Dean H. K. Fairbanks

Policies that improve drought resilience have heterogenous effects on agricultural land values. We examine the value of surface water transfers and groundwater resources in a hedonic analysis of agricultural parcels in California. We find that parcels in irrigation districts, that engage in inter-basin surface water transfers, experience increase in value in subsequent years, but the gains are short-lived and unevenly distributed. Value of groundwater stock is higher in parcels outside irrigation districts. We also find that policies to restrict groundwater substitution-based transfers, that aimed to reduce groundwater open-access externalities, have not been a deterrent against transfers in all areas.

Very low food security (VLFS) is a public health concern requiring identification of social risk characteristics within communities. This study used spatial regression to identify social vulnerability characteristics that distinguish VLFS households at the census tract-level in Fresno, California. Hunger rate came from a 2014 survey of 74 census tracts. Demographic, social vulnerability, and food access variables were assessed for fitness. VLFS was associated with income, ethnicity, household sizes, group living situations, and spatial clustering. This study documents that appropriate surveys and spatial statistics using appropriate risk characteristics should be used to inform urban planning and local food insecurity programs.

Aim  Applying water‐energy dynamics and heterogeneity theory to explain species richness via remote sensing could allow for the regional characterization and monitoring of vegetation community assemblages and their environment. We assess the relationship of multi‐temporal normalized difference vegetation index (NDVI) to plant species richness in vegetation communities.Location  California, USA.Methods  Sub‐regions containing species inventories for chaparral, coastal sage scrub, foothill woodland, and yellow pine forest communities were intersected with a vegetation community map and an AVHRR NDVI time series for 1990, 1991, 1992, 1995 and 1996. Principal components analysis reduced the AVHRR data to three variables representing the sum and temporal trajectories of NDVI within each community. A fourth variable representing heterogeneity was tested using the standard deviation of the first component. Quadratic forms of these variables were also tested. Species richness was analysed by stepwise regression.Results  Chaparral, coastal sage scrub, and yellow pine forest had the best relationships between species richness and NDVI. Richness of chaparral was related to NDVI heterogeneity and spring greenness (r² varied between 0.26 and 0.62 depending on year of NDVI data). Richness of coastal sage scrub was nonlinearly related to annual NDVI and heterogeneity (r² 0.63–0.81), with peak richness at intermediate values. Foothill woodland richness was related to heterogeneity in a monotonic curvilinear fashion (r² 0.28–0.35). Yellow pine forest richness was negatively related to spring greenness and positively related to heterogeneity (r² 0.40–0.46).Main Conclusions  While NDVI's relationship to species richness varied, the selection of NDVI variables was generally consistent across years and indicated that spatial variability in NDVI may reflect important patterns in water‐energy use that affect plant species richness. The principal component axis that should correspond closely with annual mean NPP showed a less prominent role. We conclude that plant species richness for coarse vegetation associations can be characterized and monitored at a regional scale and over long periods of time using relatively coarse resolution NDVI data.