Ownership characteristics and crop selection in California cropland

Land ownership is one of the primary determinants of how agricultural land is used, and property size has been shown to drive many land use decisions. Land ownership information is also key to understanding food production systems and land fragmentation, and in targeting outreach materials to improve agricultural production and conservation practices. Using a parcel dataset containing all 58 California counties, we describe the characteristics of cropland ownership across California. The largest 5% of properties — with “property” defined as all parcels owned by a given landowner — account for 50.6% of California cropland, while the smallest 84% of properties account for 25% of cropland. Cropland ownership inequality (few large properties, many small properties) was greatest in Kings, Kern and Contra Costa counties and lowest in Mendocino, Napa and Santa Clara counties. Of crop types, rice properties had the largest median size, while properties with orchard trees had the smallest median sizes. Cluster analysis of crop mixes revealed that properties with grapes, rice, almonds and alfalfa/hay tended to be planted to individual crops, while crops such as grains, tomatoes and vegetables were more likely to be mixed within a single property. Analyses of cropland ownership patterns can help researchers prioritize outreach efforts and tailor research to stakeholders' needs

Cooperative, cross-boundary management facilitates large-scale ecosystem restoration efforts

In California and across the United States, landscape restoration projects often require cross-boundary cooperation, though successful examples are rare and not well understood. This case study describes the Burney Gardens timber harvesting plan, a cooperative, cross-boundary meadow restoration project undertaken by private corporate forest landowners in Northern California as part of a larger collaborative restoration effort. The project is notable because it (1) received institutional support — both financial and political — from federal, regional and local sources and (2) engaged a diverse group of stakeholders in pre-project planning with multiple agency partners. This approach enabled the project plan to pass through the rigorous California regulatory system in an unusually rapid fashion despite its complexity. The collaborative model of the Burney Gardens project is relevant to other restoration efforts, particularly as diverse ownerships across the West implement large-scale projects that cross property boundaries, including those of federal and private lands

Using InVEST to assess ecosystem services on conserved properties in Sonoma County, CA

Purchases of private land for conservation are common in California and represent an alternative to regulatory land-use policies for constraining land use. The retention or enhancement of ecosystem services may be a benefit of land conservation, but that has been difficult to document. The InVEST toolset provides a practical, low-cost approach to quantifying ecosystem services. Using the toolset, we investigated the provision of ecosystem services in Sonoma County, California, and addressed three related questions. First, do lands protected by the Sonoma County Agricultural Preservation and Open Space District (a publicly funded land conservation program) have higher values for four ecosystem services — carbon storage, sediment retention, nutrient retention and water yield — than other properties? Second, how do the correlations among these services differ across protected versus non-protected properties? Third, what are the strengths and weaknesses of using the InVEST toolset to quantify ecosystem services at the county scale? We found that District lands have higher service values for carbon storage, sediment retention and water yield than adjacent properties and properties that have been developed to more intensive uses in the last 10 years. Correlations among the ecosystem services differed greatly across land-use categories, and these differences were driven by a combination of soil, slope and land use. While InVEST provided a low-cost, clearly documented way to evaluate ecosystem services at the county scale, there is no ready way to validate the results

Material and Geometric Analysis of Structures Subjected to Large Deformation

The two major focuses of this dissertation are: (1) Studying the structural behaviors of hyper-elastic membranes subjected to extremely large deformation. These membranes are used in a reconfigurable tooling system (RTS) which was under development during the course of this study. (2) Establishing a continuum constitutive model for fabric materials under in-plane large deformation through theoretical and numerical analyses. This model may also be applied to study a class of materials which involve significant internal structure reconfiguration during deformation.The RTS allows quick onsite fabrication of high temperature composite parts. RTS applications include rapid onsite repair of aircraft components. The RTS uses a hyperelastic membrane as an interface between the state-change material and model. This membrane may be subjected to 800% engineering strain during operation. In this part of the study, material properties of the membranes have been characterized through three tests: simple tension, equal biaxial tension and planar tension. Nine-term Money-Rivlin constants are obtained through data regression. Finite element simulations have been conducted to simulate the deformed shapes of a membrane around several representative geometries under various vacuum pressure and constraint conditions. Experimental results have been compared with predictions from finite element simulations. This study contributes to understanding the behavior of membrane structures under large deformations in general; the results are used to generate design guidelines for RTS applicability.Fabric materials are widely used in industry for numerous applications. They exhibit a meso-scale complexity and involve significant internal structure reconfiguration during large deformation, which prohibits the direct application of the theory of continuum mechanics when studying these materials. In the second part of this work, a unique meso-scale FEA model, utilizing new modeling techniques and boundary conditions, is developed. This model can be used to simulate the weaving/loom process, and to predict the mechanical behaviors of a representative unit of fabric subjected to multi-axial large deformations. This model has also been used to examine the mechanism of fabric internal structure reconfiguration during deformation under various load paths. An energy based continuum model for plain weave fabric is developed, where a sinusoidal shape function is used to describe the yarn waviness before and after deformation. Castigliano's theorem is applied to determine the interactions between yarns. The model presented has been validated with the FEA model, and compared with third party experiments. Favorable agreements have been found. This model has the potential for developing a general constitutive relationship for a broad class of materials which involve significant internal structure reconfiguration during deformatio