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The controls of nutrient limitation on resource allocation belowground

Shan, Shan
http://orcid.org/0000-0003-3916-8364
http://rave.ohiolink.edu/etdc/view?acc_num=miami1580078025127756

Abstract Details

, Doctor of Philosophy, Miami University, Biology.
Mechanisms by which plant-soil interactions mediate balanced plant nutrition are of interest in changing environments. Belowground, there are several different allocation processes in plants and microbes that can respond to nutrient imbalance in the environment. Optimization theory suggests that organisms preferentially allocate carbon (C) and energy toward acquisition of the most limiting resources. This study tested optimization theory, by asking if aboveground nutrient limitation controls allocation processes belowground in three aspects: root growth, C supply to rhizosphere, and production of soil extracellular enzymes. I used a nitrogen (N) × phosphorus (P) fertilization study in northern hardwood forests to answer these questions. In the first chapter, I hypothesized that P limitation aboveground will control allocation belowground to foraging and growth of roots. I found root foraging in response to P limitation, supporting expectations of optimization theory. In contrast, root growth was limited by N and did not respond to alleviating P limitation, which does not support the expectation. These results suggest that different nutrients limit aboveground (P) vs belowground (N) plant growth in the mature northern hardwood forests. In the second chapter I tested N and P effects on rhizosphere soil microbial properties in young forests, where evidence suggests stronger N than P limitation of tree growth. Optimization theory suggests lower C supply to the rhizosphere for microbial decomposition activities under high nutrient availability. I found N controls of soil microbial properties in both bulk and rhizosphere soil, but I did not find clear evidence that elevated nutrient availability suppresses C supply through the rhizosphere. In the last chapter I hypothesized that N and P limit microbial acquisition of C from complex forms in soil. I used microbial enzyme activities to test effects of alleviating N and P limitation on microbial C acquisition. I found P limitation of microbial acquisition of N, and N limitation of microbial acquisition of C. These results suggest that N and P limit different microbial processes to control microbial acquisition of the C needed for growth and metabolic activities.
Melany Fisk (Advisor)
Rachael Morgan-Kiss (Committee Member)
M. H. H. Stevens (Committee Member)
Michael Vanni (Committee Member)
119 p.
Ecology
Optimization theory, plant-soil interactions

Recommended Citations

Citations

  • Shan, S. (2019). The controls of nutrient limitation on resource allocation belowground [Doctoral dissertation, Miami University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=miami1580078025127756

    APA Style (7th edition)

  • Shan, Shan. The controls of nutrient limitation on resource allocation belowground. 2019. Miami University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=miami1580078025127756.

    MLA Style (8th edition)

  • Shan, Shan. "The controls of nutrient limitation on resource allocation belowground." Doctoral dissertation, Miami University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=miami1580078025127756

    Chicago Manual of Style (17th edition)

miami1580078025127756
154
© 2019, all rights reserved.
This open access ETD is published by Miami University and OhioLINK.