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Ecological Effects of Selenium Hyperaccumulation on Plant Community Structure and Potential Implications for Selenium Cycling
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| 자료유형 | 학위논문 |
|---|---|
| 서명/저자사항 | Ecological Effects of Selenium Hyperaccumulation on Plant Community Structure and Potential Implications for Selenium Cycling. |
| 개인저자 | Reynolds, Ray Jason Bixler. |
| 단체저자명 | Colorado State University. Biology. |
| 발행사항 | [S.l.]: Colorado State University., 2019. |
| 발행사항 | Ann Arbor: ProQuest Dissertations & Theses, 2019. |
| 형태사항 | 113 p. |
| 기본자료 저록 | Dissertations Abstracts International 81-04B. Dissertation Abstract International |
| ISBN | 9781088333006 |
| 학위논문주기 | Thesis (Ph.D.)--Colorado State University, 2019. |
| 일반주기 |
Source: Dissertations Abstracts International, Volume: 81-04, Section: B.
Advisor: Pilon-Smits, Elizabeth. |
| 이용제한사항 | This item must not be sold to any third party vendors.This item must not be added to any third party search indexes. |
| 요약 | Areas of high selenium (Se) in soils of the Western United States harbor plant species with the capacity to tolerate and then benefit from Se at very high concentrations (1,000-15,000 mg Se/kg dry weight (DW)). The main form of Se in these soils is SeO42- (selenate). Its solubility and chemical similarity to sulfate (a plant nutrient) lead plants to take up and assimilate selenate via sulfate transporters and assimilatory enzymes. Selenium is not essential for plants, but can be beneficial at tissue levels below 5 mg Se/kg DW, by reducing oxidative stress. At elevated tissue concentration, Se accumulation can lead to detrimental effects. The levels at which plants begin to experience negative effects from Se is species-dependent and extremely variable, even between and within populations.The fact that hyperaccumulators contain high levels of a potentially toxic element may have a large effect on their interactions with their community. The central questions in my research were: How does the presence of hyperaccumulators, as repositories and cyclers of Se, affect their plant community, and how may hyperaccumulators affect Se cycling in their local environment and at larger scales? Understanding how Se hyperaccumulators affect their ecological partners and local Se cycling may serve as a model for how other types of hyperaccumulators are affecting community assembly and elemental cycling in their ecosystems. Selenium hyperaccumulators may be a relatively important component in Se cycling, and their study may help in our understanding the general role of vegetation in Se cycling on regional scales.This dissertation starts with a literature review that serves as an overall introduction (Chapter 1), followed by two experimental chapters. The specific questions addressed in the first part of my studies (field seasons 1 and 2), as described in Chapter 2, were: Does the presence of Se hyperaccumulators affect the distribution and concentration of Se in soil? Do hyperaccumulators affect overall vegetation properties and species composition, and do some plant species positively or negatively co-occur with Se hyperaccumulators? In the first field season, plant survey and soil Se mapping were performed at three different sites in paired plots. Plots with and without hyperaccumulators were compared for: 1) bare ground, canopy cover and species richness, 2) relative species abundance, 3) soil Se distribution and concentration. Plots with hyperaccumulators showed an overall trend of higher bare ground, lower canopy cover, higher species richness, and 2-3-fold higher soil Se levels (in 2 of 3 sites). These trends that areas with hyperaccumulators tend to have higher and more heterogeneous Se levels, less and more variable vegetation, and altered species composition were not consistently significant across all sites, and it was hypothesized that the effect of hyperaccumulators may have been diluted by their low abundance, and the relatively large area of survey.In the second field season, a new design was implemented, focusing on areas 3 m in diameter around hyperaccumulators versus non-accumulators, in 44 paired plots on one site. Highly significant results were obtained, showing higher bare ground, lower canopy cover and higher species richness in plots with hyperaccumulators |
| 일반주제명 | Botany. Soil sciences. |
| 언어 | 영어 |
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