Forest regeneration
Forest regeneration occurs when a forest grows back following disturbance, like a harvest event or a
natural process opening the forest canopy (such as wind throw, tree aging or fire).
There are three main ways that forest regeneration occurs:
- seed production and seedling establishment
- resprouting from underground structures, such as lignotubers
- resprouting from epicormic buds, such as coppicing.
The regeneration of forests following harvest events is important. It ensures the sustainability of native forestry and maintains the ecological services that forests provide to landholders and the community in the long term.
Regeneration is a process that often occurs naturally. Sometimes, you may need to help regeneration through forest management actions. This will depend on the species, site conditions and type of harvesting undertaken.
What are forest regeneration management actions?
Regeneration management actions are techniques that promote forest regeneration after forestry operations. These actions can include:
- applying seed
- replanting with tubestock
- minimising or removing grazing pressure
- weed management
- fire management
- mechanical soil disturbance.
These management actions promote regeneration by:
- directly introducing seed or plants back onto the site
- removing competition, and
- producing conditions that are favourable for regeneration of desired species.
Where there is a risk of natural regeneration failure
Where there is a risk of regeneration failure, you may want to take regeneration management actions. For example, resulting from insufficient natural seed on site (in the case of species that rely on seed for regeneration). Weeds may outcompete regenerating tree species or high grazing pressure that suppress regeneration.
It is important to understand the characteristics of your site and the species present. This will help when deciding if you need to perform regeneration management actions.
Regeneration requirements under the PNF Codes of Practice
Farm Forestry supports the maintenance of forest health and regeneration at site and bioregional scales. The Private Native Forestry Codes of Practice (PNF Codes) outline the requirements for forest regeneration (Section 5.4, or for the Cypress and Western Hardwood Forests PNF Code, Section 5.3) and provide guidance for measuring forest regeneration (Appendix C).
Under the PNF Codes, you can use a variety of techniques to promote forest regeneration. These include a range of silvicultural approaches that can encourage optimal regeneration outcomes for the forest type and forest condition. The PNF Codes outline minimum stocking standards following a regeneration (harvesting) event.
Landholders must monitor forest regeneration, composition, and condition at 2, 6 and 10 years after harvesting has occurred. Landholders may also monitor forest regeneration following a natural disturbance. Where an area is not regenerating along a trajectory that maintains (or improves on) preharvest forest conditions, landholders must implement regeneration management actions.
Improving forest regeneration
Each forest will benefit from different approaches to regeneration management. You may achieve the best outcomes by using a combination of approaches. The silvicultural system used, and subsequent regeneration management should be tailored to your forest type and composition, the disturbance history of the forest, ecological characteristics, and the desired forest management outcomes.
Species evolve and adapt to local environmental conditions. This includes things like rainfall, temperature and fire regime. Some species are further specialised to local conditions including topography, slope, and shade tolerance. Trees compete for resources including light, nutrients, and water. Tolerance to competition for resources varies between tree species.
Shade tolerance is the ability of a species to keep growing with limited sunlight and in competition with surrounding canopy trees. It is important to understand the environmental requirements for the species in your forest.
In some cases your regeneration objectives may be to maintain the current structure and species composition within a forest.
In some cases, a forest has been subject to inappropriate management or significant past disturbance. Your objectives here may focus on improving the forest’s structure, health, and composition. This will help to enhance its future productive and environmental values.
Setting forest regeneration objectives and meeting your requirements starts with choosing what silviculture methods you will use in your forest.
You may want to use one, or a combination of silvicultural systems. This will depend on your forest management objectives and regeneration requirements.
You can learn more about silviculture systems from the range of Local Land Services forest management resources and guides.
Forest regeneration management actions
There are more management actions you can use to help drive regeneration and support a sustainable forest. These are some of the techniques to manage and improve forest regeneration.
Grazing by stock, kangaroos and wallabies or pest species can kill or impact the growth of new seedlings, resprouts and or young trees. You can practice grazing exclusion by:
- fencing areas
- using tree guards and
- rotational or tactical stock grazing (to exclude stock during early stages of regeneration).
This can help the forest to regenerate by removing extra pressure for early-stage regenerating forests. Effective management of pest species such as deer, rabbits and goats may also help reduce browsing pressures.
Forests can be vulnerable to weed invasion following disturbances. This includes harvest operations, mechanical disturbance, fire, and floods. Weeds compete for resources with native species and can hinder regeneration.
It is important to be aware of common weeds in your forest or adjacent land and how to treat them effectively. Planning weed control and ensuring appropriate biosecurity measures are undertaken during machinery operations helps to reduce the negative impacts of weeds.
Fire is a natural part of forest ecology in Australia. Many native forest species have adapted to be fire dependent. This means they rely on fire to start regeneration. Plants that regenerate after fire fall into 3 main categories:
- Obligate resprouters - These are plants that grow new shoots from dormant buds after a fire. These buds may be above or below ground
- Obligate seeders - These are plants that have fire resistant seed banks. These seed banks will germinate after a fire. These seed banks may be in the trees canopy or in the soil.
- Facultative seeders - These are plants that exhibit both postfire resprouting and post fire seeding.
For a forest with species that rely on fire to regenerate, you may use controlled burning as a regeneration tool. Consider prescribed fire following a harvest event to prepare the seed bed and promote seed fall. Fire may also be a suitable tool to manage weeds, which can also help regeneration.
When planning a prescribed fire, you should think about how to manage impacts to retained trees and habitat features. This can include:
- removing harvest residues and slash from around the base of retained trees. and
- wetting potentially vulnerable areas to reduce burn intensity before commencing fire management.
You can use mechanical disturbance to disturb the soil and reduce understory competition. This creates a favourable seedbed for regeneration. You may use mechanical disturbance in place of fire to stimulate seedling regeneration of obligate seeder species, where burning is not desirable or is likely to pose management issues. If undertaking mechanical disturbance, ensure the topsoil is not removed.
If canopy openings are unlikely to regenerate by natural means you can use reseeding or direct planting. This is also helpful when monitoring over time reveals that regeneration has been unsuccessful.
If you plan to undertake reseeding or replanting talk to your local commercial nursery. Consider the use of local provenance stock (stock that is genetically adapted to your local area).
Reseeding and replanting will depend on understanding the reasons for regeneration failure. It may require reducing grazing and browsing pressures and weed management.
What to consider when planning your forest regeneration activities
Regeneration may naturally occur following a harvest operation, but you must also monitor regeneration. You can then work out if you need to take more regeneration management actions.
Forest regeneration objectives are important. You should consider these first when developing your Forest Management Plan.
When planning and undertaking forest regeneration activities:
- Understand the regeneration requirements of the species in your forest. For example, climate, fire and shade tolerance
- Identify the site conditions, opportunities and challenges that may influence regeneration. This includes topography and slope, weeds and grazing pressures
- Outline details of the activities planned to promote regeneration. Make sure these are in the written component of your Forest Management Plan
- Plan out your monitoring. If you need to use more further management techniques, this will help you to keep track of them. You must monitor Regeneration to track composition and condition at 2, 6 and 10 years following harvesting operations.
- You must implement further regeneration management if natural or assisted regeneration has failed.
Contact Local Land Services NSW
Our team welcome your enquiries, feedback and comments.
Local Land Services is moving to nsw.gov.au. During the change, you might find the information you are looking for at lls.nsw.gov.au