Wind and seed : a conceptual model of shape-formation in the cushion plant Azorella Selago
AIMS : The sub-Antarctic cushion plant, Azorella selago, is usually hemispherical when small but frequently crescent-shaped when larger. Spatial variation in wind speed and in air-borne seed and sediment deposition is examined to determine if wind scouring and deposition patterns could contribute to...
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Online Access: | http://hdl.handle.net/2263/79523 https://doi.org/10.1007/s11104-020-04665-3 |
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ftunivpretoria:oai:repository.up.ac.za:2263/79523 2023-05-15T13:59:45+02:00 Wind and seed : a conceptual model of shape-formation in the cushion plant Azorella Selago Combrinck, Madeleine L. Harms, Thomas M. McGeoch, Melodie A. Schoombie, Janine Le Roux, Peter Christiaan 2020-08 http://hdl.handle.net/2263/79523 https://doi.org/10.1007/s11104-020-04665-3 en eng Springer http://hdl.handle.net/2263/79523 Combrinck, M.L., Harms, T.M., McGeoch, M.A. et al. Wind and seed: a conceptual model of shape-formation in the cushion plant Azorella Selago. Plant and Soil 455, 339–366 (2020). https://doi.org/10.1007/s11104-020-04665-3. 0032-079X (print) 1573-5036 (online) doi:10.1007/s11104-020-04665-3 © The Author(s) 2020 This article is licensed under a Creative Commons Attribution 4.0 International License. CC-BY Aeolian processes Airflow modelling Burial Computational fluid dynamics Positive feedback Shading Sub-Antarctic Vegetation patterning Article 2020 ftunivpretoria https://doi.org/10.1007/s11104-020-04665-3 2022-05-31T13:14:07Z AIMS : The sub-Antarctic cushion plant, Azorella selago, is usually hemispherical when small but frequently crescent-shaped when larger. Spatial variation in wind speed and in air-borne seed and sediment deposition is examined to determine if wind scouring and deposition patterns could contribute to the development of nonhemispherical shapes in cushion plants. METHODS : Computational fluid dynamic analyses were conducted for hemispherical and crescent-shaped cushion plants parameterizing models with data from A. selago habitats on Marion Island. Numerical data were contextualized with field observations to arrive at a conceptual model for shape development. RESULTS : Airflow modelling showed that both wind scouring and seed deposition of the commonly cooccurring grass Agrostis magellanica are greater on the windward side of the plant. By contrast, heavier sediment particles are predominantly deposited on the leeward side of plants, leading to burial of lee-side A. selago stems. This sediment accumulation may initiate the development of the crescent-shape in hemispherical plants by increasing stem mortality on the plant’s leeward edge. Once developed, the crescent-shape is probably self-reinforcing because it generates greater air recirculation (and lower air velocities) which enhances further deposition and establishment of A. magellanica grasses in the lee of the crescent. The conceptual model consists therefore of three stages namely, (1) negligible air recirculation, (2) sediment deposition and grass establishment, and (3) differential cushion growth. CONCLUSION : This conceptual model of plant shape development may explain the occurrence and orientation of crescent-shaped cushion plants and highlights how predicted changes in wind patterns may affect vegetation patterns. The South African National Research Foundation (NRF), the South African National Antarctic Program and the DST-NRF Center of Excellence for Invasion Biology. http://link.springer.com/journal/11104 am2021 Plant Production and Soil ... Article in Journal/Newspaper Antarc* Antarctic Marion Island University of Pretoria: UPSpace Antarctic Plant and Soil 455 1-2 339 366 |
institution |
Open Polar |
collection |
University of Pretoria: UPSpace |
op_collection_id |
ftunivpretoria |
language |
English |
topic |
Aeolian processes Airflow modelling Burial Computational fluid dynamics Positive feedback Shading Sub-Antarctic Vegetation patterning |
spellingShingle |
Aeolian processes Airflow modelling Burial Computational fluid dynamics Positive feedback Shading Sub-Antarctic Vegetation patterning Combrinck, Madeleine L. Harms, Thomas M. McGeoch, Melodie A. Schoombie, Janine Le Roux, Peter Christiaan Wind and seed : a conceptual model of shape-formation in the cushion plant Azorella Selago |
topic_facet |
Aeolian processes Airflow modelling Burial Computational fluid dynamics Positive feedback Shading Sub-Antarctic Vegetation patterning |
description |
AIMS : The sub-Antarctic cushion plant, Azorella selago, is usually hemispherical when small but frequently crescent-shaped when larger. Spatial variation in wind speed and in air-borne seed and sediment deposition is examined to determine if wind scouring and deposition patterns could contribute to the development of nonhemispherical shapes in cushion plants. METHODS : Computational fluid dynamic analyses were conducted for hemispherical and crescent-shaped cushion plants parameterizing models with data from A. selago habitats on Marion Island. Numerical data were contextualized with field observations to arrive at a conceptual model for shape development. RESULTS : Airflow modelling showed that both wind scouring and seed deposition of the commonly cooccurring grass Agrostis magellanica are greater on the windward side of the plant. By contrast, heavier sediment particles are predominantly deposited on the leeward side of plants, leading to burial of lee-side A. selago stems. This sediment accumulation may initiate the development of the crescent-shape in hemispherical plants by increasing stem mortality on the plant’s leeward edge. Once developed, the crescent-shape is probably self-reinforcing because it generates greater air recirculation (and lower air velocities) which enhances further deposition and establishment of A. magellanica grasses in the lee of the crescent. The conceptual model consists therefore of three stages namely, (1) negligible air recirculation, (2) sediment deposition and grass establishment, and (3) differential cushion growth. CONCLUSION : This conceptual model of plant shape development may explain the occurrence and orientation of crescent-shaped cushion plants and highlights how predicted changes in wind patterns may affect vegetation patterns. The South African National Research Foundation (NRF), the South African National Antarctic Program and the DST-NRF Center of Excellence for Invasion Biology. http://link.springer.com/journal/11104 am2021 Plant Production and Soil ... |
format |
Article in Journal/Newspaper |
author |
Combrinck, Madeleine L. Harms, Thomas M. McGeoch, Melodie A. Schoombie, Janine Le Roux, Peter Christiaan |
author_facet |
Combrinck, Madeleine L. Harms, Thomas M. McGeoch, Melodie A. Schoombie, Janine Le Roux, Peter Christiaan |
author_sort |
Combrinck, Madeleine L. |
title |
Wind and seed : a conceptual model of shape-formation in the cushion plant Azorella Selago |
title_short |
Wind and seed : a conceptual model of shape-formation in the cushion plant Azorella Selago |
title_full |
Wind and seed : a conceptual model of shape-formation in the cushion plant Azorella Selago |
title_fullStr |
Wind and seed : a conceptual model of shape-formation in the cushion plant Azorella Selago |
title_full_unstemmed |
Wind and seed : a conceptual model of shape-formation in the cushion plant Azorella Selago |
title_sort |
wind and seed : a conceptual model of shape-formation in the cushion plant azorella selago |
publisher |
Springer |
publishDate |
2020 |
url |
http://hdl.handle.net/2263/79523 https://doi.org/10.1007/s11104-020-04665-3 |
geographic |
Antarctic |
geographic_facet |
Antarctic |
genre |
Antarc* Antarctic Marion Island |
genre_facet |
Antarc* Antarctic Marion Island |
op_relation |
http://hdl.handle.net/2263/79523 Combrinck, M.L., Harms, T.M., McGeoch, M.A. et al. Wind and seed: a conceptual model of shape-formation in the cushion plant Azorella Selago. Plant and Soil 455, 339–366 (2020). https://doi.org/10.1007/s11104-020-04665-3. 0032-079X (print) 1573-5036 (online) doi:10.1007/s11104-020-04665-3 |
op_rights |
© The Author(s) 2020 This article is licensed under a Creative Commons Attribution 4.0 International License. |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.1007/s11104-020-04665-3 |
container_title |
Plant and Soil |
container_volume |
455 |
container_issue |
1-2 |
container_start_page |
339 |
op_container_end_page |
366 |
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1766268510728617984 |