Assessing the functional significance of wood nutrient resorption along a soil fertility gradient

Soil nutrient availability can strongly influence tree community composition in forest ecosystems. Various life strategy trade-offs in species such as changes in relative growth rate and leaf tissue turnover rate have been shown to alter tree survival along gradients of soil fertility. In addition to these traits, trees are also able to employ nutrient resorption strategies that allow for nutrients to be translocated from older tissue into more functional juvenile tissues. While nutrient translocation in leaves is well understood, radial wood nutrient resorption has received far less investigation. To investigate this, I examined pre-leaf flush wood nutrients of Quercus rubra, Quercus alba, Acer saccharum, and Acer rubrum trees in 10 sites across a nitrogen (N) and calcium (Ca) fertility gradient in a North American temperate forest in Manistee, Michigan. At each site individual trees were fertilized with N, or a combination of all macronutrients (“All”) for >10 years, along with unfertilized (“Control”) trees. I analyzed N, C, Ca, Mg, and K concentrations in these species and compared how sapwood, heartwood, and differences in sapwood and heartwood nutrient concentrations varied according to soil fertility and fertilization treatment for each species. Additionally, I re-sampled Acer species post-leaf flush and compared differences in wood nutrients pre- and post-leaf flush to investigate whether stem-wood can serve as a seasonal store of plant nutrients. I also investigated if the fraction of wood tissue comprised of ray parenchyma is related to wood nutrient re-translocation as ray parenchyma are hypothesized to be the main vector of radial wood nutrient resorption. I predicted that sapwood and heartwood nutrient concentrations would be highest in fertilized trees and trees found at high fertility sites. Additionally, I expected that trees grown at low fertility levels and without nutrient addition would have larger differences in sapwood and heartwood nutrients, indicating greater nutrient resorption. For Acer species I predicted that sapwood nutrients, and differences in sapwood and heartwood nutrients, would be lower post-leaf flush indicating nutrient draw from sapwood in support of leaf flush. I did not find any evidence for differential translocation of wood nutrients in response to soil nutrient availability, but found consistent support that sapwood nutrients serve as a seasonal repository for N. Additionally, I observed no consistent relationship between investment in ray parenchyma and wood nutrients with ray parenchyma found to only be a significant predictor of sapwood K. These results highlight the dynamic nature of wood nutrient stores and indicate that wood nutrient translocation is a complex phenomenon that is influenced by factors beyond soil nutrient availability.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Plant Biology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2022

Author dc:creator

• Flores III, Manuel Romeo

Contributors dc:contributor

• Dalling, James W.
• Leakey, Andrew D.B.
• Yang, Wendy H.

• Wood nutrients
• plant physiology
• ray parenchyma
• translocation
• temperate forest
• nutrient use
• wood anatomy
• ecology
• soil gradient

Statement dc:rights

• Copyright 2022 Manuel Flores III

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/116116

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F116116