City Of Santa Cruz: City Of Santa Cruz Works To Save Endangered Santa Cruz Tarplant At Arana Gulch

Press release from the City of Santa Cruz:

February 01, 2022

SANTA CRUZ, Calif. – The City of Santa Cruz and its partners are on a mission to save the Santa Cruz tarplant and have received a grant from the U.S. Fish and Wildlife Service to support the effort. The $22,050 grant will fund field and greenhouse experiments to understand better the species’ biology and the best methods for restoration planting. City staff, consultants, and volunteers will plant more than 1,000 tarplant seedlings in experimental plots at Arana Gulch beginning on Feb. 3, 2022.

A federally threatened and California endangered species, Santa Cruz tarplants have declined significantly at Arana Gulch, decreasing from more than 10,000 plants in the early 2000s to fewer than 250 plants in recent years. The City implemented a conservation grazing program in 2015. Still, numbers have remained low, and the team believes that the soil seedbank, which is the natural storage of seeds in the soil or on its surface, has been severely depleted.

“This project to help restore the endangered Santa Cruz tarplant is emblematic of our broader efforts to better the environment throughout our parks, open spaces, beaches, and urban forest,” said Santa Cruz Superintendent of Parks Travis Beck. “Recovery of endangered species like the Santa Cruz tarplant helps to ensure continued biodiversity, which is the foundation for the ecological health of our open spaces.”

The work is being conducted in collaboration with the UC Santa Cruz Greenhouses and the Arana Gulch Adaptive Management Working Group, a collaborative group of City staff, partners from the California Coastal Commission, California Department of Fish and Wildlife, U.S. Fish and Wildlife Department, The California Native Plant Society, University of California Cooperative Extension, UC Santa Cruz Greenhouses, and consulting biologists.

Given the low numbers of tarplant in recent years, the group has advised moving to a more active reintroduction strategy in which greenhouse-reared seedlings are “outplanted” at Arana Gulch in areas where tarplant was found historically. Field experiments began in 2021 and, with this funding, will continue in February of 2022 with the goal of comparing different approaches to planting Santa Cruz tarplant onsite.

Complementing the field studies, greenhouse experiments at the UC Santa Cruz Greenhouses will investigate different treatments to induce germination of the tarplant’s ray achenes. Ray achenes are one of two types of seeds produced by individual tarplant flowers and are believed to survive for many years in the soil. Still, the environmental cues that trigger their germination are not understood. Understanding the means to germinate these seeds may inform practical management techniques to achieve the growth of dormant seeds in the seedbank.

The Santa Cruz tarplant (Holocarpha macradenia) is an annual plant with showy yellow late summer flowers that grows in the coastal prairie habitat along California’s central coast. Currently, fewer than 22 populations of the plant exist in the state, most in Santa Cruz County. Even where habitat is protected, as at Arana Gulch, maintaining the species is difficult. As an annual plant, Santa Cruz tarplant is dependent on the seedbank in the soil and conditions that allow plants to grow from that seedbank each year and survive to flower. Competition from non-native grasses can make that growth more difficult.

“We are pleased to support the work of the City of Santa Cruz and the Adaptive Management Working Group in conserving Santa Cruz tarplant at Arana Gulch. Arana Gulch provides a designated critical habitat for the species, and plants here are believed to be genetically unique among tarplant populations. We expect that this project will help recover the Santa Cruz tarplant at Arana Gulch and yield new information that may help conserve the species at other locations,” said Mark Ogonowski, Senior Fish and Wildlife Biologist with the U.S. Fish and Wildlife Service.

About City of Santa Cruz Parks and Recreation

The mission of the City of Santa Cruz Parks and Recreation Department is to provide quality public spaces and experiences that build a healthy community, foster equity, and better the environment.

Photo: Santa Cruz Tarplant: Credit Mel Harte 2010

This press release was produced by the City of Santa Cruz. The views expressed here are the author’s own.