Forest health and habitat

This program area will investigate how harvesting is distributed through space and time. In addition, it will investigate how habitat features are retained across the landscape to support ongoing ecological function and habitat connectivity through a state forest.

Monitoring forest structure, health and regeneration

Key monitoring questions

Monitoring has been designed to answer the following questions:

  • Do harvesting conditions establish a mosaic of forest age classes at the landscape scale?
  • Do the conditions maintain functional connectivity for focal fauna species to move within and across the forest?
  • Are the conditions effective in ensuring regenerating forests meet benchmarks for forest structure, floristic composition, and coarse woody debris?
  • Are the conditions effectively promoting regeneration to maintain volume and quality for productive supply?

Monitoring to date

Forest structural data has been collected using airborne LiDAR (light detection and ranging) covering 250,000 hectares over 47 state forests. Sites were selected to cover the range of forest types, areas burnt and unburnt during the 2019/20 wildfires, fauna monitoring sites, forest inventory plots, completed and proposed harvesting areas, and areas managed for conservation.

Data was collected between June 2022 and May 2023. The map shows location of data collected.




The LiDAR data has been processed to generate forest structural metrics that improve knowledge of the forest structure at the time of data capture. Metrics include a digital terrain model, canopy height model, top height, average height, structural index, cover above 2 metres, understorey density, and measures of variation.

The forest structural metrics have been used to analyse forest connectivity and heterogeneity across the landscape and will be combined with other spatial data to answer key monitoring questions.

Data

The raw LiDAR is available on request, noting these are very large datasets that require specialised programs to analyse. This data will be made publicly available through a data portal in 2024. Data for selected forest structural metrics will also be made publicly available once analysis has been completed.

Assessing change in forest structure on coastal state forests



We engaged researchers at the University of Newcastle to analyse variation in forest structure on state forests. Using recently captured airborne LiDAR data and other spatial and non-spatial data, researchers will assess the influence on forest structural diversity of natural and anthropogenic activities including management (harvesting, prescribed fire, areas set aside for conservation), natural disturbance such as wildfire, topographic position and forest type. Building on this work, researchers will also analyse changes in forest structure using historically collected data. Spatial outputs including average canopy height and canopy cover will be produced at a range of scales.

Researchers will deliver results by mid-2024.

Monitoring impacts and recovery in fire affected forestry sites

During the summer of 2019/20, approximately 65 percent of Coastal IFOA state forests were affected by fire. The Coastal IFOA was not designed to moderate the environmental risks associated with harvesting in landscapes that have been severely impacted by fire.

The Environment Protection Authority (EPA) has issued additional site-specific conditions to the Forestry Corporation (FCNSW) that tailor protections for the specific circumstances of these burnt forests. As required by the conditions, FCNSW must work with the Commission to monitor the long-term impacts and recovery of burnt sites subject to forestry operations.

The Commission developed a plan with the FCNSW to monitor fire affected sites as part of the broader Coastal IFOA monitoring program. This plan was subject to expert review and approved by the NSW Forest Monitoring Steering Committee.

Post-fire forest recovery in the Coastal IFOA region



Professor Brendan Choat at the Hawkesbury Institute for the Environment, Western Sydney University will lead researchers to investigate the response, mechanics and rates of forest recovery since the 2019/20 wildfires in the Coastal IFOA region. Researchers will access field-based datasets collected since the fires and published literature to inform their analysis. This work will build on earlier insights delivered by researchers at the University of Wollongong on risks to achieving Coastal IFOA outcomes from changing fire regimes and inform the monitoring program’s broader five-yearly review of evidence in 2024.

Monitoring key habitat features

Key monitoring questions

Monitoring has been designed to answer the following questions:

  • To what extent do retained habitat features maintain their function?
  • Do the conditions support key habitat features to maintain fauna species within and across the forest?

Monitoring to date

Monitoring is investigating whether the Coastal IFOA conditions and protocols provide sufficient habitat features in an appropriate configuration to ensure persistence of key fauna species through time to support ongoing viability of focal species. This includes three tasks:

  • a review of hollow use by key dependent fauna
  • hollow mortality and recruitment modelling
  • occupancy analysis of key habitat-dependent species.

Project: Hollow use review


The Program has engaged Associate Professor Ross Goldingay, Southern Cross University to review the scientific literature on managing, monitoring and researching hollow bearing trees in NSW forests. The review aimed to identify cost-effective approaches to monitor hollows and highlight research gaps. In addition, the review summarised the current knowledge on hollow use by key fauna species in harvested landscapes.

The review found that most studies have been short-term in nature. There is no clear consensus on the number of hollow trees that different hollow-dependent fauna required to maintain persistence. However, some individual arboreal mammals use a subset of their dens at a high frequency - for example, between 0.1 to 1 primary den trees per hectare based on home range sizes. When managing harvested forests for fauna persistence, it is important that target fauna can access hollows that are suitable in size and appropriately spatially distributed. Management should also account for hollow attrition.

The review outlined best methods to monitor hollow use by key species including the strengths and weaknesses of each. A significant research gap is to understand how den trees either persist or are lost in a harvested landscape, particularly following fire.

This work will inform species occupancy monitoring and modelling under the coastal IFOA monitoring program and broader Forest Monitoring and Improvement Program. The work will also inform hollow simulation modelling undertaken by the Australian National University as part of the program.

Project: Perpetuating tree hollows under the Coastal IFOA



Researchers at the Australian National University (ANU), led by Professor Phil Gibbons have delivered research and recommendations to improve hollow simulation modelling on state forests. This model predicts the number of trees with hollows perpetuated under the current Coastal IFOA conditions.

Working with modellers at the Forestry Corporation of NSW (FCNSW), the researchers used the Forest Resource and Management Evaluation System (FRAMES) to model the persistence and recruitment of hollow-bearing trees under a range of scenarios. Prof Gibbons methods paper outlines the suitability of FRAMES to model persistence of hollows.

Overall, the researchers found:

  • based on data, less than 50 percent of hollow bearing trees are typically occupied by vertebrate hollow-dependent fauna; thus, using tree diameter and tree species alone to predict how many hollow-bearing trees occur will over-estimate the number of hollow-bearing trees suitable for vertebrate species
  • the number of hollow-bearing trees and number of trees with hollows suitable for occupancy by vertebrate fauna were able to be predicted using a combination of FRAMES outputs and hollow occupancy models
  • simulations for the Coffs Harbour Timber Zone showed the Coastal IFOA conditions perpetuate 8-10 trees per hectare with visible hollows and 2-3 trees per hectare with hollows suitable for occupancy by vertebrate fauna in the net-harvest area over a 200 year modelling period
  • in areas permanently excluded from harvesting (approximately 51 percent of the study area), trees with visible hollows were predicted to increase from a mean of 8 per hectare to 26 per ha and trees with hollows suitable for occupancy by vertebrate fauna were predicted to increase from a mean of 3 per hectare to 10 per hectare.

With minor changes, Prof Gibbons suggests FRAMES can be used to simulate outcomes of the current Coastal IFOA and any proposed changes to the rule set on the tree hollow resource. In addition, FRAMES can be further improved over time to better simulate impacts.

The NSW Forest Monitoring Steering Committee has endorsed Prof Gibbons recommendations, including projects to collect further data to improve hollow-specific models for FRAMES.

Explanatory note – greater gliders

Prof Gibbons’ research and report perpetuating trees with hollows under the Coastal IFOA was conducted prior to the introduction of the Site-specific biodiversity condition for Greater Gliders in the Coastal IFOA region on 16 February 2024.

Future modelling of hollow-bearing tree persistence within the Coastal IFOA region will incorporate the new requirements for tree retention within forestry operation areas specified in the Site-specific biodiversity condition for Greater Gliders in the Coastal IFOA region.

Monitoring landscape-scale trends

Spatial Vision and the NSW Department of Primary Industries Forest Science Unit will lead a consortium including RMIT University, University of New England, PF Olsen, University of NSW, NSW Forestry Corporation and the Department of Planning, Industry and Environment to deliver baselines, drivers and trends for forest health across all tenures, including Coastal IFOA state forests. Stephen Farrell and Dr Christine Stone will lead a team of over twenty eminent scientists.