- Title
- Barriers to life cycling of herbaceous perennials on restoration sites
- Creator
- Scanlon, Robert James
- Resource Type
- thesis
- Date
- 2015
- Description
- Bachelor Honours - Bachelor of Science (Honours)
- Description
- The mining industry has a long history in Australia and is an important contributor to the Australian economy. Mining activities by their nature cause impacts on the environment and current laws require sites to be returned to an acceptable post mining land use defined during the mine approval process. When mining occurs amongst native vegetation the requirement is usually for that vegetation to be restored. Much of the research undertaken on restoration of native vegetation has focused on ensuring the return of species that are visible, such as trees and shrubs. However, the larger component of plant biodiversity is in the ground layer. In order to return the full diversity of plant species post mining, understory species such as herbaceous perennials need to be integrated into the restoration works. This is a relatively new concept and many of the early restoration attempts have failed to produce a sustainable community for all strata. One of the reasons for this is the likely increase in barriers to plant life cycles. This thesis examines four barriers to life cycling and identifies how they might affect the ability to sustain a population for six species of herbaceous perennials planted on a mine restoration area in the Hunter Valley, Australia. Pollination limitation was hypothesised to be a barrier due to the likely impact of mining on the local populations of pollinators and the distance from other conspecific plant populations. Pollination was inferred by looking at seed set and viability. It was found that while the three species evaluated produced some viable seed, many of the seeds sampled for two species had low seed set. Without samples from reference populations it is not possible to tell at this point, however, the low levels of seed set suggest that pollination limitation may be a barrier to life cycling. Predation of seed by ant populations was hypothesised to affect the herbaceous perennials as predation pressure at the nearby Mt Owen mine rehabilitation site was very strong. This was tested by placing modified petri dishes with a known amount of seed from five of the species across the Restoration Site and examining how many seed were lost. Of the five species examined only one is thought to have been removed by ants. E. nutans has a soft fleshy fruit which would provide a very suitable food source to ants. Predation by ants therefore is a barrier to life cycling on the Restoration Site for only one of the targeted species. Safe site availability was hypothesised to be limited on the Restoration Site as the environment will be very different to the species’ native habitat. Microsites were examined on the Restoration Site and compared to safe sites (microsites containing seedlings) found in Reference sites. Though there was only a small sample available, only one safe site type was found to also be present on the Restoration Site. Microsite characteristics on Reference Sites were also very different to those found on the Restoration Site. Though it is suggested that safe site availability is a barrier in this study, more data is needed to conclude how strong a barrier it is. Resource limitation was hypothesised to be a barrier to plant survival and growth as mine spoil typically has a harsh chemical composition, poor water holding capacity and is limited in macro and most micro nutrients. This can also be true of subsoils and some topsoils in the area of study. This has led to remediation practices such as addition of organic material and nutrients on restoration areas. Resource limitation was examined at three levels; the Base level substrate (Spoil or Subsoil), the addition of Mulch and the addition of Organic Growth Medium (OGM). Each level was compared against the substrate effects on survival and growth. Unexpectedly, survival was no worse on Spoil than on Subsoil treatments and growth on Subsoil was only better for one species. This may be due to the unexpectedly high water holding capacity for Spoil treatments as the Spoil treatments did have more adverse soil chemistry conditions then Subsoil treatments as hypothesised. The addition of Mulch increased the survival of three species, however the only significant changes in soil physical or chemical properties was a lowering of ECse and sulfur levels. OGM was found to be nutrient rich and beneficial for the survival and growth of two of the species, beneficial to the growth but not survival of two other species and detrimental to the survival of the final two species. The lowered survival of some species could be due to nutrient levels in excess to that tolerable for these species or due to high competition for resources by other plants on OGM plots. The barrier placed by resource limitation therefore depends on the species and the substrate used as additions of Mulch made the environment suitable for survival, but OGM was required to make it suitable for growth. It is unlikely that this study will solve the problem of restoration of herbaceous perennials to mined land. The study has however shone light on the importance of some of the barriers to the establishment of life cycling in the formation of sustainable populations of herbaceous perennials on restored mined land.
- Subject
- herbaceous perennials; mining; Australia; restoration
- Identifier
- http://hdl.handle.net/1959.13/1429400
- Identifier
- uon:38708
- Rights
- Copyright 2015 Robert James Scanlon
- Language
- eng
- Full Text
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 3 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 156 KB | Adobe Acrobat PDF | View Details Download |