Historical Ecology and Landscape Change in the Central Laguna de Santa Rosa

This study synthesizes a diverse array of data to examine the ecological patterns, ecosystem functions, and hydrology that characterized a central portion of the Laguna de Santa Rosa during the mid-19th century, and to analyze landscape changes over the past 150 years. The primary purpose of this study was to help guide restoration actions and other measures aimed at reducing nutrient loads within this portion of the Laguna de
Santa Rosa watershed.

Prior to Euro-American modification of the landscape, the Laguna de Santa Rosa (hereafter, “Laguna”) supported a diverse and extensive array of wetland and riparian habitat types ranging from tule marshes and willow forests to wet meadows and vernal pools. As one of the largest wetland complexes in northern California, the Laguna was a productive ecosystem that was home to vast numbers of resident and migratory birds, fish, mammals, and other wildlife. It was this diversity and productivity that made the Laguna a focal element of the Santa Rosa Plain for generations of native Pomo people, and for 19th-century Spanish and American settlers.

Today, the Laguna continues to provide vital habitat for a host of native plants and animals, and has been recognized by the Ramsar Convention on Wetlands as a Wetland of International Importance (Ramsar 2017). However, as the population of the area has grown and land use modifications have intensified over the past 150 years, the Laguna has experienced a variety of impacts stemming from urban and agricultural development. These impacts include substantial loss of native wetland and riparian habitats, channelization of streams, alterations to streamflow and sediment dynamics, invasion of non-native species, and water quality impairments. While the Laguna still exhibits elements of its former character, the modern Laguna represents a landscape profoundly altered by over a century and a half of both direct and indirect modifications. As residents and land managers look to improve the ecological health of the Laguna and restore lost ecological functions, an understanding of what the landscape was like in the recent past, and how it has changed over time, provides a valuable starting place for envisioning its future potential.