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Sustainability of Critical Urban Ecosystem Services in the Los Angeles Metropolitan Region

Jenerette, G Darrel
University of California - Riverside
Start date
End date
1. Quantifying Trends in Community Garden Biodiversity and Soil Properties We will document the dynamics of biodiversity of plants and insects, and characterize soil conditions associated with urban agriculture. For a selected subset of plants we will further characterize dynamics of genetic and functional diversity to assess evolutionary changes (genetic diversity) occurring in gardens and resulting variation in plant production (functional diversity). The resulting data and analyses will provide necessary information to answer research questions addressing the organization of biodiversity and will be required inputs for answering questions addressing ecosystem services and disservices associated with urban agriculture. Beginning with individual plots for a single growing season and aggregated into gardens and the region for up to seven years, the degree to which biodiversity is partitioned between scales and varies between components will be evaluated through rarefaction and variance ratio statistics which are flexible and allow us to compare variability between distinct units within and between scales.

2. Assessing Efficacy and Tradeoffs of Using Vegetation to Mitigate Extreme Heat Our project provide detailed understanding of urban land surface temperature (LST) regulation, interactions of LST with evapotranspiration (ET), and relationships between these energy balance components and neighborhood socioeconomic condition across the strong climate gradient from coastal to desert southern California. We will evaluate hypotheses of land cover, meteorology, irrigation, and adjacent landscape regulation of LST and ET across the dramatic coastal to desert climate gradient in the greater Los Angeles metropolitan region using a combination of air- and space-borne data with additional in-situ measurements. We will quantify how land surface relationships essential to improving the sustainability of dryland cities, notably LST and ET, interact with socio-economic neighborhood segregation. We will further conduct and analyze in-situ measurements of diel surface temperature dynamics and energy balance of net radiation, sensible heat, and latent heat (ET).

3. Initial Estimation of Greenhouse Gas Flux Estimation From Urban Landscapes As a final component of my project I will conduct initial assessments of trace gas fluxes associated with urban landscapes across the greater Los Angeles metropolitan region. I will direct measurements at urban lawns, agricultural, and remnant wildland patches primarily focused near Riverside, CA. This work will be extended to similar measurements at coastal sites near Irvine, CA and desert sites near El Centro. I will assess spatial and temporal variation of carbon dioxide fluxes in all regions across all patch types. Within the focal area of Riverside, CA I will further assess nitrous oxide emission rates. These activities should lead to an initial estimate and advanced protocols for quantifying greenhouse gas emissions in southern California urbanized landscapes.

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1. Quantifying Trends in Community Garden Biodiversity and Soil Properties Taxonomic biodiversity inventories within crop and weed components will be assessed through complete plot level species inventories and abundance estimates for the selected community gardens in Los Angeles. Within a subset of species and gardens in Los Angeles and Riverside, we will quantify functional biodiversity through a trait-based framework relevant to the production of ecosystem services and disservices. To allow for future assessments of crop genetic biodiversity we will collect and preserve samples of maize and radish. We will expand our characterization soil nutrient and metal content in community garden soils to 100 randomly selected garden plots from the entire set of gardens.

2. Assessing Efficacy and Tradeoffs of Using Vegetation to Mitigate Extreme Heat Our work will span a coastal to desert transect of urbanization in southern California, which traverses from the ocean, across Los Angeles and the Inland Empire, and extending into the Imperial Valley. Three sub-regions will focus on UC AES field sites and their surrounding landscapes: coastal (South Coast REC), inland (UC Riverside Agricultural Operations), and desert (Desert REC) sites. We will supplement planned airborne hyperspectral and multi-band thermal imaging data with additional finer resolution visible data and repeating satellite data. Field measurements will use the recently deployed eddy covariance systems at each target site in conjunction with handheld thermal imaging system and continuous monitoring meteorological sensors. We will use a data-model assimilation approach to evaluate hypotheses and prepare for future integration as the land surface and climate modeling community makes advances in Southwestern ecosystems. Together these data and models will provide high resolution and broad extent of urban land cover patterns for connecting urban LST, ET, and demographic segregation in response to scenarios of changes to climate, vegetation, and irrigation.

3. Initial Estimation of Greenhouse Gas Flux Estimation From Urban Landscapes Landscape and seasonal variation of soil carbon dioxide will be quantified in lawn, citrus agricultural, and wildland regions of the coastal region of Irvine, CA, inland region of Riverside, CA, and desert region of El Centro. In each combination of region and land-use type we will sample three 50m transects for mid-morning soil carbon dioxide emissions, soil temperature, and soil moisture. We will analyze these data through regression and ANOVA statistics in addition to data-model fusion procedures that couple observations with process model of soil respiration. As a second activity in this objective we will deploy a new fast response nitrous oxide analyzer within the Riverside region to estimate potential emissions of this potent greenhouse gas. Few examples of whole ecosystem nitrous oxide measurements are available and an important set of activities will be identifying the limits and capabilities of the new instrument.

2012/01 TO 2012/12
OUTPUTS: Our work in the past year has connected the project to stakeholders, extension agents, and students throughout the region. Through the project we have presented initial findings on urban agricultural patterns to community garden groups throughout Los Angeles. These interactions have been both formal presentations at garden meetings and informal interactions with gardeners. We have worked with urban agricultural extension advisor, Rachel Surls, to communicate our findings, develop better tools inform the public, and submit new research proposals for extramural funding. We have also provided a lecture for a landscape architecture course at UCLA on biodiversity and soil conditions in community gardens of Los Angeles. Initial work on urban heat islands associated with the Los Angeles metropolitan area have suggested new directions for quantifying the benefits and water costs associated with urban vegetation. Based on our desert carbon cycling research, I presented highlights of recent work at the UC AES sponsored Habitat Conservation Plan Climate Change Workshop, held in Palm Desert, May 2012. This presentation helped disseminate research on sustainability to the broader network of extension specialists and advisors throughout California. Nationally, we presented a webinar sponsored by the Environmental Protection Agency that highlighted landscape and ecosystem sensitivities to coupled global changes and the potential implications for sustainable regions.
PARTICIPANTS: Jenerette was the PI of the project and oversaw all aspects of research and outreach activities and provides direction for ongoing plans. Oikawa was a postdoctoral researcher working with Jenerette on the project. She obtained training opportunities for installing and maintaining eddy-covariance instrumentation in an urbanized landscape. Buyantuyev was a postdoctoral researcher working on the project is directing urban remote sensing activities in southern California. He has obtained new training in advanced applications of image interpretation software. Clarke is a graduate student working with Jenerette on the project. She conducted the field surveys of tree biogeography for Los Angeles and has initiated studies of urban agricultural systems. She has obtained training in international research and communication with the public. Velasco is a graduate student working with Jenerette on the project. She has conducted field surveys of tree biogeography in the greater Los Angeles metropolitan region. Eberwein is a graduate student working with Jenerette on the project. She participated and obtained training with installing and maintaining eddy-covariance instrumentation in an urbanized landscape and is developing new instrumentation facilities for measuring urban trace gas fluxes. Allsman is a laboratory technician who participated in several project activities. Juster, Ricio, Antes, Contreras are undergraduate students who have been participating with the project in conjunction with graduate students and postdocs.
TARGET AUDIENCES: The target audience for the project are urban residents of southern California. Our surveys have covered much of the region and are relevant to all residents. Our work with urban energy dynamics targets water and energy agencies. Our work with community gardens is directly targeted towards urban agriculturalists and agencies addressing urban food security.
PROJECT MODIFICATIONS: Not relevant to this project.

IMPACT: The outcomes and impacts from the project are primarily related to changes in knowledge. I have identified an annual pattern in the strength of vegetation and urban temperature relationships that peaks in the summer when the need for vegetation cooling is highest. Further analyses of annual patterns suggests land surface temperatures can be predicted based on regional air temperature and relative humidity patterns and the density of vegetation. The relationships conform to well established ecophysiological relationships observed at leaf and whole plant scales in diverse environments. Further these analyses has estimated the water costs associated with vegetated urban cooling and thus begins to provide a framework for assessing both the services and costs associated with providing ecosystem services to urban residents. A second study has sampled the tree species diversity and patterns from 300 sample points located throughout Los Angeles, CA. This study has documented a much higher diversity of trees than native to southern California with trees derived from a global distribution of home ranges and habitats. The pattern of vegetated coverage was closely related to neighborhood income, with more vegetation in higher income neighborhoods, while the pattern of biodiversity was better related to historical settlement patterns. Third, research conducted in this project has developed new metabolic frameworks to describe whole ecosystem net carbon exchanges following discrete precipitation events. This work describes ecosystem pulses of activity associated with substrate, microbial, and temperature variation. These findings provide a framework to scale processes associated with terrestrial feedbacks to climate change from genetic regulation to whole ecosystem functioning. These results are particularly relevant for understanding carbon sequestration patterns in the drylands of southern California. Finally, newly initiated activities on urban community gardens have documented large plant biodiversity within these gardens that supply a variety of ecosystem services. Further studies in these gardens have also identified potential for metal contamination in these gardens. We have identified a need for reconciling the many benefits and potential concerns associated with urban agriculture.

Funding Source
Nat'l. Inst. of Food and Agriculture
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Food Preparation and Handling
Chemical Contaminants
Heavy Metals
Food Defense and Integrity