March Speaker Report: Tim Rival, TRC, on trees and the greening of the Toowoomba Region

 

Do you enjoy a surprise? Only if it's a pleasant one? Our March meeting speaker's presentation brought more than a single one for me, but also a little perplexity.

Firstly, I was surprised and delighted to hear that our Regional Council now has a staff position dedicated to trees in the region - the TRC Parks and Urban Forest Policy Officer. Tim Rival is the first to hold this position, having previously worked for 12 years in the gardens section of Parks and Gardens. As part of his role Tim is the contact point for tree-related components of development assessments, which certainly sounds like a vital function from the point of view of naturalists.

My second surprise was to do with "urban forest". What picture do you conjure up from this phrase? My mind went to the numerous bushland parks that our region features - surely, they are forests. It turns out that these have a special team to attend to their specialized maintenance needs. But the big emphasis of "urban forest" is on planted tree canopy coverage, especially in built-up areas. I have to admit this had not occurred to me as "forest", so it struck me as a novel idea - is this so for you?

Moving through the streets of Toowoomba I always lament the typical planting of a number of well-separated lone trees in straight lines on footpaths: surely that doesn't constitute a forest? That's not how a true forest grows! I also recall two mini-arboretums which flourished on private allotments in the northern half of Green-wattle Street - lost in recent years to housing.

So, those were the surprises for me. Now, on to what Tim conveyed to us in his illustrated talk.

What the speaker said: Tim advised that TRC is placing substantial emphasis now on green issues, and that the rule-of-thumb (a green one of course!) being applied is: what does the community expect? He also said that participating in Council opportunities for input on greening matters (planning feedback workshops, policy forums, letters to councillors, representations to councillors both by individuals and groups) really makes a difference - we need to let them know "what the community expects". His position attends to development assessment advice, tree planting, and policy and procedures.

Development assessment advice: Developers have to submit a landscape plan for approval as part of the proposed development plans. Council requirements include sufficient and satisfactory curbside tree planting. In earlier times the Council did the street tree planting but now the developer is responsible for this; after one year the care of these trees is transferred to the Council.

A particular development issue - the Bunya pines, corner James and Neil Streets; TRC is insisting the large trees on this site be retained and protected. Since 90% of tree roots abide in the top 600 mm of soil, access to air and rainfall for these has to be preserved for the health of the tree. (The diameter of the trunk is measured 1.5 metres from ground level to calculate the area that must be protected.) Some of the trees on this site require 13-15 metre clearance for their root spread, so the Council can require the developer to ensure this, even to the point of altering their design re drainage, etc.

Tree cover: Canopy cover in urban areas is one of the vital measures behind tree planting. This affects decisions re where, what, and when planting will be done. Our region uses the national standard (perhaps more an aim) of 40% canopy cover in its urban areas - the score for our region is currently 19.1%. Refer to Greener Places Better Spaces (greenerplacesbetterspaces.com.au) for a national body with this urban greening emphasis. The measure of "canopy to population density" is surveyed regularly, and this helps decide foci for planting. Other large councils also use this.

Planting: TRC aims to plant an average of 3,000 trees annually across the region's urban areas. Most attention is given to streets and parks. When over-mature trees need to be removed the aim is to replace them with a big tree, with their roots positioned downwards (you may have noticed in some Toowoomba streets, as I have, a current project to deal with large roots breaking curbing - the method must be successful since the trees are OK and new patches of curbing and drainage are obvious).

For species selection the aim is "right tree, right location". TRC liaise with Ergon and the authorities for roads and footpaths. Features sought are species diversity and attractiveness via flowers and changes in foliage colour (for which our area is famous). Monoculture is now avoided.

Community planting days including National Tree Day are promoted and facilitated, and mass plantings (e.g. in Black Gully, on Bridge and Holberton Streets) and regeneration are supported. Soil preparation can be done well ahead by Council workers, including, where appropriate, deep ripping then mulching to encourage beneficial microbial development in the soil. Where the ground is severely compacted, e.g. some areas at Pittsworth, and of low nutrient level the soil can be fracked with oxygen as the first step.

Tube stock is the best to use; it is less likely to have root defects, e.g. root distortion/twisting, through handling and potting. Some trees require the symbiotic relationship supplied by their requisite specific fungi, especially some native trees. The mycorrhizal fungi enable the tree to obtain nutrients even when the roots are unable to do this well.  

Answers to questions put to the speaker:

• Exotic trees are found to be lasting only about 15 years because of climate change so the choice is tending towards natives.
• Need to link isolated vegetation patches for wildlife corridors especially birds, including planting on National Tree Day for this purpose.
• Mistletoe removal is not always beneficial, but Council policy allows for it.
•  Food (fruiting) trees - some have been planted in Margaret Street between Ruthven and Neil Streets, also herbs. Citizens can phone Tim, via TRC service centres, for a consultation form to be emailed to them to put requests on this topic.

(Report by Margaret Compton)