Tree Decline Project

Research into Tree Decline and Death in the

Coorong and Tatiara Districts

Federation unity graphic Writing graphic 

 

The Tree Decline and Death Project aims to reduce threats to remnant native vegetation by investigating the causes of tree decline and death in this region.

Large trees are a valuable and treasured part of our landscapes – but they are in decline, and juvenile trees that are regenerating won’t be filling the void anytime soon. The Coorong and Tatiara Local Action Plan have tasked the Centre for Environmental Management, Federation University Australia with researching this issue over the next couple of years.

It is clear that there is large range of issues, not limited to:

Galahs and Corellas ringbarking trees Effects of drought and climate stress
Insects defoliating trees Lime Chlorosis
Mundulla Yellows Mistletoe and Dodder infestation
Plant pathogens Increased soil salinity.........and more

It is also evident that these stress factors interact with each other. We plan to look into some of the primary causes of stress, as well as these interactions.

We have three main goals for this project:

(1) to collate and synthesise knowledge of the issues,

(2) address some key research questions about tree decline, particularly regarding interactions between stress factors, and

(3) provide recommendations for managing tree decline, adapting to environmental changes, and for restoring trees in the landscape.

The initial stages of this project have involved extensive consultation with local stakeholders. We want to use local knowledge as much as possible to help inform and drive our research. We have quite a few ideas for innovative ways of addressing tree decline issues, and we’re excited by the possibility of making some headway on this issue.

Literature Review

We prepared a review to evaluate the current knowledge of issues that potentially lead to tree decline and tree death in the Coorong Tatiara LAP regions. We aimed to highlight research priorities for the region. We reviewed issues that were highlighted by either the literature or by discussions with landholders and stakeholders in the region. The review covers a range of tree decline issues, including (among others) drought, psyllid infestations, wood borers, damage by galahs and corellas, dryland salinity, soil compaction, Mundulla Yellows, and plant pathogens. The full review can be accessed at http://bit.ly/203YhWG

The overwhelming theme from the review is that we require a better understanding of the extent and severity factor causing tree decline across the region. For each factor we need to ask: How widespread is the issue? Which tree species are affected? Is the issue associated with land management practices, landscape position, soil types, or climatic events or cycles? Based on the review, we proposed two further studies to be conducted as part of the Tree Decline and Death Project, discussed below.

 

Nutrient implant experiment

This experiment will rigorously test if nutrients are significantly affect tree health. We are trialling the use of tree stem implants to deliver nutrients to trees, in order to bypass high pH soil conditions that can alter soil nutrient availability. In October 2015 

We selected 10 sites in the Keith and Bordertown area that had >10 trees that displayed symptoms of yellowing and poor health for treatment with nutrient implants. We have recently resurveyed the trees and are currently analysing our data. A report of our findings will be prepared in the coming months. Comparing the response of trees across the different treatments may reveal which nutrients are most influential.

Citizen science webpage

The aim of this study is to generate spatially-explicit data about tree decline issues in the region. The knowledge of the local community will be a valuable resource for determining the extent and severity of the various tree decline issues. As such, we are developing a website that will allow landholders and other citizens to upload symptoms of tree decline from their area, along with other land management information. This data will allow researchers to identify correlations between symptoms and other factors such as soil type, landscape position and land management, and ultimately to develop better-targeted management of tree decline issues. After an initial trial period with selected land managers, the website will be made available to the public.

Further research

We have a student at Federation University – Rebecca Martin who is conducting research in the glasshouse on the fate of tree seedlings in soil collected from different parts of the region, including roadsides. Her study will address questions about the potential for tree regeneration of different species in the region.

Towards the end of the project, we will synthesise our findings and provide management recommendations. This will be informed by the citizen science and tree implant experiments, the initial literature review, and other knowledge gained through discussions with stakeholders and land managers. If you have any questions about this project, please contact Nick Schultz at n.schultz@federation.edu.au

 

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