Healing Damaged Landscapes
The Society for the Practice of Ecological Restoration (Australasia) has recently outlined six key principles:
- Ecological restoration practice is based on an appropriate local indigenous reference ecosystem.
- Restoration inputs will be dictated by level of resilience and degradation.
- Recovery of ecosystem attributes is facilitated by identifying clear targets, goals and objectives.
- Full recovery is the goal of ecological restoration but outcomes may take long timeframes.
- Science is essential to good practice but the two processes are synergistic.
- Social aspects are critical to successful ecological restoration.
The standards also cover Planning and Design
- The Society for Ecological Restoration provides a number of key reports available here.
- The International Union for the Conservation of Nature (IUCN) also provides Project Management Tools here and here and Monitoring and Evaluation guidelines (PDFs).
- Best practice management guide for environmental weeds CRC for Australian Weed Management (PDF).
- Byron Shire Bush Regeneration Guidelines
Many guidelines available focus on using pesticides as the main technique or what they perhaps facetiously call ‘best practice’. Nevertheless, they contain much useful information.
Reading your landscape
Centre yourself in the landscape and learn to read your country. This is an ongoing process. What does your land look like – site-specific mapping:
- geology, soils, and drainage – these will influence both the nature of the natural vegetation and the weeds that are likely to grow;
- distribution of vegetation communities and their health;
- target weed distributions and their abundance;
- areas free of invasive plants of concern;
- cultural heritage sites of significance – these will require liaison with the appropriate stakeholders;
- location of roads, tracks and trails – these indicate the likely source ongoing disturbance and weed invasion.
Other useful information:
- flora – these supplement vegetation community mapping. The list is also a guide for species selection if planting is intended.
- fauna – list the species that are known or likely to be present. If they are utilising the weeds for food, shelter, refuge, or nesting then weed removal will need to be done slowly so that alternative habitat will be provided.
- presence of threatened species – what are the environmental conditions that they favour.
- fire history and the timing and frequency of appropriate fire regimes.
- sedimentation and nutrient levels in creeks and water bodies – these may indicate upslope or streambank erosion, or provide the conditions for the growth of waterweeds.
Planning and determining priorities
Now that you have your information about the site and its weeds together, and can clearly identify functioning and impaired communities and ecosystem processes, you can construct your management plan. A planned approach will save you money and time.
- Developing your strategic plan
- Develop a Good Monitoring Program
1. A goal is an overarching principle that guides decision making.
Your goal is a long-term vision of future conditions you are aiming for. Goals for management of invasive species may include conservation of threatened species, weed containment, large-scale weed population reduction, prevention of new infestations, resource protection, marrying agricultural production with ecological improvements, etc. It is important to think long-term – communities may take decades to really improve. Some may never approximate their original condition. Remember, short-term weed control will not result in long-term success unless the causes of weed invasion are addressed.
2. Objectives are specific, measurable steps that can be taken to meet the goal.
The strategy developed will depend on your objectives which will be tailored to site conditions and available resources. Objectives should be quantifiable so that progress can be measured.
Each site and weed needs to be addressed individually and priorities determined depending on the situation and your ultimate objective.
- target Priority weeds – those which have been identified as highly invasive on your site;
- protect intact bushland;
- clear isolated infestations of a high priority species or a new weed incursion that is known to be a problem in other areas;
- many projects begin with the least affected and work towards more affected;
- work on areas of high ecological value – including threatened species, endangered ecological communities or regionally-significant vegetation communities;
- prevent new weeds establishing;
- develop connectivity between habitat patches through the provision of corridors;
- protect cultural heritage sites;
- rehabilitate cleared areas, tracks and trails;
- work in recreational areas to control damage.
Particularly if your site is large or diverse, your plan may divide the site into key management areas addressing both the causes of weed invasion as well as the weeds themselves.
3. Developing your strategic plan
It is worth exploring if your site (or part of it) is likely to respond to weed removal by natural regeneration. Much of the regeneration that has happened has been natural – simply by taking the threatening pressure off, like logging, or grazing. Additionally, some of the landcare grants we have seen have been wasted as the site was well on the way to controlling weeds itself through natural succession. Natural succession also avoids the problem of introducing plants not adapted to the site or soils which may have contaminants. It is also cost effective and will require little follow-up.
Some tips for strategic planning:
- Consider the area of infestation and other site characteristics
- Focus on key management areas and priorities;
- The timing of control will depend on weed biology. Prevent the formation and release of viable weed seeds, and proliferation of rhizomes and other propagules of perennial weeds.
- The importance of follow-up. It is a wasted opportunity if an excellent kill of original plants is followed by rapid unchecked regrowth. The timing of follow-up should also be based on the biology of the species – for example, some you can leave for years, others will require removal before flowering. Also, do not focus so much on primary work that the weeds are reaching maturity behind you.
- When practical, interrupt vegetative propagation by invasive perennial weeds through timely removal of top growth.
- Find the weed’s weak points—possibly the stages in its life cycle that are most vulnerable to control tactics—and stresses to which the weed is sensitive; these can be exploited to remove them at critical times. For instance, Bitou Bush is not competitive in established natural communities – its strategy is to rapidly establish after fire so removing it at an early stage is effective.
- Understand species performance – some weed control methods can enhance the performance of new invaders, retarding establishment of desirable plant communities. For instance, herbicide control can encourage the proliferation of annual weeds and set the successional stage backwards.
- delaying control until just before plants become reproductive will maximise the natural mortality of seedlings and juveniles.
- work strategically and at the pace of the bushland recovery. Regular and consistent attention is better than spasmodic work. Understand and adopt organic principles of weed control.
- consider the need for fertility or water management.
4. Develop a Good Monitoring Program
Monitoring provides information on how species or populations change over time, as well as their impacts on ecosystem and the impact of management practices. It also detects any new plant invasions. Monitor the regeneration of both native species and the control of weeds. Revisit your management plan on the basis of the project’s success. Areas of natural regeneration should also be monitored to evaluate changes. In addition, monitor other environmental or disturbance conditions which facilitate or inhibit regeneration. Maintain good records and update your weed maps regularly. Review and refine your project annually.
Steps in implementation typically include site and plant preparation (if required), selection of appropriate method and tools for each weed, and maintenance. Continuous adaptive management incorporates new information determined as the project progresses.
- Follow a timeline for achievement of goals;
- Ensure that proper timing of control methods and follow-up occurs;
- Limit the spread of established weeds;
- Keep soil disturbance to a minimum. Disturbance favours the establishment of many weeds. It brings buried weed seed to the surface thereby releasing dormancy, and creates favourable conditions for the germination of wind dispersed weed seed.
- Avoid working in areas where weeds are actively shedding seed.
- If fires occur either accidentally or as part of management, control weeds immediately to limit their spread.
- weeds that are extensively used by animals as food, protection, or shelter should be removed in stages as replacement habitat is in place.
To plant or not to plant?
Although planting may show immediately results, it is not always the most ecologically appropriate solution to restoring an area. It is also costly both in time and money. However, if it is used, there are some rules worth applying:
While they were both written before a fuller scientific understanding of the health effects for fauna (and humans) and soil persistence of glyphosate, the following manuals are excellent resources for the strategic repair of rainforests:
- Goosem, S., & Tucker, N.I.J. 2013. Repairing the Rainforest. 2nd ed, Wet Tropics Management Authority and Biotropica Australia P/L. Cairns.
- Big Scrub Rainforest Landcare Group, 2005. Subtropical Rainforest Restoration.
Other useful pointers for planning are Rainforest: Ecological Principles for the Strategic Management of Weeds in Rainforest and Guideline, Weeds and Rainforest published by the (now defunct) Cooperative Research Centre for Australian Weed Management.
Rainforest species are adapted to particular successional stages – some species will grow once pioneer species have changed soils microbiomes and moisture conditions, others will only grow after the senescence or death of earlier species. Weeds can be strategically used in the early stages to facilitate these soil, moisture and canopy changes. Changes in attitude to non-native species can be seen in the 2005 document from the Rainforest CRC – A New Role for Weeds in Rainforest Restoration?
Rainforest revegetation projects are often undertaken but an assessment of large government investments though the National Heritage Trust in north Queensland found that “only about half the area reported as revegetated was actually forested after six to 11 years. About half of this forested area was in poor or very poor condition – often due to a lack of monitoring or maintenance.”
Taylor R. (2009) Low success from rainforest revegetation investment. Ecos 33, 151.
Dr John Kanowski says that “past approaches to rainforest restoration have drawn too heavily on successional models derived from intact rainforest systems. Instead, we require a more sophisticated understanding of the dynamics of restored sites in heavily modified landscapes, where for example the seed rain is always likely to have a significant exotic component….. rainforest restoration is a long-term endeavour. The short-term funding paradigm that has prevailed in many replanting projects, particularly government schemes, has served restoration objectives poorly and resulted in a great waste of money.”
Kanowski, J., 2010. What have we learnt about rainforest restoration in the past two decades? Ecological Management and Restoration 11:2-3.
Riparian and wetland
It is pointless controlling weeds along waterways, if they occur higher up the catchment – the source of seed is not controlled. Aquatic perennials will also be dispersed over large distances by floodwaters. Many wetland or riparian systems have had their resources and processes changed beyond recognition. However, consistent weed control and re-establishment of local native plant species will help in sustainable management of these areas. Restoring riparian vegetation helps to reduce the presence of weeds, stabilises banks, shades the waterway (which minimises evaporation), and provides habitat for local fauna. In some cases, non-native species will aid bank protection and the re-establishment of ecosystem processes.
An Introduction and User’s Guide to Wetland Restoration and Enhancement is an excellent outline of wetland restoration. Although developed by the US EPA, it has excellent guidelines on planning, implementation and monitoring. Common activities they note in site preparation may include: removing rubbish, removing polluted soils; bringing in appropriate soils or substrates; plugging or removing drains; fencing out cattle or other herbivores.
The Malloon Institute has been established to demonstrate the philosophy and practice of Peter Andrews in rehydrating landscapes. Peter’s Natural Sequence Farming is based on a holistic view of water, air, soil, plant and animal interactions in the landscape. It uses natural functions where possible, or careful mimicry of them and their natural sequences, to address soil and water degradation and biodiversity loss. It focuses on plant function in the landscape and often uses non-native species to restore or enhance natural function.
A good example of floodplain restoration is Peter Marshall’s work with the Yass Landcare Group (NSW).
Publications concerning riparian management are available from the Australian River Restoration Centre.
Grassed up – general guidelines for revegetating with Australian native grasses is available to view on-line.
In the selection of seeds, Whalley et al. (2013) determined that although “Many restoration guidelines strongly recommend the use of local sources of seed in native plant revegetation projects“, in fact, “the common Australian native grasses so far studied have revealed complicated breeding systems that provide the evolutionary resilience necessary for coping with the variable Australian climate as well as with future climate change“. They argue that “studies on Australian native grasses provide clear evidence that distinct adaptive advantages may be gained by sourcing non-local provenance seed, which is matched to the environment of the revegetation site, and which contains appropriate stress tolerance genes, or by mixing populations from several locations to increase the genetic diversity of seed sources“. They provide some general guidelines for sourcing seed “depending on the purpose of the revegetation, the degree of environmental modification of the site and the characteristics of the species of choice“.