Thinking Inside the Box Gum Grassy Woodland

The “Thinking inside the Box Gum Grassy Woodlands project” is ending and has been a huge success.

Delivered in the Boorowa, Yass and Upper Lachlan local areas (Ngunnawal and Gundungurra Country) since 2019; the project has seen 42 private land holders partner with South East Local Land Services and the NSW Environmental Trust, together contributing time and money to improve the extent and condition of Box Gum Grassy Woodlands (BGGW). This partnership has achieved considerable outcomes for this critically endangered ecological community. This includes protecting 211ha of existing Box Gum Grassy Woodlands (BGGW) by installing 22,775 metres of fencing and revegetating another 213ha of BGGW with 20,330 tubestock and 43kgs of native seed.

This project aimed to address 3 key threats to BGGW:

• Threat 1: Loss of native ground layer plant species cover and diversity
• Threat 2: Lack of regeneration of shrubs and trees
• Threat 3: Habitat degradation due to incursion of exotic plants (naturalised and regionally significant weeds).

Through a quantitative monitoring program undertaken over the last 3 years we have glimpsed how our investment in fencing, alternative water and revegetation has alleviated these threats. It has also provided valuable insight into areas where we need to improve.

How we approached it:

Over 310 individual points on 21 properties were baselined in the autumns of 2020 and 2021. These sites were revisited in autumn 2023

Threat 1: Loss of native ground layer plant species cover and diversity

A long history of inappropriate grazing regimes being applied within Box Gum Grassy woodlands remnants has led to a major decline in the diversity and cover of the native ground layer.

Our monitoring results show the project has helped to facilitate and protect increases in total native ground cover on investment sites.

Particularly noteworthy was a 10% increase (on average) in the cover of Kangaroo Grass. Kangaroo Grass (Themeda triandra) is considered an ecological indicator of a sites capacity to bounce back from ecological decline. It is very sensitive to inappropriate grazing management and nutrient enrichment.

At this point no major change was detected in the diversity or cover of native forbs, rushes, sedges, lilies and orchids. These plants are a more minor component of the ground layer than the grasses and changes are harder to detect using our monitoring methods. Hopefully in the long term we will begin to see increases in these plants.

Threat 2: Lack of regeneration of shrubs and trees

One major threat to BGGW is a lack of regeneration of trees and shrubs. Continuous grazing and agricultural soil nutrient enrichment have led to a situation where many tree species are unable to germinate and survive. The net result of this is that many remnants are the “living dead”. When no new tree are coming through to replace the old ones, in this way whole remnants are lost without a single tree being cut down. LLS investments aimed to facilitate new cohorts of natural regeneration and where necessary, plant new trees.

The combination of excluding livestock, and favourable climatic conditions saw an increase in natural regeneration of native trees of around 16% over the monitoring period. This new cohort of trees now sets up a succession of generations as older trees age and die.

Revegetation was mostly successful with survival rates between 70% and 93%. However, it is still early days in determining long term success. Challenging wet conditions persisted over the monitoring period. This meant that revegetation varied from too dense, to too sparce depending on whether it was direct seeded, or hand planted. Management will continue to focus on infill planting to benchmark densities in areas with poor survival.

Where revegetation is too dense, shading of the ground layer can cause a loss of habitat for ground species. Therefore, thinning or disturbance of direct seeded revegetation may be required. We will be continuing to have these conversations with our project partners and landholders going forward.

Threat 3: Habitat degradation due to incursion of exotic plants (naturalised and regionally significant weeds)

After the drought broke in late autumn 2020, wet seasonal conditions persisted until autumn 2023. As expected, we saw a significant increase in the cover of exotic pasture grasses. Despite this, we did see a modest decrease in the cover naturalised broad leaf weeds. This is likely to be due the exclusion of livestock allowing grasses to outcompete most broad leaf exotics.

Moving forward the Local Land Services team will provide advice and support to land holders who have partnered in the project. Our focus will be sustainable grazing management in Box Gum Grass Woodland remnants, ensuring the success of plantings and reducing the threat of weeds to protect biodiversity in these areas.

Read more about the work Local Land Services does to protect Box Gum Grassy Woodlands.