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Natural Resources

191 – Multiple States in Grassland Systems: Invasion & Environmental Feedbacks

Principal Investigator: Dr. Katharine Suding, Department of Environmental Science, Policy & Management, University of California – Berkley. For more project information, click here.

Often in invasions exotic species appear to push the system across a threshold, creating in an alternative vegetation state that is very difficult to restore. While this pattern is consistent with many theoretical predictions concerning multiple stable states, there have been few empirical tests. The proposed research will promote the teaching, training and understanding of restoration and multiple state dynamics in California grasslands, one of the most invaded ecosystems in the United States. Through field experiments, it will investigate several factors that will aid in restoration and conservation: whether variation in soil nitrogen availability creates refugia for native and exotic grasses, whether intermediate levels of nitrogen supply can generate both exotic- and native-dominated states, whether feedbacks between vegetation and soil microbes create positive feedbacks and lead to the formation of multiple states, and whether regional colonization differences between exotic and native species overwhelm these local interactions. 

205 - Run-off Potential of Urban Use Insecticides from Concrete Surfaces

Principal Investigator: Dr. Jay Gan, Department of Environmental Sciences, University of California – Riverside. For more project information, click here.

Due to increasing urban insecticide use and a worldwide urbanization trend, contamination of urban surface water systems by urban-use insecticides has become an emerging environmental concern. However, the sources of contamination are poorly understood. Hardscapes, such as concrete, are one of the dominant surface coverage types in urban areas. They perform the roles of runoff conduit and facilitator, which promotes off-site transport of chemicals, such as insecticides, after their application around homes. However, insecticide runoff potential from urban hard surfaces (UHSs) has seldom been studied, and standardized evaluation methods are not existent. This lack of knowledge prevents an essential understanding of the significance of UHSs in non-point runoff of contaminants in urban watershed, and further hinders the identification of the contributions of urban-use insecticides to the overall aquatic contamination.

Therefore, the general objective of this study is to improve the current understanding of the persistence and runoff potential of urban-use insecticides, such as synthetic pyrethroids and fipronil, on UHSs, especially concrete. In the present study, methods will be developed to evaluate the runoff potential of pyrethroids and fipronil from concrete surfaces after deposition, and a range of factors influencing the runoff process will be weighed. These variables include insecticide type, formulation, concrete types, duration of contact time before runoff, and runoff patterns. Results from this work will provide an original evaluation of the role of concrete on insecticide persistence and runoff behaviors under different conditions and will be helpful for the development of contamination mitigation and regulation practices.

216 – Pharmaceuticals in Recycled Water

Principal Investigator: Dr. Jay Gan, Department of Environmental Sciences, University of California – Riverside. For more project information, click here.

The scarcity of water, exacerbated by rapid urbanization and/or climate changes, places an enormous pressure on water supply in many arid and semi-arid regions. This scarcity, makes the reuse of municipal treated wastewater an economically and environmentally critical option for agricultural irrigation. Its use will rise as water scarcity escalates. However, the presences of organic contaminants such as pharmaceuticals and personal care products (PPCPs) may pose a threat to crops irrigated with treated wastewater. It is imperative to investigate the potential plant uptake of PPCPs prior to wide-scale implementation of wastewater irrigation of crops, particularly plants consumed raw.  Eight plants (Tomato, carrot, bell pepper, cucumber, lettuce, broccoli, spinach, celery) have been selected which represent a wide range of vegetables that are grown above and below ground to examine various aspects of plant uptake of PPCPs. Each plant will be grown according to industry standards for irrigation, pest management and fertilization.

217 - Native Seed Storage and Processing

Principal Investigator: Dr. Jutta Burger, Managing Director - Science and Stewardship, Irvine Ranch Conservancy. For more project information, click here.

Restoration of native habitat is often hampered by the availability and expense of local seed. In order to solve this problem and to guarantee the supply of a high diversity of local native species, the Irvine Ranch Conservancy has established a 12.5 acre native seed farm that produces an average of 1000lbs of seed from over 40 species annually for restoration activities that it implements across the Irvine Ranch Natural Landmarks. Whereas the actual farming operations take place on property managed by the Irvine Valencia Growers in nearby Orchard Hills, the Conservancy is partnering with the UC ANR South Coast Research and Extension Center to utilize its facilities for these activities. Indirectly, the Center will be facilitating the Conservancy’s growing knowledge of competitive abilities and reproductive output of local native species gathered in part through additional collaboration with UC Irvine and Chapman University.

218 - Scaling Soil Respiration Dynamics Across Land-Use

Principal Investigator: Dr. Darrel Jenerette, Department of Botany and Plant Sciences, University of California – Riverside. For more project information, click here.

Human land-use change alters ecosystems through modifications of surface and air temperature, biota, hydrologic routing, and carbon and nitrogen cycling. Soil-atmosphere CO2 flux (Rs) is a dominant process influencing ecosystem functioning. To better understand the effects of land-use change on ecosystem processes, we will evaluate two complementary questions. First, what regulates the spatial and temporal variation of Rs across mixed-use lands? Second, how do soil temperature and moisture influence the spatial and temporal variation of Rs? We will measure Rs during the summer and winter months across three major land-cover types in this region – mesic residential, citrus agriculture, and wildland – at three sites spanning a coastal to desert climate gradient in southern California. Analysis across multiple scales – microsite, land-cover, site, and region – will be used to examine scaling relations associated with the variation in Rs. Temporal influences on Rs for each land-cover will be measured by sampling in the months of July through September, and December through February (n=78 land cover-1 x 3 land-covers x 3 sites x 2 seasons). To capture the fine scale and event-driven variability of Rs we will install continuous soil sensor systems at each land-use type at each site. This will allow us to piece apart the difference in event driven flux event as well as seasonal and annual trends. Water and substrate addition experiments will also be performed at these sites to examine the limiting variables to Rs.