Sub-Antarctic plant-soil interactions in a changing world: plant N acquisition and growth under warming on Marion Island
type: CreativeWork
description: It is widely accepted that in cold ecosystems, strong abiotic (e.g., temperature) controls over soil decomposition processes result in N-limited plant productivity and soils replete in organic N (oN, e.g., amino acids) but not inorganic N (iN, i.e., NH4 + and NO3 - ). Recent advances in our understanding of plant N use have shown that cold ecosystem plants meet the bulk of their N requirements through direct oN acquisition. Climate warming in cold ecosystems under global change is expected to alleviate the temperature limitations to soil decomposition, effectively increasing N-availability through iN release. This has resulted in predictions for stronger indirect than direct effects on plant productivity. Additionally, increasing iN fractions may affect coldecosystem plant nutrition by altering the N-form predominantly acquired from oN to iN. Investigations into plant oN acquisition and the effects of soil warming on plant productivity are largely restricted to northern high latitudes, leaving southern cold ecosystems such as the subAntarctic underrepresented. Sub-Antarctic soils are typically replete in oN but not iN, however, plant oN uptake has not been accounted for in terrestrial N-budgets. Furthermore, the islands are experiencing high rates of climate change including increasing temperatures. This thesis examines sub-Antarctic plant-soil interactions, investigating whether sub-Antarctic grasses acquire oN and how soil warming affects plant growth and nutrition. Potted and field experiments were run with four common grasses (Polypogon magellanicus, Poa cookii, Agrostis stolonifera, and Poa annua) from sub-Antarctic Marion Island (MI, -46.9, 37.8). I hypothesised that sub-Antarctic grasses acquire oN which affects plant growth relative to iN and that soil warming influences plant growth directly and indirectly through stimulating microbial iN mineralisation and plant nutrition by altering bioavailable oN and iN soil fractions. Grasses supplied with either 15N-e…
abstract: It is widely accepted that in cold ecosystems, strong abiotic (e.g., temperature) controls over soil decomposition processes result in N-limited plant productivity and soils replete in organic N (oN, e.g., amino acids) but not inorganic N (iN, i.e., NH4 + and NO3 - ). Recent advances in our understanding of plant N use have shown that cold ecosystem plants meet the bulk of their N requirements through direct oN acquisition. Climate warming in cold ecosystems under global change is expected to alleviate the temperature limitations to soil decomposition, effectively increasing N-availability through iN release. This has resulted in predictions for stronger indirect than direct effects on plant productivity. Additionally, increasing iN fractions may affect coldecosystem plant nutrition by altering the N-form predominantly acquired from oN to iN. Investigations into plant oN acquisition and the effects of soil warming on plant productivity are largely restricted to northern high latitudes, leaving southern cold ecosystems such as the subAntarctic underrepresented. Sub-Antarctic soils are typically replete in oN but not iN, however, plant oN uptake has not been accounted for in terrestrial N-budgets. Furthermore, the islands are experiencing high rates of climate change including increasing temperatures. This thesis examines sub-Antarctic plant-soil interactions, investigating whether sub-Antarctic grasses acquire oN and how soil warming affects plant growth and nutrition. Potted and field experiments were run with four common grasses (Polypogon magellanicus, Poa cookii, Agrostis stolonifera, and Poa annua) from sub-Antarctic Marion Island (MI, -46.9, 37.8). I hypothesised that sub-Antarctic grasses acquire oN which affects plant growth relative to iN and that soil warming influences plant growth directly and indirectly through stimulating microbial iN mineralisation and plant nutrition by altering bioavailable oN and iN soil fractions. Grasses supplied with either 15N-e…
author: Pallett, Nita
keywords: Biological Sciences
date published: 2023
date modified: 2026-07-22T22:22:43Z
provider: University of Cape Town
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Department of Biological Sciences

PropertyValue
property ID: Handle
value: http://hdl.handle.net/11427/39805