerant invasive species removal project was initiated at the Hiouchi Visitor Center. English ivy, English holly, cotoneaster, and vinca, had become dominant. Native vegetation is presently returning to areas cleared of ivy.

Scope of the Project - Spread of ivy to old-growth redwood forests threatens superlative individual groves and the integrity of the redwood ecosystem in the Hiouchi/Jedediah Smith area. Although much was accomplished at the Hiouchi Visitor Center, not all of the ivy could be immediately eradicated. Surveys concurrent with removal have identified an additional eighty acres of redwood forest that are infested with English ivy and other shade-tolerant invasive exotic plants. These pilot projects have clearly defined the scope of the work that still needs to be done. This information has been entered into the park’s GIS (see attached maps on digital orthophotoquads showing the project area and the locations of the infestations).

Methods – Rare plant surveys are currently underway in the areas targeted for control work, and any rare plants found will be protected from disturbance. Protection measures will include flagging locations, designating footpaths to prevent trampling, and utilizing minimal hand removal of nearby English ivy. If no plants are found, work will proceed in steps as follows: Above-ground ivy will be severed by cutting with hand tools to eliminate sources of seed dispersal. Vines in the treetops will be left to die. Vines and roots systems near the base of trees will be removed to prevent sprouting and return to the canopy. When removing ivy from the base of the trees, care will be exercised to minimize damaging the trees, and retain the aesthetic character of the area. Vinca and ivy vines spreading along the ground will be removed, beginning with outliers, and moving systematically into larger infestations. Once the bulk of the ivy is gone, the remaining roots will be removed by hand. Cotoneaster and English holly will be pulled by hand or with a weed wrench. Wheelbarrows, buckets, and pitchforks will be used to transport material to nearby burn piles. Treated areas will be periodically revisited and retreated as necessary to pull re-sprouts or to remove vines that may have been missed. Since resprouting is most vigorous the first spring, crews will return to pull resprouts and seedlings at least four times the first season. It will then take two years of follow-up treatment to reduce ivy, vinca, cotoneaster, and English holly infestations to a maintenance level that can be managed within the park budget. With this method, it is possible to selectively retain and encourage re-growth of native plants. Ivy tends to hide and suppress native plants. When ivy is removed, these native plants rebound and flourish. Re-planting is not required.

A record will be maintained of all ivy control work. Sites will be monitored for at least three years, and any new growth removed immediately, as specified in the park's Exotic Plant Management Plan. Techniques, success, and costs will be reported on the park's exotic plant management web site.

California Conservation Corps (CCC), California Department of Corrections (CDC), California Department of Forestry (CDF), California Department of Parks and Recreation (CDPR), RNSP Resource Management and Science support crews, under the supervision of RNSP Vegetation Management staff will do the work.

 
FUNDING

 
REFERENCES

Skinner, M. W., and B. M Pavlik (editors). 1994. California Native Plant Society’s Inventory of Rare and Endangered Vascular Plants of California. CNPS Publication No. 1, Fifth Edition. Sacramento, California.

United States Department of the Interior (USDI). 1995. Exotic Plant Management Plan and Environmental Assessment. USDI National Park Service, Redwood National Park, Orick, California. 104 pp.

Westbrooks, R. 1998. Invasive plants, changing the landscape of America: Fact book. Federal Interagency Committee for the Management of Noxious and Exotic Weeds (FICMNEW). Washington D. C. 109 pp.

 
ALTERNATIVE ACTIONS, SOLUTIONS AND IMPACTS

No Action.  Do not remove English ivy and other invasive, shade-tolerant species. This alternative would allow continued spread of the current, incipient populations of English ivy into the park’s old-growth coast redwood forests. With time, all forested areas of RNSP would become heavily infested.

Delayed Action.  Begin removal of English ivy and other invasive, shade-tolerant species at a later time. This alternative would allow continued spread of the current, incipient populations of English ivy further into the park’s ancient coast redwood forests. With time, exponentially more forested areas of RNSP would become infested, and the cost of control would increase proportionally.

COMPLIANCE CODE(S): EXCL

 
CRITERIA CONSIDERED IN SUBMITTING THIS PROJECT FOR FUNDING

1. Significance of the Resource or Issue to the Park: How important is the resource or issue to the park involved, relative to it’s other resources and issues? Weighting Factor = X2 Redwood National Park (REDW) was established in 1968 by PL 90-545, "to preserve significant examples of the primeval coast redwood forests"; the redwood forest ecosystem is the prime resource of Redwood National and State Parks. English ivy is a threat to the very reason for establishing the park. In 1983, REDW was designated an International Biosphere Reserve for this unique world resource. In addition to the ecosystem itself, ivy threatens listed plant and animal species resident in these forests. Maple-leaved checkerbloom and Indian pipe have been listed as rare and/or endangered in California by the California Native Plant Society and are known to occur in forest areas of Jedediah Smith State Park and Redwood National Park (Skinner and Pavlik, 1994). Aerial English ivy vines may also infest nesting cavities that may otherwise be suitable for the northern spotted owl and marbled murrelet which are Federally listed as threatened under the Endangered Species Act. Other known wildlife species of special concern who's habitat may be threatened by ivy include the white-footed vole, and the red tree vole. This ivy control project is ranked #4 in the REDW Resource Management Plan behind T&E Species (1), Watershed Rehabilitation (2), and Exotic Plant Management (3). RMP projects (1) and (2) are statutory requirements at REDW.

2. Severity of Resource Threat, Problem, or Need(s): Weighting Factor = X3 English ivy is a perennial, highly shade tolerant, invasive, non-native vine. Ivy can completely cover the forest floor, suppressing seedlings of coast redwood and other plants native to the redwood forest. Ivy climbs the trees where it flowers and its fruit is dispersed by birds. The ivy around Hiouchi presently is in an early stage of spread, but vines in the trees are already flowering and fruiting. Delayed control will allow further dispersal and will require exponentially higher control costs in the long run. As much as 80,000 acres of redwood forest could become infested and disrupted if the currently infested 80 acres are not treated now.

3. Problem definition and information base: How well is the problem defined? Weighting Factor = X2 The nature of the problem with English ivy and associated shade tolerant exotic plants in Redwood National and State Parks is well understood by park staff. The extent and distribution of these species has been carefully documented (see orthophotoquad maps), and the park staff have demonstrated through an 18-acre pilot project that they can address the problem successfully. Park staff have also determined that the threat extends beyond the 80 acres currently invaded to potentially include 80,000 acres if action is not taken soon.

4. Feasibility: Weighting Factor = X3 The project objectives are clear: to remove known infestations of ivy from around the Hiouchi Visitor Center and infested areas of Jedediah Smith State Park in order to prevent further spread into surrounding coast redwood forests, and to thereby encourage return of native species and restore the native ecosystem and natural character of the area. The park’s pilot projects have shown that the methodology proposed is effective and that the proposed timeline for treatments and follow-up treatments during this three-year project will be successful in bringing these invasions to a maintenance control level.

5. Problem resolution: Will the proposed use of funds contribute directly to decisions or actions that, when implemented, will meaningfully resolve a management issue? Weighting Factor = X3 Completion of this project will resolve the current threat to the surrounding redwood forest from the invasions of English ivy, English holly, vinca, and cotoneaster around the Hiouchi Visitor Center and Jedediah Smith State Park. The park also understands the need for vigilance in monitoring and follow-up maintenance to ensure re-infestation does not occur, and the park is committed to conducting these activities with parkbase resources.

6. Transferability: How widely will the project protocols or results be useful? Weighting Factor = X1 Ivy invasions are a nationwide problem with the most severe impacts occurring in ecosystems in the Pacific Northwest (Westbrooks 1998). This project will be well documented; and the techniques, success, and costs will be fully documented. The Redwood National and State Parks are in an excellent position to communicate the results of this project broadly and effectively, as they maintain a series of web pages with information specific to the exotic plant management program. The park staff updates these web pages as new information is learned. Any new information on ivy eradication will be posted.

7. Cost effectiveness: Given problem statement and proposed methodology, are the cost estimates realistic and commensurate with the results to be produced? Weighting Factor = X2 Costs are realistic and well researched, as they were calculated based upon prior experience with a large pilot project at Marshall Pond in Redwood National and State Parks. California Conservation Corps and California Department of Corrections crews are stationed in Redwood National and State Parks where they participate in numerous park projects. These crews have proven themselves to be the most cost effective labor source for this type of exotic plant control project. A biological science technician is needed to supervise these work crews and document the control efforts.

8. Project Support: What resources (including in-kind contributions) are the park, region or other partner(s) willing to commit to this project? A detailed description of total project costs, including contributions is required. Weighting Factor = 2X. As shown in the proposed budget (Table 1), a total of 39% of the project costs are covered by the park and its partners. In addition to these itemized in-kind contributions, the California Department of Parks and Recreation will provide office space for the project, and the follow-up maintenance work of this project's cost will be borne by Redwood National and State Parks base funding.

http://www.nps.gov/redw/REDW-ivy.htm
Submitted May 15, 2000