On growth patterns and mechanisms in Mediterranean-alpine shrubs
On growth patterns and mechanisms in Mediterranean-alpine shrubs
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DissertationDate of Exam
03.05.2023Date of Publication
22.05.2023Advisor
Löffler, JörgCo-Referee
Pape, RolandMetadata
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Abstract
In the context of open questions on the adaptability of alpine ecosystems to future global warming, this cumulative doctoral dissertation studies three Mediterranean-alpine shrub species using a novel dendrometer-based approach. Under climate change, cold-adapted Mediterranean-alpine might become exposed to severe summer droughts and milder winters. However, the complexity of driving forces of shrub growth, associated with above-ground biomass gain in these shrubs is not yet fully understood. Here, we used the shrub species Cytisus galianoi as a target species, which was abundant at all sites across the Sierra Nevada, Spain. C. galianoi co-occurred with Astragalus granatensis at exposed ridges and with Genista versicolor at snow-covered slopes. In contrast to previous dendroecological studies, that commonly use an anatomical ring-width-based approach, we aimed at understanding stem diameter changes, water-related stem expansion and contraction, and physiological growth mechanisms by using long-term high-resolution dendrometer measurements. From our overall findings, we deduced the species´ strategies to cope with winter cold and summer drought constraints. Using soil temperature and soil moisture data recorded directly at the growing sites, we identified the species-specific environmental controls of growth. With different statistical approaches, robust and significant driver constellations were found and allowed to argue for pronounced carry-over effects, which addresses the resource acquisition during favourable periods prior to the actual growth phase. Such effects were clearly visible for C. galianoi, which as a frost tolerant, green-stemmed species, was found to likely profit from cold and snow-free winters by mobilizing assimilates from winter photosynthesis for major spring growth. As a drought tolerant species, C. galianoi showed severe summer stem contractions, and had strong water-related stem diameter increase due to rehydration in autumn, while growth rates were minor. Using this combined winter cold and summer drought adapted growth strategies, C. galianoi was shown to perform best at all alpine sites due to high growth plasticity. Compared to the two co-occurring shrub species, the combined cold and drought tolerance growth strategies in C. galianoi led to highly competitive advantages. We synthesized the different growth strategies and addressed a) the overall growth performance in C. galianoi over its distributional range across the Sierra Nevada, b) the advantages and disadvantages of the growth strategies in a green-stemmed vs. a seasonal dimorphic species, and c) the growth differences in comparison of two green-stemmed species at shared sites.
Subjects
Anpassungsstrategien, Klimawachstumsbeziehungen, Dendroökologie, Sierra Nevada (Spain), Cytisus galianoi, Genista versicolor, Astragalus granatensis, adaptation strategies, climate-growth relations, dendroecology
Classification (DDC)
550 GeowissenschaftenRelated Publications
https://doi.org/10.3112/erdkunde.2022.dp.01Albrecht, Eike Corina: On growth patterns and mechanisms in Mediterranean-alpine shrubs. - Bonn, 2023. - Dissertation, Rheinische Friedrich-Wilhelms-Universität Bonn.
Online-Ausgabe in bonndoc: https://nbn-resolving.org/urn:nbn:de:hbz:5-70696
Online-Ausgabe in bonndoc: https://nbn-resolving.org/urn:nbn:de:hbz:5-70696
@phdthesis{handle:20.500.11811/10856,
urn: https://nbn-resolving.org/urn:nbn:de:hbz:5-70696,
author = {{Eike Corina Albrecht}},
title = {On growth patterns and mechanisms in Mediterranean-alpine shrubs},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2023,
month = may,
note = {In the context of open questions on the adaptability of alpine ecosystems to future global warming, this cumulative doctoral dissertation studies three Mediterranean-alpine shrub species using a novel dendrometer-based approach. Under climate change, cold-adapted Mediterranean-alpine might become exposed to severe summer droughts and milder winters. However, the complexity of driving forces of shrub growth, associated with above-ground biomass gain in these shrubs is not yet fully understood. Here, we used the shrub species Cytisus galianoi as a target species, which was abundant at all sites across the Sierra Nevada, Spain. C. galianoi co-occurred with Astragalus granatensis at exposed ridges and with Genista versicolor at snow-covered slopes. In contrast to previous dendroecological studies, that commonly use an anatomical ring-width-based approach, we aimed at understanding stem diameter changes, water-related stem expansion and contraction, and physiological growth mechanisms by using long-term high-resolution dendrometer measurements. From our overall findings, we deduced the species´ strategies to cope with winter cold and summer drought constraints. Using soil temperature and soil moisture data recorded directly at the growing sites, we identified the species-specific environmental controls of growth. With different statistical approaches, robust and significant driver constellations were found and allowed to argue for pronounced carry-over effects, which addresses the resource acquisition during favourable periods prior to the actual growth phase. Such effects were clearly visible for C. galianoi, which as a frost tolerant, green-stemmed species, was found to likely profit from cold and snow-free winters by mobilizing assimilates from winter photosynthesis for major spring growth. As a drought tolerant species, C. galianoi showed severe summer stem contractions, and had strong water-related stem diameter increase due to rehydration in autumn, while growth rates were minor. Using this combined winter cold and summer drought adapted growth strategies, C. galianoi was shown to perform best at all alpine sites due to high growth plasticity. Compared to the two co-occurring shrub species, the combined cold and drought tolerance growth strategies in C. galianoi led to highly competitive advantages. We synthesized the different growth strategies and addressed a) the overall growth performance in C. galianoi over its distributional range across the Sierra Nevada, b) the advantages and disadvantages of the growth strategies in a green-stemmed vs. a seasonal dimorphic species, and c) the growth differences in comparison of two green-stemmed species at shared sites.},
url = {https://hdl.handle.net/20.500.11811/10856}
}
urn: https://nbn-resolving.org/urn:nbn:de:hbz:5-70696,
author = {{Eike Corina Albrecht}},
title = {On growth patterns and mechanisms in Mediterranean-alpine shrubs},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2023,
month = may,
note = {In the context of open questions on the adaptability of alpine ecosystems to future global warming, this cumulative doctoral dissertation studies three Mediterranean-alpine shrub species using a novel dendrometer-based approach. Under climate change, cold-adapted Mediterranean-alpine might become exposed to severe summer droughts and milder winters. However, the complexity of driving forces of shrub growth, associated with above-ground biomass gain in these shrubs is not yet fully understood. Here, we used the shrub species Cytisus galianoi as a target species, which was abundant at all sites across the Sierra Nevada, Spain. C. galianoi co-occurred with Astragalus granatensis at exposed ridges and with Genista versicolor at snow-covered slopes. In contrast to previous dendroecological studies, that commonly use an anatomical ring-width-based approach, we aimed at understanding stem diameter changes, water-related stem expansion and contraction, and physiological growth mechanisms by using long-term high-resolution dendrometer measurements. From our overall findings, we deduced the species´ strategies to cope with winter cold and summer drought constraints. Using soil temperature and soil moisture data recorded directly at the growing sites, we identified the species-specific environmental controls of growth. With different statistical approaches, robust and significant driver constellations were found and allowed to argue for pronounced carry-over effects, which addresses the resource acquisition during favourable periods prior to the actual growth phase. Such effects were clearly visible for C. galianoi, which as a frost tolerant, green-stemmed species, was found to likely profit from cold and snow-free winters by mobilizing assimilates from winter photosynthesis for major spring growth. As a drought tolerant species, C. galianoi showed severe summer stem contractions, and had strong water-related stem diameter increase due to rehydration in autumn, while growth rates were minor. Using this combined winter cold and summer drought adapted growth strategies, C. galianoi was shown to perform best at all alpine sites due to high growth plasticity. Compared to the two co-occurring shrub species, the combined cold and drought tolerance growth strategies in C. galianoi led to highly competitive advantages. We synthesized the different growth strategies and addressed a) the overall growth performance in C. galianoi over its distributional range across the Sierra Nevada, b) the advantages and disadvantages of the growth strategies in a green-stemmed vs. a seasonal dimorphic species, and c) the growth differences in comparison of two green-stemmed species at shared sites.},
url = {https://hdl.handle.net/20.500.11811/10856}
}
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