Field Collective

Photo: Caitlin Atkinson

Eco-Patch Test Garden

PROJECT LOCATION: Potrero Hill, San Francisco, CA
SIZE: 900 sq foot (first stage)
PROJECT PARTNERS: Dogpatch & NW Potrero Hill Green Benefit District & Potrero Gateway Park & California Native Plant Society 
PROJECT TYPOLOGY: Biodiversity demonstration garden
ROLE: Project manager, designer and volunteer coordination
STATUS: Installation completed 2020, currently undergoing monitoring

Check out Field Collective’s article (part one) about the Eco-Patch published with Pacific Horticulture. Part two and a video documentary will be released in October.

The Eco-Patch is a garden featuring native San Francisco plants with the intention of providing wildlife habitat and restoring biodiversity. The project is part of the larger Potrero Gateway Project, which is a community initiative that involves the reclamation of Caltrans land for the benefit of the neighborhood and biodiversity.  This particular piece of land is situated above serpentine bedrock, which underlies portions of San Francisco (see map below). The selection of plants that survive and thrive in serpentine conditions highlights the unique natural history of the site and creates habitat for wildlife, such as the Bay Checkerspot Butterfly, which have coevolved with those plants.

The Eco-Patch is intended to serve as a catalyst for change by showcasing the ecological and aesthetic benefits of habitat restoration. By design, the Eco-Patch encourages imitation, as it seeks to show the positive impact that a network of habitat patches can have on biodiversity. Geographic isolation caused by habitat fragmentation is one of the leading causes of biodiversity loss. Research in landscape ecology tells us that if enough patches within close proximity are restored, many species, especially insects and birds can island hop and reestablish, especially if there are corridors connecting them.

In San Francisco there is already a precedent for habitat corridors composed of patches that create stepping stones for wildlife. In particular, the Eco-Patch project is inspired by the success of the Green Hairstreak Butterfly Corridor led by Nature in the City. Currently, the habitat corridors needed to get rare and endangered wildlife that depend on serpentine adapted plants from their current locations to the Potrero Eco-Patch do not exist. However, if enough patches are planted, wildlife can access the Eco-Patch and beyond. 

The increased use of regionally native plantings is critical if we are to transform our urban and suburban landscapes into patches of biodiverse and resilient habitat. Yet the dormancy and deciduousness of California plants, often in part a result of their adaptation to our summer dry climates, can make them challenging to work with and often at odds with people’s aesthetic sensibilities. This juxtaposition forms the foundation of our work with the Eco-Patch test garden.

TEST PATCH

The first stage of the Eco-Patch is a 900 square foot test patch that includes a select number of plants from our proposed list. Monitoring of the test patch will determine the site suitability of specific plants and the success of different weed management strategies. Installation, maintenance, and monitoring of the test patch is a volunteer effort with funding for material costs from the Dogpatch & Northwest Potrero Green Benefit District. 

The test patch is anchored by an existing Coast Live Oak that serves as a keystone species. Plant selection is based on the criteria of being native to San Francisco, and of having high habitat value. Additional considerations include being low-water use, wind tolerant, and adapted to or tolerant of serpentine soils. Eight combinations of plants are being tested to ensure dynamic seasonal changes and aesthetic harmony. Each combination of plants is then divided into three different management zones to test alternative management approaches to removing existing vegetation and weed removal. The knowledge and experience gained in the test patch, including cost, time and labor will inform the management approach for the full Eco-Patch project.

WIDER RESEARCH GOALS

The Eco-Patch test garden forms part of a wider research goal for Field Collective. Our aim is to design and implement additional test gardens that we will use to research different mixes of regionally native plants. We hope to publish our results and have information on species, spacings, composition etc. widely available. We want to shift the current hesitancy from many towards the idea of planting with California natives. Through our test gardens we will design with phenological (seasonal) changes, sequential blooming, and both evergreen and deciduous plants, to create dynamic, beautiful plant mixes that work both for human aesthetics and the needs of local insects and birds.

This work has its foundations in the ‘Mixed Perennial Plantings’ strategy from researchers in Switzerland and Germany. ‘Mixed Perennial Plantings’ are plant mixes developed through rigorous research and then widely applied to landscapes in the public realm. Our goal is to adapt their research strategies to a California context and hopefully contribute to the growing movement of like-minded citizens to improve biodiversity and ecological resilience.

Photo: Caitlin Atkinson

Photos: Caitlin Atkinson

Photos: Caitlin Atkinson

Map of serpentinite within San Francisco. The current fragmented native patch network. A connected native patch network, achieved through the community planting native habitat in their own backyards.

An Eco-Patch volunteer sheet mulching. We are testing three different weed management strategies at the Eco-Patch Test Garden: 1) Sheet mulching; 2) Sheet mulching + filler species; 3) Solarization. Photo credit: Scott Cole

PHOTO CREDITS:  2.  Stan Spencer;   3. 2011 Barry Breckling – CalPhotos, used under CC BY-NC-SA 3.0 / Cropped from original    |    Regents of the University of California, Berkeley. Accessed on December, 19, 2020. Available online at: http://calphotos.berkeley.edu/ 

Eco-Patch Test Garden plant procurement – Ecotype locations and quantities secured.    |   Using local ecotypes (plants of known genetic origin) was important for our project partners, the California Native Plant Society. Using local ecotypes aids in sustaining local genetic diversity and takes advantage of a plant’s evolutionary adaptations to local conditions.

The test garden layout – eight different plant mixes to be tested, each trialed with a different weed management strategy.

We are inviting the community to join us in the process of monitoring and observation through the citizen science app, iNaturalist. Through data collected on iNaturalist, we can monitor the presence of wildlife and plant phenology within a quarter mile of the site. This diagram shows how you can view recent observations within the Eco-Patch monitoring area using the iNaturalist interface.
Photo credit: eddie@naturetrip.com
iNaturalist: https://www.inaturalist.org/projects/potrero-eco-patch-monitoring-area

Additional signage designed by neighbor, artist, and Eco-Patch volunteer Michael Kerbow. Photo credit: Jean Bogiages