Graduation Year

2014

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Department

Biology

Degree Granting Department

Integrative Biology

Major Professor

David B. Lewis, Ph.D.

Committee Member

Susan Bell, Ph.D.

Committee Member

Jody Harwood, Ph.D.

Keywords

carbon, ecology, homogenization, nitrogen, phosphate, Urban

Abstract

Soils are critical to ecosystem function as they provide essential nutrients for primary producers, habitat and organic energy for decomposers, and storage of organic matter. Irrigation with reclaimed water is an increasingly popular water conservation strategy; yet its high salinity and nutrient content potentially affect soil properties. In this study, set in a residential neighborhood of Tampa (U.S.). I tested whether there are distinct lawn system management strategies characterized by systematic differences in reclaimed water usage and irrigation and fertilization practices. I then investigated whether soil biogeochemistry responds to lawn system management strategy.

My results indicated that amendment strategy, which includes water source type, frequency of fertilization, and frequency of irrigation varies among residents of comparable neighborhoods. In this case, these three categories of management behaviors tend to co-occur. Analysis of irrigation water samples collected in this study showed significant differences between potable and reclaimed water. Mainly, reclaimed water had higher conductivity and phosphate content than potable water. When looking at the soil biogeochemical characteristics of the study area I found that there were significant differences in soil nutrients and microbial biomass across amendment strategy. Soils with a high amendment strategy (frequently irrigation with nutrient-rich reclaimed water, plus frequent fertilizer addition) showed higher conductivity and a higher microbial biomass than soils on lawns with a low amendment strategy (infrequent irrigation with dilute potable water, plus infrequent fertilizer addition). A positive correlation between soil conductivity and microbial biomass was observed. These findings suggest that high amendment strategy increases the input flux of some nutrients to the soils and acts as a nutrient resource for soil microorganisms. The differences between soil and microbial biomass amendment strategy support the idea that decisions made by individuals about which management intensity strategy to use do affect the spatial variability of the ecosystem. These results contribute to the hypothesis of urban ecological urbanization by looking at the vertical social interactions between municipalities and individual homeowners. These interactions might explain the observed spatial variability of ecological characteristics. The results of this research affect the way information about the advantages of using reclaim water is advertised, in particular to homeowners.

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