South-eastern Australia's grassy woodland ecosystems support a unique and diverse flora and fauna. Millions of hectares of these woodlands were converted into productive agricultural land.
In western Sydney, more than 100,000 ha of Cumberland Plain Woodland were reduced to small fragments before the end of the nineteenth century. During the post-war era, land use began to change as Sydney's urban population grew. Farmlands between Prospect Reservoir and Hoxton Park were acquired in the 1980s to create a greenbelt within the developing urban region of western Sydney. As part of a vision to recreate Cumberland Plain Woodland (which was later listed as a Critically Endangered ecological community), a thousand hectares of the green belt were planted with locally native trees and shrubs over the decade from 1992 to 2002. In 2002, we began our research to monitor the success of these plantings.
Aim
This project aims to develop robust methods for evaluating the success of native woodland restoration on retired agricultural land and apply them to a major restoration project.
Key research questions
- What are appropriate methods and metrics for detecting change in the biodiversity values of restoration plantings?
- What is the pace and direction of temporal trajectories in woodland structural features and composition of plant, invertebrate and avian communities within restoration plantings?
- What ecological traits differentiate native species that respond positively to restoration treatments and those fail to respond?
- What site features enhance the chance of successful woodland restoration (i.e. rapid trajectories towards reference states)?
- How do alternative management strategies influence the pace and direction of restoration trajectories?
To answer these questions, we are studying the communities of plants, birds and invertebrates within plantings of different ages and comparing them to stands of Cumberland Plain Woodland and untreated pastures.
Findings
After the first ten years, many of the planted trees had survived and begun to develop into saplings, and the dense ground layer of weedy grasses had begun to thin beneath the planted trees.
However, there was little evidence of the new plant community developing into Cumberland Plain Woodland or differentiating from untreated pastures, with few native plant species having entered the system in addition to those planted. Studies of invertebrate communities returned similar results.
We are currently investigating changes in plant and bird communities of the plantings over the 20 years since their establishment. Vegetation sampling was completed in 2013 and bird sampling is currently underway.
