Applying ecological site concepts to adaptive conservation management on an iconic Californian landscape

TitleApplying ecological site concepts to adaptive conservation management on an iconic Californian landscape
Publication TypeConference Proceedings
Year of Publication2017
AuthorsSpiegal S, Bartolome J, White M
Conference Name2017 Society for Range Management Meeting
Date Published01/2017
Publisher2017 Society for Range Management Meeting
Conference LocationSt. George, Utah
ARIS Log Number337201
Abstract
Tejon Ranch is a spectacular landscape valued for its biological diversity, livestock production, and cultural heritage. Situated at the convergence of three of California’s major biogeographic zones, it is the largest, contiguous private property in the state. Since 2008, the ranch has operated under a conservation agreement tailored toward conservation and economic outcomes. We developed an ecological site group model to inform adaptive conservation-focused grazing on 40,000 ha of grasslands on the ranch. Each ecological site group (ESG) is based on a “geologic landform” class:  a unique combination of biogeographic region, geologic material and age, dominant formative geomorphology, elevation, and slope that supports a distinct set of soils and vegetation dynamics. We randomly established 57 permanent plots within the geologic landform classes. Sampling these plots over several years allowed us to evaluate the spatial and temporal variation within and among geologic landform classes and to build data-driven, quantitative ESGs and state-and-transition models (STMs). Using these models, we developed hypotheses about suitable management practices for conservation goals. We discuss in detail the Holocene Flats ESG, which we identified as having the highest potential for the enhancement of conservation values through altered grazing practices predicted to favor several taxa, including the San Joaquin kit fox, blunt-nosed leopard lizard, and native annual forbs. The predicted responses are currently being tested and monitored, but the ESG/STM conceptual framework has already helped conservation land managers and graziers to better understand how the variation in the Tejon landscape affects the distribution of conservation targets and the specific locations where management can be tailored to enhance biodiversity.