Thesis
Resilience of a sub-tropical riparian rainforest in Australia to major flood
Southern Cross University
Master of Environmental Science and Management (MEnvSc&Mgt), Southern Cross University
2023
DOI:
https://doi.org/10.25918/thesis.314
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Abstract
Riparian rainforests are part of a complex set of interactions between hydrology, geomorphology, and vegetation ecology. Flooding in riparian forests is an essential disturbance process and riparian species have evolved functional traits to persist with riparian stressors. Traits may include responding to disturbance by vegetative regeneration or by life history strategies (seedling recruitment). Riparian soils are vulnerable to undergoing periodic erosion and deposition, potentially causing alterations in essential plant–soil feedbacks. Climate change models predict increased frequency and intensity of flooding and the implications of this on these high conservation value ecosystems is unknown. This research aimed to answer the following questions: (i) what is the resilience of old growth riparian rainforests after severe flooding? (ii) what is the resilience of riparian soils after severe flooding? Abundance and structurally based flora surveys and soil physical and chemical assessment were undertaken at the riparian rainforest at Rocky Creek, The Channon Gorge in late 2021. After catastrophic flooding in early 2022, sites were remeasured at regular intervals after flood, and the identity and abundance of resprouting individuals and seedling recruits were additionally recorded. Species richness and native plant density significantly increased after flooding; smaller plants (<10 m height and <10 cm DBH) were the most affected. Over half the rainforest taxa present demonstrated the capacity to persist after flood by resprouting or recruiting seed; new taxa were resprouting and new native taxa were being recruited to the site up to 1-year post-flood. There was a significant change in floristic composition before and immediately after flood (P= 0.026), but at one year after the flood the community was becoming more floristically similar to its pre-flood composition. Diverse soil types at varying stages of pedological development were recorded. Surface soil nutrient levels changed significantly after flood due to erosion and twelve months post-flood soil nutrients had not fully recovered. The riparian rainforest community exhibited high resilience to high intensity flooding. Soil properties, physical and chemical had low resilience to high intensity flooding. If high-impact events co-occur immediately after flood when system resilience is lowered there is risk for the initiation of positive feedbacks involving soil erosion-nutrient loss and impeded vegetation recovery to cause further degradation. The temporal limitations of this research do not allow for measuring the success rates of post-flood germinated seedlings. Future research should investigate this further and the influence of erosion and soil nutrient status on this success.
Details
- Title
- Resilience of a sub-tropical riparian rainforest in Australia to major flood
- Creators
- Leandra Martiniello
- Contributors
- Graeme Palmer (Supervisor) - Southern Cross UniversityJohn Campbell Grant (Supervisor) - Southern Cross UniversityAndrew G Baker (Supervisor) - Southern Cross University
- Awarding Institution
- Southern Cross University; Master of Environmental Science and Management (MEnvSc&Mgt)
- Theses
- Master of Environmental Science and Management (MEnvSc&Mgt), Southern Cross University
- Publisher
- Southern Cross University
- Number of pages
- xi, 135
- Identifiers
- 991013149013302368
- Copyright
- © LM Martiniello 2023
- Academic Unit
- Faculty of Science and Engineering; Forest Research Centre; School of Environment, Science and Engineering
- Resource Type
- Thesis