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Nitrogen cycling in the northern hardwood forest: soil, plant, and atmospheric processes

Nave, Lucas Emil
http://rave.ohiolink.edu/etdc/view?acc_num=osu1196187071

Abstract Details

2007, Doctor of Philosophy, Ohio State University, Evolution, Ecology, and Organismal Biology.
Nitrogen (N) is the nutrient most limiting to plant growth (NPP) in temperate forests. In N-limited temperate forests, most of the N required for NPP is recycled between soil and plant N pools by the microbial process of N-mineralization (Nmin). However, human activities have increased atmospheric N deposition (Ndep) to forests in the last 50-100 years, and this surplus N may increase NPP. But, forest responses to Ndep are not satisfactorily understood, and depend on how atmospheric N inputs are partitioned between soils and plants. From my field data collection at a mature forest site, I estimated that NPP required 51 kg N ha-1 yr-1, most of which was used for fine root and leaf production (62% and 31%, respectively). Each year, Nmin supplied 87% of Nreq, and Ndep contributed an additional 13%, 4% of which was due to canopy retention of Ndep (Ncr). Data from my mesocosm 15N-labelling experiment suggested that very little (<10%) of Ncr observed in the field was actually taken up by trees, and the majority of Ndep (>85%) was assimilated into soil pools. These results suggest that Ndep could not have significantly increased forest NPP at UMBS over the time scale of my studies. My greenhouse experiment corroborated this conclusion, with tree seedlings showing no significant increase in photosynthesis or growth in response to Ndep at ambient rates. However, Ndep to forest ecosystems has been occurring for decades in industrialized regions, and most of the N inputs have been incorporated into soil organic matter (SOM). Research across temperate forests has suggested that forests exposed to large N inputs over time exhibit decreased soil C/N ratios, which are associated with faster Nmin rates. Using meta-analysis, I verified this pattern in the literature, and discovered novel relationships between forest soil properties and their responses to N inputs. My results demonstrated a long-term, quantitative relationship between Ndep and Nmin, and suggest that NPP may increase in temperate forests affected by Ndep.
Peter Curtis (Advisor)
102 p.
Biology, Ecology
hardwood forest; nitrogen cycle; nitrogen deposition; nitrogen mineralization; canopy nitrogen uptake; net primary productivity

Recommended Citations

Citations

  • Nave, L. E. (2007). Nitrogen cycling in the northern hardwood forest: soil, plant, and atmospheric processes [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1196187071

    APA Style (7th edition)

  • Nave, Lucas. Nitrogen cycling in the northern hardwood forest: soil, plant, and atmospheric processes. 2007. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1196187071.

    MLA Style (8th edition)

  • Nave, Lucas. "Nitrogen cycling in the northern hardwood forest: soil, plant, and atmospheric processes." Doctoral dissertation, Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1196187071

    Chicago Manual of Style (17th edition)

osu1196187071
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© 2007, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.