Restoration and Conservation in Horticulture

Friday, October 21 at 1:00-2:40 pm, Cedar Room

Session Description: This session will examine horticulture as a part of long-term conservation and for restoration. Sessions will discuss managing the recovery of a damaged or destroyed ecosystem that has been degraded, damaged or destroyed through traditional ecological knowledge and scientific understanding, and how horticulture can support these activities.

Session Chairs: Renee Murphy (Intrinsyx Environmental, CA, USA) and Cris Sarabia (Palos Verdes Peninsula Land Conservancy, CA, USA)

25.1    Microbial endophytes and salt conditioning treatments on native tree establishment in challenging ecosystems

Renee P. Murphy (Intrinsyx Environmental, Mountain View, CA, USA) 

The Salton Sea is increasing in salinity and toxicity as water becomes scarce. Desert habitat preservation and maintenance are vital to the ecosystem and the overall health of the community in the surrounding area. Survival rates of restoration efforts in this inhospitable environment may improve with the application of endophytes as research has shown in previous studies conducted on brown field, salt marsh and toxic mine sites.

Two native tree species, honey mesquite (Prosopis glandulosa Torr. var. torreyana) and Palo Verde (Parkinsonia florida), were grown from seed in September 2021. The two species were divided in four treatment groups each: (1) control (no treatment); (2) endophytes; (3) salt water; and (4) salt water and endophytes. Saplings were inoculated with 750ml of endophytes with establishment of true leaves. Salt conditioning treatment consisted of four applications of salt water 4 weeks beginning gradually until concentration was equal to sea water at 35% salinity. 

In December 2021, trees were transported to Mecca, California to an area north of the Salton Sea on Torres Martinez Desert Cahuilla tribal land. After the exposed playa was cleared of invasive tamarisk, 6 blocks (9 rows each) were established across 22 acres. Holes were dug and pre-watered. Landlife cocoons were used to contain deionized water that were filled using a water truck. Height (cm) and DRC (diameter at root collar) measurements were taken on delivery of 900 of each species. Monthly data was collected rated on Scale 1-5 (1-mortality, 3-survival, 5-new growth).

Data was collected for a year to determine if any treatment will have a higher success rate of survivability on the transplanted native trees. This research will establish a protocol for larger future restoration projects within the Torres Martinez Tribe and other challenging ecosystems.

25.2    Restoring Native Habitat to East Anacapa Island

Ian Sexton (California Institute of Environmental Studies, Ventura, CA, USA)

Over a century of intensive land use, including sheep ranching and the introduction of invasive species such as iceplant and rabbits at East Anacapa Island (EAI), has resulted in significant loss and degradation of native flora and fauna communities. Due to the cumulative and severe impacts to the soil and native seedbank, native vegetation communities have not recovered on their own despite the removal of sheep, rabbits, and a concerted effort by Channel Islands National Park (CINP) to remove red flowered iceplant. The shift from native coastal shrub communities to a non-native landscape of grasses and iceplant has resulted in widespread ecological damage, including the loss of habitat that supports nesting seabirds and landbirds, seasonally transitory migratory birds, salamanders, and pollinators (e.g., native bees and butterflies). The changes in soil moisture, soil chemistry, and seed competition caused by this shift has also negatively impacted rare and endemic plants such as the island mallow. Active, intensive restoration actions are necessary to restore the native plant communities that support wildlife on EAI. In partnership with CINP, other NGOs, and many community and student volunteers, California Institute of Environmental Studies (CIES) has been actively restoring native habitat to EAI since 2016. From 2016-2021, CIES has rebuilt the on-island nursery, collected seed on island, grown and out planted 25,000 native plants over 4 acres of EAI known as Lighthouse slope restoration plot, and maintained these areas by controlling invasive plant species. Building on our past efforts, we continue to refine restoration techniques through adaptive management, so we can increase our impact and reduce the effort required to control non-native plants. CIES has received funding to scale up restoration efforts over the next 3-5 years, with a goal of restoring an additional 10 acres by 2025.

25.3    Survival and Growth in Experimental Plots at a Santa Rosa Island Restoration Site

Marisol Villarreal (San Francisco State University, San Francisco, CA, USA), Dr. Kathryn McEachern (United States Geological Survey, Ventura, CA, USA), Stephen Bednar (Tejon Ranch Conservancy, Frazier Park, CA, USA)

Restoration ecology is the science of healing a damaged landscape. In practice this sometimes includes planting native species that were present in the plant community before damage occurred. To recover late-successional plant communities in heavily damaged landscapes, however, it is often more practical to begin restoration at early successional stages. Such is the case for the Cloud Forest Restoration Project on Santa Rosa Island, within the Channel Islands National Park off the coast of Southern California. This area receives moisture from year-round fog which once was intercepted by the plant canopy, dripping to the ground and nourishing growth. This historical “cloud forest” community of chaparral with emergent groves of bishop pines (Pinus muricata) and island oaks (Quercus tomentella) was eroded away to bedrock during overgrazing in the 1800s. Restoration goals are to slow the continuing erosion and develop vegetation that can harvest fog and improve soil conditions for eventual chaparral regrowth. Restoration techniques involve the installation of “fog fences” and early-successional plants along coco-fiber wattles, to slow erosion, capture fog-drip and jump-start vegetation recovery. This experiment evaluated survival and growth of coyote brush (Baccharis pilularis) and purple needlegrass (Stipa pulchra) planted in 2016, in experimental plots across four different substrates types. The treatments were assessed by comparing different growth parameters for measurements taken between 2016 and 2019, inclusive. Results vary across substrates, but in general survivorship and growth gains were greatest for B. pilularis in the combination fog and wattle treatment. While S. pulchra survivorship was indifferent to treatment, growth of survivors benefited from both treatments. Additionally, both species performed better where the bedrock was covered with remnant soil, silt, or construction debris than on bare bedrock.

25.4    Creating a Local Seed Source of Native Milkweeds Collected from Wild Populations in San Diego County

Jonathan Snapp-Cook (US Fish and Wildlife Service, San Diego, CA, USA), Ann Baldridge (Resource Conservation District of Greater San Diego County, CA, USA), Sarah Maisonneuve (Earth Discovery Institute, San Diego, CA, USA)

There is general consensus within the scientific community that in order to support the declining western monarch butterfly population, native milkweeds should be preferentially planted instead of the tropical variety (Asclepias curassavica), as the latter has been shown to harbor harmful parasites and curtail sexual diapause and migration in monarchs. However, the availability of native milkweed species to both home growers and conservation practitioners in San Diego County is very limited. In 2018, the San Diego Pollinator Alliance (SDPA), a pollinator conservation group made up of local, state, and federal partners, found that there was no reliable source of native milkweed that had been locally propagated, and therefore evolved to thrive in southern California’s unique climatic conditions. Commercially, most of the seed stock used to propagate native milkweed species was from northern California sources. In response, the SDPA is establishing a seed bank of native milkweeds, grown from seed collected from regionally wild populations. We are working with land managers, seed producers, nurseries, and other partners to collect seed and grow native milkweeds in nurseries, farms, and on public lands. The resulting seeds and plants are intended for use at any scale, including ecological restoration projects, home gardens, and school gardens where we engage students from underserved communities to install and support pollinator habitats in their own communities. SDPA started the project in 2019, with narrowleaf milkweed (A. fascicularis), added woollypod milkweed (A. eriocarpa) in 2020, and added the early emerging California milkweed (A. californica) in 2022. Additionally, we are developing best practices and distributing instructional materials for growers and gardeners who wish to propagate and grow native milkweeds. The relatively low cost methods described here can be replicated to support monarch butterflies across their range in California.

25.5    Seed LA: on a mission to increase the availability of locally adapted native seeds to conserve and enhance the ecological diversity of the Greater Los Angeles area

Cris Sarabia (Palos Verdes Peninsula Land Conservancy, Rancho Palos Verdes, CA, USA, Seed LA collaborative member)

Seed LA, the Los Angeles Regional Native Seed Network, is a collaborative of Los Angeles-based organizations working together to increase the availability of locally adapted native seeds to conserve and enhance the ecological diversity of the Greater Los Angeles area. Los Angeles County is the most populous county in the United States, and the Greater Los Angeles area is the second-largest metropolitan region. Continued urban expansion in this already highly urbanized region provides significant challenges to habitat restoration. Urban greening efforts that will steward and protect the precious and threatened biodiversity of Greater Los Angeles are underway, and locally-sourced seed is urgently needed to address this demand. Using locally-sourced seeds in these projects can increase their impact by establishing resilient plant populations that are well adapted to the local climate and soils, support relationships with local wildlife populations, and contribute to an authentic sense of place for residents. Seed LA members identify healthy populations within our region, collect seeds with permission, process and store those seeds in a decentralized seed bank, and make them available for use in local restoration and urban greening projects. In this presentation Seed LA will share its history, challenges, accomplishments and goals for the future.