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In California, after three decades of water market development, volume of water traded in the market remains lower than desired. Total volume of water traded annually accounts for just around 2%–5% of total water used. Vast difference in the marginal values of water in agriculture and urban or environmental uses suggest that significant economic gains can be achieved by easing the barriers to trading water across sectors. This paper draws attention to the role of state and local policies in restricting water transfers. Using novel, purpose-built, satellite-mapped data of a sample of water-trading irrigation districts in California, this paper shows how districts' water transfer decisions are made in response to conflicting pressures of drought-induced high-water demand against the need to support the agricultural economy and the environment in water-exporting areas. The time period under study is 1991–2019, which spans the entire history of water market activity in California from inception to maturity, and helps illustrate the role of changing local and state policies on irrigation districts' water market participation. Despite policy-induced restrictions, this paper shows that sample irrigation districts are highly responsive to demand in water-buying areas, have increased the volume and frequency of water transfers, particularly in the last decade. This paper highlights important research and policy questions about the distribution of economic and environmental effects of water transfers in source area communities that could affect the future potential of water markets in easing structural and drought-induced water scarcity in California. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This study utilizes forest stand structures and fuel profiles to evaluate the influence of different types of silvicultural treatments on fire severity in the Blacks Mountain Experimental Forest (BMEF), located within Lassen National Forest of northeastern California. We compare the severity of fire, assessed based on tree crown and bole scorch on 100 ha experimental treatment plots, following a wildfire started on adjacent national forest lands. Non-parametric statistical testing showed that selective thinning combined with prescribed surface fuel burning is the most effective method for preventing crown fire and minimizing fire severity in an interior Pinus ponderosa forest. These results also suggest that various combinations of the silvicultural treatments assessed can be effective at reducing the potential for severe fire spreading into wildland-urban interface (WUI) areas (supporting defensible space CA law PRC 4291), while suggesting approaches for U.S. Forest Service lands that can result in more resilient ecosystems in similar western U.S. forests treated with similar silvicultural methods. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract Aim To identify and quantify biotic and abiotic factors associated with the regional gradients in the distribution and abundance of bird communities restricted and endemic to the Succulent and Nama Karoo biomes of South Africa. Location The arid Nama and Succulent Karoo biomes in South Africa. Methods The quarter degree grid cell (QDGC) was used to extract environmental data, while the bird data previously atlased, was linked to the same geo-referenced system, using a geographical information system (GIS). Bird species were grouped into different life-history assemblages. A quantitative, systematic analysis of the different bird communities spanning the Karoo was undertaken to examine contributions of broad- and local-scale physical environmental and biotic factors to regional variations in the species composition, using multivariate statistical and spatial analytical tools. These included two indirect gradient methods; principal components analysis (PCA) and detrended correspondence analysis (DCA), and two direct gradient methods; canonical correspondence analysis (CCA) and redundancy analysis (RDA). Results Principal components analysis results showed that the selected environmental variables accounted for about 85% of the variation in the region. The first two principal gradients defined regional temperature seasonality and variability especially in winter and summer. The third principal gradient mainly defined summer rainfall areas in association with the coefficient of variation of rain and regional primary production, while the fourth gradient defined winter rainfall areas, growth days and elements of landscape structure. CCA/RDA analysis produced shortened hierarchically ranked explanatory variables for each bird assemblage. Stepwise gradient analysis results showed summer rain, rainfall concentration, topographic heterogeneity and annual evapotranspiration, as the most important climate variables explaining species occurrence. Landscape, in... [ABSTRACT FROM AUTHOR]

Surveys of trade in wildlife products utilised in traditional medicine were conducted between 1997 and 1999 on the western boundary of the Kruger National Park, South Africa. Although the extent of trade and numbers of people operating in this sector were lower than other regions of South Africa, this study again highlighted the value of indigenous wildlife products to subsistence economies. Apart from cultural diversity, socio-economic differentiation occurred at a number of levels, (i) There were socio-economic differences between the traders and vendors. (ii) Gender differences were apparent, with women earning significantly less than men and having to undergo more social challenges in their operation in the market place, (iii) Operational differences were noted between the vendors and traders, as well as between the street and pension day vendors. (iv) Multidimensional Scaling (MDS) highlighted the socio-economic differentiation at the household level, emphasizing in particular one of the most vulnerable groups, the elderly. The potential influence of this socio-economic differentiation needs to be considered during the development of Community-Based Conservation programmes, if the dual aims of conserving biodiversity and improving the lives and livelihoods of those who traditionally rely on medicinal plants are to be met. [ABSTRACT FROM AUTHOR]