Unearthing in-situ nutrient uptake rates: an assessment of underlying assumptions used for their prediction

• Main Author: Ng, Jing Cheng
• Other Authors: Kelly Andersen
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Science::Biological sciences::Ecology
• Online Access: https://hdl.handle.net/10356/156728
• Institution: Nanyang Technological University

Plant nutrient acquisition is a functional trait that has widespread importance ranging from individual growth to ecosystem productivity and processes. Trait-based approaches seek to make general predictions about ecosystem functioning based on functional traits. However. these rest on the assumptions that measured traits impact fitness, and can be predicted by environmental parameters. In-situ nutrient uptake rates were measured for Campnosperma auriculatum and Shorea curtisii for NO3-N, NH3-N and PO4-P uptake. Plasticity was detected in PO4-P and NO3-N nutrient uptake rates based on the test medium. NH3-N uptake rates displayed species-specific differences in plasticity. Root nutrient uptake rates should thus be reported alongside concentrations of nutrient media used to allow for fair trait comparison across studies. Uptake rates of all nutrients are all positively correlated with one another, with no preferential uptake across PO4-P and NO3-N. All nutrient uptake rates were not significantly correlated with root carbon exudation rates. NH3, NO3, and PO4 nutrient uptake rates do not reflect plant-available soil nutrient gradients, and may thus not be predictable across geographical scales. Additionally, nutrient uptake rates are orthogonal to both the collaboration and conservation gradients described by root morphological traits in the root economic space. This orthogonality challenges the assumption that widely measured "soft", morphological traits are accurate surrogates of "hard" functional traits.