Sheep grazing + monitoring at Calabazas

August 22, 2019

Several hundred sheep have arrived at our Calabazas Creek Open Space Preserve! Sheep from Sweetgrass Grazing Company will spend the next several weeks grazing about 50 acres of grassland near the Nun’s homestead, an area that was home to early settlers in the late 1800’s and early 1900’s. The grazing is helpful in removing invasive plants species like yellow star thistle, and in reducing fire fuel loads on the property.

Ag + Open Space stewardship staff have also been out on the property installing monitoring transects to track yellow star thistle’s density and spread in response to treatment methods such as grazing.

Transect monitoring for this project involves picking a starting location near yellow star thistle patches, laying a measuring tape for a prescribed distance and counting yellow star thistle plants within quadrats laid at intervals along the tape. The quadrats are squares made of PVC pipe. Staff also note all plant species present within one meter of the transect length, in order to create a record of native plant diversity and the presence of any other invasive species within these grasslands.

With GPS tracking, these exact same spots will be revisited annually to monitor yellow star thistle to see how it responds to grazing, where it may be spreading, and where to focus prevention and removal efforts.

Monitoring is an important part of what’s known as “adaptive management,” in which close attention is paid to the effects of land management actions so that these actions can be adjusted as needed for the best outcome on the land.

Ag + Open Space purchased the 1,290-acre Calabazas Creek Open Space Preserve in 2004 for just over $9M. Guided tours, co-hosted with such partners as LandPaths and Sonoma Ecology Center, allow visitors to enjoy the wildflowers, ferns, oaks, redwoods, and open grasslands that cover the property. To support our staff in stewarding the land, trained volunteer patrollers continue to visit and care for the property. Learn more about volunteering with Ag + Open Space here >>

The next free outing at Calabazas is a fire ecology hike co-hosted by Ag + Open Space and LandPaths on Saturday, August 31st. The property was broadly affected by the 2017 Sonoma Complex Fires, and the hike will look at the importance of fire ecology on the land, and how native plants have evolved over time to adapt to fire. Due to the condition of the Preserve as a result of the Nuns Fire, this hike is for adults only. See details and register here >>

On September 22nd, our partners at Sonoma Ecology Center are hosting a free Autumn Equinox Hike at Calabazas. Equinox comes from the Latin words for equal night. As autumn begins, the temperatures drop and daylight wanes further. But there is still plenty of daylight in the northern hemisphere! This strenuous hike with substantial elevation gain will be on established trails. More on the hike and sign-ups here >>