“Ivy Deserts” of Mission Trail Nature Preserve

ABSTRACT: English Ivy is a non-native, invasive evergreen perennial vine; it has no natural predators or pests to keep it in check. Mission Trail Nature Preserve consists of “Ivy Deserts” – areas of the park so dominated by ivy that no other vegetation grows. As a result, the mature and old Monterey Pine and Coast Live Oak trees are disappearing over time with no new young trees to replace them because ivy suppresses the sprouting of seedlings. Photos of ivy on tree trunks, canopies and on the ground are show. Explanations for “Why is ivy bad on trees?” and “Why is ivy bad when growing on the ground?” are presented. Selected excerpts from the City’s General Plan/Coastal Land Use Plan concerning “invasive species” in Mission Trail Nature Preserve are referenced.

View of Fallen Monterey Pine with Ivy on Trunk over Serra Trail
Thursday, February 28, 2008

View of Ivy on Multiple Tree Trunks, Serra Trail

View of Two Monterey Pine trees with Ivy on Trunks to Upper Canopy, Serra Trail

View of Ivy on Ground & Tree Trunks, Serra Trail

View of Ivy, Serra Trail

View of Ivy “Carpet” on Ground, Serra Trail

Close-Up View of Cape Ivy, Willow Trail, East of Trail

View of Invasive Cape Ivy on Ground & Tree Trunks, Willow Trail, East of Trail

Why is ivy bad on trees?
• The added weight of the ivy can cause mature trees to come down in a storm. For example, on a large tree in Olympic National Park, 2,100 pounds of ivy was removed from a single tree.

• Once ivy is in the tree canopy it shades out the trees leaves or needles.

• English ivy can strangle tree, especially at the base of the trunk.

• Dense ivy cover deprives the tree's bark of normal contact with air and microorganism.

• Thick ivy mats accelerate rot.

• Fast-growing ivy competes for nutrients and water.

Why is ivy bad when growing on the ground?
• Ivy provides nesting places for rats and other vermin.

• English ivy's shallow root structure makes it a poor choice for erosion control and it can contribute to erosion in some cases.

• Ivy limits understory regeneration of native trees, shrubs and plants by blocking sunlight and shading out native plants. (i.e. No regrowth of native plants.)

• Fast-growing ivy competes with native plants for nutrients and water.

• Ivy changes the natural succession of the forest. If you look around your will see few young tree to replace the mature trees when they come down. Ivy also creates "ivy deserts", where other plants, native to our environment, do not grow.

Life History
English ivy is evergreen, very tolerant of shade and will grow in full sun. English ivy has two distinct life phases, juvenile and adult. In the juvenile stage English ivy is a climbing and creeping vine. As the vines climb, rootlets sprout from the leaf nodes thereby firmly attaching the plant to available vertical structures. It does not strangle the host plants, as do some other non-native climbing vines. The rootlets do not penetrate the bark of trees and are not considered parasitic. In the adult or reproductive phase, E. ivy produces a woody erect stem either from the ground or off of existing climbing vines. Leaves of adult plant differ from the juvenile plants by having lighter green leaves, and an ovate to rhombic shape. In order to flower English ivy requires a greater amount of sunlight. Birds eat the berries, although in small amounts due to their mild toxicity. The seeds need to be scarified in order to germinate.

ADDITIONAL INFORMATIVE LINKS:
English Ivy:
http://plants.usda.gov/java/profile?symbol=HEHE

http://www.invasive.org/browse/subject.cfm?sub=3027

http://www.nps.gov/plants/ALIEN/fact/hehe1.htm

Cape Ivy:
http://www.nps.gov/archive/redw/c-ivy.htm

http://www.cal-ipc.org/ip/management/ipcw/pages/detailreport.cfm@usernumber=41&surveynumber=182.php

Cape-ivy, English ivy
http://www.cal-ipc.org/ip/inventory/weedlist.php

REFERENCE:
General Plan/Coastal Land Use Plan
Coastal Resource Management Element

Selected, relevant excerpts from the City’s General Plan/Coastal Land Use Plan, as follows:

Mission Trail Nature Preserve.
Mission Trail Nature Preserve lies along much of the City's eastern boundary and is the largest ESHA in the City.

Management guidelines for Mission Trail Nature Preserve should be implemented that respond to the following issues of habitat quality and enhancement and control of invasive vegetation:

Reduce the introduction and spread of invasive horticultural species

P5-105 Implement the recommendations of all existing Master Plans considering prioritized needs and available funding:
a. Mission Trail Nature Preserve Master Plan

Mission Trail Nature Preserve
O5-27 Reduce the introduction and population of invasive horticultural species in the Preserve. (LUP)

O5-28 Prepare annual maintenance plans for habitats within the Preserve. Encourage native vegetation to re-establish on sites previously mowed, cut,or invaded by exotic species. (LUP)

P5-122 Organize volunteer work groups to remove non-native plants from the Preserve. The California Department of Forestry and Fire Protection crews from Gabilan Camp could be used to assist in this effort. (LUP)

P5-124 Consider removal of both intentionally introduced plants and invasives by instituting an annual program through joint efforts of contract workers and volunteers. (LUP)

Environmentally Sensitive Habitat Areas
G5-12 Identify, protect and manage Environmentally Sensitive Habitat Areas (ESHAs) to ensure their long-term integrity and the biological productivity of these habitats. (LUP)

P5-159 Maintain and enhance the resource value of environmentally sensitive habitat areas in consultation with a qualified biologist and in coordination with the California Department of Fish and Game. Remove any non-native, invasive vegetation from sensitive habitats. (LUP)

O5-37 Reduce the introduction and spread of invasive horticultural species into and within identified ESHAs. Encourage a volunteer program of citizens and property owners to participate in maintenance and enhancement of sensitive habitats Develop a Stewardship Program based on the premise that resource management is a cooperative effort between the City and its citizens. (LUP)

O5-38 Manage environmentally sensitive habitats in Mission Trail Nature Preserve to maintain and enhance their natural integrity. Preserve and protect Mission Trail Nature Preserve native plant, wild animal and bird populations. (LUP)