California Sea Grant College Program

particularly in urban ecosystems. The project site, Manzanita Canyon, is located in the heart of a

“disadvantaged” community in San Diego, California. In urban watersheds such as this, ecosystems

provide services disproportionate to their size, yet are also highly vulnerable to climate change hazards

because of the heavy reliance on services and the relatively degraded state. This two-year project

improved water quality and climate resilience of an urban ecosystem and an underserved community by

engaging 2,253 community members in stewardship activities; restoring 7.56 acres of native coastal

scrub ecosystem, including planting, maintaining and monitoring 1,536 natives; and removing 22 metric

tons (758 m3) of invasive plants and trash. Findings from this project formed the basis of the following

stewardship recommendations:

1. Community engagement was most effective when community-based leaders or organizations

were involved in the motivation and recruitment of volunteers. Further, local recruitment was

effective, with 64% of volunteer effort contributed by neighbors, and 59% of effort contributed

by youth (through clubs and schools.)

2. Trash cleanup efforts should be focused on areas of illegal dumping and abandoned homeless

camps, with added effort near storm drains during the rainy season. Solutions closer to the

source of these inputs are also needed, such as improved social and housing programs for the

homeless; stricter enforcement and education surrounding illegal dumping; expansion of free

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large-item curbside pickup and drop-off location services; improved clean street strategies (e.g.,

more efficient street sweeping, neighborhood-driven litter reduction and cleanup strategies);

and collaboration with businesses and industry to improve incentives for reducing use of

common trash items, especially plastics.

3. Establishment of native plants requires not only native plantings, but also invasive plant

removal, and slope stabilization measures (e.g., closing renegade trails, use of erosion control

barriers). Planting in diverse clusters that include nearby well-established plant species; and

watering, weeding and fencing, especially in times of drought, should decrease planting

mortality due to stress, competition and herbivory.

4. Ecosystem restoration takes time. After two years of restoration efforts, restored plant

communities and substrates were on a trajectory of resembling reference plots, but were still

significantly different. Continued maintenance such as weeding and watering should facilitate

system development as native plantings establish and grow, and increasingly confer benefits

such as provision of year-round complex habitat, reduction of fire fuel (annual plants), and

resistance and resilience of the community to fire and drought.

This project strengthened the climate resilience of this urban community and section of watershed

by alleviating common urban stresses, namely non-native plant cover and trash pollution, known to

increase the vulnerability of an area to climate change impacts, such as increased intensity and

frequency of fire, drought, and flooding that results from more intense but less frequent storms.

Removal of 138 m3 (13 metric tons) of trash from urban waterways improved channel flow thereby

reducing risk of flooding, and reduced risk of contamination on site and downstream. Removal of

620 m3 (8.62 metric tons) of invasive plant material reduced risk of wildfire, by reducing fire fuel

levels, and lessened competition with fire- and drought-resistant natives. Planting of 1,537 native

perennials, totaling 73 m3 of native plant biomass by the end of the project, increased the

ecosystem’s carbon storage capacity, and added the complex and stable habitat that is associated

with plants that have diverse morphologies, perennial life cycles, and evolved resistance to drought

and fire. Further, community engagement not only provided needed help, but also increased public

awareness of the value of and threats to local coastal ecosystems, and the ways in which everyday

actions, such as planting natives and picking up trash, can influence the health of our environment

now and into the future.