Eleven degrees - eucalypts and climate change

Research by the National Environmental Research Program shows that most eucalypts grow best at an optimal temperature of 11°C. Above or below 11°C, eucalypts grow more slowly. Large trees in particular are affected most. As growth rates drop, trees will recover more slowly from bushfire and landscapes will be transformed for ever.

Below 11°C, the trees’ growth is slowed by a reduced metabolic rate. Above 11°C increased rates of evaporation and respiration result in reduced growth.

The Australian Conservation Foundation MyClimate Tool indicates that Drouin’s average daily maximum temperature from 1960-1990 was 19°C. The prediction for Drouin in 2050 is for the average daily maximum temperature to be 1·6°C hotter. Some areas within Australia will experience predicted increases of more than 4°C and the ‘winter’ season will virtually disappear.

The European Union’s Copernicus Climate Change Service just announced that Sunday 21^st July 2024 was the world’s hottest day since the 1940’s. DEECA and the CSIRO predict that Gippsland rainfall will continue to decline and that by 2050, Traralgon’s climate will be more like the current climate of Bairnsdale.

All types of eucalypt forest are under threat by rising global temperatures and reduced rainfall. Let’s hope that nature can adapt.  

 

 

New BBS policy to manage trees

At the council meeting 3^rd July, both a Tree Management Plan and a Tree Policy document were adopted. You can download both documents from the BBS website.

Mayor Cr Annemarie McCabe: “Trees play a vital role in creating healthy, thriving and sustainable communities throughout Baw Baw,” she said.  “They improve the physical and mental health of individuals and families, hold cultural significance and support environmental sustainability. Baw Baw Shire aims to balance the management of trees on Council land with these sentiments in mind, while ensuring the safety of community members and infrastructure.”

Brooker Park Warragul

The Tree Management Plan covers the management of trees that are alongside roads and paths managed by Council, in Council managed open space and, in the vicinity of electric lines where Council is responsible for the clearance of trees. The Plan also establishes a clear set of guidelines for Council and the community. 

McNeilly Park Drouin

The Tree Management Policy will become the overarching document informing how Council manages it's urban and rural trees, while also outlining Council’s position and legal requirements for tree management. 

Princes Way Drouin

The motion to adopt the two documents was moved by Cr Kostos and seconded by Cr Cook who both praised the officers for preparing the detail in the plan and the policy and both pointed out the positive feedback from the community.

It is envisaged (hoped?) that the two ‘documents’ might provide some protection for one of this shire’s most valuable assets – its trees.

Performance though is the only valid test.

 

Habitat tree conservation

Habitat tree: “A standing live or dead tree providing ecological niches (microhabitats) such as cavities, bark pockets, large dead branches, epiphytes, cracks, sap runs, trunk rot and root substrate for fungi and soil biota.”

Researchers say around 300 species of native Australian animals rely on tree hollows for their survival. 13% of terrestrial amphibians need hollows in trees. 10% of our reptiles, 15% of native birds and a whopping 31% of our mammals make use of tree hollows for breeding, refuge or protection (Gibbons and Lindenmayer). Close to 100 species of our threatened wildlife are hollow-dependant.

The Gang-gang Cockatoo, now threatened, is hollow dependant

Our iconic eucalypt species are great at forming hollows but many take over one hundred years to form significant cavities. Large old trees are better at sequestering carbon too. Consequently, our oldest trees and our dead trees are the most valuable trees.

Our state and federal governments recognize the values habitat trees provide to forest biodiversity. The Victorian Flora and Fauna Guarantee Act lists the loss of hollow-bearing trees as a threatening process. The ‘loss of hollow-bearing trees in native forests and woodlands due to ecologically unsustainable forestry practices’ is listed as a key threatening process by the Australian Government’s Department of Climate Change, Energy, the Environment and Water.

Healthy urban tree cover should include old and dead trees too. Yes, old and dead trees can present an unacceptable risk in some urban situations but it should be obligatory for urban planners to take this into account and not allow development to encroach too close to such important ecological components. Conservation of habitat trees should be an integral part of local government tree policies.

It’s time we stopped cutting down our old and dead trees!