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Abstract Detail


Super, Laura [1], Guy, Robert [2].

The impact of simulated climate change and nitrogen deposition on conifer phytobiomes and associated vegetation.

Anthropogenic change can impact abiotic and abiotic factors in ecosystems, their plants, and their associated organisms, i.e., the phytobiome. This research examines the effect of simulated warming and nitrogen deposition on conifer seedling phytobiomes in six clear-cuts and six forest edges. Each clear-cut and each forest edge had four treatments in a 5 x 5 (15 m x 15 m), 25 subplots, grid: i) only simulated warming with passive open top chambers (OTC, n = 6), ii) only simulated nitrogen deposition with added ammonium nitrate (N fertilizer, n = 6), iii) both (OTC and N fertilizer = 6), or iv) neither (control = 6 or 7). Preliminary results of 2.5-year-old seedlings show that OTCs increased overall tree height in clear-cuts (P = 0.004), and N fertilization increased overall tree height in forests (P = 0.032). Each subplot had three tree species, a tree consortium, and these were differentially impacted by the treatments, with Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco) height increasing with OTCs in clear-cuts only, western red cedar (Thuja plicata  Donn  ex  D.Don) not showing a response overall, and western hemlock (Tsuga heterophylla  (Raf.)  Sarg.) increasing in height with N fertilizer overall, but not significantly in either location separately. The results suggest that, in these Pacific Northwest forest edge ecosystems with often limited understory, seedling growth would benefit from increased nitrogen deposition, perhaps because of less competition with other understory plants. In clear-cuts, supplemental nitrogen may have been intercepted by the larger numbers of competing plants, especially newly invading weeds that thrive in high light environments. The OTCs likely enhanced growth on open clearcuts and not at the forest edge because they are less effective at modifying the microclimate under partial shade. Fieldwork suggests that the warming effect varies depending on where the OTC is located, very close to edge versus further in, south-facing, etc. Forthcoming results will examine the associated communities of vegetation, as well as the plant microbiome (prokaryotes and eukaryotes) for shoots, roots, and soil. Each tree consortium of three phytobiomes may be impacted by its milieu; subplot-level data such as vegetation cover, vegetation diversity, and soil properties will be summarized to relate to phytobiomes. This research improves basic knowledge and is useful for understanding how nitrogen and warming may synergistically impact Pacific Northwest areas disturbed by clear-cutting.

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1 - University of British Columbia, 3041-2424 Main Mall, Vancouver, BC, V6T 1Z4, Canada
2 - University Of British Columbia, Forest & Conservation Sciences, 3041-2424 Main Mall, Vancouver, BC, V6T 1Z4, Canada

anthropogenic effects
climate change
nitrogen deposition

Presentation Type: Oral Paper
Session: ECO3, Ecology: Climate Change
Location: /
Date: Tuesday, July 20th, 2021
Time: 3:00 PM(EDT)
Number: ECO3001
Abstract ID:1011
Candidate for Awards:Ecological Section Best Graduate Student Paper

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